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Specifications

_______________________________________________________________________

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Input Impedance

15 k

Ω

, 600

Ω

selectable

Output Load Impedance

600

Ω

(floating)

Frequency Response

20 Hz to 20 kHz

1 dB

Gain

40 dB,

1 dB

Distortion

> 0.5% T.H.D. from 50 Hz – 15 kHz with limiting,

at 1.1 seconds release setting. Output of +20 dBm

with no greater than 0.5% T.H.D.

Signal-to-Noise Ratio

> 85 dB

Attack Time

Adjustable, from 20 to 800 microseconds

Release Time

Adjustable, from 50 milliseconds to 1.1 seconds

Stereo Operation

Left channel Attack and Release links to right channel

in LINK mode

External Connections

XLR

Meter

Gain Reduction (dB) and Output (dB)

Power Requirements

100V - 240V, auto-sensing power supply

Power Connector

Detachable IEC power cable

Fuse

T2A 250V, 5mm x 20mm

Dimensions

19" W x 3.5" H x 12.25" D (two rack unit)

Weight

9.6 lb. (with box, 14.8 lb.)

Summary of Contents for 2-1176

Page 1: ...Model 2 1176 Dual 1176LN Limiting Amplifier Universal Audio Part Number 65 00047 Universal Audio Inc Customer Service Tech Support 1 877 MY AUDIO Business Sales Marketing 1 866 440 1176 www uaudio com ...

Page 2: ...hing performance or use of this material Copyright 2009 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 2 1176 1176LN 6176 2 610 LA 610 LA 2A 2 LA 2 LA 3A 710 4110 81...

Page 3: ...ned largely on our modern 6176 Channel Strip which utilizes gain reduction circuitry designed to evoke the highly recognizable blackface sound of the original D E versions of the 1176 Those versions were characterized by their transformer input stage LN circuitry and a Class A 1108 style output stage Later versions replaced the Class A output stage with a push pull Class AB output stage and eventu...

Page 4: ...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 groundi...

Page 5: ... The Technical Stuff History of the 2 1176 Compressor Limiter Basics About All Button Mode About Class A Operating the 2 1176 in Link Mode Making A Custom Insert Cable Maintenance Information Meter Calibration Changing Voltage Changing Fuses 2 1176 Circuit Details Glossary of Terms Recall Sheet Specifications Additional Resources Product Registration Warranty Service Support 35 ii iii 2 4 7 8 9 15...

Page 6: ...k if possible Step 2 Make sure the front panel power switch is in its down OFF position and then connect the supplied IEC power cable to the rear panel AC power connector On the rear panel set the Input Z switch for both channels to their up 15KΩ position unless you are interfacing with vintage equipment in which case the corresponding Input Z switch should be placed in its down 600Ω position Step...

Page 7: ...all four Ratio buttons on an 1176LN simultaneously Note that selecting a Ratio of 1 1 1 results in no gain reduction but that the color of the 2 1176 channel is still imparted to the signal This has the same effect as setting the 2 1176 to BYPASS mode Also try varying the Input level and Attack and Release times for different compression and limiting characteristics Note that unlike many other dev...

Page 8: ... what the channel s VU meter displays either the amount of gain reduction GR or the final output level 4 When 4 is selected a meter reading of 0 corresponds to a level of 4 dBm at the rear panel output see 2 on page 7 When GR Gain Reduction is selected the leftmost position the channel s meter will read 0 dB when there is no incoming signal or when no compression is being applied If the release ti...

Page 9: ...eans 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 higher ratios 12 1 or 20 1 are selected the channel is limiting instead of compressing Note that higher Ratio settings also set the threshold higher see page 18 for more information The Ratio switch allows six different modes of operation for each channel of the 2...

Page 10: ...imes as well as a change in the bias points Consequently the meter will go wild often resting at maximum Engineers typically use the ALL Ratio 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 20 for more information When operating the 2 1176 in LINK mode the Input and Output knobs should normally be set to the s...

Page 11: ...vel output signal of each 2 1176 channel This signal will normally be routed via a patchbay to a channel or bus insert return 3 Input Z switch When in the up position the input impedance for that channel will be 15K ohms suitable for interfacing the 2 1176 with most modern devices When in the down position the input impedance for that channel will be 600 ohms typical of older vintage gear In some ...

Page 12: ...Interconnections __________________________________________________________ 8 ...

Page 13: ...the 1176 LN was used with a low ratio resulting in a very natural smooth sound and even performance being captured Strapping the compressor across the vocal when mixing and adding just a little more squeeze gave it the presence it needed to sit consistently in the mix with a nice top end to the sound And Michael Cooper writing in the November 2004 issue of MIX reported that Set to a 20 1 ratio and...

Page 14: ...ise drum sounds The 1176 has long been the compressor of choice for engineers for kick drum snare drum and overhead or ambient mics I ll always place one big mic like a U47 Neumann or a ribbon mic such as a Coles or Royer five or six feet in front of the drums confides Grammy winning engineer Jay Newland Norah Jones I try to get the whole drum set to sound good through that one mic and then put it...

Page 15: ...ssive way Let s say you have a medium tempo 4 4 rock beat an excellent scenario for using ALL Ratio In this application you d probably have a lot of input level a slowish attack so that the transients sneak through and a quick release The sonic result is extraordinary First the kick drum causes a great concussion which is enhanced by the unique ALL Ratio distortion As it does so the other frequenc...

Page 16: ... The wide range of control settings and the fast action limiter makes the 2 1176 a serious compression toolkit for the artistic engineer The 2 1176 can serve as a perfect complement for acoustic and electric bass as well In his Sound on Sound magazine review in June 2001 Hugh Robjohns observed that the original 1176 was often celebrated as a compressor for bass and I certainly found the re issue s...

Page 17: ...t level the more these descriptive terms come into play You ll find that the 1176 is most transparent when doing gain reduction of 4 dB or less This will serve to subtly reign in dynamic variations in the audio while still adding its characteristic tone In addition the extremely fast attack time offered by the 2 1176 which enable it to control peak levels as well as sustained tones allows it to ef...

Page 18: ...e gain reduction circuitry is disconnected in Bypass mode the signal continues to pass through the 2 1176 transformers thus picking up their signature sound Ducking Applications When the 2 1176 is placed in stereo Link mode the Input knobs in each channel serve to mix the two incoming signals to the side chain circuit of both channels In most musical applications you will want the left and right s...

Page 19: ...eleased in 1967 was denoted the 1176A but was revised to the model AB only a few months later with improvements in stability and slightly reduced noise The following year saw revision B with further minor changes to the preamplifier circuit These models all featured a brushed aluminum faceplate with a blue meter section 1176 Revision B Revision C released in September 1970 saw two major changes On...

Page 20: ...utnam Sr started Universal Audio Studio Electronics and UREI built products that are still in regular use decades after their development In 1999 Putnam s sons Bill Jr and James Putnam re launched Universal Audio In 2000 the company released its first product a faithful reissue of the original 1176LN revision D E which quickly garnered rave reviews finding a home in hundreds of professional and pr...

Page 21: ...vels causing distortion While many of today s digital recording media approach or even exceed 120 dB of available dynamic range quiet passages of recorded music can still be lost in the ambient noise floor of the listening area which in an average home is 35 to 45 dB Despite the increased dynamic range compression is especially important when recording digitally for two reasons One it helps ensure...

Page 22: ...h describes the amount of increase required in the incoming signal in order to cause a 1 dB increase in output A ratio of 1 1 therefore means that for every 1 dB of increase in input level there is a corresponding 1 dB increase in output level in other words there is no compression being applied A ratio of 4 1 however means that any time there is an increase of 4 decibels in the loudness of the in...

Page 23: ...ase times these are the parameters which most affect how tight or how open the sound will be after gain reduction The attack time describes the amount of time it takes the limiter compressor circuitry to react to and reduce the gain of the incoming signal usually given in thousandths of a second milliseconds or even millionths of a second microseconds A fast attack kicks in almost immediately and ...

Page 24: ... time on the attack of initial transients a phenomenon which might be described as a reverse look ahead The ratio goes to somewhere between 12 1 and 20 1 and the bias points change all over the circuit thus changing the attack and release times as well The unique and constantly shifting compression curve that results yields a trademark overdriven tone that can only be found in this family of limit...

Page 25: ...annel the compressor will be more sensitive to transients occurring in the left channel This can sometimes be useful in broadcast applications where you might want to duck a musical bed for example whenever an announcer is speaking see page 14 for more information Making A Custom Insert Cable In order to ensure unity gain the input and output to a compressor are normally derived from a mixer chann...

Page 26: ...ins 1 cold and 3 ground together on each XLR connector Only solder pin 3 as you will also need to solder an audio lead into pin 1 2 On both XLR connectors solder the hot white lead into pin 2 and solder the cold black lead into pin 1 as well as the other end of the bus wire as described in the previous step 3 Solder the hot white lead from the cable connected to the male XLR to the tip connection ...

Page 27: ...the meter is as follows 1 Power on the 2 1176 2 Set the Meter switch for the channel being calibrated to its 4 position 3 Set the Input control for the channel being calibrated fully off turn the knob fully counterclockwise 4 Use a small screwdriver to slowly adjust that channel s Zero Set potentiometer so that its meter reads 0 dB Watch how the meter settles before completing the calibration Chan...

Page 28: ...wer fuse is located on the power supply circuit board inside the 2 1176 directly behind the AC power connector accessed by removing the top panel of the 2 1176 Always remove the power cord before checking or changing the fuse The required fuse is a T2A 250V 5mm x 20mm Never substitute a different fuse type ...

Page 29: ...gn and performance is critical to the sound of the device This transformer was distinguished by the fact that it used several additional sets of windings to provide feedback a practice widely used in the tube amplifiers of the era which made it an integral component in the operation of the output amplifier Putnam spent a great deal of time perfecting the design of this tricky transformer and caref...

Page 30: ...ed by a transformer The purpose of this section is to reduce the signal level so as not to overdrive the FET based gain reduction stage Additionally the adjustable input level is used to control the amount of compression This input circuit was used in Revisions A F With Revision G a differential op amp input instead of the attenuator transformer input stage was used Gain Reduction Stage Figure 3 G...

Page 31: ...lower the gain hence reducing the signal level This is the basis of the limiting action Note that the 1176 is a feedback style compressor since the sidechain circuit samples the signal level after the gain reduction LN Circuitry The LN circuit which appeared in revisions C and later was designed to reduce the distortion that the FET introduced in the gain reduction stage FETs are inherently nonlin...

Page 32: ...ransformer designed by Bill Putnam Sr Aside from offering output impedance matching the transformer forms an integral part of the feedback network used to stabilize the output stage Note that later revisions F and beyond used a push pull class AB output stage Revision E was essentially the same as revision D Revision E added 220 Volt operation as well as a 10 MΩ resistor across the ratio switch to...

Page 33: ... This is then fed to CR2 Note that the signal applied to CR2 is 180 out of phase with the signal at CR3 Since they are out of phase the combination of CR2 and CR3 act as a full wave rectifier The output of the rectifiers are then filtered by C22 which smooths the signal This DC voltage is proportional to the level of the input signal A bias level is applied to the diodes by the Ratio switches This...

Page 34: ...hat their active components are drawing current and working throughout the full signal cycle thus yielding a more linear response This increased linearity results in fewer harmonics generated hence lower distortion in the output signal Clipping A particularly harsh form of audio distortion caused when the loudness of an incoming signal exceeds an audio recording device s capability to represent it...

Page 35: ...y A gradual transition is called soft knee while a more rapid transition is called hard knee Soft knee compression and limiting is generally more desirable for musical applications Limiter A compressor that operates at high compression ratios of 10 1 or higher Limiting A more severe form of compression where a high compression ratio of 10 1 or higher is being used Limiting Amplifier A synonym for ...

Page 36: ...of wire wound on a common core of magnetically permeable material Audio transformers operate on audible signal and are designed to step voltages up and down and to send signal between microphones and line level devices such as mixing consoles recorders and DAWs Transient A relatively high volume pitchless sound impulse of extremely brief duration such as a pop Consonants in singing and speech and ...

Page 37: ...Recall Sheet __________________________________________________________ 33 ...

Page 38: ...Bm with no greater than 0 5 T H D Signal to Noise Ratio 85 dB Attack Time Adjustable from 20 to 800 microseconds Release Time Adjustable from 50 milliseconds to 1 1 seconds Stereo Operation Left channel Attack and Release links to right channel in LINK mode External Connections XLR Meter Gain Reduction dB and Output dB Power Requirements 100V 240V auto sensing power supply Power Connector Detachab...

Page 39: ... if you re having trouble with your device is to check for any loose or faulty external cables bad patchbay connections grounding trouble from a power strip and all inputs outputs mic line Hi Z etc If your problem persists call tech support at 877 MY UAUDIO or send an email to hardwaresupport uaudio com and we will help you troubleshoot your system Canadian and overseas customers should contact th...

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