Universal Audio 1176AE User Manual

Model 1176AE

Anniversary Edition Limiting Amplifier

Universal Audio Part Number 65-0010

Revision 1.0

Universal Audio, Inc.

Customer Service & Tech Support: 1-877-MY-AUDIO

Business, Sales & Marketing: 1-866-UAD-1176

www.uaudio.com

Notice

This manual provides general information, preparation for use, installation and operating instructions
for the Universal Audio 1176AE.

The information contained in this manual is subject to change without notice. Universal Audio, Inc.
makes no warranties of any kind with regard to this manual, including, but not limited to, the implied
warranties of merchantability and fitness for a particular purpose. Universal Audio, Inc. shall not be
liable for errors contained herein or direct, indirect, special, incidental, or consequential damages in
connection with the furnishing, performance, or use of this material.

Copyright

© 2008 Universal Audio, Inc. All rights reserved.

This manual and any associated software, artwork, product designs, and design concepts are subject
to copyright protection. No part of this document may be reproduced, in any form, without prior written
permission of Universal Audio, Inc.

Trademarks

1176AE, 1176LN, 2-1176, 6176, 2-610, LA-610, LA-2A, 2-LA-2, LA-3A, 4110, 8110, SOLO/610,
SOLO/110, 2192, DCS Remote Preamp, UAD and the Universal Audio, Inc. logo are trademarks of
Universal Audio, Inc. Other company and product names mentioned herein are trademarks of their
respective companies

Contents of This Box

This package should contain:

• One 1176AE Solid-State Limiting Amplifier

• 1176AE Operating Instructions

• IEC Power Cable

• Registration Card

Thank you for purchasing the 1176AE Solid-State Limiting Amplifier.

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This very special, limited-run 1176AE unit is a celebration of Universal

Audio’s 10-year anniversary since refounding, fifty years since the
original founding of the company, and over 40 years since the original
release of the most recognized studio limiter ever made. This hand-built,
customized unit is one of only 500–a fitting tribute to the legend that is
the 1176, and Bill Putnam Sr.’s amazing audio design legacy.

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Final Assembly by

Tested by

Universal Audio, Inc. • 1700 Green Hills Rd. • Scotts Valley, CA • 95066-4926

A Letter From Bill Putnam, Jr.

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It is hard to believe that it has been over 40 years since my father first designed the 1176 limiter. One
of the characteristics that my father exhibited was a love for new technologies and innovation. I can
only imagine my father’s excitement about the potential represented by transistors and
semiconductors, which has often been called the most important invention of the 20
father got to watch the emergence of semiconductors from a lab in Murray Hill New Jersey (Bell), into
devices that became consistent and dependable. He was aware that FETs (field effect transistor)
exhibited a voltage-variable resistance characteristic that made them appropriate for use in
compressors and limiters.

The challenge presented by these early devices was threefold – 1) how to create a circuit which was
repeatable and predictable even with variation in part characteristics and 2) how to minimize the
noise which was a natural result of the nonlinear behavior exhibited by the FETs, and 3) to do so in a
way which sounded good. These were the key design challenges at heart of the innovation embodied
in the 1176. I wish that I could say that I had clear memories of his work on this project, but alas, I
was 3 years old when he started selling the first 1176s. This is a personal reminder of how long this
product has been around, while still maintaining its relevance (especially!) in the modern digital
recording environment. However, I do remember visiting the lab that he had set up near our home in
Tarzana, California where he did much of the work on the 1176 along with other early products. This
exposure to creative innovation and excitement about new technologies made a big impact on me.

It has been 10 years since my brother and I started putting together plans and ideas to re-create
Universal Audio as a company that would bridge the growing divide between analog and digital
electronics, old vs. new. The 1176LN was the first hardware product we decided to make; largely due
to the pride my father took in not only its commercial success, but also its creative and technical
success. As a matter of chance, the day that we shipped our first 1176LN out of my garage in Santa
Cruz, was February 20th, 2000, which was also my father’s birthday (he would have been 80). The
reformed Universal Audio has been shipping 1176s for over 8 years now!

At some point in time as limiters and compressors were leaving their sonic imprint on the music that
we listened to and grew up with, they expanded their role from strict tools into ‘tone boxes’, providing
a broad creative pallet with which to craft and manipulate sound for artistic purposes. With that as
the backdrop, we are presenting the 1176AE (Anniversary Edition), which I feel is a unique
embodiment of our respect for the past, while also introducing several new sonic possibilities for the

1176.

I am often asked about the difference between “Blackface” 1176s and the earlier “Bluestripe” units.
One of the main differences is the nature of the program-dependent compression characteristics. In
the Anniversary Edition, we are going back to the program dependent characteristic of the Bluestripe,
which provides a subtle, but distinct character difference. We have added a user-selectable, “super­slow” attack setting, which creates all sorts of new uses for the unit. With a nod to the 176 limiter
(the tube forerunner of the 1176), the unit offers a gentler ratio array of 2:1, 4:1 and 8:1 while retaining
the high 20:1 setting. This also opens up the unit to greater sonic variety with more “multi-button”
configurations than any previous 1176 before it. I thank you for your purchase of this unit and support
for Universal Audio. I hope that it finds a nice home in your rack, and that it plays even a small part
in your pursuit of your creative and musical goals. Have fun! Make music!

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century. My

-Bill Putnam Jr.

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Important Safety Instructions
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Before using this unit, be sure to carefully read the applicable items of these operating instructions and the
safety suggestions. Afterwards, keep them handy for future reference. Take special care to follow the warnings
indicated on the unit, as well as in the operating instructions.

1. Water and Moisture - Do not use the unit near any source of water or in excessively moist environments.

2. Object and Liquid Entry - Care should be taken so that objects do not fall, and liquids are not spilled, into
the enclosure through openings.

3. Ventilation - When installing the unit in a rack or any other location, be sure there is adequate ventilation.
Improper ventilation will cause overheating, and can damage the unit.

4. Heat - The unit should be situated away from heat sources, or other equipment that produce heat.

5. Power Sources - The unit should be connected to a power supply only of the type described in the
operating instructions, or as marked on the unit.

6. Power Cord Protection - AC power supply cords should be routed so that they are not likely to be walked
on or pinched by items placed upon or against them. Pay particular attention to cords at plugs,
convenience receptacles, and the point where they exit from the unit. Never take hold of the plug or cord
if your hand is wet. Always grasp the plug body when connecting or disconnecting it.

7. Grounding of the Plug - This unit is equipped with a 3-wire grounding type plug, a plug having a third
(grounding) pin. This plug will only fit into a grounding-type power outlet. This is a safety feature. If you
are unable to insert the plug into the outlet, contact your electrician to replace your obsolete outlet. Do
not defeat the purpose of the grounding-type plug.

8. Cleaning - Follow these general rules when cleaning the outside of your 1176AE:
a. Turn the power Off and unplug the unit
b. Gently wipe with a clean lint-free cloth
c. If necessary, moisten the cloth using lukewarm or distilled water, making sure not to oversaturate it

as liquid could drip inside the case and cause damage to your 1176AE
d. Use a dry lint-free cloth to remove any remaining moisture
e. Do not use aerosol sprays, solvents, or abrasives

9. Nonuse Periods - The AC power supply cord of the unit should be unplugged from the AC outlet when left
unused for a long period of time.

10. Damage Requiring Service - The unit should be serviced by a qualified service personnel when:
a. The AC power supply cord or the plug has been damaged: or
b. Objects have fallen or liquid has been spilled into the unit; or
c. The unit has been exposed to rain; or
d. The unit does not operate normally or exhibits a marked change in performance; or
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The unit has been dropped, or the enclosure damaged.

11. Servicing - The user should not attempt to service the unit beyond that described in the operating
instructions. All other servicing should be referred to qualified service personnel.

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Table of Contents

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A Letter From Bill Putnam, Jr. .............................................................................................

Important Safety Instructions ..............................................................................................

Two Page, Two Minute Guide To Getting Started ....................................................................

Front Panel .......................................................................................................................

Rear Panel ........................................................................................................................

Interconnections ...............................................................................................................

Insider’s Secrets ..............................................................................................................

The Technical Stuff ............................................................................................................

History of the 1176LN .............................................................................................

Compressor / Limiter Basics ...................................................................................

About “All-Button” Mode (And Other Multi-Button Modes..............................................

About Class A .......................................................................................................

Making A Custom Insert Cable ................................................................................

Terminal Strip Connections ....................................................................................

Maintenance Information ........................................................................................

Calibrations .............................................................................................

Zero Set .......................................................................................

“Q” Bias ......................................................................................

Meter Driver Null ...........................................................................

Stereo Operation and Calibration ..................................................................

Changing the Voltage Selector ....................................................................

Changing Fuses ........................................................................................

1176LN Circuit Details ............................................................................................

Glossary of Terms .............................................................................................................

Recall Sheet ......................................................................................................................

Specifications ...................................................................................................................

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Additional Resources / Product Registration / Warranty / Service & Support………Inside cover back

The Two Page, Two Minute Guide To Getting Started
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No one likes to read owner’s manuals. We know that.
We also know that you know what you’re doing—why else would you have bought our product?

So we’re going to try to make this as easy on you as possible. Hence this two-page spread, which we
estimate will take you approximately two minutes to read. It will tell you everything you need to know
to get your Universal Audio 1176AE up and running, without bogging you down with details.

Of course, even the most expert of us has to crack a manual every once in awhile. As the saying
goes, “as a last resort, read the instructions.” You’ll find those details you’re craving—a full
description of all front and rear panel controls, interconnection diagrams, insider’s secrets, history,
theory, maintenance information, block diagrams, specifications, even a glossary of terms—in the
pages that follow.

Manual conventions:

 Means that this is an especially useful tip

 Means that this is an especially important bit of information

And when we need to direct you to a page or section elsewhere in the manual, we’ll use the universal
signs for rewind () or fast forward ().

Getting Started With Your 1176AE:

Step 1: Decide where the 1176AE is to be physically placed and place it there. The 1176AE is housed
in a standard two-rackspace 19" chassis, and so we recommend that it be securely mounted in a rack
if possible.

Step 2: On the rear panel, make sure the voltage selector switch is set correctly for the voltage in
your area. On the right side of the front panel, make sure the bottom Meter button (OFF) is pressed in,
and then connect the supplied IEC power cable to the rear panel AC power connector.

Step 3: Mute your monitors and then, using balanced cables with XLR connectors, make connections
to the 1176AE rear panel XLR line input and output. Most often, these connections will be to a patch
bay or to and from a channel or bus insert on a mixer. (Alternatively, the rear panel terminal strip can

be used for input and output connections; see page 20 for information about its use, and  see
page 8 for an interconnection diagram)

 Make only one type of input connection (XLR or terminal strip) to the 1176LN.

However, both outputs can be used simultaneously.

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The Two Page, Two Minute Guide To Getting Started

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Step 4: On the right side of the front panel, depress the +4 Meter button. This not only turns on the

power to the 1176 but also ensures that the meter displays the final output level. (NOTE: Depressing
any Meter button other than OFF also has the effect of powering on the 1176AE; when powered on, the
front panel meter lights up.)

Step 5: Set the Input and Output knobs to approximately 24 (their 12 o’clock position) for unity gain.

Step 6: Set the Attack and Release knobs fully counterclockwise and disengage all ratio buttons (in

the case of the 1176AE, this the sole method for bypassing gain reduction).

Step 7: Unmute your speakers and begin monitoring the 1176AE output. At the source, raise the level
of the input signal until the 1176AE meter shows optimum signal strength (around 0 VU, with
occasional excursions into the red, but with no audible distortion).

Step 8: With all ratio buttons out, signal is passing through the 1176AE circuitry but with a
compression ratio of 1:1, thus adding “color,” but with no gain reduction. Depress the 2 Ratio button
(2:1) and slowly raise the Attack knob to hear the effect of moderate compression on your signal.

Step 9: Experiment by selecting different Ratios, and by trying various “Multi-Button” combinations
(pressing in all more than one ratio button simultaneously). Also try varying the Input level and Attack
and Release times for different compression and limiting characteristics, including the “SLO” Attack
time found in the far counter-clockwise position (a solid “click” will accompany SLO mode). Note
that, unlike many other devices, the 1176AE attack and release times are faster when their associated
knobs are turned clockwise, and slower when they are turned counterclockwise. Set the Meter switch
to GR in order to view the amount of gain reduction being applied to the signal. Note that as you
increase the amount of gain reduction (by raising the Input level and/or selecting higher ratios), the
overall signal may be attenuated. If necessary, you can make up the difference by turning the Output
knob clockwise. Depress either the +8 or +4 Meter buttons in order to view the final output level. A
meter reading of 0 corresponds to an output level of either +8 dBM or +4dBm at the 1176AE output,
respectively.

 For more information, refer to the “Front Panel” and “Rear Panel” sections on pages 4 - 7.

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Front Panel
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(1) Input - Determines the level of the signal entering the 1176AE, as well as the threshold.

Higher settings will therefore result in increased amounts of limiting or compression.

(2) Output - Determines the final output level of signal leaving the 1176AE. Once the desired amount
of limiting or compression is achieved with the use of the Input control, the Output control can be
used to make up any gain lost due to gain reduction. To set the desired output level, press the +4 or
+8 Meter button and then alter the Output knob as required. ( see #7 on page 6)

(3) Attack - Sets the amount of time it takes the 1176AE to respond to an incoming signal and begin
gain reduction. The 1176AE attack time is adjustable from 20 microseconds to 800 microseconds
(both extremely fast), plus the 1176AE offers a unique, fixed 10ms “SLO” Attack when this control is
“clicked” to the far counter-clockwise position. The attack time is fastest when the Attack knob is in
its fully clockwise position, and is slowest when it is in its fully counterclockwise position.



Disengaging all ratio buttons disables compression altogether (The standard 1176LN has
also has an OFF position to the attack control for bypass in addition to this method);
however, signal continues to pass through the 1176AE circuitry. This i s commonly used to
add the “color” of the 1176LN without any actual gain reduction.

 When a fast attack time is selected, gain reduction kicks in almost immediately and

catches transient signals of very brief duration, reducing their level and thus "softening" the
sound. Slower attack times allow transients to pass through unscathed before limiting or
compression begins on the rest of the signal.

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Front Panel

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(4) Release - Sets the amount of time it takes the 1176AE to return to its initial (pre-gain reduction)

level. The 1176AE release time is adjustable from 50 milliseconds to 1100 milliseconds (1.1
seconds). The release time is fastest when the Release knob is in its fully clockwise position, and is
slowest when it is in its fully counterclockwise position.

 If the release time is too fast, "pumping" and "breathing" artifacts can occur, due to the

rapid rise of background noise as the gain is restored. If the release time is too slow,
however, a loud section of the program may cause gain reduction that persists through a
soft section, making the soft section difficult to hear.

 Unlike many other devices, the 1176AE Attack and Release times get faster, not slower,

as their corresponding knobs are turned up (clockwise).

(5) Ratio - These four buttons determine the severity of the applied gain reduction. (A ratio of 4:1, for

example, means that whenever there is an increase of up to 4 decibels in the loudness of the input
signal, there will only be a 1 dB increase in output level, while a ratio of 8:1 means that any time
there is an increase of up to 8 dB in the input signal, there will still only be a 1 dB increase in output
level.) When the highest ratio (20:1) is selected, the 1176AE is limiting instead of compressing. Note
that higher Ratio settings also set the threshold higher. (

The 1176AE Ratio buttons allow four different modes of operation:

2 - Selects a 2:1 ratio (mild compression).

4 - Selects a 4:1 ratio (moderate compression).

8 - Selects an 8:1 ratio (severe compression).

20 - Selects a 20:1 ratio (hard limiting).

 see page 16 for more information)

 “All-Button” is famous trick employed my many engineers to achieve extreme compression

characteristics and increased distortion. This technique has been expanded with the 1176AE,
with several “Multi-Button” combinations offering a wider array of tonality. Playing with
various combinations will yield audibly different compression characteristics—try it!
Important: The identical compression characteristics of “All-Button” found on the 1176LN
standard unit is achieved with the 1176AE by pushing in only the top three ratios: 20:1, 8:1
and 4:1—All four will yield a slightly tamer sound.

 Engineers typically use “All-button” mode on drums or on ambience or room mics. It can

also be used to “dirty” up a bass or guitar sound, or for putting vocals “in your face.”

(

see page 18 for more information)

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Front Panel
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(6) Meter - A standard VU meter that displays either the amount of gain reduction, or output level,

depending upon the setting of the Meter Function switch. ( see #7 below) Occasionally, the meter
may require calibration. (

(7) Meter Function – These four buttons power the unit on (or off) and determine what the 1176AE’s
front panel VU meter displays: either the amount of gain reduction (GR), or the compressor’s output
level (+8 or +4). When “+8” is selected, a meter reading of 0 corresponds to a level of +8 dBm at
the rear panel outputs. When “+4” is selected, a meter reading of 0 corresponds to a level of +4
dBm at the rear panel outputs. ( see #3 and #4 on the following page) Depressing the OFF
position has the effect of powering off the 1176AE.

 see page 21 for instructions for calibrating the 1176AE meter)

 In order to obtain a specific amount of limiting or compression on the 1176AE, begin by

setting both the Input and Output knob to approximately 24 (their twelve o’clock positions)
for unity gain. Set the Ratio as desired, then set the Attack and Release controls to
approximately “4” (their 12 o’clock positions) so that some gain reduction is enabled.
Depress the Meter GR button so that the meter shows the amount of gain reduction, then
slowly turn the Input control up until the desired amount of gain reduction is achieved.
Finally, adjust the Attack and Release times until they are suitable for the program material
and make up any gain necessary by raising the Output knob (depress the Meter +4 or +8
buttons to have the meter display the final output level).

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Rear Panel

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(1) AC Power

here. If fuse replacement is required, use only a 125 mA time delay (slow blow) fuse for operation at
115 V, or a 63 mA time delay (slow blow) fuse for operation at 230 V. Note that the 1176AE has no
dedicated on-off Power button; instead, depressing the Meter OFF button ( see #7 on the previous
page) has the effect of powering the unit off.

Connector / Fuse Holder - Connect a standard, detachable IEC power cable (supplied)

 Never substitute different fuses other than those specified here!

(2) XLR INPUT - Connect line-level input signal to this balanced XLR connector. Pin 2 is wired

positive (hot). This signal will normally be arriving via a patchbay from a channel or bus insert send.

(3) XLR OUTPUT - A balanced XLR connector carrying the line-level output signal of the 1176AE.
This signal will normally be routed via a patchbay to a channel or bus insert return.

(4) Terminal Strip - Because it predated standard XLR connectors, the original 1176AE provided

terminal strips for input and output line-level connections, and so, in addition to providing a convenient
XLR input and output (
two terminals for input connections, the next terminal for chassis ground, and the next two terminals for
output connections. The rightmost two terminals are used for connection of a remote meter. (
page 20 for a complete listing of all terminal strip connections) If an input connection is made to the
terminal strip, be sure that there is no connection also made to the XLR input.

 see #2 and #3 above), that feature has been retained here. Use the leftmost

 see

 In order to avoid induced noise, make only one type of input connection (XLR or terminal

strip) to the 1176AE.

(5) 1176SA connector - Used for stereo linking of two 1176AEs. ( see page 22 for stereo

interconnection instructions.)

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