UREI 7110 LA-12 LA-22 Compressor

Last Update 05-31-2025

Gotta start somewhere... the first compressors I owned were a pair of Alesis 3630s. I used them for a few years for vocals in my PA system. In the studio I experimented using the 3630s on bass guitar, drums, and was disappointed. This was sufficient for vocals in a live band but not a studio tool. The transients did not sound natural, the sound quality was harsh, the bandwidth was constricted, gaps in the audio spectrum were audible, and the compression effect was not transparent. There was a 3rd party modification that offered to improve the sound; I installed the modification in one of my 3630s so I could perform an A/B comparison with the unmodded stock 3630 (both units had the rev D circuit boards). The modification was disappointing, I heard literally no difference in sound quality or transients.

Then a friend was selling a pair of JBL/UREI 7110 compressors so I grabbed them. I have a "soundcheck" CD that I play through audio devices to judge the sound quality, and program material are the "acid test" of compressors. Good grief, what a difference the 7110 makes. Fuller sound, smoother compression, none of the constricted bandwidth and audio spectrum gaps of the 3630s. The 7110 detector/VCA operation SMOKED the 3630, modded and stock. The 3630s are nicknamed the "dirty 30s" for a reason; Alesis made them by the thousands and they were cost effective. You get what you pay for with compressors, and you pay a little more for 7110s but the sound improvement is an order of a magnitude over the 3630s. Others might find the 3630s useful, but not in my work so I sold the 3630s.

Gotta start somewhere...

My JBL/UREI 7110s, UREI LA-12s, and UREI LA-22s are all the same core circuits so this webpage will cover all of them. The 7110 is the original design, the LA-xx models are derivatives. They all have 1) the smooth "knee" compression action of the classic UREI LA2A that makes the compression transparent and less abrupt (patented "SmartSlope" in UREI speak), 2) threshold/ratio/attack/release/output controls for the averaging (RMS) detector, 3) dual meters for gain reduction and input or output levels, 4) AUTO mode for automatic program-dependent attack/release times, 5) detector inputs (side chain) for ducking and de-essing, and 6) dual peak/averaging detectors which can be blended using the DETECTOR control.

The DETECTOR control is seldom found on other compressors. The reason for the DETECTOR blend action of peak/averaging detectors is that it approximates how the human ear responds to different peak/averaging ratios depending on the source - pure sounds such as flutes are 3dB, the human voice is 10dB, higher ratios for sources heavy with harmonics, short duration percussive sources, and synthesizers. With program material, a compressor alone is not a complete solution; enter the peak limiter. The DETECTOR control also alters the peak limiter threshold; with the control set to full clockwise at peak, the peak limiter threshold is 20dB lower than averaging. This action serves to balance sources of mixed ratios in a busy mix and smooth the wild dynamics with certain sources IE singers and wind instruments. At extreme positions of the DETECTOR control or anywhere in between, it minimizes "pumping" effects and offers another degree of dynamic balance.

These tables summarize the features of these models:

Model	MainsVoltage	#Channels	VCA Element	Audio Input	Detector Input	Audio Output	BalPinHot	BarrierStrip	StereoLinkSw
7110	120VAC only	1	SSM-2014	Bal/Unbal	Bal/Unbal	Bal/Unbal	Pin 3	Chassis/Earth/StereoLink/Inputs/Outputs	n/a
7110EX	100/120/220/240VAC	1	SSM-2014	Bal/Unbal	Bal/Unbal	Bal/Unbal	Pin 3	Chassis/Earth/StereoLink/Inputs/Outputs	n/a
LA-10	100/120/220/240VAC	1	SSM-2018	Bal/Unbal	Bal/Unbal	Balanced	Pin 2	Chassis/Earth/StereoLink	n/a
LA-12	100/120/220/240VAC	2	SSM-2018	Bal/Unbal	Bal/Unbal	Balanced	Pin 2	Chassis/Earth/StereoLink	yes
LA-22	100/120/220/240VAC	2	SSM-2018	Bal/Unbal	Bal/Unbal	Balanced	Pin 2	Chassis/Earth/StereoLink	yes

Model

Output Xfmr

Peak

RMS

Transient

Threshold

Ratio

OutputGain

AutoMode

Peak/RMS Blend

Limiter Threshold

Metering

Expander

Freq Selective

7110

Optional

yes

Attack
Release

(-)40dBu
to (+)10dBu

1.5:1 to
infinity:1

(+/-)20dB

yes

(-)10dBu
to (+)24dBu

16Segment GainReduction,
Input or Output

7110EX

Optional

yes

Attack
Release

(-)40dBu
to (+)10dBu

1.5:1 to
infinity:1

(+/-)20dB

yes

(-)10dBu
to (+)24dBu

16Segment GainReduction,
Input or Output

LA-10

yes

Attack
Release

(-)40dBu
to (+)10dBu

1.5:1 to
infinity:1

(+/-)20dB

yes

(-)10dBu
to (+)24dBu

12Segment GainReduction,
Input or Output

LA-12

yes

Attack
Release

(-)40dBu
to (+)10dBu

1.5:1 to
infinity:1

(+/-)20dB

yes

(-)10dBu
to (+)24dBu

12Segment GainReduction,
Input or Output

LA-22

yes

Attack
Release

(-)40dBu
to (+)10dBu

1.5:1 to
infinity:1

(+/-)20dB

yes

(-)10dBu
to (+)24dBu

12Segment GainReduction,
Input or Output

yes

The 7110 has no bypass switch, but a relay provides true bypass with the power off. All of the units have a trimpot accessible through a front panel hole that adjusts meter zero reference between (-)15dBu to (+)4dBu, for those system operating at (-)10dBv levels or (+)4dBu levels.

The 7110s are the first good compressors I have owned. Great on many sources especially bass guitar and kick drum - nice punchy transients. Very low noise with optimal settings. The averaging detector works really well with program material, not an easy task. Other 7110 owners have reported that the compressor/limiter settings can achieve the 1176 "all ratio buttons in" and the Distressor "Nuke mode" sound. Most compressors are effective for a narrow set of instruments - no one compressor sounds great with everything. These units with its DETECTOR control is closest to the one-compressor-does-it-all tool.

Upon learning of the LA models, I added two LA-12s and two LA-22s. I use the LA-12s for vocals in the studio or the stage, they are very transparent. The LA-22s serve as processors for other instruments, and the frequency selective compression ("narrow band limiting") can be a real problem solver. This thing can turn a dog of a snare drum or kick drum into a punchy monster. I had a post-processing project for a live recording, and when the guitar player turned on his talkbox it squealed often into his microphone. The squealing was enough to be offensive. I tried many processors to tame that squealing; a deep notch from my channel EQ or parametric EQ impacted the guitar tone, a standard compressor muted the guitar altogether. So I used the narrow-band limiting feature of the LA-22. The LA-22 features a bandpass EQ which has controls for frequency range, center frequency, and "Q" (0.12 to 2.5 octave bandwidth). When narrow-band limiting is enabled, the peak limiter is disabled. There is a switch to monitor the output of the EQ for precise setting. So I configured the EQ to "focus" on the problem frequency of the squeal, then set the threshold/ratio of the compressor, and it conveniently compressed only the squeal while leaving the rest of the guitar tone unaffected.

Another post processing project had a song with the drummer playing marching band rudiments on his snare drum. I felt the rudiments were getting buried in the mix and turning it up was not the solution. So I exploited the expander mode of the LA-22 whereas instead of lowering the signal per ratio setting in compression mode, the expander mode RAISED the signal per ratio setting. With the right threshold setting, that made a nice marching band snare drum effect.

One problem with the LA-22 is that it has so much circuitry inside that it gets hot. All that heat is trapped inside and damages the internal components. It is recommended that a 1U of blank space be left above each LA-22 to allow passive convection (heat rises). Some owners had to cut out vents in the top panel so that heat could escape.

Compressors are like guitar amps - they only sound good with certain instruments. The classic 1176 is a favorite for vocals, another brand works good on drums, another brand works good on bass guitar, etc. These 7110/LA-1x/22 compressor are very flexible compressors; UREI combined two of their famous dynamic processors, the 1176 and the LA-4 limiter. These sets work well on many sources and can sound natural or grungy. The additional features on the LA-22 can be a real problem solver. I have a pair of these models, giving me ten channels of compression - more than enough for most songs/bands. I typically reserve the 7110s for bass guitar (one for studio, one for stage) as the optional output transformer makes the sound fuller and improves the low end. Transformer part is Jensen #16-14550 or JT-11, not sure if Jensen still makes them. The LA-12 are usually reserved for vocals; I found a setting where they sound natural and transparent, all I have to adjust between singers is threshold and output gain. The LA-22 are my "catch-all" devices, usually on drums with one or two channels kept open for problem sources.

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