Ashly PQX-572, PQX-571 User Manual

PQX-571
PQX-572

Parametric Equalizer

Operating Manual

ASHLY AUDIO INC.

847 Holt Road Webster, NY 14580-9103 Phone: [phone]

Toll-Free: [phone] Fax: [phone] Inter net: http://www.ashly.com/

Operating Manual - PQX 571 and PQX 572 Parametric Equalizer

Table Of Contents

1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 UNPACKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 AC POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4 CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.1 Balanced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.2 Unbalanced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4.3 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5 CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5.1 Low Shelving Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5.2 Parametric Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5.3 High Shelving Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5.4 Master Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5.5 Clip Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

6 TYPICAL APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6.1 Connecting Into a Sound System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6.2 General Tone Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6.3 Feedback Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

6.4 Console Channel Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6.5 Large Room Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6.6 Small Room Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

7 THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

8 TROUBLESHOOTING TIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

9 DIMENSIONAL DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

10 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

11 WARRANTY INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

12 SCHEMATICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-11

- WARNING -

THIS APPARATUS MUST BE EARTHED

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Operating Manual - PQX 571 and PQX 572 Parametric Equalizer

1. INTRODUCTION

Congratulations on your purchase of an Ashly
PQX series parametric equalizer. Like graphic equaliz­ers, parametric equalizers allow you to boost or cut se­lected frequencies. Unlike graphic equalizers however,
parametric equalizers can tune in the exact frequencies
you want and control the bandwidth of each selected fre­quency band, resulting in very precise control of frequency
response.

The Ashly PQX series equalizers are a third gen­eration design including many refinements on our origi­nal PQ models. Lower noise, greater headroom, addi­tional filters, full 20Hz -20KHz range on all parametric
filters and additional connector types are the result. The
parametric filters are still based on the “state variable”
type circuit, and a separate summing amplifier is used
for each filter so that no interaction between bands oc­curs.

2. UNPACKING

As a part of our system of quality control, every
Ashly product is carefully inspected before leaving the
factory to ensure flawless appearance. After unpacking,
please inspect for any physical damage. Save the ship­ping carton and all packing materials , as they were care­fully designed to reduce to minimum the possibility of
transportation damage should the unit again require pack­ing and shipping. In the event that damage has occurred,
immediately notify your dealer so that a written claim to
cover the damages can be initiated.

The right to any claim against a public carrier
can be forfeited if the carrier is not notified promptly and
if the shipping carton and packing materials are not avail­able for inspection by the carrier. Save all packing mate­rials until the claim has been settled.

3. AC POWER

Your PQX equalizer should be connected to a
standard 3-wire grounded electrical outlet supplying 120
Volts, 50-60 Hz (some export models are wired for 240
Volts, and are labeled as such). To reduce the risk of
ground loop hum, connect all audio equipment to the same
electrical power source. Removal of the ground pin is
both unlawful and dangerous, as a potential shock hazard
could result.

This unit will perform normally within an AC
voltage range of 94 to 130 volts. Voltages less than this,
as found in “brown-out” conditions, will reduce headroom
and decrease power supply regulation. While this may
affect performance, the equalizer will continue to func­tion during a brown-out. This unit has an internal line

fuse. In the unlikely event that the fuse should blow,
refer the product to a qualified technician for servicing.
Overall power consumption is less than 15 watts.

4. AUDIO CONNECTORS AND CABLES

4.1 Balanced

Ashly uses electronically balanced inputs on all
equalizers. The inputs and outputs can be used balanced
or unbalanced. Your PQX series equalizer is provided
with three different connector types. 1/4 inch stereo phone

jacks, three pin XLR type connectors, and a terminal strip
will allow interfacing to most professional audio prod­ucts. The (+) signal is on the tip of the phone plug and
pin 2 of the XLR connector. The (-) signal is on the ring
of the phone plug and pin three of the XLR. To achieve
best performance, we recommend using balanced connec­tions between all components in your system, as this re­duces ground-loop induced hum and common-modenoise.

4.2 Unbalanced

If either inputs or outputs are used unbalanced,
the signal is on the (+) connection and the (-) connection
must be tied to ground. A mono phone plug used as an
unbalanced connection will automatically ground the ring
of the jack which is the (-) connection. When using a
stereo plug, XLR connector, or the terminal strip for un­balanced input or output connections, the signal (-) MUST
be tied to the sleeve, or a significant loss of signal level
may result.

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Operating Manual - PQX 571 and PQX 572 Parametric Equalizer

4.3 Grounding

The terminal strip has two ground con­nections, one for input ground and one for chassis
ground. The equalizer is shipped with a jumper
strap connecting these two grounds. Normally,
this strap should be left in place so the chassis
and input grounds are connected. In a rack-mount
installation where the equalizer is connected to
other equipment with unbalanced inputs or out­puts, and the rack itself provides a good electrical
connection between the equalizer chassis and the
other equipment, it may be desirable to remove this strap
to isolate the input ground from chassis ground and avoid
a ground loop. Unless you have such an installation and
have a hum problem you can’t solve by other means (ie:
using balanced input and output connections), leave the
ground jumper strap in place.

5. CONTROLS

5.2 Parametric Filters (Filters No. 2-6)

1. Range Switch

Each parametric filter has a normal center fre­quency range of 200Hz-20KHz. Depressing the range
switch divides the center frequency by 10, providing a
range of 20Hz-2KHz.

5.1 Low Shelving Filter (Filter No. 1)

1. Low Shelf Level

The nature of a shelving filter is such that the fre­quency response ramps up to a plateau and then levels off
again, hence the term “shelf”. This level control knob ad­justs the boost or cut of the signal below the tuned filter fre­quency as selected by its outer concentric frequency knob.
The level which is indicated on the panel dial is the decibel
level of the flat portion of the shelf. (see drawing)

2. Low Shelf Frequency

This control adjusts the frequency below which
the shelving filter affects the level. The frequency which
is indicated on the panel dial is the midpoint of the shelf’s
sloping response.

2. Level Control

The band of frequencies selected by the frequency
and bandwidth controls are increased or decreased up to
15dB by this control.

3. Frequency Control

This outer concentric knob adjusts the center fre­quency of the filter action. Tick marks on the face panel
are calibrated to ISO 1/3 octave center frequencies.

4. Bandwidth Control

This inner concentric Knob allows control of the
width of frequencies around the center frequency (some­times called “Q”), and is a key reason parametric equaliz­ers are such a precise tool. With it, you can affect a wide
(3.3 octaves) response, or a narrow (.05 octaves) band.
To give an example, you could effectively boost or cut by
15dB a middle C on the piano without affecting the adja­cent B or D at all!

5. EQ In/Out Switch

The individual filter is engaged by depressing this
switch. Since the filter is bypassed when the EQ switch
is out, it is recommended that the EQ switch be out when
no filter action is required. This is preferable to “zero­ing” the level control when considering optimum noise

Low Shelf Level Response

performance.

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