Alesis MODFX PHILTRE User Manual

Reference Manual

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Copyright 2002, Alesis. All rights reserved
Reproduction in whole or in part is prohibited.
Specifications subject to change without notice.
All trademarks are the property of their respective holders.

7-51-0119-A
8/2002

Table of Contents

Introduction....................................................................3

Welcome! .........................................................................................................3

About the Philtre ...........................................................................4

Important features of your Philtre..............................................................4

Philtre Key Features ......................................................................................5

How to Use This Manual.............................................................6

Safety Instructions/Notices .....................................7

Important Safety Instructions (English)............................ 7

CE Declaration Of Conformity................................................9

FCC Compliance Statement......................................................9

Instructions de Sécurité Importantes (French) .........................................10

Lesen Sie bitte die folgende Sicherheitshinweise

(German) ..................................................................................................12

Quick Start Guide ........................................................15

If you can’t wait to get started......................................................................15

Hook it up to a synthesizer...........................................................................15

A quick overview of the controls ...........................................16

Rear Panel........................................................................................................16

Connections ....................................................................17

Unpacking and Inspection............................................................................17

Installing in a Rack .........................................................................................17

Power................................................................................................................17

Connecting to the Channel Inserts of a mixing console: ........................19

Connecting to the Main Outputs of a mixing console: ...........................20

Connecting to the Aux Send/Return of a mixing console: ....................21

Connecting to the inserts on an instrument amplifier: ............................22

Connecting to equipment with XLR inputs and outputs:.......................23

About audio cables.........................................................................................23

Using the ModLink........................................................................24

Using the Philtre ..........................................................25

What is filtering?............................................................................ 25

Filter curves, orders, and slopes ..................................................................26

Modulating the filter frequency ...................................................................26

What is Tempo Sync? ....................................................................................27

To turn Tempo Sync off: ..............................................................................27

Description of Controls...............................................................28

Rate ...................................................................................................................28

Depth................................................................................................................29

Phreeq...............................................................................................................29

Regen ................................................................................................................30

TYPE Rocker Switch.....................................................................................36

Steep..................................................................................................................38

Reset Mod........................................................................................................38

Tap Tempo......................................................................................................39

Bypass...............................................................................................................40

Using the Foot Switch...................................................................................40

Sample Settings.............................................................41

Blank Settings Templates..............................................................................44

Troubleshooting............................................................45

1

Table Of Contents

Troubleshooting Index................................................................ 45

Avoiding ground loop noise.........................................................................47

Line conditioners and spike protectors ......................................................48

Care and Maintenance ................................................................ 49

Cleaning............................................................................................................49

Refer all servicing to Alesis...........................................................................49

Obtaining repair service ................................................................................50

Specifications.................................................................51

Audio Input.....................................................................................................51

Audio Output..................................................................................................51

Audio Performance........................................................................................51

Mechanical.......................................................................................................51

Index...................................................................................53

Warranty/Contact Alesis ...........................................54

Alesis Limited Warranty................................................................................54

Alesis Contact Information ..........................................................................55

2

Introduction

F

Welcome!

Thank you for making the Alesis Philtre a part of your studio.
Since 1984, we've been designing and building creative tools for
the audio community. We believe in our products, because we've
heard the results that creative people like you have achieved with
them. One of Alesis' goals is to make high-quality studio
equipment available to everyone, and this Reference Manual is an
important part of that. After all, there's no point in making
equipment with all kinds of capabilities if no one explains how to
use them. So, we try to write our manuals as carefully as we build
our products.

The goal of this manual is to get you the information you need as
quickly as possible, with a minimum of hassle. We hope we've
achieved that. If not, please drop us an email and give us your
suggestions on how we could improve future editions of this
manual.

We hope your investment will bring you many years of creative
enjoyment and help you achieve your goals.

Sincerely,
The people of Alesis

or more effective
service and product
update notices, please
register your Philtre
online at:

www.alesis.com/
support/
warranty.htm

3

Introduction

About the Philtre

Your new Philtre is a member of the Alesis ModFX family of
performance effects boxes. This particular ModFX unit is a filter
effect with modulation.

Each ModFX unit provides a different set of sound effects and
signal processing, and they are easy to arrange and connect to each
other. With a uniform, friendly, uncomplicated user interface and
high-resolution digital processing, the ModFX product line is
perfect for keyboardists, guitarists, and any other studio or live
performance artists.

Important features of your Philtre

High Resolution Processing

The Philtre internally uses 28-bit stereo digital signal processing.
The digital-to-analog and analog-to-digital conversion is sampled
at 48kHz with 24 bits of resolution. That means you can get the
effect you want, without adding unwanted noise and distortion.

ModLink

If you’re using multiple ModFX boxes to make your own unique
effects chain, ModLink makes it easy to hook up without needing
patch cords between units in the chain. The nine-pin connectors
built into each side of the case enable a ModFX box to transfer
digital audio and word clock directly to another. Any number of
units can be connected together.

Configurable Modulation

The Philtre features configurable modulation. The user can
control the shape, rate, and depth of the modulation, and it can be
triggered by the audio input itself. The rate of modulation can be
synchronized to the tempo, both by tap tempo and by audio input.

4

Philtre Key Features

• Four different filter types, with steep slope switch and

adjustable regeneration

• Five different modulation sources, including Trigger and

Envelope for note-by-note filter sweeping

• Tempo synchronization keeps filter effect in time with the

music

• Tap Tempo makes it easy to set the speed of modulation by

tapping a beat on the top panel

• Uniform, friendly, uncomplicated user interface—no fiddling

with complicated menus or “hidden” knobs

• Reset Mod lets you reset the phase of any modulation shape

from its beginning

• Stereo processing via four 1/4” unbalanced connectors

• ModLink port, a cable-free connection that transfers digital

audio and word clock to other boxes in the ModFX family

• Footswitch connection to control the bypass function

• Ability to mount 3 ModFX boxes in the optional ModFX

rack adapter

• Input trim control to adjust input level

• Internal 28-bit digital processing

• 24-bit D/A and A/D conversion at 48kHz sampling rate for

quiet, distortion-free effects

• External 9VAC power supply included

Introduction

5

Introduction

H

How to Use This Manual

A little technical knowledge will help you get the most out of your
gear...it’s really pretty simple. This manual is divided into the
following sections describing the various functions and
applications for the Philtre. While it's a good idea to read through
the entire manual once carefully, those having general knowledge
about effect devices should use the table of contents to look up
specific functions.

Chapter 1: Quick Start. If you're already experienced with effect
boxes, this will get you started using the Philtre right away. It's a
short guide to the essential elements of hooking it up and using it
for the first time. A brief tour of the front and rear panels also
directs you to the chapters focused on individual features.

Chapter 2: Connections gives detailed instructions for connecting the
Philtre to a variety of typical audio systems. It also discusses the
process of linking the Philtre with other ModFX devices.

Chapter 3: Using the Philtre explains the controls of the Philtre and
their functions.

Chapter 4: Sample Settings provides a selection of sound charts
created by the sound designers at Alesis for you to try.

Near the end of the manual are troubleshooting tips,
specifications, and an index to help you find what you're looking
for.

elpful tips an d ad v ic e a re
h ig hlig h te d in a sh a de d b ox
lik e th is

Whe n so m ething im po r ta nt
a pp ea rs in the ma nua l, a n

e xc la ma tio n m ar k (like th e
o ne s ho wn at le ft) will a pp ea r
with so m e ex p la na to r y te x t.
This sy m bo l ind ic ate s th a t
this in for ma tio n is vita l whe n
o pe ra tin g th e Philtr e.

6

Safety Instructions/Notices

Important Safety Instructions (English)

Safety symbols used in this product

operating and maintenance instructions in the literature
accompanying this unit.

the unit that can cause dangerous electric shocks.

voltages that can cause dangerous electrical shock.

This symbol alerts the user that there are important

This symbol warns the user of uninsulated voltage within

This symbol warns the user that output connectors contain

Please follow these precautions when using
this product:

1. Read these instructions.

2. Keep these instructions.

3. Heed all warnings.

4. Follow all instructions.

5. Do not use this apparatus near water.

6. Clean only with a damp cloth. Do not spray any liquid cleaner
onto the faceplate, as this may damage the front panel
controls or cause a dangerous condition.

7. Install in accordance with the manufacturer's instructions.

8. Do not install near any heat sources such as radiators, heat
registers, stoves, or other apparatus (including amplifiers) that
produce heat.

9. Do not defeat the safety purpose of the polarized or
grounding-type plug. A polarized plug has two blades with
one wider than the other. A grounding-type plug has two
blades and a third grounding prong. The wide blade or the
third prong are provided for your safety. When the provided
plug does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.

10. Protect the power cord from being walked on or pinched,
particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.

Continued next page

7

Important Safety Instructions

11. Use only attachments or accessories specified by the
manufacturer.

12. Use only with a cart, stand, bracket, or table designed for use
with professional audio or music equipment. In any
installation, make sure that injury or damage will not result
from cables pulling on the apparatus and its mounting. If a
cart is used, use caution when moving the cart/apparatus
combination to avoid injury from tip-over.

13. Unplug this apparatus during lightning storms or when unused
for long periods of time.

14. Refer all servicing to qualified service personnel. Servicing is
required when the apparatus has been damaged in any way,
such as when the power-supply cord or plug is damaged, liquid
has been spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not
operate normally, or has been dropped.

15. This unit produces heat when operated normally. Operate in a
well-ventilated area with at least six inches of clearance from
peripheral equipment.

16. This product, in combination with an amplifier and
headphones or speakers, may be capable of producing sound
levels that could cause permanent hearing loss. Do not
operate for a long period of time at a high volume level or at a
level that is uncomfortable. If you experience any hearing loss
or ringing in the ears, you should consult an audiologist.

17. Do not expose the apparatus to dripping or splashing. Do not
place objects filled with liquids (flower vases, soft drink cans,
coffee cups) on the apparatus.

18. WARNING: To reduce the risk of fire or electric shock, do
not expose this apparatus to rain or moisture.

8

Important Safety Instructions

CE Declaration Of Conformity

See our website at:

http://www.alesis.com

FCC Compliance Statement

This device complies with Part 15 of the FCC rules. Operation is
subject to the following two conditions: (1) This device may not
cause harmful interference and (2) this device must accept any
interference received, including interference that may cause
undesired operation.

NOTE: This equipment has been tested and found to comply
with the limits for a Class B digital device, pursuant to Part 15 of
the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation.
This equipment generates, uses and can radiate radio frequency
energy and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which
can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of
the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment and receiver.

• Connect the equipment into an outlet on a circuit different

from that to which the receiver is connected.

• Consult the dealer or an experienced radio/TV technician for

help.

9

Important Safety Instructions

Instructions de Sécurité Importantes (French)

Symboles utilisés dans ce produit

de fonctionnement et de maintenance dans la documentation
jointe avec ce produit.

tension non isolée à l’intérieur de l’appareil pouvant engendrer des
chocs électriques.

sur les raccordements de sorties, représentant un risque
d'électrocution.

Ce symbole alèrte l’utilisateur qu’il existe des instructions

Ce symbole avertit l’utilisateur de la présence d’une

Ce symbole prévient l'utilisateur de la présence de tensions

Veuillez suivre ces précautions lors de
l’utilisation de l’appareil:

1. Lisez ces instructions.

2. Gardez ces instructions.

3. Tenez compte de tous les avertissements.

4. Suivez toutes les instructions.

5. N’utilisez pas cet allareil à proximité de l’eau.

6. Ne nettoyez qu’avec un chiffon humide. Il est potentiellement
dangereux d'utiliser des pulvérisateurs ou nettoyants liquides
sur cet appareil.

7. Installez selon les recommandations du constructeur.

8. Ne pas installer à proximilé de sources de chaleur comme
radiateurs, cuisinière ou autre appareils (don’t les
amplificateurs) produisant de la chaleur.

9. Ne pas enlever la prise de terre du cordon secteur. Une prise
murale avec terre deux broches et une troisièrme reliée à la
terre. Cette dernière est présente pour votre sécurité. Si le
cordon secteur ne rentre pas dans la prise de courant,
demandez à un électricien qualifié de remplacer la prise.

10. Evitez de marcher sur le cordon secteur ou de le pincer, en
particulier au niveau de la prise, et aux endroits où il sor de
l’appareil.

Suite de la page suivante

10

Important Safety Instructions

11. N’utilisez que des accessoires spécifiés par le constructeur.

12. N’utilisez qu’avec un stand, ou table conçus pour l’utilisation
d’audio professionnel ou instruments de musique. Dans toute
installation, veillez de ne rien endommager à cause de câbles
qui tirent sur des appareils et leur support.

13. Débranchez l’appareil lors d’un orage ou lorsqu’il n’est pas
utilisé pendant longtemps.

14. Faites réparer par un personnel qualifié. Une réparation est
nécessaire lorsque l’appareil a été endommagé de quelque sorte
que ce soit, par exemple losrque le cordon secteur ou la prise
sont endommagés, si du liquide a coulé ou des objets se sont
introduits dans l’appareil, si celui-ci a été exposé à la pluie ou à
l’humidité, ne fonctionne pas normalement ou est tombé.

15. Puisque son fonctionement normale génère de la chaleur,
placez cet appareil au moins 15cm. des équipments
péripheriques et assurez que l’emplacement permet la
circulation de l’air.

16. Ce produit, utilisé avec un amplificateur et un casque ou des
enceintes, est capable de produite des niveaux sonores
pouvant engendrer une perte permanente de l’ouïe. Ne
l’utilisez pas pendant longtemps à un niveau sonore élevé ou à
un niveau non confortable. Si vous remarquez une perte de
l’ouïe ou un bourdonnement dans les oreilles, consultez un
spécialiste.

17. N'exposez pas l'appareil à l'égoutture ou à l'éclaboussement.
Ne placez pas les objets remplis de liquides (vases à fleur,
boîtes de boisson non alcoolique, tasses de café) sur l'appareil.

18. AVERTISSEMENT: Pour réduire le risque du feu ou de
décharge électrique, n'exposez pas cet appareil à la pluie ou à
l'humidité.

11

Important Safety Instructions

Lesen Sie bitte die folgende Sicherheitshinweise (German)

Sicherheit Symbole verwendet in diesem
Produkt

Funktionieren und Wartung Anweisungen in der Literatur gibt, die
diese Maßeinheit begleitet.

Spannung innerhalb der Maßeinheit, die gefährliche elektrische
Schläge verursachen kann.

Spannungen enthalten, die gefährlichen elektrischen Schlag
verursachen können.

Dieses Symbol alarmiert den Benutzer, daß es wichtige

Dieses Symbol warnt den Benutzer der nicht isolierten

Dieses Symbol warnt den Benutzer, dem Ausgabestecker

Folgen Sie bitte diesen Vorkehrungen, wenn
dieses Produkt verwendet wird:

1. Lesen Sie die Hinweise.

2. Halten Sie sich an die Anleitung.

3. Beachten Sie alle Warnungen.

4. Beachten Sie alle Hinweise.

5. Bringen Sie das Gerät nie mit Wasser in Berührung.

6. Verwenden Sie zur Reinigung nur ein weiches Tuch.
Verwenden Sie keine flüssigen Reinigungsmittel. Dies kann
gefährliche Folgen haben.

7. Halten Sie sich beim Aufbau des Gerätes an die Angaben des
Herstellers.

8. Stellen Sie das Gerät nich in der Nähe von Heizkörpern,
Heizungsklappen oder anderen Wärmequellen (einschließlich
Verstärkern) auf.

9. Verfehlen Sie nicht den Zweck des grounging Terminals auf
dem Netzstecker. Dieses Terminal wird für Ihre Sicherheit zur
Verfügung gestellt.

10. Verlegen Sie das Netzkabel des Gerätes niemals so, daß man
darüber stolpern kann oder daß es gequetscht wird.

Fortsetzung auf nächster Seite

12

Important Safety Instructions

11. Benutzen Sie nur das vom Hersteller empfohlene Zubehör.

12. Verwenden Sie ausschließlich Wagen, Ständer, oder Tische, die
speziell für professionelle Audio- und Musikinstrumente
geeignet sind. Achten Sie immer darauf, daß die jeweiligen
Geräte sicher installiert sind, um Schäden und Verletzungen zu
vermeiden. Wenn Sie einen Rollwagen benutzen, achten Sie
darauf, das dieser nicht umkippt, um Verletzungen
auszuschließen.

13. Ziehen Sie während eines Gewitters oder wenn Sie das Gerät
über einen längeren Zeitraum nicht benutzen den Netzstecher
aus der Steckdose.

14. Die Wartung sollte nur durch qualifiziertes Fachpersonal
erfolgen. Die Wartung wird notwendig, wenn das Gerät
beschädigt wurde oder aber das Stromkabel oder der Stecker,
Gegenstände oder Flüssigkeit in das Gerät gelangt sind, das
Gerät dem Regen oder Feuchtigkeit ausgesetzt war und
deshalb nicht mehr normal arbeitet oder heruntergefallen ist.

15. Dieses Gerät produziert auch im normalen Betrieb Wärme.
Achten Sie deshalb auf ausreichende Lüftung mit mindestens
15 cm Abstand von anderen Geräten.

16. Dieses Produkt kann in Verbindung mit einem Verstärker und
Kopfhörern oder Lautsprechern Lautstärkepegel erzeugen, die
anhaltende Gehörschäden verursachen. Betreiben Sie es nicht
über längere Zeit mit hoher Lautstärke oder einem Pegel, der
Ihnen unangenehm is. Wenn Sie ein Nachlassen des Gehörs
oder ein Klingeln in den Ohren feststellen, sollten Sie einen
Ohrenarzt aufsuchen.

17. Setzen Sie den Apparat nicht Bratenfett oder dem Spritzen
aus. Plazieren Sie die Nachrichten, die mit Flüssigkeiten
(gefüllt werden Blumevases, Getränkdosen, Kaffeetassen)
nicht auf den Apparat.

18. WARNING: um die Gefahr des Feuers oder des elektrischen
Schlages zu verringern, setzen Sie diesen Apparat nicht Regen
oder Feuchtigkeit aus.

13

Important Safety Instructions

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14

1 Quick Start Guide

I
p

p

If you can’t wait to get started

The Alesis Philtre is a unique product, but its basic hookup and
operation is similar to other effects units in most respects. If
you're experienced with signal processors, this chapter is a
"shorthand" guide for those who want to start using the Philtre
right away. If you have questions about any of the features, don’t
worry – later chapters will unveil the mysteries of the Philtre's
special features.

Hook it up to a synthesizer

1. First, make sure the power is off to all the components
you’re connecting to: amp, mixer, and instruments.

2. Pull the Philtre and its power supply out of the package.

3. Using a pair of 1/4” instrument cables, plug the outputs
of the synthesizer into the INPUTS on the back of the
Philtre.

4. Connect the OUTPUTS of the Philtre to the inputs of a
mixer, powered speakers, or instrument amplifier.

5. Insert the power jack of the Philtre’s power adapter into
the POWER 9VAC input on the rear panel of the
Philtre and plug the power adapter into an AC outlet
(preferably on a power strip with its switch off).

f you're new to signal

rocessing...

s ta rt with th e mo re de ta ile d
ins tr uc tio ns fo r ho o ku p a nd
o pe ra tio n sta rtin g in th e n ex t
c ha

ter .

The Philtre doesn’t have a POWER switch of its own. The
moment you plug in the power, its top panel LEDs will come on.

6. Turn the power on to the system: the keyboard, then
the Philtre’s power strip (if it’s not already on), then the
mixer, then the amp.

7. Turn the INPUT TRIM knob on the back of the Philtre
while playing the keyboard to adjust the input level. The
SIGNAL LED on the top panel will light green, not red,
when the level is correct.

8. Experiment with the knob and button settings on the
Philtre to create different sounds.

For more detailed information on connecting the Philtre, see
chapter 2: Connections.

15

Quick Start Guide

1

A quick overview of the controls

TYPE

The TYPE s witch s ele cts the
k in d of filte r as s h own b y th e
LED s ne x t to th e switc h. S ee
p ag e 3 6.

REG EN
( re ge ne r atio n)

This in c re as e s
g ain at th e
filte r c or ne r for
a s ha rp e r filte r
p ea k. I n Ba n d
m od es it a ls o
s ets th e wid th
o f th e b an d.

PHREEQ

D eter min es th e
fre qu en c y
c en te r o r
c or ne r o f th e filte r .

Rear Panel

Plu g th e p owe r ad ap ter in
h er e.

STEEP

This in c re as e s th e s lo pe of the
c ho se n filte r c ur ve s .

Res et Mo d

Retar ts th e m od ulation fr om
the b eg inn in g o f its c yc le.
G en er ate s a trigg er in
TRI GG E RED m od e, o r
c ha ng es th e p atte rn in
PATTERN mo de .

BYPASS le ts s ign al pa ss
thr ou gh with o ut a ny filte ring .

The FOO T SWI TCH ma y be
c on ne cte d to an y mo m en ta r y
p ed al, to en g ag e th e BYPASS
fun ctio n .

TAP TEMPO

Activ e in TEMPO S YNC
m od e

o nly. Tap a re gu la r

b ea t on th is bu tton , a nd th e
m od s pe e d of th e Ph iltre will
b e se t a t so m e mu ltiple o f th at
b ea t, a s s et by the RATE
k no bs .

MOD ULATI ON
SELECT s witc h s elec ts

the typ e o f wav e us e d to
m od ulate the filter

fre qu en c y.

The RATE
k no b affec ts
the m od u la tio n
s pe ed , in
c oo pe ra tio n
with th e
TEMPO S YNC
a nd TAP
TEMPO
b utto ns . Se e
p ag e3 9.

D EPTH

c on tr ols the
d ep th o f the
m od ulation .

SIG NAL LED

Whe n th is lig hts gr e en , the
Philtre is g e ttin g a n in p ut
s ig na l. Whe n it’ s r ed , it’ s
s ee in g too m u ch lev e l, s o tur n
d own th e ins tru me nt ...

...or th e TRI M co ntro l h er e
o n th e b ac k p an el.

The Mod Link co nnec tor s le t
y ou a rr a ng e s ev er al Mo dFX
u nits in a c h ain, with ou t
h av in g to us e inp ut an d
o utpu t c ab le s ins id e the
c ha in .

16

I NPUTS a nd O U TPUTS a re
s ta nd ar d 1 /4 ” lin e- lev el
jac ks . Plug sing le - ch an n el
d ev ic e s i n to th e
LEFT/MO NO in p ut.

I f yo u’ r e us ing a Mo dLin k
c ha in , y ou o n ly n ee d to
c on ne ct to th e firs t u nit’s
inp ut, a nd th e la st un it’ s
o utpu t.

2 Connections

M

I
f

A

D

Unpacking and Inspection

Your Philtre was packed carefully at the factory. The shipping
carton was designed to protect the unit during shipping. Please
retain this container in the highly unlikely event that you need to
return the Philtre for servicing.

The shipping carton should contain the following items:

• Philtre with the same serial number as shown on the
shipping carton

• Power Adapter

• This instruction manual

To register your purchase, go to the Alesis website at

www.alesis.com.

Installing in a Rack

The Philtre is designed for tabletop use, but can also be installed
in a standard 19" audio equipment rack. For rack mounting,
contact your Alesis dealer for the ModFX Rack. This rack shelf
holds three ModFX units in a 3-space high 19” rack.

Power

The Philtre comes with an AC power adapter that transforms
the voltage from a standard outlet into 9 volts AC (830 mA).
Plug the small end of the power adapter cord into the Philtre’s
POWER 9VAC socket and then plug the adapter itself into a good
quality, noise-free AC power source of the proper rating.

The supplied AC line adapter is designed only for the destination
to which the unit is shipped. To use the Philtre in another
country, contact your Alesis dealer for a P3 adapter suitable for
the electrical system in the country you are traveling to.

ak e su r e yo u r ea d the

initial Im po r ta nt S a fe ty

n s t r u c t i o n s c h a p t e r a t t h e
ro nt o f this m an ua l.

void “popping”:

on ’t p lug th e po we r a da p te r
into th e Philtr e un til a ll othe r
a ud io c a bles ha ve b e en
h oo ke d u p. Mak e su r e yo u r
a mp lifie r or po w e r e d
s pe ak er s a re switch e d off
whe n plu gg in g in th e Philtr e
to av oid d am a ge .

17

Connections

M

F

f

f

2

Connecting audio

The Philtre will work in many different applications, whether you
are connecting an instrument directly into it, or connecting it
through a mixing console. But since the Philtre is a stereo
effect unit, it’s important to know whether the source will be
stereo or mono.

Mono In, Mono or Stereo Out

If you’re connecting a guitar or bass directly to the Philtre, hook it
up this way:

1. Connect a 1/4" phone cord to the [LEFT/MONO] INPUT
of the Philtre from a mono source. (The Left input will then
feed both inputs of the effect.)

2. Connect another 1/4" phone cord from the LEFT OUTPUT
of the Philtre to an amplification system or mixer input.

3. If the amp or mixer is stereo, connect a second 1/4" phone
cord from the RIGHT OUTPUT of the Philtre to the other
input of the stereo amplification system, or the next mixer
input.

4. If you’re connecting directly to a stereo mixer, pan the two
channels hard left and hard right to get the maximum effect.

Whe n co n ne cting a ud io
c ab le s a nd /o r tur nin g po wer
o n an d o ff, m ak e su r e th a t all
d ev ic es in y o ur s ys tem a r e
tur ne d o ff a n d th e v olum e
c on tr ols a re tu rn ed do wn .

Turn up the trim...

os t gu ita rs an d ba s se s h av e

r elativ e ly lo w ou tp u t le v els.

or the qu ie tes t effec t, tu rn

u p th e v olum e o n th e g uitar to

ull, th en c r an k up th e
[ TRIM] c on tr o l on th e ba c k
o f th e Philtr e un til the
S IG NAL LED o n its to p pa n el

la sh es re d while y o u pla y,
the n ba c k it off a b it.

18

Connecting to the Channel Inserts of a

I

mixing console:

Most recording consoles have a jack near the mic and line inputs
labeled "Insert". This is typically a TRS jack with the send and
return on the same jack. To use the Philtre as a channel insert, you
will need an insert cable (not included).

Connections

2

Ring:

Insert return

Tip: Sleeve:

Insert send Insert Ground

This cable splits the TRS insert jack into two unbalanced mono
connectors. Usually, the tip is connected to the INPUT of the
Philtre and the ring is connected to the OUTPUT of the Philtre.
However, this may be reversed on some recording consoles.
Check your mixer’s Reference Manual to be sure or just try it both
ways – this won’t damage the Philtre.

For stereo operation, you would use two insert cables, inserted
into two adjacent channels of the mixer. One would send and
receive signal to the left channel of the Philtre, and the pan pot of
that mixer channel would normally be panned to the left. Pan the
next mixer channel, for the right side of the Philtre, to the right.

nsert SEND:

To ModFX INPU T

Insert RETURN:

From ModFX OUTPUT

19

Connections

2

Connecting to the Main Outputs of a mixing
console:

In addition to channel inserts, most mixing consoles have main
insert jacks near the main outputs. You can use insert cables to
connect the Philtre to the main L/R bus the same way you
connect it to a pair of channels. Simply connect one insert cable
to the left main insert of the mixer, and connect the two mono
jacks to the left INPUT and OUTPUT of the Philtre. Use another
insert cable to connect the right main insert to the right INPUT
and OUTPUT of the Philtre.

Alternatively, you could plug the mixing console’s main outputs
directly into the Philtre’s inputs, then feed the Philtre’s outputs to
your monitor amps or mixdown recorder. However, with this
method if you fade down the volume at the end of the song, the
sound quality may change as you fade. That’s why it’s better to
use insert jacks, if they’re available.

20

Connecting to the Aux Send/Return of a

I
f
P

f

f

mixing console:

The Philtre, like other filters and equalizers, is designed for in-line
processing, not for the send/receive kind of processing typically
used for reverb units. However, plugging a group out or pre-fader
Aux send from a mixer into the Philtre will allow you to process a
mix of several instruments, from any mixer channel that has its
aux send raised or is assigned to that group. The essential point is
that the Aux send should be the pre-fader type, not an “effect
send”. There shouldn’t be any direct (post-fader) signal in the
main mix from any channels going through the Philtre.

Connections

2

To do this, connect a single cable from the Aux Send Out
(sometimes labeled “Aux Out”) to the [LEFT/MONO] input of
the Philtre. Use two separate cables to connect the [LEFT
OUTPUT] and [RIGHT OUTPUT] of the Philtre to the left and
right inputs of a stereo Effect Return, or to two adjacent mixer
channels panned to left and right.

Fro m Aux /Eff S en d

To re tu r ns

f yo u use m ixe r cha nnels

o r t h e r e t u r n s f r o m t h e

hiltre , b e su re th e Aux

S en ds o r g ro u p as sig nm en ts

or tho s e ch a nn els a re tu rn ed

a ll the wa y o ff to a vo id

ee db ac k .

21

Connections

d

P

2

Connecting to the inserts on an instrument
amplifier:

The insert send on a guitar or bass amp is usually labeled "effects
send and return" or "insert send and return". This allows you
to preamplify your instrument before phasing it and sending it
to the power amp.

Most guitar amps are single channel, so connect a single insert
cable (see page 19) from the amp to the LEFT INPUT and LEFT
OUTPUT of the Philtre. Some amps have separate “effect send”
and “effect return” jacks; for these, use standard cables. Check
the manual of your amplifier for details.

N e v e r c o nn e c t t he
P hi lt r e be t w e e n t he
p ow e r a m p an d t he
s pe a k e r !

The h ig h p owe r le ve ls cr e ate
b y th e p ower am p will
d es tr oy th e c ir cu itr y of th e

hiltre .

If you are using a dedicated rack-mount preamplifier, another
method would be to insert the Philtre between the preamp and the
input(s) of the power amp.

22

Connecting to equipment with XLR inputs

D

M

N

D

y

and outputs:

Connections

2

If you are connecting the Philtre to a product with XLR balanced
inputs and outputs, you will need to convert this signal to a 1/4”
unbalanced connector. Make sure that Pin 2 of the XLR
connector is connected to the Tip of the 1/4” adapter or cable.

Watch out for high levels, however: some XLR sources put out
levels close to the maximum the Philtre can accept (about +12
dBu) even when its trim is at minimum. Lower the level of the
source if the [SIGNAL] LED flashes red.

About audio cables

The connections between the Philtre and your studio are your
music’s lifeline, so use only high quality cables. These should be
low-capacitance shielded cables with a stranded (not solid) internal
conductor and a low-resistance shield. Although quality cables
cost more, they do make a difference.

Route cables to the Philtre correctly by observing the following
precautions:

• Do not bundle audio cables with AC power cords.

• Avoid running audio cables near sources of

electromagnetic interference such as transformers,
monitors, computers, etc.

• Do not place cables where they can be stepped on.

Stepping on a cable may not cause immediate damage,
but it can compress the insulation between the center
conductor and shield (degrading performance) or reduce
the cable’s reliability.

• Avoid twisting the cable or having it make sharp, right

angle turns.

• Never unplug a cable by pulling on the wire itself.

Always unplug by firmly grasping the body of the plug
and pulling directly outward.

on't use line

transformers:

an y XLR-to- 1 /4 " ad a pter s

s old at elec tro nics stor e s ar e

OT a da p te rs , b ut
tra ns fo r me rs (a nd v e ry lo w
q ua lity tr an s fo rm er s a t tha t) .

o n ' t u s e t h e s e o n the o u tp ut
o f th e Philtr e—th ey 're
u nn ec es s ar y a nd g en e ra lly
s ou nd a wfu l b ec au se th ey
d on 't h a ve th e he ad r oo m to
h an dle the Philtre 's ou tpu t.
G et a h a rd -wire d ad a pter or
c ab le fr om y o ur p ro fes sio na l
a ud io d e aler , o r ma k e on e

o u r s e l f f r o m c o m p o n e n t s .

23

Connections

j

j

j

A

2

Using the ModLink

The Philtre can be connected to other effect boxes in the ModFX
family via the ModLink. The ModLink is a cable-free connection
between two ModFX units that transfers digital audio and word
clock. The 9-pin male connector on the left side of the unit is the
ModLink IN port. The 9-pin female connector on the right side is
the ModLink OUT port. By directly connecting two ModFX units
via the ModLink, audio and power will pass from the left-most
unit to the right-most unit.

Inputs AC adapter Outputs

Master First Slave Second Slave

ud io Flow

What about the 1/4”

acks on the slave

units?

Whe n a u nit is a sla ve to
a no th er un it, its aud io input

ac ks a r e dis ab le d; it will ge t

its a ud io in p ut d ig ita lly fro m
its Mod Lin k p or t. The o u tp ut

ac ks , h owev e r, a re alwa y s
a ctiv e; so a n a ud io ou tp u t
c an b e tap pe d fro m a ny
lin ke d u nit, with ou t
inter ru p ting th e flo w to th e
r es t of th e c ha in .

The audio signal flows from left to right. The Master will send its
digital audio output to the First Slave, and the First Slave will, in
turn, send its output to the Second Slave.

24

3 Using the Philtre

This section defines the different kinds of filters and modulations,
and explains the functions of the Philtre’s controls in greater
detail. The technical information in the next few pages will help
you get the most out of your gear...it’s really pretty simple.

What is filtering?

An audio filter is a special kind of tone control that filters out
certain frequencies. Just as a water filter lets water through but
stops dirt and rust particles, audio filters let the frequencies you
want flow through, while stopping the rest. Every kind of audio
equipment has filtering or filter sections in it. If you have two­way speakers in your studio, each tweeter is protected by a high-pass
filter that lets the treble through while keeping the bass out (so you
don’t blow the tweeter), and the woofer may be connected to a low-
pass filter that keeps the high frequencies out. If you have three­way speakers, a band-pass filter lets only the midrange frequencies
get through to the midrange driver.

While most filters are used for equalization and crossovers,
engineers discovered that powerful filters moved around
dynamically could be a useful and creative special effect. The
Philtre falls into this special class of filters, that includes wah-wah
pedals and voltage-controlled filters on synthesizers.

25

Using the Philtre

3

Filter curves, orders, and slopes

When you look at a graphic display of their frequency response,
every filter has a slope—gentle or steep, like the slope of a hill. The
passband—the frequency range that the filter lets through—looks
like a flat plateau. The frequency at the edge of that plateau, just
as the response starts to go downhill, is called the corner frequency.
Then, the frequency response goes down at a particular slope,
measured in decibels per octave. The slope is determined by the
number of components or poles in the filter. A simple single-pole
filter, the gentlest kind, rolls off frequencies at a rate of 6
dB/octave above its corner frequency; a four-pole filter is a much
steeper 24 dB/octave.

In the Philtre, the PHREEQ control determines the corner
frequency, and the STEEP switch allows you to quadruple the
slope. The REGEN control increases gain at the corner
frequency, further changing the filter characteristics. You hear
this at high settings as the filter beginning to “whistle” as the
harmonics near the corner frequency all begin to peak together
due to phase addition; this is also called resonance or “Q”.

Modulating the filter frequency

All the rest of the controls on the right-hand side of the Philtre are
designed to modulate or dynamically change the filters’ corner
frequencies. If the DEPTH control is at minimum, and you move
the PHREEQ control around by hand, you’ll hear the effect of
changing the corner frequencies. The Modulation section of the
Philtre essentially does the same thing: it moves the frequency of
the filter around dynamically, under control of an LFO (Low
Frequency Oscillator). Not only does the Philtre give you a lot of
modulation options, it can automatically synchronize the
movement of the filter frequency with the speed of the music
using the Tempo Sync features.

26

Using the Philtre

I
R

R
f

What is Tempo Sync?

Three of the five mod sources in the Philtre have a repeating cycle
over time (Triangle, Sample/Hold, and Pattern). Sometimes, you’ll
want the rate of that cycle to match the beat of your music instead
of being random. For example, you can set the rate so that the
sweep of the filter completes each cycle once per measure, or to a
tremolo-like effect that happens in sixteenth notes. The TEMPO
SYNC feature of the Alesis ModFX series not only lets you set a
tempo naturally by tapping on the TAP TEMPO button, it can
automatically adjust its speed slightly relative to the audio input,
after setting the basic speed using the TAP button.

To use Tempo Sync:

You can set the Philtre to TEMPO SYNC mode as follows:

1. Press the down side of the [MODULATION] rocker switch to
select the next modulation type.

You can see the type of effect by the LED lit next to the name—for
example, TRIANGLE, SAMPLE/HOLD, ENVELOPE and
so on.

2. Keep pressing the rocker switch through all the normal modes
until you enter TEMPO SYNC mode, and then advance to the
type of modulation you want.

Both the Mod Type and TEMPO SYNC LEDs will be lit. For
example, if you press the down side of the rocker switch when you’re in
PATTERN mode, the Philtre will go to TRIANGLE/TEMPO
SYNC mode. At this point, the TAP TEMPO LED will start
flashing at the last speed it was set to (or the default of 120 bpm).

3. Tap the [TAP TEMPO] button several times to set the desired
tempo.

The TAP TEMPO LED will flash in time to the hits. As long as
the [RATE] control is in the center position, the modulation speed will
match the tempo.

4. If the tempo isn’t quite right, “tap” a steady, discrete beat on
any instrument connected to the input. The internal processor
will then synchronize the tapped tempo with the audio input.
The processor will make slight alterations to the tempo such
that it stays synchronized with the beat of the audio input.

The RATE knob is
different in Tempo
sync mode

n TEMPO S YNC m od e, th e

ATE kn o b ac ts as a
m ultiplier to the s p ee d s et b y
TAP TEMPO, s o y ou c a n’ t
g et the te mp o to ch a ng e
s ligh tly b y a djus tin g th a t
k no b. Note tha t ch a n g e s t o

ATE wo n ’t a ffe ct th e

la sh in g o f the TEMPO LED .

3

To turn Tempo Sync off:

Simply press the UP side of the [MODULATION] switch
repeatedly until the Tempo Sync LED goes off, then select the
modulation waveform you want.

27

Using the Philtre

t

M

3

Description of Controls

Rate

The [RATE] knob changes the filter modulation speed. When the
mod source is set to ENVELOPE it affects the attack and release
time of the envelope, in TRIGGERED mode it affects the release
time. In all other modes it affects the LFO (low frequency
oscillator) speed.

In normal modulation modes (TEMPO SYNC LED off), turning
the [RATE] knob alters the rate continuously from very slow to
very fast. Turn the knob clockwise for a faster speed, counter­clockwise for a classically-slow sweep.

Rate knob operation in TEMPO SYNC mode

When the Philtre is in TEMPO SYNC mode, the fundamental
modulation speed is set by the TAP TEMPO function, and the
rate knob is used to adjust that rate to an even fraction or multiple
of the current tempo:

• With the knob indicator in the 12 o’clock position, the mod
rate will be the same as tempo (one cycle per quarter note).

•Turn the knob to the left to set the mod rate to half of the
tempo (i.e., one cycle per half note), or full counter-clockwise
to set it to a quarter of the tempo (once per measure).

•Turn the knob to the right to set the modulation to twice the
tempo (eighth notes), or all the way to four times the tempo
(sixteenth notes).

S ee the de sc r ip tion s o f the

od ulation s o ur ce s for m o re
c om plete d eta ils of ho w
[ RATE] r elate s to e a ch ty pe .

Se e t he de sc r ip t i on of
T A P T EM P O f o r
i mp or t a n t ti p s on u s in g

hi s f e a t u r e .

The diagram below shows where you can set the [RATE] knob to
modulate the filter at different multiples of the tempo during
TEMPO SYNC mode.

T hi s di a gr a m do e s n o t
a pp ly w h e n t h e mo d
s ou r c e is se t t o
E N V EL O P E o r
T RI G G ERE D .

28

Depth

f

f

Using the Philtre

3

The [DEPTH] knob controls how much modulation will be
applied to the filter frequency. Turn the knob clockwise for a
deeper effect. Turning [DEPTH] all the way counter-clockwise
turns modulation off completely, leaving the filter fixed at the
[PHREEQ] position. Depth interacts with the [PHREEQ]
control (see next page).

Phreeq

The [PHREEQ] knob changes the corner frequency of the
Philtre’s high pass and low pass filters, and the center frequency
of the band pass and band stop filters. Its effect varies depending
on the filter type, the setting of the [STEEP] switch, and the
[REGEN] control, as will be explained later.

LOW PASS: Frequencies above the [PHREEQ] setting will be

rolled off. Turn clockwise to let more high end through.

HIGH PASS: Frequencies below the [PHREEQ] setting will be

rolled off. Turn counter-clockwise to let more low end
through.

BAND PASS: Frequencies above and below the band centered at

the [PHREEQ] setting will be rolled off. The width of the
band is set by the [REGEN] control; if [REGEN] is at
minimum the bands are so far apart that moving [PHREEQ]
may not have an audible effect except near the maximum or
minimum settings.

U nlik e s om e o th er e ffe cts ,
[ DEPTH] in th e Ph iltre
d oe sn ’t de cr e as e th e a mo u nt
o f filte re d s ig na l in th e m ix ;
tha t’ s a c on s ta nt. In ste ad , it
c on tr ols h ow mu ch th e

re qu en c y of th e filte r will be
m ov ed u p a nd do wn b y the
m od ulation s o ur ce .

To he ar ho w PHREEQ
wor ks f o r y ours elf , tur n

[ DEPTH] all the way off, an d
m ov e [PH REEQ ] m an ua lly
while listen ing . Tr y all fou r

ilte r typ es . Tu rn [REG EN]
u p un til y ou ca n he a r a ton e,
a nd e xp e rime n t with ra is ing
the [ DEPTH ] c on tr ol at
d iffe re n t [PH REEQ ] s ettin gs .

BAND STOP: Frequencies within the band centered at the

[PHREEQ] setting will be rolled off. Again, the width of the
band is set by [REGEN]: at the minimum setting, almost the
entire audio range may be rolled off, and at the maximum
setting only a narrow notch.

29

Using the Philtre

3

Regen

The [REGEN] knob does several different things depending on
the filter type. But in each filter it increases the amount of filter
resonance (how much gain is added near the corner frequency),
which creates a peak in the response as shown below:

[REGEN] at minimum

[REGEN] at maximum

• To increase resonance, turn [REGEN] clockwise.

• For no resonance (REGEN off), turn [REGEN] counter­clockwise.

Regen in Band Pass and Band Stop modes

In addition to its resonance function, the [REGEN] knob adjusts
the width of the bands in Band Pass and Band Stop filters.

In BAND PASS mode, with [REGEN] set to minimum, the high
and low corners of the band are extremely far apart, so that on
program material without much low or high end there may be little
audible effect (depending on the setting of the PHREEQ knob).
As you increase the [REGEN] setting, the low pass filter corner
moves down, and the high pass filter moves down, making the
middle “plateau” narrower and narrower. At the maximum
[REGEN] setting, with the addition of filter resonance, the Band
Pass filter essentially becomes a narrow notch filter with a very
high “Q”:

Band Pass: Low [REGEN] Band Pass: High [REGEN]

• To make the band narrower, turn [REGEN] clockwise.

30

Using the Philtre

In BAND STOP mode, with [REGEN] set to minimum, the band
that is being attenuated is relatively wide. As you increase the
[REGEN] setting, the stop band gets narrower. At the maximum
setting, with the addition of filter resonance, the Band Pass filter
essentially becomes a narrow notch filter with a high “Q”, like a
parametric EQ set to its narrowest setting:

Band Stop: Low [REGEN] Band Stop: High [REGEN]

• To make the band stop filter narrower, turn [REGEN]
clockwise.

3

31

Using the Philtre

3

Modulation Select Switch

The up/down rocker switch on the right side of the unit selects the
modulation source for the Philtre. The LEDs next to the switch
light up to indicate the current mode. There are five kinds of
modulation available, explained below. The rocker switch also
selects TEMPO SYNC mode, as explained earlier.

Triangle

This mode uses a triangle wave to modulate the filter effect. Use
this when you want the filter to move up and down in regular,
smooth waves.

Sample/Hold

This mode selects a sample and hold wave for the filter’s
modulation. The filter’s center frequency will jump randomly
around the center setting, holding a setting until it’s time for the
next one. The left and right channel filter settings are randomly
set apart from each other, creating an interesting stereo effect.

32

Using the Philtre

y

Triggered

This is one of the most useful effects in the Philtre for lead
players. Instead of using a repeating wave or LFO, the filter is
kept low (at the point set by the [PHREEQ] control) until there’s
an accent in the incoming signal. An accent (a sudden increase
above the average input audio level) is called a trigger. This trigger
“fires” an envelope wave with a fast attack at the filter frequency,
so it’s like using a synthesizer’s VCF (voltage controlled filter) on
the audio input. Pressing the [RESET MOD] button will also
cause a trigger.

The decay time of the trigger (how long it takes after an accent for
the filter to close down again) is set by the [RATE] control: the
trigger will be very short when [RATE] is turned full clockwise,
and longer when turned “down” (counter-clockwise).

Note that since there’s no repeating waveform in Triggered mode,
the TEMPO SYNC/TAP TEMPO features have no effect.

3

Trigger reacts directly
to your playing

With a little p ra ctice a n d
s om e ca r eful le ve l a djus tme nt
o f yo ur in str um en t, yo u’ ll
a djus t to th e fee l o f ho w l ou d

o u h a v e t o p l a y t o g e n e r a t e
a trigg e, an d h ow s oft to p la y
to ke ep th e filte r fro m
trigg er ing .

Triggering with a
volume pedal

With su s ta in e d so un d s, y o u
c an trig ge r the Philtr e b y
u sing a vo lu m e p ed al, o r th e
v olum e k no b o n th e
ins tr um e nt itse lf. Tr y it!

33

Using the Philtre

R

A
f

3

Envelope

Like Trigger, Envelope modulation takes its cue from the input
signal instead of using a periodic wave. In Envelope mode, the
filter frequency follows the average amplitude envelope of the
incoming signal—the louder you play, the higher the filter
frequency will move. Envelope is used in “auto-wah” effects, and
for making dynamics more pronounced.

How quickly the filter responds to level changes in the incoming
input is controlled by the [RATE] knob. The most obvious effect
of the [RATE] control is to slow down the attack time of the
envelope. In this sense, Envelope is the opposite of Trigger: on
similar inputs, Envelope “swoops up” where Trigger would
“swoop down”. However, it’s actually more complex than that.
Think of the [RATE] control as being a “shock absorber” on how
quickly the filter frequency will follow the changes in level of
incoming sound. At low [RATE] settings, the filter responds
slowly, both up and down. At midrange settings, it more quickly
moves, in sync with individual notes. At the highest range, the
filter almost jitters as it tries to follow the envelope of the
incoming signal exactly.

In this mode, TEMPO SYNC/TAP TEMPO features have no
effect.

ate settings are the

key to Envelope mode

t lo w [ RATE] s ettin gs , the

ilte r will g ra du a lly op e n up
o nly if yo u p la y se v er al no te s
in a ro w—lik e y ou we re
tur ning an EQ k no b d ur in g a
c re sc en d o. Abo ve th e “1 2
o ’c lo ck ” s ettin g, th e en v elop e
will fo llo w e ac h no te, m a king
the c ha r ac te r is tic “an alo g
s yn th es ize r” so un d.

34

Using the Philtre

R

I

p

Pattern

This mode randomly generates a 16-step sequence to modulate the
filter and repeats it over and over. Pattern mode makes the filter
jump quickly from step to step, sometimes with a glide between
steps. It sounds somewhat like “sample and hold” modulation,
except that the pattern will step through the same 16 steps over
and over, instead of being random.

• Press the [RESET MOD] button to generate a new 16-step
pattern.

• Try using the [RATE] knob, or the TEMPO SYNC/TAP
TEMPO features, to make the steps of the pattern play in
sync with your music. Keep in mind that the pattern has 16
steps per 4 beats, so adjust the RATE knob accordingly.

3

ATE in Pattern

mode

You c an th in k o f Pa tte rn
m od e as be in g 4 x th e r ate o f
the o th e r mo d ulatio n s ou r ce s.

n T e m p o S y n c m o d e , t u r n t h e
[ RATE] k no b full clo ck wis e
( 1/4 sp e ed ) to ge t o ne s tep

er b ea t, th e s am e a s
Trian gle a t a 1 2 o’ c lo ck
s etting of [ RATE] .

35

Using the Philtre

3

TYPE Rocker Switch

The up/down rocker switch on the left side of the unit selects the
type of filter. The LEDs next to the switch light up to indicate the
current type. There are four types available, explained below.

Low Pass

Perhaps the most-popular type of filter effect, the Low Pass filter
has a 2-pole, 12 dB per octave slope that cuts the high frequencies
above the corner frequency set by the [PHREEQ] knob. Most
synthesizer filters are low pass filters, as are wah-wah pedals.

When [STEEP] is on, the Low Pass filter slope increases to 8-pole,
rolling off the high frequencies at a rate of 48 dB per octave.

High Pass

The High Pass filter has a 2-pole, 12 dB per octave slope that cuts
the low frequencies below the corner frequency set by the
[PHREEQ] knob. The most common use of high pass filters is to
cut rumble out of microphones; as an effect they can create an
intentionally-thin “transistor radio” sound by cutting out the low
frequencies.

When [STEEP] is on, the High Pass filter slope increases to 8­pole, rolling off low frequencies at 48 dB per octave.

36

Using the Philtre

Band Pass

The Band Pass filter has two 2-pole, 12 dB per octave slopes: one
rolling off high frequencies above the center, and another rolling
off low frequencies below the center. It’s like a high pass filter
combined with a low pass filter, with the corners set to let the
midrange through. The distance between the two slopes is set by
the [REGEN] knob: the band lets most of the audible frequency
spectrum through at the lowest [REGEN] setting, and narrows
considerably at full clockwise rotation (see page 30 for an
illustration of this).

When using modulation, a Band Pass filter is often used when you
want an effect similar to Low Pass, but you don’t want the high
end to disappear completely as the filter center moves towards the
low end. Acoustically, it mimics the effect of sound being pointed
in different directions, toward and away from the listener, as in a
rotary speaker or the “helicopter” effect.

When [STEEP] is on, the Band Pass filter slopes increase to 8­pole, or 48 dB per octave. This steep slope isn’t as obvious as in
other filters, however, if the band is set relatively wide.

3

Band Stop

The Band Stop filter is the reverse image of the Band Pass filter.
Instead of preserving the frequencies in the midrange near the
center, it cuts them off, so only the edges are heard. The distance
between the two slopes is set by the [REGEN] knob: the band is
fairly wide at the lowest [REGEN] setting, and becomes a notch
filter at full clockwise rotation (see page 31 for an illustration of
this). When you modulate a Band Stop filter, the sound will
alternate between cutting out the low mids, and the upper mids,
while leaving the extreme high and low frequencies (if the
PHREEQ knob is at the center).

When [STEEP] is on, the Band Stop filter slopes increase to 8­pole, or 48 dB per octave.

37

Using the Philtre

3

Steep

For a more dramatic filter effect, press the [STEEP] button.
[STEEP] quadruples the number of filter poles being used. This
means that more frequencies are rejected, and if [REGEN] is
turned up, the resonance effect is more pronounced.

Here is a chart of the effect of the [STEEP] button:

Normal slope Steep slope

2 p ole (12 dB/o ctave) 8 p ole (48 dB/o ctave)

Reset Mod

Press this button to reset the phase of the filter modulation source
as follows:

• In TRIANGLE mode, press [RESET MOD] to start the wave
from the top of its phase.

• In TRIGGERED mode press this button to generate a fast­attack trigger envelope to momentarily open the filter, even
when the audio signal hasn’t generated its own trigger.

• In PATTERN mode press this button to generate a new 16­step pattern.

38

Using the Philtre

Tap Tempo

This button affects the speed of the effect whenever the
[MODULATION] switch is set to a TEMPO SYNC mode. At
any time you can tap this button along with the music to set a new
tempo. The Tap Tempo light will flash at the current tempo.

3

Tap Tempo technique

For a reliable tempo setting, make several taps in a row at a
consistent speed, especially if you’re changing the tempo
drastically. Watch the flashing of the light to see the current
tempo of the Philtre.

Adjusting tempo with audio input

After the basic tempo has been set using the [TAP TEMPO]
button, the Philtre will automatically make small adjustments to its
tempo by “listening to” the audio input. You try this out by
“tapping” on an instrument (playing sharp chords, or beats,
without sustain or notes inbetween) at almost the same speed as
the Philtre’s tempo LED, or by slightly changing the speed of a
drum machine feeding the inputs. The Philtre can derive a beat
from a complex musical input, as long as it is reasonably close to
the original “tapped” tempo. The tempo can adjust up or down
about 15% from the original tempo tapped in.

How Tap Tempo works with Tempo Sync and
the Rate knobs

When TEMPO SYNC mode is enabled, the rate of the modulation
will be based on the tempo currently being flashed, multiplied by
the position of its [RATE] knob: when it’s in the middle position
(around “12 o’clock”), the speed of the triangle, sample/hold, or
the pattern, will be the same as the tempo. (Tap Tempo has no
effect on Triggered or Envelope modulations.) See the earlier
descriptions of the [RATE] knob and Tempo Sync for more
information.

To get fast
modulations...

it is n’ t n ec e ss ar y to ta p a t a
h ig h sp e ed if y ou wa nt th e
e ffec t to mo d ulate a t eig hth or
s ix te en th no tes . J u st ta p on
the q ua rter - no t e b e at, the n
tur n th e [ RATE] k no b to the
r ig ht to d ou b le o r q ua dr u ple
the s pe e d ma d e by Ta p
Tem po .

39

Using the Philtre

3

Bypass

This button sends the signal directly from the input to the output
without any effect. Press [BYPASS] to check the sound of the
source without any effect from the Philtre. When the red
BYPASS LED is lit, phasing is turned off. The Bypass function
can also by activated by the foot switch.

Since the Philtre is a digital effect, signal always passes through the
digital A/D–D/A conversion process, so that digital signal will
flow through to other effects in a ModLink chain even when
[BYPASS] is on. So, unlike old analog effects, this is not a
“hardwire” bypass switch—the Philtre must be powered on to
pass signal through, even in bypass mode. Similarly, the [TRIM]
control is always active, since it’s an analog control regulating the
level feeding the analog-to-digital converters.

Using the Foot Switch

If you need to bypass the effect but your hands aren’t free, simply
connect any momentary footswitch (such as those used for
keyboard sustain pedals, either NC normally closed or NO
normally open) to the [FOOT SWITCH] jack on the rear panel.
The footswitch will turn the BYPASS LED on and off.

40

4 Sample Settings

A

While there’s nothing like discovering new sounds for yourself, we
thought it would be a good idea to provide some sample settings
of the Philtre to help get you started. Simply set the knobs on
your Philtre so they’re at the positions shown, and press the rocker
switches so each effect is in the mode shown by the LEDs. Feel
free to modify these any way you want to suit your particular
playing style.

Ghost in the Fog

G oo d on pr og r am m ate rial;
m ur ky with m o me nts o f
c la rity . Pr e ss [ RES ET MO D]
to ch an g e th e p atte rn , a nd
[ TAP TEMPO ] to
s yn ch ro n iz e to th e b ea t

uto Wah

The e nv e lo pe fo llowe r cr e ates
the a uto wah e ffe ct
a utom atica lly a s yo u p la y ;
u se the [I NPU T TRIM] *
k no b to fi ne - tu ne th e effec t.

41

Sample Settings

A

H

A

4

Slow Sweep

it [ TAP TEMPO] o n the
d ownb ea t o f e ve ry 2 nd ba r,
a nd this s ettin g will op e n an d
c lo se th e filte r ov e r two b ar s.

Sample and Hold

c la ss ic sa m ple an d h old
s ou nd th at fo llows the time o f
the m us ic, with s ix tee nth
n otes a t this s ettin g, if y ou h it
[ TAP TEMPO ] in qu ar ter
n otes .

Triggered Zap

r es on a nt h igh p as s “za p ”
s ou nd tr ig ge r ed fro m the
a ud io in p u t . U s e t h e [ I N P U T
TRI M] to tun e the tr ig ge r
thr es ho ld.

42

Sample Settings

B

F

B

p

and Passion

The b an d p as s filte r m ov e s in
tim e with th e m us ic in th is
s etting . Ta p q ua rte r no tes
into [TAP TEMPO ], a n d

r e s s [ R E S E T M O D ] t o

c ha ng e the p a tter n.

lank

ill in yo ur own fa v or ite
s etting s h er e . Pho toc op y the
n ex t pa g e if yo u ne e d mo r e
s pa ce .

4

43

Sample Settings

4

Blank Settings Templates

44

5 Troubleshooting

[

[

Troubleshooting Index

If you experience problems while operating your Philtre, please
use the following table to locate possible causes and solutions
before contacting Alesis Product Support for assistance.

Symptoms Cause Solution

No audio output s. No input audio( SIGNAL

[TAP T EMPO] button is
not working

Mod Linked units are n ot
working p roperly

Distorted sound Inp ut level too h igh

Sounds th in, no botto m
end

Buz z or h um fro m
out puts

LED doesn ’t flash).
Bad cables.Rep lace t he cab les.
Destination is turned

down.

[IN PUT TRIM] kn ob is
turned down

PHREEQ] is at minimum

in Low P ass mo de

In Envelo pe mod e, not
receiving enoug h level, and

DEPTH] is at m aximum

Inp ut cab les are conn ected
to a linked unit

Power is no t conn ected Go take a walk
Not in Tempo Sync mod e Select Tempo Sync mod e

Power dropo ut to one of
the units in th e chain

(SIGNAL LED on fro nt
pan el flashes red)

[PHREEQ] knob is set
hig h, in High P ass mo de

Aud io cab les are crossing a
power cable or a power
adapter.

Pro blem w ith th e source Try bypassing t he Philt re

Bad cables Rep lace t he cab les

Test with a known good
inp ut.

Check the connections
and the level of th e mixer
or amp th at the Philt re is
con nected to.

Adjust th e knob to th e
pro per level.

Adjust th e knob to th e
pro per level, or use
ano ther filter mo de

Increase input signal,
change [P HREEQ] and/
or [DEPTH], or increase
[RATE].

Con nect t he inp ut cab les
to the Master o f the link
chain

Plug in a power supply to
ever y unit in a chain.

Turn down the so urce, or
the TRIM cont rol on th e
Philt re’s back panel.

Change th e sett ings

Make sure that t he Philt re
and its audio cables are
kep t away fro m power
cab les an d wall warts.
Don ’t wrap cable in t ight
bun dles.

by connecting t he inp ut
cab les to the o utput cables
and see if the problem
rem ains.

45

Troubleshooting

5

Symptoms Cause Solution

AC hum Gro und lo op Place all equip ment in the

Whistles or ton es in
out put

Can ’t hear Envelope [RATE] set too low t o

[REGEN] set too high Red uce [REGEN] settin g,

t rack input

studio on a com mon
gro und (see next page)

or turn [STEEP ] off
Set [RATE] to th e midd le

of its range, o r chan ge the
TYP E.

46

Troubleshooting

Avoiding ground loop noise

In today’s studio, where it seems every piece of equipment has its
own computer chip inside, there are many opportunities for
ground loop problems to occur. These show up as hums, buzzes
or sometimes radio reception and can occur if a piece of
equipment "sees" two or more different paths to ground. While
there are methods to virtually eliminate ground loops and stray
radio frequency interference, most of the professional methods are
expensive and involve installing a separate power source just for
the sound system. Alternatively, here are some helpful hints that
professional studio installers use to keep those stray hums and
buzzes to a minimum.

KEEP ALL ELECTRONICS OF THE SOUND
SYSTEM ON THE SAME AC ELECTRICAL
CIRCUIT.

Most stray hums and buzzes happen as a result of different parts
of the sound system being plugged into outlets of different AC
circuits. If any noise generating devices such as air conditioners,
refrigerators, neon lights, etc., are already plugged into one of these
circuits, you then have a perfect condition for stray buzzes. Since
most electronic devices of a sound system don’t require a lot of
current (except for power amplifiers), it’s usually safe to run a
multi-outlet box or two from a SINGLE wall outlet and plug in all
of the components of your system there.

5

KEEP AUDIO WIRING AS FAR AWAY FROM AC
WIRING AS POSSIBLE.

Many hums come from audio cabling being too near AC wiring.
If a hum occurs, try moving the audio wiring around to see if the
hum ceases or diminishes. If it’s not possible to separate the audio
and AC wiring in some instances, make sure that the audio wires
don’t run parallel to any AC wire (they should only cross at right
angles, if possible).

TO ELIMINATE HUM IF THE ABOVE HAS FAILED:

1. Disconnect the power from all outboard devices and
tape machines except for the Philtre, the mixer and
control room monitor power amp.

2. Plug in each tape machine and outboard effects device
one at a time. If possible, flip the polarity of the plug of
each device (turn it around in the socket) until the
quietest position is found.

3. Make sure that all of the audio cables are in good
working order. Cables with a detached ground wire will
cause a very loud hum!!

47

Troubleshooting

5

4. Keep all cables as short as possible, especially in
unbalanced circuits.

If the basic experiments don’t uncover the source of the problem,
consult your dealer or technician trained in proper studio
grounding techniques. In some cases, a "star grounding" scheme
must be used, with the mixer at the center of the star providing the
shield ground on telescoping shields, which do NOT connect to
the chassis ground of other equipment in the system.

Line conditioners and spike protectors

Although the Philtre is designed to tolerate typical voltage
variations, in today’s world the voltage coming from the AC line
may contain spikes or transients. These can cause audible noises,
and they can stress your gear and, over time, possibly cause a
failure. There are three main ways to protect against this, listed in
ascending order of cost and complexity:

• Line spike/surge protectors. Relatively inexpensive,
these are designed to protect against strong surges and
spikes, acting somewhat like fuses in that they need to
be replaced if they’ve been hit by an extremely strong
spike.

• Line filters. These generally combine spike/surge
protection with filters that remove some line noise
(dimmer hash, transients from other appliances, etc.). A
good example is the Isobar™ series from Tripp Lite.

• Uninterruptible power supply (UPS). This is the
most sophisticated option. A UPS provides power even
if the AC power line fails completely. Intended for
computer applications, a UPS allows you to complete an
orderly shutdown of a computer system in the event of a
power outage. In addition, the isolation it provides
from the power line minimizes all forms of
interference—spikes, noise, etc.

48

Troubleshooting

Care and Maintenance

Cleaning

Disconnect the AC cord, then use a damp cloth to clean the
Philtre’s metal and plastic surfaces. For heavy dirt, use a non­abrasive household cleaner such as Formula 409™ or Fantastik™.
DO NOT SPRAY THE CLEANER DIRECTLY ONTO THE
FRONT OF THE UNIT AS IT MAY DESTROY THE
LUBRICANTS USED IN THE SWITCHES AND CONTROLS!
Spray onto a cloth, then use cloth to clean the unit.

Refer all servicing to Alesis

We believe that the Philtre is one of the best signal processors that
can be made using current technology, and should provide years of
trouble-free use. However, should problems occur, DO NOT
attempt to service the unit yourself unless you have training and
experience. Service on this product should be performed only by
qualified technicians. NO USER-SERVICEABLE PARTS
INSIDE.

5

49

Troubleshooting

5

Obtaining repair service

Before contacting Alesis, check over all your connections, and
make sure you’ve read the manual.

Customers in the USA and Canada:

If the problem persists, contact Alesis and request the Product
Support department. Make sure you have the unit’s serial number
with you. Talk the problem over with one of our technicians; if
necessary, you will be given a return order (RO) number and
instructions on how to return the unit. All units must be shipped
prepaid and COD shipments will not be accepted.

For prompt service, indicate the RO number on the shipping label.
Units without an RO will not be accepted. If you do not have
the original packing, ship the unit in a sturdy carton, with shock­absorbing materials such as Styrofoam pellets (the kind without
CFCs, please) or "bubble-pack" surrounding the unit. Shipping
damage caused by inadequate packing is not covered by the Alesis
warranty.

Tape a note to the top of the unit describing the problem, include
your name and a phone number where Alesis can contact you if
necessary, as well as instructions on where you want the product
returned. Alesis will pay for standard one-way shipping back to
you on any repair covered under the terms of this warranty. Field
repairs are not authorized during the warranty period, and repair
attempts by unqualified personnel may invalidate the warranty.

Customers outside the USA and Canada:

Contact your local Alesis distributor for any warranty assistance.
The Alesis Limited Warranty applies only to products sold to users
in the USA and Canada. Customers outside of the USA and
Canada are not covered by this Limited Warranty and may or may
not be covered by an independent distributor warranty in the
country of sale. Do not return products to the factory unless you
have been given specific instructions to do so.

50

Specifications

A

Audio Input

Input Connectors: 2 unbalanced 1/4” jacks

Maximum Input Level: +10 dBV

Nominal Level: -10 dBV

Input Impedance: 470kΩ

Input Converter Resolution: 24-bit, 48 kHz sampling

Audio Output

Output Connectors: 2 unbalanced 1/4” jacks

Maximum Output Level: +9 dBV

Output Impedance: 500Ω

Output Converter Resolution: 24-bit, 48 kHz sampling

Audio Performance

(Analog In to Analog Out)

Signal To Noise Ratio: >100 dB A-weighted

THD+N: < 0.005%

Frequency Response: ± 1dB from 22Hz to 22kHz

Internal DSP Resolution: 28-bit

ll m ea s ur em e nts do n e ov e r
a 2 2H z – 2 2k H z ra ng e with a
1 kH z sin e wa v e at - 1 dBFS
inp ut. I mp ed an c es a r e
m ea su re d a t 1 kH z.

Power Consumption: 7 Watts max (9VAC Alesis P3)

Mechanical

Size: 2.1” H x 5.8” W x 3.9” D

Weight: 12.6oz. (357 g)

(53mm H x 148mm W x
98mm D)

51

Specifications

6

This page intentionally left blank.

52

Index

amplifier, 21
audio input

tempo set by, 39
Aux Send/Return, 20
BAND PASS, 25, 29, 30, 37, 38

BAND STOP, 29, 30, 37, 38
BYPASS, 16, 40

with foot switch, 40
cables, 22
Control diagram, 16
corner frequency, 26
decibels per octave, 26
DEPTH, 16, 29, 45
digital converters, 40, 51
digital signal processing, 4
DSP, 51
ENVELOPE, 34, 46

and RATE knob, 28

and Tempo Sync, 39
filtering, 25
FOOT SWITCH, 16, 40
ground loop, 47
grounding, 7
guitar, 18
HIGH PASS, 25, 29, 36, 38
Hums and buzzes, 47
INPUTS, 15
INPUTS and OUTPUTS, 16
Insert Cables, 19
levels, 22
LFO, 28
LOW PASS, 25, 29, 36, 38
manual, 6
mixing console hookup, 20
ModFX, 4, 23
ModLink, 4, 16, 23
Modulating, 26
MODULATION switch, 16, 27, 32
mono source

plug into left input, 18
notch filter, 30, 37
OUTPUTS, 15

on ModLink slave units, 23

Pattern, 27, 35, 38
PHREEQ, 16, 26, 29
poles, 26
POWER 9VAC, 15
power adapter, 16, 17
Power cable, 7
Q, 26
Rack mounting, 17
RATE, 16, 28

in Envelope mode, 34
in Pattern mode, 35
in Tempo Sync mode, 27, 39

in Triggered mode, 33
Rear Panel, 16
REGEN, 16, 26, 30, 46

in BAND modes, 29, 37
Reset Mod, 16, 38

in Triggered Mode, 33
resonance, 26

controlled by REGEN knob, 30
Safety, 7
Sample/Hold, 32
SIGNAL LED, 15, 16, 18, 22
slope, 26, 36, 38
STEEP, 26, 36, 38
stereo, 18, 19, 32
synthesizer, 15
Tap Tempo, 16, 27, 39
Tempo Sync, 26, 27

effect on RATE knob, 28

in Envelope mode, 34

in Triggered mode, 33
transformers, 22
Triangle, 27, 32, 38
TRIGGERED, 33, 38

and RATE knob, 28
TRIM, 15, 16, 18

active in bypass mode, 40
TYPE, 16, 36
voltage-controlled filters, 25
wah-wah, 25
XLR, 22

53

Warranty / Contact Alesis

F

Alesis Limited Warranty

ALESI S CORPORATI ON ("ALES IS") war rants this product to be free of defects
in material and workmanship for a perio d of one (1) year for parts and for a period of
one (1) year for labor from the date of original retail purchase. This warranty is
enforceable only by the original retail purc haser and cannot be t ransferre d or assigned.
For the most effective service, the pu rchaser should re gi ster the purchase on the
ALESI S website at http://www.ale sis.com/support/warranty.htm.
Duri ng the warranty period ALESIS shall, at its sole and absolute option, either repair
or replace free of charge any product that proves to be defective on inspection by
ALESI S or its aut horized service representative. In all cases disputes concerning this
warranty shall be resolved as prescribed by law.
To ob tain warra nty service, the purc haser must first call or write ALESI S at the
address and tel ephone numb er available on the Alesis Website t o obtain a Return
Autho rization Num ber and i nst ructions concerning where to return the unit for
service. All inquiries must be accompanied by a description of the problem. All
autho rized returns must be sent to ALESIS or an autho rized ALESIS repair facility
postage prepaid, insured and properly packaged. Proof of purchase must be
presented in the form of a bill of sale, canceled ch eck or some other positi ve proof
that the product is within the warranty period. ALESIS reserves the r ight to update
any u nit returned for repair. ALESI S reserves the right to change or improve desig n
of the p roduct at any time without prior notice.
This war ranty does not cover claims for damage due t o abuse, ne glect, alteration or
atte mpted repair by unauthorized personnel, and is limited to failures arising during
normal use that are due to defects in material or workmanship in the product.
THE ABOVE WARRANTIE S ARE IN LIEU OF ANY OTHER
WAR RA NT IE S O R R EPRESENTATIONS WHETHER EXPRESS OR
IMPLIED OR OTHERWISE, WITH RESPECT TO THE PRODUCT, AND
SPECIFICALLY EXCLUDE ANY IMPLIED WARRANTIES OF FITNESS
FOR A PARTICULAR PURPOSE OR MER CHANTABILITY OR OTHER
IMPLIED WARRANTIES. Some states do not allow limitations on how long an
implied warranty lasts, so the above limitation may no t apply to you.
IN NO EVENT WILL ALESIS BE LIABLE FOR INCIDENTAL,
CONSEQUENTI AL, INDIR ECT OR OTHER DAMAGES R ESULTING
FROM THE BREACH OF ANY EXPRESS OR IMPLIED WARRANTY,
INCLUDING, AMONG OTHER THI NGS, DAMAGE TO PROPERTY,
DAMAGE BASE D ON INCO NVENIENCE OR ON LOS S OF USE OF THE
PRODUCT, AND, TO THE EXTENT PERM ITTED BY LAW, DAMAGES
FOR PERSONAL INJURY. Some states d o not allow the exclusion or limitation of
incidental or consequential damages, so the above limitation or exclusion may not
apply to you.
THIS CONTRACT SHALL BE GOVERNED BY THE INTERNAL LAWS
OF THE STATE OF CALIFORNIA WITHOUT REFERENCE TO
CONFLICTS OF LAWS. This warranty gi ves you specific le gal rights, and you may
also have other rights required by law which vary from state to state.
This war ranty only applies to products sold to purchasers in the United States of
America or Canada. The terms of this warranty and any obligations of Alesis under
this warranty shall apply only within the c ountry of sale. Without limiting the
foregoing, repairs under this warranty shall be made only by a duly authorized Alesis
service representative in the count ry of sale. For warranty information in all other
count ries please re fer to your local distributor.

or more effective
service and product
update notices, please
register your Philtre
online at:

http://www.alesis.com/supp
ort/warranty.htm

54

Warranty/Contact Information

Alesis Contact Information

Alesis Studio Electronics
Los Angeles, CA USA

E-mail: [e-mail]
Website: http://www.alesis.com

Alesis Philtre Reference Manual
Revision 1.0 by Dan Tinen

Copyright 2002, Alesis. All rights reserved
Reproduction in whole or in part is prohibited. Specifications
subject to change without notice. Trademarks are the property of
their respective holders.

7-51-0119-A
8/2002

55