Universal Audio 1176LN Limiting Amplifier
It was Bill Putnam himself who, in 1966, was responsible for the initial design of the
1176. Its circuit was rooted in the 1108 preamplifier which was also designed by Putnam.
As is evident from entries and schematics in his design notebook, he experimented with
the recently developed Field Effect Transistor (F.E.T.) in various configurations to
control the gain reduction in the circuit. He began using F.E.T.s as voltage variable
resistors, in which the resistance between the drain and the source terminals is controlled
by a voltage applied to the gate. His greatest challenge was to ensure that distortion was
minimized by operating the F.E.T.s within a linear region of operation.
After several unsuccessful attempts at using F.E.T.s in gain reduction circuits, Putnam
settled upon the straightforward approach of using the F.E.T. as the bottom leg in a
voltage divider circuit, which is placed ahead of a preamp stage.
The output stage of the 1176 is a carefully crafted class A line level amplifier, designed
to work with the (then) standard load of 600 ohms. The heart of this stage is the output
transformer, whose design and performance is critical. Its primary function is to convert
the unbalanced nature of the 1176 circuit to a balanced line output, and to provide the
proper impedance matching to drive the line impedance of 600 ohms. These two jobs are
accomplished by the primary and secondary windings whose turns' ratio defines the
impedance ratio.
This transformer is critical due to the fact that it uses several additional sets of windings
to provide feedback, which makes 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 carefully qualified the few vendors capable of producing it.
The first major modification to the 1176 circuit was designed by Brad Plunkett in an
effort to reduce noise--hence the birth of the 1176LN, whose LN stands for low noise.
Numerous design improvements followed, resulting in at least 13 revisions of the 1176.
Opinion has it that the D and E blackface revisions sound the most “authentic”.
Both the 1176 and the LA-2A remain in daily use. Busy engineers and producers’
comments about both the 1176 and the LA-2A demonstrate their impact on the industry:
Mike Shipley (Def Leppard, Shania Twain, Blondie): "I grew up using 1176s --- in
England they were the compressor of choice. They're especially good for vocals, which is
also what I primarily use the LA-2 for. Most anything else I can do without, but I can't be
without at least a pair of 1176s and an LA-2A. For example, on the Enrique Iglesias
project I'm currently mixing, I'm using both an 1176 and an LA2 on his voice, which is
not unusual for me.
“The 1176 absolutely adds a bright character to a sound, and you can set the attack so it's
got a nice bite to it. I usually use them on four to one, with quite a lot of gain reduction. I
like how variable the attack and release is; there's a sound on the attack and release which
I don't think you can get with any other compressor. I listen for how it affects the vocal,
and depending on the song I set the attack or release--faster attack if I want a bit more
bite. My preference is for the black face model, the 4000 series--I think the top end is
especially clean.”
Allen Sides has always been known for his golden ears when it comes to the sound of
equipment. The owner of Ocean Way Studios in Los Angeles and Nashville, he's also a
speaker designer and engineer who is especially respected for his work with live
musicians, including orchestra and string dates. Among his recent credits are work with
the Goo Goo Dolls, Alanis Morissette and Green Day. Sides brings his different
perspectives into play when he talks about using the 1176.
“The 1176 is standard equipment for my sessions. I just used them last night, as a matter
of fact, on a project for singer Lisa Bonet that Rob Cavallo was producing at Ocean Way.
We were recording drums and I used them on the left/right overheads as effects limiters.
It's something I learned from (engineer) Don Landy, who worked with Randy Newman a
lot. I mult the left and right overheads and bring them back on the console, then insert a
pair of 1176s into a pair of the mults. Push in 20 to one and four to one simultaneously
and it puts the unit into overdrive creating a very impressive sound.”
Murray Allen is a veteran engineer and Director of Post Production for the San Francisco
Bay Area company Electronic Arts. He has a fascination for gear both old and new and
he explains why he thinks the 1176 has been so popular for so long. “It has a unique
sound to it that people like, it's very easy to operate, and it does a great job. You have just
two controls relative to the ratio of compression. You have input and output and you have
attack and release. That's all there is. It's still my favorite limiter for Fender basses and
string basses, because you don't know it's working. It doesn't change the way the bass
sounds, it just keeps the level at a more controllable place.”
Mixer Ken Kessie (En Vogue, Tony! Toni! Tone!, Celine Dion) is known for being
experimental. “Seems like everybody knows the basic tricks for the 1176,” he says, “But
here are two that might be lesser known. If you turn the attack knob fully
counterclockwise until it clicks, the 1176 ceases to be a compressor and acts only as an
amplifier. Sometimes this is the perfect sound for a vocal. And of course the unit can be
overdriven, adding another flavor of distortion in case your plug-ins are maxed out!”
“Then, for that hard-to-tame lead vocalist (the one that backs up from the mic to whisper
and leans in for the big ending chorus), try an 1176 followed by a DBX 165. Use the
1176 as a compressor, and the DBX as a peak limiter...it's guaranteed to be smooth as
silk.”
Jim Scott shared a Grammy for Best Engineered Album for Tom Petty's Wildflowers.
He's also known for his work with Red Hot Chili Peppers, Natalie Merchant and Wilco.
“I use 1176s real conservatively and they still do amazing things,” he comments. “I'm
always on the four to one button, and the Dr. Pepper--you know, 10 o'clock, 2 o'clock,
and it does everything I need. “
“I always use them on vocals. I use them on room mics, on acoustic guitars--sometimes
in mixing I'll sneak a little on a snare drum or a separated channel of a snare drum. I'm
not one of those guys who leaves it on everything, but I'd have to say I've used an1176 on
everything at one time or another.”
“They have an equalizer kind of effect, adding a coloration that's bright and clear. Not
only do they give you a little more impact from the compression, they also sort of clear
things up; maybe a little bottom end gets squeezed out or maybe they are just sort of
excitingly solid state or whatever they are. The big thing for me is the clarity, and the
improvement in the top end.”
Retail:
$2000+
Used:
$1200-2000+
dep on condition / age / model variation.
Verdict:
Industry standard, used by the best. Used on most of the best selling albums over the last few decades.
