Yorkville AP812, AP818 User Manual

OWNER'S MANUAL

MANUEL DE L'UTILISATEUR

The exclamation point within an equilatereal triangle is
intended to alert the user to the presence of important
operating and maintenance (servicing) instructions in
the literature accompanying the appliance.

Le point d’exclamation à l’intérieur d’un triangle équilatéral

est prévu pour alerter l’utilisateur de la présence

d’instructions importantes dans la littérature accompag­nant l’appareil en ce qui concerne l’opération et la

maintenance de cet appareil.

This lightning flash with arrowhead symbol, within
an equilateral triangle, is intended to alert the user to
the presence of uninsulated “dangerous voltage”
within the product’s enclosure that may be of sufficient

magnitude to constitute a risk of electric shock to persons.
Ce symbole d’éclair avec tête de flèche dans un triangle

équilatéral est prévu pour alerter l’utilisateur de la présence d’un
« voltage dangereux » non-isolé à proximité de l’enceinte du
produit qui pourrait être d’ampleur suffisante pour présenter
un risque de choque électrique.

IMPORTANT SAFETY INSTRUCTIONS

safety-4v7 • May 7/2008

CAUTION: TO REDUCE THE RISK OF ELECTRIC

SHOCK, DO NOT REMOVE COVER (OR BACK).

NO USER SERVICEABLE PARTS INSIDE.

REFER SERVICING TO QUALIFIED

SERVICE PERSONNEL.

FOLLOW ALL INSTRUCTIONS SUIVEZ TOUTES LES INSTRUCTIONS

Instructions pertaining to a risk of fire,

electric shock, or injury to a person

Read Instructions: The Owner’s Manual should be read and understood before operation

of your unit. Please, save these instructions for future reference and heed all warnings.

Clean only with dry cloth.
Packaging: Keep the box and packaging materials, in case the unit needs to be

returned for service.
Warning: To reduce the risk or fire or electric shock, do not expose this apparatus to rain or

moisture. Do not use this apparatus near water!
Warning: When using electric products, basic precautions should always be followed,

including the following:

Power Sources

Your unit should be connected to a power source only of the voltage specified in the
owners manual or as marked on the unit. This unit has a polarized plug. Do not use
with an extension cord or receptacle unless the plug can be fully inserted. Precau­tions should be taken so that the grounding scheme on the unit is not defeated. An
apparatus with CLASS I construction shall be connected to a Mains socket outlet with
a protective earthing ground. Where the MAINS plug or an appliance coupler is used
as the disconnect device, the disconnect device shall remain readily operable.

Hazards

Do not place this product on an unstable cart, stand, tripod, bracket or table. The
product may fall, causing serious personal injury and serious damage to the product.
Use only with cart, stand, tripod, bracket, or table recommended by the manufacturer
or sold with the product. Follow the manufacturer’s instructions when installing the
product and use mounting accessories recommended by the manufacturer. Only use
attachments/accessories specified by the manufacturer

Note: Prolonged use of headphones at a high volume may cause
health damage on your ears.

The apparatus should not be exposed to dripping or splashing water; no objects

filled with liquids should be placed on the apparatus.

Te rminals marked with the “lightning bolt” are hazardous live; the external wiring

connected to these terminals require installation by an instructed person or the use of
ready made leads or cords.

Ensure that proper ventilation is provided around the appliance. Do not install near

any heat sources such as radiators, heat registers, stoves, or other apparatus
(including amplifiers) that produce heat.

No naked flame sources, such as lighted candles, should be placed on the apparatus.

Power Cord

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. If the
provided plug does not fit into your outlet, consult an electrician for replacement of the

obsolete outlet. The AC supply cord should be routed so that it is unlikely that it will be
damaged. Protect the power cord from being walked on or pinched particularly at plugs. If
the AC supply cord is damaged DO NOT OPERATE THE UNIT. To completely disconnect
this apparatus from the AC Mains, disconnect the power supply cord plug from the AC
receptacle. The mains plug of the power supply cord shall remain readily operable.

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

Service

The unit should be serviced only by qualified service personnel. Servicing is required
when the apparatus has been damaged in any way, such as 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.

AVIS: AFIN DE REDUIRE LES RISQUE DE CHOC

ELECTRIQUE, N’ENLEVEZ PAS LE COUVERT (OU LE

PANNEAU ARRIERE) NE CONTIENT AUCUNE PIECE

REPARABLE PAR L’UTILISATEUR.

CONSULTEZ UN TECHNICIEN QUALIFIE

POUR L’ENTRETIENT

Instructions relatives au risque de feu,

choc électrique, ou blessures aux personnes

Veuillez Lire le Manuel: Il contient des informations qui devraient êtres comprises avant

l’opération de votre appareil. Conservez. Gardez S.V. P. ces instructions pour consultations
ultérieures et observez tous les avertissements.

Nettoyez seulement avec le tissu sec.

Emballage: Conservez la boite au cas ou l’appareil devait être retourner pour réparation.
Avertissement: Pour réduire le risque de feu ou la décharge électrique, n'exposez pas

cet appareil à la pluie ou à l'humidité. N’utilisez pas cet appareil près de l’eau!
Attention: Lors de l’utilisation de produits électrique, assurez-vous d’adhérer à des

précautions de bases incluant celle qui suivent:

Alimentation

L’ appareil ne doit être branché qu’à une source d’alimentation correspondant au
voltage spécifié dans le manuel ou tel qu’indiqué sur l’appareil. Cet appareil est équipé
d’une prise d’alimentation polarisée. Ne pas utiliser cet appareil avec un cordon de
raccordement à moins qu’il soit possible d’insérer complètement les trois lames. Des
précautions doivent êtres prises afin d’eviter que le système de mise à la terre de
l’appareil ne soit désengagé. Un appareil construit selon les normes de CLASS I
devrait être raccordé à une prise murale d’alimentation avec connexion intacte de mise
à la masse. Lorsqu’une prise de branchement ou un coupleur d'appareils est utilisée
comme dispositif de débranchement, ce dispositif de débranchement devra demeurer
pleinement fonctionnel avec raccordement à la masse.

Risque

Ne pas placer cet appareil sur un chariot, un support, un trépied ou une table instables.
L’appareil pourrait tomber et blesser quelqu’un ou subir des dommages importants.
Utiliser seulement un chariot, un support, un trépied ou une table recommandés par le
fabricant ou vendus avec le produit. Suivre les instructions du fabricant pour installer
l’appareil et utiliser les accessoires recommandés par le fabricant. Utilisez seulement
les attachements/accessoires indiqués par le fabricant

Note: L'utilisation prolongée des écouteurs à un volume élevé peut
avoir des conséquences néfastes sur la santé sur vos oreilles. .

Il convient de ne pas placer sur l’appareil de sources de flammes nues, telles que

des bougies allumées.

L’appeil ne doit pas être exposé à des égouttements d’eau ou des éclaboussures

et qu’aucun objet rempli de liquide tel que des vases ne doit être placé sur l’appareil.

Assurez que lappareil est fourni de la propre ventilation. Ne procédez pas à
l’installation près de source de chaleur tels que radiateurs, registre de chaleur, fours
ou autres appareils (incluant les amplificateurs) qui produisent de la chaleur.

Les dispositifs marqués d’une symbole “d’éclair” sont des parties dangereuses
au toucher et que les câblages extérieurs connectés à ces dispositifs de
connection extérieure doivent être effectivés par un opérateur formé ou en utilisant
des cordons déjà préparés.

Cordon d’Alimentation

Ne pas enlever le dispositif de sécurité sur la prise polarisée ou la prise avec tige de
mise à la masse du cordon d’alimentation. Une prise polarisée dispose de deux lames
dont une plus large que l’autre. Une prise avec tige de mise à la masse dispose de
deux lames en plus d’une troisième tige qui connecte à la masse. La lame plus large ou
la tige de mise à la masse est prévu pour votre sécurité. La prise murale est désuète si
elle n’est pas conçue pour accepter ce type de prise avec dispositif de sécurité. Dans
ce cas, contactez un électricien pour faire remplacer la prise murale. Évitez
d’endommager le cordon d’alimentation. Protégez le cordon d’alimentation. Assurez­vous qu’on ne marche pas dessus et qu’on ne le pince pas en particulier aux prises.
N’UTILISEZ PA S L’APPAREIL si le cordon d’alimentation est endommagé. Pour
débrancher complètement cet appareil de l’alimentation CA principale, déconnectez le
cordon d’alimentation de la prise d’alimentation murale. Le cordon d’alimentation du
bloc d’alimentation de l’appareil doit demeurer pleinement fonctionnel.

Débranchez cet appareil durant les orages ou si inutilisé pendant de longues périodes.

Service

Consultez un technicien qualifié pour l’entretien de votre appareil. L'entretien est
nécessaire quand l'appareil a été endommagé de quelque façon que se soit. Par exemple
si le cordon d’alimentation ou la prise du cordon sont endommagés, si il y a eu du liquide
qui a été renversé à l’intérieur ou des objets sont tombés dans l'appareil, si l'appareil a été
exposé à la pluie ou à l'humidité, si il ne fonctionne pas normalement, ou a été échappé.

S2125A

Introduction

Your new AP812/818 Mixer/Amplifier is designed and built to provide long-term trouble
free performance. Drawing on over thirty years of experience in the design and manufac­ture of powered mixing consoles, Yorkville engineers were able to optimize the design
of the AP812/818. Including comprehensive features such as rack-mountability, quiet
internal fan cooling, two stereo input-channels with cue buttons, headphone monitoring
(of both the cue and monitor busses), phantom powering, dual 9-band EQ’s, power amp
channels and EQ’s assignable to Left/Right stereo operation or Main/Monitor mono opera­tion, 255-preset digital signal processing, dual level-meters, 800 watts of stereo power
built-in, both 1/4-inch phone plugs and Speakon® output connectors.

Terminology

• 3-pin microphone inputs are referred to as XLR connectors.

• 1/4-inch jack sockets are called phone connectors.

• Balanced 1/4-inch inputs or outputs are called TRS or Tip-Ring-Sleeve

• Master control and mixing channels are called busses.

• Overload indicators are called Clip LED’s.

• Patch cables with dual conductors plus shielding and ring-tip-sleeve (stereo) 1/4-

inch phone plugs are referred to as balanced patch cables.

Basic Features

Channels 1 - 8 (1 - 14)

• XLR MIC and balanced TRS LINE inputs with low-noise input circuit design.

• Balanced LINE inputs accept either balanced or unbalanced lines.

• PHANTOM power (24 volts).

• Extremely wide input GAIN-adjustment.

• MONitor send controls are post-EQ and pre-fader.

• Three-band EQ with +/-15 dB of range and a sweepable mid (80 Hz - 8 kHz).

• Post-EQ, post-fader, EFX (effects) send controls.

• PAN controls provide constant gain levels at all settings.

• Increased circuit headroom and gain for a more flexible mix.

• Gold internal bus-interconnects for long life and maximum signal integrity.

• CLIP LED’s indicate even the briefest peaks, and fire at -3 dB, well before the

onset of actual clipping, at any and all active channel stages.

Stereo Channels (9/10, 11/12, 15/16 & 17/18)

(see diagram on following page)

• Left and Right 1/4-inch balanced TRS LINE inputs accept either balanced

or Unbalanced lines.

• The LEFT TRS input may be used for connecting a mono source and will inter-
nally patch it to the RIGHT channel input circuitry.

• LEFT and RIGHT RCA inputs.

• LOW, MID and HIGH frequency shelving EQ (+/- 15 dB).

• BALANCE control

• CUE buttons let you preview these channels through headphones with the

level faders shut off.

1

Master Features

• SELECT and MODIFY masters provide up 255 presets of reverb, delay

and other effects.

• Separate EFX TO MAIN and EFX TO MONitor masters.

• internal effects subsystem, based on the A.R.T. 16-bit digital effects processor,

delivers crystal clear performance.

• MASTER EFFECTS fader lets you insert the internal effect quickly and easily.

• MASTER EFX SEND con-
trol with it’s own CLIP

LED to help prevent
overloading the circuitry
at this stage.

• LEFT and RIGHT MAIN
faders - in fact all fad-
ers - feature 0 dB refer-
ence markings.

• MONitor master fea­tures its own CLIP LED
to help you avoid moni­tor distortion.

• The PHONES level
controls the headphone
amplifier which moni­tors the CUE bus when a
CUE button is depressed
and the MONitor bus
when it is not.

• The MAIN - MONitor
EQ/AMP push-button

lets you configure the

AP812 as either left-right
stereo with a separate

nine-band EQ for each
channel, or as a mono
system with one ampli­fier channel and EQ for
the MAIN PA speakers
and the other amplifier
channel and EQ for the
MONITOR speakers.

2

Power Amplifier Features

• A total output of 800 watts with well-proven, reliable AUDIOPRO technology.

• Industry leading specifications for distortion, damping, and efficiency.

• Comprehensive protection against low or even shorted loads, overheating and

DC damage to speakers.

• A combination of standard 1/4-inch and high-current Speakon® output connectors.

Feature Details & User Tips

Channel Strips

Inputs

Each channel has both a MIC and LINE input (except for channels 9/10 & 11/12

(15/16 & 17/18) which have RCA type inputs as well as 1/4-inch TRS inputs). The

LINE input will accept either balanced or unbalanced signals from all types of sources
and the MIC input is optimized for low-impedance microphones. The LINE input
is Tip-Ring-Sleeve balanced, with the Tip in phase, the Ring reverse phase and the
sleeve, Ground. The XLR is wired Pin 1= Ground, Pin 2 = in phase & Pin 3 = reverse

phase. This configuration is the standard throughout the world.

User tip: Problem; Hum and Buzz When Source is Unbalanced...
Unbalanced connections may be made to the LINE input with an unbalanced shield-

ed cable. However, field or leakage-induced ground currents between separate pieces
of equipment can sometimes produce hum and buzz. Most electronic instruments, for
example, still use unbalanced connections. If the equipment has more than one out­put feeding the mixer, even floating the circuit ground may not help.

CAUTION: We urge you to NEVER remove the ground-pin on the AC cord or other­wise disable the earth safety Ground connection as doing so can expose you to a seri­ous shock hazard. Additionally, your radio interference problems will likely increase
and in some cases your hum problems will get even worse.

What to do: Hum and buzz can be safely reduced or eliminated with the AP812/818’s
input balancing, even when the signal source is unbalanced, Simply use standard Tip­Ring-Sleeve balanced patch cables. However, in some worst-case instances it may be
necessary to create a special patch cable. In this case, use a 1/4-inch TRS (stereo) cable.

Attach a 1/4-inch TRS (stereo) plug to the end which will plug into the mixer’s
balanced-input as follows; 1) solder shield to Sleeve, 2) solder wire #1 to Tip, 3)
solder wire #2 to Ring. Now attach the mono plug to the other end of the cable as
follows: 4) solder the shield and wire #2 to the Sleeve, 5) solder wire #1 to the tip.
Now connect this mono end to the output of the unbalanced piece of equipment and
the stereo end to the AP812/818’s LINE input.

This technique will always reduce hum, and it can be used to connect any equipment
having a Balanced INPUT to any other equipment having an Unbalanced OUTPUT.

Phantom Power Button & LED

Located on the back panel near the SPEAKER outputs, this push-button activates the

24 Volt PHANTOM POWER feature built into the AP812/818. When the PHANTOM
POWER is activated, the +24V LED on the front panel (just below the PHONES jack) will

illuminate. Now you may connect condenser microphones to any channels without the
need for external power supplies. You may also connect dynamic mics to any channels
with the PHANTOM POWER activated without any problems or loss of sound quality.

Gain Control

With signal applied to the input, adjust this control so that occasional flashes of the
CLIP LED are observed. This will ensure that the signal level fits comfortably within
the channel strip’s headroom ~ low enough to prevent distortion, and yet high
enough to preserve the signal to noise ratio. This control covers a wide range, so it
may seem rather sensitive until you’re used to it.

Monitor Send

The MON send control is post-EQ & pre-fader. This means that the bit of channel sig­nal it sends to the MASTER MONitor bus is tapped off at a point after the channel EQ
circuitry, and before the level fader. As a result it is not affected by the channel fader.

3

This means that you custom-equalize for the monitor system using the AP812/818’s
EQ2 equalizer or an external EQ patched between the AP812/818’s MON OUT jack

and the external power amp you are using for monitors.

User tip: In order to shut a channel off completely, it will be necessary to turn down
the MON send, as well as the channel fader.

3-Band EQ

Equalization is varied by four controls labeled HIGH, MID, SWEEPABLE MID (variable
from 80 Hz to 8 kHz), and LOW. Each control can either boost or cut the amplitude
of its frequency band by 15 dB. This is a considerable amount of gain change, roughly
equivalent to a 150% variation in audible loudness. It is therefore wise to use boost set­tings of not more than +3 dB to +6 dB in order to avoid feedback and/or distortion.

User tip: On the other hand, -15 dB of CUT-capability can come in handy for solving
certain mic or line problems. For example, substantial LOW and HIGH cuts can help
get rid of feedback plus puffing and thumping noises from harmonica mics. Flattop
guitar mics or transducers can often benefit from a slight MID cut to fatten the sound,
and direct or miked bass inputs usually benefit from a fairly substantial LO cut to
avoid main system distortion.

3-Band EQ - Channels 9/10, 11/12, (15/16 & 17/18)

LOW, MID & HIGH shelving EQ is provided for the stereo channels. Here again, the
gain range is plus/minus (+/-)15 dB. As a result, care should be taken in adjusting the
EQ above center position as a small adjustment can represent a large gain change.

Effects Send

The EFX send control varies the amount of post-EQ, post-fader channel signal
sent to the master EFX bus. The output of the EFX bus goes first to the EFX SEND
/ FOOTSWITCH jack and then to the internal 16-bit processor. The output of the
effects processor then goes to the MAIN master section to be mixed with the signals
going there direct from the input channels.

Cue Button - Channels 9/10, 11/12, (15/16 & 17/18)

The CUE feature enables you to preview channel signals via headphones before they
go to the main and/or MONitor bus. The CUE signal is post-EQ so that the channel
equalization will be in effect through the headphones. However, it is pre-fader so you
will need to shut the channel off through the mains and monitors when cueing. Use
the PHONES LEVEL to adjust cueing volume.

To employ this feature, simply follow these steps:

a) Connect a tape or CD-player to channel 9/10 and/or 11/12 (15/16, 17/18).
b) Pull the channel fader all the way down and turn the MON send off.
c) Depress the CUE button. Now that channel will have prominence through

your headphones.

d) Cue up your tape or CD track through the phones, then put it on play hold/

pause.

e) When you are ready to insert the recorded material, simply punch the CUE

button into the up position, then take the recorded material off play hold/
pause and bring up the channel fader and MON send to the desired mix lev-
els.

User tip: When you have inserted the cued material into the monitors, you will be
able to adjust its monitor mix level via headphones since the monitor bus signals
are always present through the phones when no channels are on CUE. The recorded
material’s main mix level will be audible to you through the main speaker system.

Pan or Balance Controls

This control directs the post-fader output of the channel between the LEFT and
RIGHT MAIN masters. In a stereo setup, the PAN/BALance can be used to position
the aural image of the channel left or right within the stereo listening field.

4

Channel Faders

This adjusts the levels of both the post-EQ channel
signal headed directly for the LEFT and RIGHT MAIN
master bus (via the PAN/BAL pot), and the EFX send
signal headed for the master EFX bus. The channel fader
does not control the MONitor send level.

Clip LED

The channel CLIP LED watches all the active electronic
stages in the channel circuit. Whenever any stage’s
signal peak approaches clipping to within 6 dB, the
CLIP LED circuitry captures and displays this event. See
under GAIN control for more about this feature.

Monitor Master & Clip LED

This control regulates the overall level of the master

MONitor bus. The CLIP LED, like the others, fires at 6 dB
below the onset of actual clipping so that a small amount

of activity is quite acceptable. If the LED flashes frequent­ly, reduce the MON MASTER setting, or possibly one or
more of the channel MON send settings. The output of
the MON MASTER bus goes to the MON OUT jack. It
also goes to the EQ/AMP ASSIGN button where it can
be directed to the EQ2 equalizer and then to the RIGHT­channel of the built-in stereo power amplifier. Regardless
of the EQ/AMP ASSIGN button’s operation, the MONitor
signal remains available at the MON OUT jack so that it
can be used to drive an additional amp/speaker system.

Mon Out Jack

Located in the upper right area beside the PHONES
jack, MON OUT is the output of the monitor bus. It
is at line level (do not connect speakers to it directly)
and unbalanced. Connect your monitor power amp
or powered monitors here.

User tip: If another monitor system is in use, perhaps
full-range enclosures running off the main PA mix
as side-fills, you could connect a tape deck here
to record live performances. Plug a single 1/4-inch

male-to-dual 1/4-inch female Y adapter into the
MON OUT jack. Now simply run two of the appro-
priate patch cables (probably 1/4-inch male-to-RCA
male) into the tape deck’s L & R line level inputs.

You will now have the advantage of being able to
mix for recording, independent of the PA mix.

Left & Right Main Masters

EQ/Amp Assign Button

The MAIN master faders receive signals from the chan­nel PAN/BAL controls and determine the output signal
levels at the L & R PRE-EQ LINE OUTPUT jacks.

User tip: Regardless of the ASSIGN button’s func­tion, the PRE-EQ LINE OUTPUT jacks will always
carry the unequalized L & R stereo mix. This can be
useful if you are recording the live performance.

The MAIN faders also determine the signal levels
destined for the EQ/AMP ASSIGN button where they
are directed as follows:

5

a) Up in the L & R position, the ASSIGN button directs the Left & Right MAIN

master signals to EQ1 and EQ2 respectively. Thereafter, they go in two direc­tions at once to the L & R (AMP 1 and AMP 2) inputs of the built-in power
amplifier and to the L & R POST EQ LINE OUTPUT jacks.

b) Down in the MAIN/MON position, the ASSIGN button also does two things.

First, it sums some of the LEFT and RIGHT MAIN signals into a single mono
signal and directs it to the input of EQ1, the output of which is then split and
goes to both the LEFT power amp channel and to the POST EQ MAIN (L)
LINE OUTPUT jack. Secondly, the button takes some of the MON MASTER’s
output signal and routes it to the input of EQ2, thereafter to be split and rout­ed to the RIGHT channel of the built-in power amplifier and to the POST EQ

MON (R) LINE OUTPUT jack.

User tip: The stereo operating mode of the AP812 would be with the EQ/AMP ASSIGN
button up in the L & R position. This would supply up to 800 watts of stereo power (400
watts/channel) plus separate L & R 9-band EQ’s for the main system speakers. Power and
equalization for the monitors would come from a separate power amplifier and graphic
EQ. With the EQ/AMP ASSIGN button down in the MAIN/MON position, you now have
400 watts of mono power @ 4 ohms plus a single 9-band EQ for the main PA speakers,
also 400 watts @ 4 ohms and a single 9-band EQ for the monitors. Connect main PA
speakers to the AMP 1 SPEAKER OUTPUT's and monitors to AMP 2 SPEAKER OUTPUTS.
See under SPEAKER CONNECTIONS for suggested speaker impedances.

Pre & Post EQ Line Outputs

These are the outputs of the L & R main mixing busses. They are all at line level (do
not connect speakers directly) and unbalanced. The PRE EQ outputs are not affected

by either of the graphic equalizers. The stereo main mix is available from them at all
times, regardless of the EQ/AMP ASSIGN button setting. These would be available

for connecting a secondary mixer perhaps for a house PA, broadcast and/or recording

purposes. These outputs, although not balanced, have been designed to supply the
noise-canceling benefits of balanced outputs as long as the inputs of the unit (power
amp or mixer) you are con­necting them to have bal-
anced inputs, and you use
TRS balanced cables.

6

The POST EQ output

signals are affected by the
graphic equalizers. They are

also affected by the EQ/AMP
ASSIGN button. With the

button up in the L & R MAIN
position, these jacks receive
the output of EQ1 at the L
MAIN jack and EQ2 at the R MON jack. With the EQ/AMP ASSIGN button down in
the MAIN/MON position, the L MAIN jack receives mono (left & right mixed togeth­er) main mix signal from EQ1 and monitor signals from EQ2. The POST EQ outputs
are best for driving power amplifiers whether for main or monitor speaker systems.

EQ1 & EQ2 Graphic Equalizers

The Q factor is greater in cut-mode than in boost-mode, which is desirable when
using the EQ for feedback control. Up to 12 dB of cut or boost is available. For more
information about their internal routing, see under LEFT & RIGHT MAIN MASTERS
and EQ/AMP ASSIGN BUTTON above.

User tip: As with all graphic EQ’s, minimal variations above or below center settings
are always recommended. The only exception to this rule might be in the fight against
feedback, but even there the ideal solution is to separate the offending speaker from
the offending mic or at least aim them in different directions. This way the whole sys­tem’s natural frequency response does not have to be compromised because of one mic
and one speaker. Ideally, a Real-time Frequency Analyzer and Pink Noise would be
employed before the audience arrives to help you pre-adjust the EQ (s) to cut obvious
system/room response spikes likely to cause feedback later on. Without such devices

you can achieve a vaguely similar result by simply turning up the level until a mic feeds

back, then reacting accordingly (this may or may not involve the EQ’s). In any case, the

prime suspect whenever feedback starts is always a monitor. A graphic EQ with a MIC

level input can be inserted between the offending mic and the mixer input to solve that

channel’s problem without altering the whole monitor system response.

Effects Bus Routing Overview

The AP812/818’s effects bus receives and mixes down all the channel EFX SEND sig­nals. Its output is regulated by the MASTER EFX SEND control and is internally routed,
first to the EFX SEND / FOOTSWITCH jack. This is a switching jack which normally
allows the signal to proceed
internally to the effects pro-

cessor. But when a jack is

inserted here, the switching
function reroutes the effects
bus signal out the jack to
either an on/off footswitch or
whatever you have patched
it to, probably an external
effects unit, or possibly
something else if you have
decided to do without effects
and perhaps feed a broadcast
transmitter or recording unit.
In any case, the output of the
internal digital effects proces­sor is permanently routed
to the MASTER EFX fader
and thereafter to the LEFT &

RIGHT MAIN MASTER bus­ses, also to the EFX to MON

master control and thereafter
to the monitor bus.

Master EFX Send Control & Clip LED

For the quietest performance,
you should run the MASTER EFX SEND level as high as possible without causing distor­tion. With the channel EFX SEND controls turned up roughly half-way and signals com­ing into the channels, increase the MASTER EFX SEND level until some EFX CLIP LED
activity is observed, then turn it back down slightly until the flashing stops. You may now
re-adjust the channels EFX levels as desired. The MASTER EFX SEND may now be used to
tailor the EFX mix on all channels at once.

Digital Effects Processor

The internal Digital Effects Processor is a full 16 bit, 20 kHz bandwidth DSP-based effects
subsystem developed by Applied Research & Technology in Rochester, New York. It has
been custom programmed with 255 effects ranging from reverb to echo and special effects.

The selection of effects was determined in collaboration with a panel of sound engi-

neers experienced in live performance mixing. The panel was asked to choose effects

which would be of the most practical use in actual live performance situations. As

a result you will find the

internal system to be more

than adequate for most

applications.

EFX Footswitch/ Send Jack

A standard on/off footswitch

(optional) plugged into this

jack will enable you to turn
the internal effects system

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on and off. Optionally, this jack may be employed to feed the EFX signal to an
external effects unit the output of which could be returned via an input channel ­perhaps channel 9/10 or 11/12 (15/16,17/18) if the effects unit is stereo. In this
mode, the channel fader would become the master effects return control, therefore

be sure to set that fader fairly low and adjust to desired levels. Be sure to turn the

EFX send control off in order to avoid creating a loop. Also, be sure to pull the EFX
MASTER fader down to the off position.

Phones Jack, Level Control & Sources

The PHONES jack accepts standard stereo headphones and is located in the upper
right area of the panel. The PHONES level control is located in the lower right area.
The source for all headphone signals is the MONitor bus until a CUE button is
depressed at which time only the cued channel can be heard through the phones.

Level Meters

These meters follow either the Left and
Right MAIN bus activities or a mono mix of

the mains on the Left-meter and monitors
on the Right-meter, all depending on the
position of the EQ/AMP ASSIGN button. If
either or both CLIP lights at the top of the
level meters is flashing too much of the
time, lower the appropriate MAIN MASTER
level to avoid possible distortion on peaks.

Amp 1 & 2 Inputs

These are switching jacks which enable
you to directly access either or both chan­nels of the built-in power amplifier while
disconnecting them from normal internal
functions. This permits you to insert an
external-EQ, a processor /crossover (e.g.

élite) or a compressor/limiter between the

mixer section’s POST EQ LINE OUTPUTS
and the AMP 1 & AMP 2 INPUTS thus pro­viding the 100% signal processing essential
for these functions to work properly.

User tip: If you have an electronic-cross­over or processor/crossover, you can drive
subwoofers and full-range cabinets in a
biamped system with the AP812/818. The hookup goes as follows:

1. With the EQ/AMP ASSIGN button down in the MAIN/MON position, run a patch
cable from the POST EQ MAIN (L) LINE OUTPUT to the input on an electronic
crossover/processor.

2. Now run a second patch cable from the low-frequency or subwoofer output on
the crossover to the AP812/818’s AMP 1 INPUT and a third patch cable from the
crossover’s high-frequency or full-range output to the AP812/818’s AMP 2 INPUT.

3. Now connect two 8 ohm subwoofers or one 4 ohm subwoofer to the AMP
1 SPEAKER connector/s and two 8 ohm full-range cabinets to the AMP2
SPEAKER connector/s.

4. The complete system is now functional, not including monitors. How-ever, if you

need to vary the comparative volume levels of the subwoofer/s relative to the full­range cabinets, another setup will be required with an external power amp for
the subwoofers or employing powered subwoofers. In that system, AMP 1 would
be for full-range speakers and AMP 2 would be for monitors. In other words, this
is a standard setup but with the MAIN (L) LINE OUTPUT going to the input of
the processor/crossover and then to an external amp driving the subwoofer/s, or
simply direct to the input of a powered subwoofer (ours have crossovers built in).

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Power Amplifier - General

The AP812/818 has a built-in 800 watt stereo power amplifier. Each channel has an
input sensitivity of +4 dBv (1.4 volts RMS) for full-power output and each can deliver
over 400 watts into a 4 ohm speaker load. These amplifiers incorporate computer
designed internal heatsinks and a variable-speed fan which automatically provides
quiet operation consistent with cooling requirements. Cool air is drawn into the front
of the mixer, and heated air is expelled along the bottom of the back. Even at maxi­mum power, this arrangement results in quiet, dependable performance.

PLEASE NOTE: THE AIR VENTS AT THE FRONT AND BOTTOM REAR OF THE
MIXER ARE ESSENTIAL FOR PROPER
OPERATION. BLOCKING THE
FREE FLOW OF AIR THROUGH
THE MIXER WILL RESULT IN
SYSTEM SHUT-DOWN DUE
TO OVERHEATING. REPEATED
OVERHEATING MAY EVENTUALLY
CAUSE DAMAGE. PLEASE KEEP THE
VENTS FREE OF OBSTRUCTIONS.

Speaker Connections

Two 1/4-inch jacks and one Speakon®
connector are in parallel with each amp-channel output stage. This allows the use of
speaker cables equipped with either type of connector. For full-power applications we
recommend 14-gauge cables equipped with the Speakon® connectors. This will reduce
risk of resistance buildup. The Speakon® system, developed in recent years by Neutrik

in Switzerland, features block-style contacts capable of handling large amounts of

power and the connectors lock down to prevent accidental kick-outs.

Connect one or two 8 ohm speakers or one (only) 4 ohm speaker to each chan-

nel. When connecting the Speakon’s®, push them in firmly and twist in a clockwise

motion. Push the tab and twist counter-clockwise to disconnect.

User tip: To connect two (8 ohm) speakers to one or both of the AP812’s powered
output channels via the Speakon
cable, e.g. Yorkville model SP2-25SS or SP2-50SS with Speakons® at both ends
(most higher-powered speaker enclosures now feature Speakons® as well) from the
AP812/818 to one of the enclosures. Now run a second cable from one cabinet to the
next via their dual, parallel inputs.

®

connectors, run a single Speakon® -equipped

Power Amplifier Protection

The AP812/818’s power amplifier is protected from damage due to open, shorted or
excessively low speaker loads. It will continue to run into a low (less than 4 ohms)

overall speaker impedance or even a total short-circuit for a brief time, however the
amplifier’s defense system will be activated. First, the built-in limiter will reduce output
power levels and the fan speed may increase. Then, if the condition worsens, a thermal
protection circuit will shut the power amplifier down. When this happens, check your
system for restricted air intake/exhaust at the AP812/818. Also check for shorted cables
or connectors and/or reduce the number of speakers being driven. In a few minutes
when it has had a chance to cool down, power amp function will resume.

User tip:
a) If the power amplifier shuts down as above, the mixer section will continue to

function. This means that, if the AP812/818’s power amp fails to come back on
(unlikely) and you have a spare power amplifier available, you can connect it to
the AP812/818 via the LINE OUTPUT jacks. See under PRE and POST EQ LINE

OUTPUTS for further information regarding connections.
b) Because the amplifier is also protected against open-circuit conditions, you

may use the AP812/818 without any speakers connected, for example if you
wanted to do some recording.

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