1176 FET Compressor Teardown pt 1: Circuit and Compression Secrets

[@Espresso101]

Ok, same comment as the GAP 73...a follow-up teardown of this 1176 but comparing a budget and a higher end unit so we can see what's different, what shortcuts were taken on the budget model, what makes the higher end version more expensive, etc. Say Klark Teknik 76 ($400) and a UA 1176 ($2k) or even a Warm Audio 76 ($600). It would be nice to know what compromises we're making, and what are getting when deciding which one to go with.

[@IzharAshdot]

Thank you Peterson! You demystified the FET Compression method in such a simple and coherent way.

[@acdnrg]

As someone who got into audio electronics from the user side (just swapping dead pots etc), I started doing eurorack DIY kits, but without any understanding. Soldering by numbers, so to speak. Compared to other EE tutorials, this finally bridges the gap between electronics basics and what is actually happening when the circuit is in action. Many, many thanks, this is so valuable in better understanding the things I use. Top notch!

[@housemana]

O+c/mutablediys/thonknation/muffwiggler assembler-to-builder pipeline type of beat . . . i feel u man 🔌 longtime tinkerer of simpler circuits (guitar pedals and PA gear) and was doing okay, didn't need to understand much, but got bit by the eurocrack builder bug going on a decade ago now , and I haven't been well since!! 🤣 been hanging on by the BoM for most the designs i've been cranking out... a constant chore to keep up with these circuits but on the flipside entails endless prog & learning potential - a rich rewarding space to spend time in.

[@tbobbyelectric]

Hey Peterson! I'd VERY MUCH like to see some sort of API vs. CAPI TearDown Comparison Video...? 312 vs. 312? Or, something to do with the 2500 Comp? One of my favorite Comps.... Even the UA Plug-In Version. We did Neve, a few weeks ago, lets try an API video!? Just thinking outloud. By the way, THIS 1176 Video was AMAZING!!!! Thanks SO much for your brilliance and work ethic, and EVERYTHING else you've provided for us, over the passed few years.... You are muchly appreciated! I LOVE ALL of my Colours, and my Colour Pre, and I cannot wait for the 2 Channel Rack Unit!!!! Be well. Stay well.

[@PetersonGoodwyn]

Thanks for the ideas! Yes I would love to do a 312 next. Though I plan to stay away from directly comparing the quality of two units, seeing as I'm in the industry myself! And thanks so much for the kind words, really appreciate it.

[@peterbrandt7911]

Thank you ever so much. I'm such a noob, when it comes to circuits, even though I'm old as a rock. In addition to my last proposal, I'd like to see a teardown of the Klarkt Teknik units, since they're a such in cheap entry point here in Europe. (All three are between $250 and $350 here).

[@PetersonGoodwyn]

Thanks I would love to take a look at those as well

[@peterbrandt7911]

@@PetersonGoodwyn @Behringer, can you help us out there?

[@austinmark1987]

I cannot describe how fantastic these gear tear down videos are! I’ve been a professional audio engineer and mixer for 15 years now, and these videos finally helped me truly understand what is happening inside the gear I work with everyday at the studio. Much thanks and respect. I discovered you through the vintage API mic preamp tear down and the Neve 33609 tear down. Two pieces of gear I use at the studio and never truly understood what makes them magical under the hood! I only knew the sound :)

[@ruffrecords]

I think you do not fully understand the side chain. If you look at the FET RDS curve over its entire range you find there are regions that correspond to different ratios. It is the slope of this curve that sets ratio. The 1176 side chain alters the section of the RDS curve the FET operates over by altering its dc bias. This is nothing to do with threshold, it just changes the ratio. Threshold is changed separately in the side chain so that the curves for the different ratios match each other better. You can see this clearly in the user manual curves. By the way, 20dB is 10 times voltage ratio not 100 times. Cheers Ian

[@gold27b]

That makes sense. An important point that was missed.

[@Lantertronics]

These gear descriptions are fantastic! Check out the API 525C; instead of using the JFET as the lower leg in a voltage divider, it has the JFET running from the negative terminal of one of their 2520 op amps to ground, with their op amp in a classic non-inverting amplifier configuration. The only other place I can think of that uses that kind of configuration is the Scholz Rockman. All the others I can recall, like the Shure Level-Loc, use it in a passive attenuator as in the 1176.

[@DMKahn]

Amazing. Done lots of kits, never understood anything about the electronics part. Keep explaining like I'm 5. haha!!

[@PetersonGoodwyn]

Great to hear!

[@BiotechRecords]

Ratio is actually Threshold. I've always wondered why different ratios on 1176 don't really sound so different.

[@Padillajose]

Me too! Now we know!

[@christophermonk4879]

dude I have built 22 of these Hairball kits and I feel like I still learned a ton from these teardown videos. You are awesome and probably the reason I got into DIY audio so thank you!

[@thegreenguy8837]

What do you need 22 1176 compressors for, if you don´t mind me asking?

[@ramencurry6672]

One of these days I’d like to own a Hairball unit. Just for fun even though I already own a compressor

[@BrooseWayniac]

Empirical labs Distressor and Fatso would be interesting to demistify... as they scrubbed down the values... but would be very interessting to see how this Units look from inside, and behave like 3 compressors in one... Thanks for this really more than interessting knowledge niche that you are filling... Greatings from Germany... iam still looking for some people who ordered Diy re assambling kids to germany, because of customs questions

[@distortimus7631]

"Let's imagine you are the FET." Me: "But I am fat." 😂

[@andrescase6492]

I guess Im randomly asking but does someone know a way to log back into an instagram account?? I was dumb forgot the login password. I would appreciate any assistance you can give me

[@orionfranklin2636]

@Andres Case Instablaster ;)

[@andrescase6492]

@Orion Franklin I really appreciate your reply. I got to the site thru google and Im trying it out now. Takes a while so I will reply here later with my results.

[@andrescase6492]

@Orion Franklin It did the trick and I now got access to my account again. I am so happy! Thanks so much, you saved my ass!

[@orionfranklin2636]

@Andres Case Glad I could help :)

[@resolversoftware5088]

amazing insight!!!!

[@nickgnjatovic9535]

You Sir, are a legend!

[@bsteeltx]

I've been an electrical engineer for over 20 years, and although analog was never my strength, I sat through MANY circuit and design lectures in EE classes in school that were quite painful. I have to say you have a knack for presenting this sort of information in a clear and easy to digest way. Great job, keep this stuff coming.. please!

[@EdEditz]

It's rediculous that you have to fork out about 10 grand for an original unit now. You're paying for the hype but that's what people seem to want so who am I to knock it :)

[@radicalfreq]

these teardown videos are amazing! couldn't thank you enough, look forward to seeing more of these.

[@PetersonGoodwyn]

Glad you like them!

[@freedomradio5602]

Among other issues I think you are wrong about the frequency response in your "teardown"; the FET doesn't care about this as long as it abides by it's circuit and is inband to its design . I don't get what you are trying to say, a limitation in frequency response? That would be very inaccurate and yes, it is a ratio/threshold based on a baseline measurement. You forgot to mention this.

[@AnalogDude_]

So you can use DPDT switches instead? what about the output transformer? it has 2 windings, what brand/model/type is that and is it available at Don Audio? the input transformer could be a Neutrik NTE... 1 to 1, right? To bad it needs a 5M pot for the release, not so easy to come by.

[@Rhuggins]

What an unbelievably valuable channel. This video for example continues to help people years after its publication. If you had a premium group or patreon I would gladly support

[@TheNickmeeks1]

Ok so great video as always! Q: I know the 1176 attack is less than 1ms, evan at its slowest, but its doesnt sound like it. Sounds more like 10-20ms at its slowest. As it is a feed back compressor there seems that there is 'something' delaying the signal in the detector circuit. What do you think what is the 'real world' attack, is there a way to measure it?

[@joek81981]

Hey, I landed here because I recently bought a UA Max pedal that claims to have 1176 heritage. After seeing this video, I've learned a couple things: No matter what Universal Audio says, my pedal has nothing in common with the real thing. At best, its an accomplished pedal builder's take on an impression of a dream about the real thing. Also, it does some stuff with your phone, but it don't do that 4-button thing, I tell you that. Also, I knew that ratio knob was horseshit.

[@Linguae_Music]

Wait, you said 6 decibels is not twice as loud to us because we hear logarithmically. but the decibel scale isn't linear to begin with. Every 6 decibels is perceived as twice as loud. I'm pretty certain of this. I looked it up! Google Says its between 5 and 10db to be percieved as "twice as loud" (Depending on what you define as a reference loudness, because it isnt linear to our perceptions... and also the spectral content of the sound, as this is also not percieved linearly... in fact its percieved non-linearly in two different ways xD) So around 6db is "twice as loud" for most sounds, as a sort of amorphous guideline. I think thats a fair assessment.

[@spinach1999]

You must be asked this a lot, but can you do a video on the Fairchild 670? Or if you can't do that the Alison Research Gain Brain?

[@DECIFERTHIS09]

can you build the simplest neve pre possible maybe on a bread board and explain the logic in each step?

[@zachary963]

So... does this mean all buttons in mode just drops the threshold to the floor? And that’s why it’s so stinking compressed?

[@josuebeaucage4294]

Thanks for the overview ! Next would be FET mics ! Like the U47 for example !

[@alextotheroh8071]

Heck yeah! Thank you! I can't believe I've never heard that the ratios aren't true ratios... I wonder if any of the plugin emulations also have an input level dependent thing going on.

[@PetersonGoodwyn]

Thanks! And great question. I would assume any plugin clone of the 1176 would emulate the way it actually does compression, otherwise it would sound quite different.

[@els1f]

When I watched that part I had to pause the video and calm down a second 🤯 🤣

[@bk3720]

Great video, now how do I make a Boba Fett compressor? 😁😁😁

[@anthonyman8008]

Revive claims they are superior, anyone know?

[@AragonDubs]

I don't know how to thank you for all this, I have learned a lot. I follow you from the beginning and I have always liked your way. I work with a 1178 and other equipment, I transfer analog to digital, film, shellac, etc. I don't know a better team than 1178, myself and other colleagues around the world. easy, fast and sounds very very good. Thank you Peterson!

[@monkeyxx]

You just blew my mind, thanks for the insight.

[@rocketsauce5067]

You are a dream crusher, No control. I won't have it.

[@bambinom5359]

Creepy and bad things happen to ppl who record ppl without there knowledge

[@itsakoreanthing]

This is awesome! Please do every piece of hardware that you can lol

[@michellepackman1484]

So fun thank you!

[@audiofreq]

Tube-tech CL1B teardown next!!!!!

[@jacobsteel]

Great presentation, thank you! :)

[@chrisroberts2266]

Im sorry to say that your description of the ratio is not correct and the capability to change ratio is and was perfectly possible. The ratio control in this case on the 1176 also adjusts the threshold, it is a ration setting but also changes the threshold. The idea of the combination is to change the amount of compression without changing the perceived volume and so create user friendly simple compressors, like the dbX 160VU with very simple and limited controls.

[@PetersonGoodwyn]

Don't take my word for it. Check out Monte M's response here about how fixed ratio settings on a feedback, FET compressor are impossible: groupdiy.com/index.php?topic=65756.0

[@chrisroberts2266]

​@@PetersonGoodwyn I'm not taking your word for it. I think you have misunderstood the theory. A FET compressor needs to be feedback in order linearize its control, where as a VCA can be controlled by either the signal going to it or from it as it attenuates based on a known repeatable mV/dB control signal. This requires an extra step in the sidechain after turning the audio into a DC voltage (rectification) it must pass through a Log amp to make its relationship correct as V/dB is a linear control of a log scale, the audio. Because of the non linearity the feed forward isn't possible (being accurate anyway) with a FET or optical compressor so it has to "get there by trial and error" with a feedback loop that makes the process more accurate. however, this is not to say that you cant have ratios because you do (that's how gain works in a mic amp for example, with a feedback ratio). If you only send a portion of the output signal back to the FET it will only react to a RATIO of the output signal. This is what the 1176 does. The misleading thing is that they also increase the threshold as you select the ratio from 4-8-12-20. As such you are incorrect in your video because the 4 8 12 20 controls are indeed ratio controls. the Scamp S01, Compex F760 to name two famous compressors are both FET feedback and have ratio controls, that are indeed ratio controls.

[@PetersonGoodwyn]

@@chrisroberts2266 Thanks for your response. I understand that the ratio control affects FET bias and threshold simultaneously. But the ratio is only affected by the Rgs curve of the FET. So the ratio is affected, but not in the linear, predictable way the front panel labels would imply, and ratio is still variable wrt to signal level.

[@chrisroberts2266]

@@PetersonGoodwyn The ratio control doesn't effect the fet bias, if it effected the bias, the output level would change with the compressor switched to off at the attack control (because the off control only stops audio to the side chain) when you select different ratios. It actually sets a voltage that the audio signal must overcome to change the voltage on the gate of the fet to change gain. What you mean is that the linearity (over depth of compression) of a given ratio is limited by the linearity of the FET. This would only be relevant as a feed forward design and so this is exactly why it is a feedback compressor to reduce (remove in practical terms) this effect, it has nothing to do with the compressors ability to have a ratio and the linearity is not directly linked to the curve of the FET because of the feedback loop.

[@chrisroberts2266]

@@PetersonGoodwyn the two sections of the Ratio switch, the first set on the left of the circuit is fed from the audio path is the ratio setting. it sets how much of the audio is converted to control signal. the second set of switch elements (on the right of the circuit diagram) set the threshold by applying an offset voltage before the diodes. The ratios are set dependent of the amount of audio fed back to the control circuit and are quite accurate within the design limits of the unit.

[@AriomesterDaniel]

These teardown videos are the best!! Thank you A LOT!!!

[@delusionwalker8852]

Good sir you are of epic proportions awesome! you satisfy all of my audio engineering nerdiness. Great fluent simple and clean explanetion, easy to listen to, good visual work, easy to follow, no hectic, not too slow, not too shallow not too deep, simply great video. All I can say is to repeat what I said at the beginning of this comment, Good sir you are of epic proportions awesome! Thank you very much for this content!

[@PetersonGoodwyn]

Wow, thanks!

[@joeblack007forever]

Really like and appreciate your vidéos! It's clearly explained and very interesting. Hope it will be a long serie covering a lot of legendary studio gear's. You will become the Studio gear circuit reference :)

[@PetersonGoodwyn]

Thanks, will do!

[@Wizardofgosz]

Just finished two of these. Love them.

[@DiegoCarvacho]

:) thanks for sharing

[@Erudotic]

Great teardown in the sense of showing us the insides and explain what is what, I love it, great work! However..... Well, staying 'out of the weeds" concerning the whole dB thing concerning the ratio sadly went south quote a bit. I can't begin to point out the discrepancies but you have some of your definitions of units mixed up : dB appears to mean dBv at one point, audible dB at another. Our does it? I got confused at the point you stated that 6 dB is nog a doubling in volume, wich in audible dB's it is. Then you go on about the voltages and there is clear you meant 6dB increase in voltage. But then in that same movement you speak suddenly of 60 dB on that context, clearly now you must be talking of audible dB', Bruder of it were still voltage we'd be talking 400v? I may have not remembered the exact numbers exactly correct, but this is about the gist of what I got in before I soothed off.

[@RemyRAD]

You certainly understand your 1176 theory of operation. Aren't they wonderful. All of them. I can use any of them. I used to have five Rev-D's. Those are all gone now. Now I just have a couple of H's and a relatively brand-new Hairball Rev-F. Which is a D front end and a G output. And they all work like FET limiters are supposed to. With all of these little Nuance differences. That while it's a big difference. It's not a big difference. It's just a difference. And I really kind of agree with a former colleague by the name of Bob Clearmountain. I'm rather more partial to the G and H versions. Not that I didn't love my five, D versions. I most definitely did. I well I guess I grew beyond them. Because at one point. I also had eight, PYE, PDM limiters and sold those also. Years ago. At the time they weren't exactly just right for me. Later they would have been that I had already sold them. Oh well. Easy equipment come. Easy equipment go. And I kind of made a killing on them. So I miss them but I don't. I've now lived without them all these years long. But also did not care for their 15 kHz bandwidth restriction. I could live with that. I liked better than that. I knew what I was losing. I could hear what I was losing. But it was pulse duration modulation limiting. Like the EMT PDM limiters. But British style. Kind of like microphones versus consoles. They both make the world's best. But they don't both make the world's best others. When reversed. The UK not known as much for their microphones as their consoles. Germany the other way around. And while Neumann made a big audio console. How many folks do you know had them? Right, no one. And who made Neve microphones? A Japanese company. See? I mean Se. As in S and E. And well it's not really a Rupert microphone per se. And how many hits do you know recorded with those microphones? Right, none. Just like the hits recorded on Neumann audio consoles. Back in the early 1970s. Can you tell I'm originally a high school dropout by my English grammar? I can.. RemyRAD

[@BCEpedals]

Just discovered this channel! You’ve done a great job breaking it down into simpler portions. I’m more experienced in amp/pedal building but this has me wanting to get into rack gear and compressors now lol!

[@CharlesTsaiE]

This gave me a big understanding of this compressor,but still i have 2 questions which i can't figure out from the schematic.1st is why the threshold is fixed?is they design it or the limitation of FET？,2nd is how the release control work.Thx a lot

[@G_handle]

You are my hero.

[@oscarrivas7240]

Cool video! Doesn't look like you've made a video in a while, but if you do, I'd love to see you breakdown a STA-Level. It's one of my favorites and would love to see what makes it so special!

[@hoofbags]

Probably an enhancement mode N channel MOSFET. What's interesting about these is, the conductive element is bidirectional and the source and drain are interchangeable. The true level of expertise is how they manage to use a side chain but not introduce oscillation. I use home made optical compressors, using a Light Dependant Resistor and when I substituted the LDR for a much faster photodiode, the item went unstable and broke into oscillation. I'd love to know the FET type number: I know it certainly isn't a 2N3819. Thanks for showing us the internals. 🙂

[@kenzingzong6704]

A 2n3819 would work fine in this application. The trick with using JFETs is allowing a small controlled amount of the audio source itself back into its gate along with the control voltage which puts it into its linear region thus cancelling distortion it would otherwise cause when used as a voltage controlled resistor. Usually the audio fed back into it would come after its gain stage to allow faster attack times because of the larger current to charge the capacitor/resistor for the control voltage. Self oscillation is usually a cause of the gain reduction being too large where the compressor starts to work beyond limiting causing increasing volume levels to compress in reverse instead of a steady level. In my experience FET compressor circuits rarely experience this compared to LDRs which can be driven far too hard messing with stability.

[@hoofbags]

@@kenzingzong6704 well explained, thanks. Using an LDR as a gain reduction element is fine on the attack but the slow on recovery so is audible. Consequently, I find it works well on an audio source but not really great for guitar. It's an intriguing subject, all on its own. The developers spent time for R n D and is why compressor and limiter units like the one in your upload, are expensive. For me, its back to the solderless breadboard! Again, thank you. 🙂

[@shatteredsquare]

what's the actual fixed ratio then?

[@RadiAsian]

dude I love your channel

[@PetersonGoodwyn]

Thank you!

[@rndmknbs]

wow, thanks for your explanation, very clear and interesting!

[@illaarocc9469]

I really enjoy these teardowns! Your easy to understand way of teaching audio circuitry keeps me on board for the whole video. Thanks therefore!

[@PetersonGoodwyn]

Great to hear!

[@Audiojunkk]

So glad to have found your channel. So great to learn all this about gear I work with everyday! Thank you so much for your effort making these videos!

[@amorte666]

I would love to see a tear down of a la3a or la2a

[@TweezerBleezer123]

Wow. Learned some real crazy things here.

[@PetersonGoodwyn]

Thanks I'm so glad!

[@phpimusique9373]

just amazing! thanks for that!

[@Or5mr]

Inmediately subscribed

[@zoolmakesmusic4920]

I found this very helpful. Thank you!

[@DonSolaris]

Hi! What do you use for this pretty schematics graphics on the paper?

[@tHaH4x0r]

Just a minor technicality that is often overlooked, 6:15 the variable resistor is not attached quite right. The arrow denotes the wiper of the pot, thus if it were a 10k pot R2 in this circuit would always present 10k, instead of the varying resistance you expect. The arrow should be connected to either ground or the signal (usually ground). This also lines up with how it should be connected in real life, since it is a three terminal device, not a 2 terminal one.

[@PetersonGoodwyn]

Thanks for the comment. That's true about a potentiometer, but the symbol I used is for a variable resistor or rheostat which has two terminals.

[@chrisclarkeML]

I love your videos but please consider using some deEsser on your voice! The S-es get quite sharp.

[@xqpaudio6667]

Nice to see you on here, Peterson, and a very informative video. Well said.

[@monty4924]

I miss the teardown videos. Bring back!

[@catface101]

Do you think when they were making it they intended to include the All Buttons In mode or is it a happy accident?

[@alextotheroh8071]

Surely a happy accident... I have to imagine they assumed people would just press one button at a time. Just a guess though.

[@PetersonGoodwyn]

I agree with Alex. In All Buttons In mode the meter goes a bit crazy and shows things that aren't actually happening, so I have to assume they didn't intend it.

[@Excellent2009able]

Wondering which is the highest end clone of the 1176’s ? I’d love a really good one, could afford to pay over half the new price of a LN if something close to it is available? :) I’ve tried a few cheaper clones and preferred the Spark plugs tbh :)

[@psypsiproduction]

just go with Hairball audio, they are basicaly 1to1 to original

[@AgustinDavidF]

It is a real pleasure to hear you, you could be a very nice teacher!

[@Brainbox97]

what a well crafted video, this is such a useful resource! It'd be great to make this a little series, maybe the la-2a next?

[@PetersonGoodwyn]

Thank you so much! Yes I plan to keep going with this series, as soon as I can get my hands on an LA-2A I will tear it down!

[@alextotheroh8071]

I feel like the LA-2A is a lot tougher because there don't seem to be any DIY clone kits. Just schematics. Which makes it VERY expensive in terms of either money or time. Would love to be proven wrong if anyone has a link though!

[@PetersonGoodwyn]

Agree, I'm hoping I can find someone with a bunch of vintage gear who's willing to lend it to me to tear down :)

[@Espresso101]

@@PetersonGoodwyn you should look into Audioscape stuff. They're based out of FL and make great clones of vintage gear at an affordable price.

[@RaunoPaananenAudio]

Great inffo!

[@CleanCutAudio]

wow wow wow wow wow

[@BufferStuffBuddha]

Man this series is phenomenal. You should do a comparison of similar units but one in standard rackmount and the other in 500 series.

[@hamidkarimioffical]

❤❤❤❤❤🇮🇷🇮🇷🇮🇷🇮🇷🇮🇷

[@absoluteenergy1]

This is so awesome 🤯

[@peterbigblock]

Cool explanation!

[@DavidImrie]

Great. more like this please! hows about a pultec eq? if there's a particular piece of high end gear you think is easily cloneable on a budget, that would be good to do.

[@anchovian_consular_service7130]

bumping this teardown recommendation. seems like the intuitive next choice :-D

[@soundscrazy]

Very cool info!

[@MissionFitnessCTC]

Great video!

[@JohnDoe-mv4ks]

Any chance at a Part II on attack / release?

[@producermind9030]

Very cool.

[@DragonBiscuit]

Awesome 👏

[@ricksalt6860]

Thanks .

[@andreitimotin3599]

Looks like a hairball kit ))

[@PetersonGoodwyn]

Good eye ;)

[@Owenkelleberger]

You are a great teacher thanks!

[@PetersonGoodwyn]

Thank you!

[@benjaminjoeBF3]

great work, love to see the quirks of these designs, expecially when they sound so good while being so "wrong" ;)

[@PetersonGoodwyn]

You and me both! It's always fun to open a vintage circuit and see what wacky/brilliant stuff they did.

[@catface101]

Sweet Oktava!

[@PetersonGoodwyn]

Thanks! It's a Jolymod, has served me well for 15 years and going.

[@bambinom5359]

Prayers end of your job