Designing a simple audio compressor from scratch

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In this episode, we'll DIY our way towards a simple audio compressor circuit, based on my diode VCA. If you want to build along, here's the bill of materials:
1x TL074 quad op amp
1x TL072 dual op amp
11x 1N4148 small signal diode
1x 10 uF capacitor
1x 100k log potentiometer
2x 100k lin potentiometer
1x 20k lin potentiometer
10x 100k resistor
2x 20k resistor
2x 14k resistor
1x 4k7 resistor
1x 1k resistor
Chapters
00:00 Intro & what is compression?
04:21 Rough circuit structure
06:12 Diode VCA
09:48 Peak detector
14:19 Voltage subtractor
16:24 The gap & how to get rid of it
21:34 The ratio control
23:32 Attack & release
27:45 Sidechaining & outro

[@UnwelcomeGuestVideos]

The extra effort here with the animations was definitely appreciated on my end! I love that you slipped a side chain feature in at the very end! Beautiful stuff Mortiz!

[@MoritzKlein0]

glad to hear - doing the animations is super fun, will definitely expand on this in the future.

[@mbrombert]

@@MoritzKlein0 Agreed. This new approach is really well done and looks great. Thanks for the awesome content!

[@c1ph3rpunk]

@@MoritzKlein0 what did you use for those animations? They’re super helpful.

[@executorarktanis2323]

@@MoritzKlein0 Animation helped me a lot here thanks

[@San.Tarcisio]

animations super helped

[@erich1394]

I am a hobbyist C++ Audio DSP programmer, so I understand exactly what a compressor does and the functional blocks used to control it, but the actual breakdown of specific implementations using electronic components has always eluded me. Looking at electronic circuits without experience made it difficult to see the "boundaries" between components. Your video has helped me realize that obtaining generalized knowledge of common audio electronics sub-assemblies and the ability to identify those sub-assemblies is the key to my understanding audio electronics in general. I feel significantly less intimidated about designing audio circuits after watching this video. Thank you so much for the work that you do!

[@simonlinser8286]

Yeah, thinking in modules i guess. It's what makes any tear down or circuit analysis video good, is them kind of circling part of the board and saying what it is and then the individual components, and it's the right way to think of circuits. I guess the only difference is when you don't know and see a circuit board it looks over overwhelming but if you can break it down into its parts or sections it's more approachable.

[@jacobhn2]

I hacked a Yamaha compressor GC2020 to have a 10-second release time, it was so that when I watched a movie the sound was absolutely perfect and without it going beyond the dynamics and when the scenes with low volume the compressor slowly turned up the volume. Attack time=0, Release time=10sec or less

[@widepen93]

I'm in a similar boat designing a pi DSP drum machine+synth. Care to share your favorite resources of getting to understand compressors? This video helps but im trying to soak up some more. Thanks!!

[@TheRailroad99]

Yeah, that's what engineers (have to) do... Divide and conquer. Doesn't matter if it's HW or SW. chop it into simple modules and test them thoroughly

[@pollo.888]

Ive taken the full electronics series of courses in my degree track. Stumbling across these videos makes everything I've learned click.

[@elluisito000]

As a pedal designer, compressors have always puzzled me. This is a very nicely done video describing how they work. Thanks

[@chrismathewsjr]

i don't work in music any more but one of my favorite things is asking "pedal designers" simple things like "what does an NPN transistor do" and "how does ground work"?

[@executorarktanis2323]

@@chrismathewsjr lmaoo how does it go then

[@dieSpinnt]

@@executorarktanis2323 I am more basic. I would first ask why he uses his assumptions(or delusions?) on his hypothetical designers with an example in the style of the Brothers Grimm? What stupid (and the totally unnecessary blanket insulting taunt) stuff he's talking up there? A totally insane straw man about how transistors work... thrown out of context to make himself important. Great! Now we all know the kind of people he dislikes: music pedal designers. Did someone ask for that? Or does this childish BS interest anyone? As @elluisito000 said, it is a very interesting topic. Just search for "boss compressor schematic" or "Formant", "Parametric Multiband", "Hollis", "Teletronix", and so on. Not a bad idea to learn from the experts ... or ancients ... or ancient experts!:) Have fun playing and soldering, all (including our braggart).

[@executorarktanis2323]

@@dieSpinnt holy thanks man

[@matturner6890]

@@chrismathewsjr I'm not an obstinate prick anymore, but one of my favourite things is asking guys like this simple things like "how do you talk to people at parties without them all leaving"?

[@famitory]

i have been looking for a good compressor circuit that didn't need any fancy components (monolithic VCA chips, OTAs, special FETs , or LDR tuning) for a long time and finally here one is.

[@adamdev9391]

2:02 - My god. This is the best explanation of compression I have ever seen

[@gooball2005]

This was a great video! I especially appreciate how you went into your circuit design process, building it up on a breadboard and addressing any hurdles as you came across them. Great work!

[@jacobrepp787]

Amazing, thank you for bringing this subject to life. Great graphics, animation and as usual clear and deep explanations.

[@Triggs-Music]

absolutely astonishing how well you put together this info.

[@punman5392]

You should modify the peak detector to use a precision rectifier instead of a half wave single diode like you use. That way you can reuse the circuit for an envelope detector to control a VCF without noticeable wobble when playing bass frequencies. The big downside to half wave peak detectors like that is that with bass frequencies you tend to hear a lot of wobble in the envelope as it’s only acting on half the peaks.

[@JoseLuisGarcia1234]

starting the year with incredible stuff! thanks so much for all your effort and great content, you are a truly unique channel in youtube 🔥

[@visionary4040]

awesome video! love the animations, they make everything feel much more intuitive

[@longdongsilver4719]

Your descriptions are, as always, clear and simple. And I love your animations.

[@JamesPearson]

Brilliant Moritz, this is such a great circuit and beautifully explained as always. The animated visuals are a treat, thanks for all the effort with that - I know it wasn't easy. Looking forward to building this sometime. Happy New Year when it comes :)

[@MoritzKlein0]

let me know how it went once you do!

[@SeanPorio]

Awesome video! Always super informative and well-explained. Hope you keep making more great videos this year!

[@abhijithcpreej]

Absolutely beautiful! I love these types of breakdowns!

[@francescoprontera9957]

Amazing work ! Wanna see more of this in the future ! Keep going man

[@wedkarzkosma]

Thank you Moritz! Great explanation and I really like the animations you made.

[@kernealalpiniste6293]

The animation is great ! Really helps Great videos, as always !

[@mymodularjourney]

Great description of the functionality. Thanks for the video.

[@spiesonmars]

Your use of animations is great - it really helps to understand what's going on in the circuit. Nice work!

[@GerardoLeon-zd2kl]

So much dedication on this video. Thank you so much for making it, its so useful and wondrous!!

[@neekonsaadat2532]

Moritz you are great. Thank you for all of your hard work to spread this knowledge!

[@SomeWeirdCat]

This single video is more useful than any of my circuits classes ever were

[@kcbanner]

Have been watching this channel from the beginning, these animations are so good at explaining these concepts - this channel is a such a good resource!

[@majordabalert]

Awesome video. I’ve been really interested in building a compression circuit so this is kind of a godsend. Really great video structure too. Thanks

[@cadflo]

Thank you so much for this!! Ive been waiting for this type of video to start making my own comp. Time to get to work!!

[@ulfschoneberg6452]

Toller klarer Stil, tolle Videos, danke Mortiz!

[@2012TheAndromeda]

This is so elaborate and well explained. Wow. The animations are great too. Thank you!

[@jorgezuniga3956]

Genuinely very detailed and well taught. Thank you for showing this. Love the content!

[@oveschleisner-meyer8139]

I love your clear and visually decription - great.

[@jregns]

Brilliant walk through and animations! I especially like the step by step explanation and problem solving when the next issue arise. Thanks! 😊✨

[@TheBigChoppa]

Appreciate that you shared from the process of designing vs explaining a schematic! This definitely shed some light on a few basic ways compressors can have unique characteristics. Thank you for the hard work!

[@brunohaas3421]

This just helped me so much in understanding compression, thank you!

[@lettersnstuff]

I’m not sure how I haven’t had your videos in my recommended yet but I’m genuinely excited to have found your channel

[@michael-rommel]

Thank you, Moritz, for this outstanding video! It was one of the best that I have seen in a long time! Very comprehensive and comprehensible!! Tempted to get your series of modules just to support you in this effort!!

[@PeterJaquesMusic]

This is really great! I'm just diving into circuit design, so this was still over my head, but you explain things so well that I started to get it, even though I need to understand the real basics first. I'll definitely be checking out your other content! thanks!

[@Sharky_31]

The Grafiks are amazing. Well done

[@frankjrgensen1439]

This is by far the best explanation I’ve seen on compressors and the building blocks involved. Thanks a bunch!

[@unchaynd7266]

Brooo cool! Excited to see this!

[@camjones9213]

What a great explanation of compression circuits - these videos really helped me whilst studying Audio electronics

[@moliver_xxii]

circuit using diodes as variable resistors always make me happy and smile. they are always so surprising but work great. thanks!

[@alemassa6632]

Beautifully explained, you're a great speaker.

[@FirstnameLastname-gl1hh]

Very thorough easy to understand explanation, great job

[@kevinknutson4596]

Your visualizations are wonderful and these videos help get my head around a lot of EE concepts xD

[@DumblyDorr]

Love your videos! Perfect level of detail, great explanations, clear visuals. Hope you got through the annual Silvester-war in Neukölln okay :) The beat from your drum-machine being almost exactly that of Massive Attack's "Angel" also brought a big smile to my face.

[@MoritzKlein0]

at some point i was really sure someone must be firing a machine gun in front of my window. absurd stuff.

[@CircularMirror7]

Another great video. Loving the Animations. 🔥 🔥 Luckily my DIY system needs a analog compressor. Happy new year 🎉

[@joshuakendall3965]

Wow, your educational videos are superior to all others. So elegantly constructed and informative. I thank you.

[@takislontras4563]

Finally !!! I was hoping you would touch the subject!! Awesome content my friend. My best youtube suggestion video in ages :)

[@xpump876]

Nice explanation and walk-thru !

[@matzer8846]

Great stuff in this video ... thanks a lot for your in depth analysis

[@lukaswalczak93]

This is exactly, how to learn analog circuit design. I absolutely love how you describe every single detail. That shows that you truly understand what you are doing, making it really really helpful for others to understand these concepts. So helpful, thank you so much.

[@McTroyd]

Thanks for the video! It's a lot simpler than it seems, which explains why this was doable back in the era of vacuum tubes(/valves). Love the animations as well. 👍

[@vinjetho1609]

i've been wanting to learn about signal processing, and electronics in general, for a while, but it all just seemed so confusing. the animations and visualizations in this video were amazing, and helped finally feel like i have a chance at understanding things! thank you so much for this amazing video!

[@javierpiles]

Animations were very helpful for the explanation! Thanks!

[@mats4011]

so much knowledge, well taught, with meaningfull explainations and stunning visuals. I learnt a lot. Thank you for this amazing work!

[@Mario_DiSanto]

This is a great video. Well-done.

[@autofigure00]

youre videos are extremely helpful and a major godsend

[@DrMoe.Lester]

I've been binging your videos. If only electronics at school was explained how you present it! Thank you so much for your efforts, looking forward to more videos.

[@thomashowe855]

I have been looking for a way to make a diy compressor. Thanks Moritz!

[@infantino93]

Been getting into DIY pedals lately, I must say you may be the most concisely informative 'tutor' I've stumbled across. Learned a ton, thanks.

[@AMTunLimited]

I was just thinking about this! I plan on making my own Eurorack in the new year and my first module is going to be ab envelope follower as it's one of the few things I don't already have on hand, and I realized that ducttaping it to a VCA would be instant compressor! Excited to watch this

[@kellerdev2905]

Wow, great ideas! Compressor is a must to make a nice mix, I've struggled with adding a little bit of soft clipping on a couple of iterations to increase the loudness this way, but that's much more professional sounding!

[@delusionwalker8852]

Dude, you are amazing!!!!! You explain and show things just how I like it straight to the point, concise explanation no bullshit. Thank you so much!!!!!

[@juanvicentedelrio716]

I have been on the audio scene for over thirty years, I mean on the electronics field rather than in the use of the machines, and believe me...I have never found a book or document that explains in both easy and comprehensive way the subject you have gift us on this video. Not only the practical design and the theory behind (without getting into heavy design issues) but, also, the perfect animation and perfectly chained explanation. I have subscribed immediately to your channel. Thank you for your work.

[@BristlyBright]

Just paused at 8 minutes to say WOW! The animations! They really help to grasp the flow in a much easier way! Thank you!!! 🙏

[@marouaniAymen]

This is one of my best electronic related videos that I watched so far. It did give me some inspiration on how to multiply two signals together or how to do frequency modulation.Thanks.

[@blacklion79]

Best explanation how basic compressor works I ever seen.

[@anthonyhart7878]

The add level of quality was really noticeable with this one. This was a great video.

[@Zadagu]

I always wanted a video which explains how compressors are engineered and never found one on YT, to this day. Thank you very much! Finally I got some insights.

[@cspower7259]

Loving the diagrams. Gives a really good way to visualize whats going on. Its kind of what my mind see, when looking at a circuit diagram.

[@laptoprecai]

I just discovered your channel and loved it! Great stuff man please keep up the great work!!

[@prsm3]

Diese Videos sind einfach so informativ wie eine Doppelstunde Physik Leistungskurs, wirklich sehr gute Qualität und man kann einfach alles so leicht verstehen!

[@electron7373]

Excellent presentation quality - you must put a lot of time and creative effort into each video. Thanks Moritz!

[@Scanlaid]

So glad I found your channel. Went to school for mechE, this is basically all magic.

[@VandalIO]

Man ! I loved this ! Learned so much from your video :)

[@doBobro]

Animation o_O. It's amazing how well fluid pressure analogy works here. Oscillating membranes are mesmerizing.

[@AndersWeijnitz]

Best compressor walk-through on Earth!

[@jimgoodinmusic]

Moritz great one! I will add this one to my build list and it gives me some confidence to do it having built your VCA. The side chaining feature is cool in this - I don't know the term but I believe I have heard the effect. I've still got to finalize the breadboard version of your ADSR - still playing with and understanding a bit. Thanks for being a great teacher and resource for the DIY mod community!

[@GGAPDIY]

This video, explanation and animation is truly amazing! Please do one on EQ and/or a Mic Pre-amp!!

[@ahmedelmazaty9459]

you are the perfect teacher of delivering information thanks a lot.❤

[@BennosProject]

Its the first time i really understand what a crompressor does! Thank you!

[@manobabicz]

It is unbelivable that i try to make a compressor with sidechaning since last fall (without any succes), and your video is just came to my face and covers everything! This new animations makes a really nice illustration, and as i see you implemet this really well with motion. You are a really kind person to share this knowledge in a professional way. Perfect stuff! Deserve more attention.

[@AngadBagga]

I finally understood what a VCA is. Thanks.

[@roelandriemens]

I am really compressed by this explanation Moritz. 😜 Great video.

[@Matim4ik]

Wow, Moritz! First of all, I've learnt so much by watching your videos. But this one is on the next level. Super cool animations, easy to follow. You made me to get into soldering modules. I've got a lot of yours Erica MK DIY kits. And now I'm trying to come up with my own designs. PS: I hope you will release the compressor DYI kit as well.

[@nicksix71]

Wonderful! Wonderful! Wonderful! Thanks for a great video!

[@heslip7042]

What a great video. The drawings and animations are fantastic. As an electrical engineer, I've very much enjoyed this.

[@migrantfamily]

21:42 I love that sound! I need to build this for my acoustic pedalboard.

[@monoamiga]

Your videos are a treasure.

[@MrShmazoo]

I’m a current EE student with a budding passion for computer music and find this video incredibly inspiring. Thanks for the detailed explanation and impeccable animations!!

[@chitlitlah]

I just built this circuit with some changes for my guitar. Since unamplified guitar voltages are a few hundred mV at most, I only used one diode on each side of the diode bridge and didn't attenuate the signal going through it. Other than that, I replaced the potentiometers with fixed resistors since I don't have any pots on-hand and changed two or three resistor values, but that's it. It works really great as a compressor.

[@juanbarcelosalves]

hey, I'm trying to recreate this circuit for the same purpose as you, for a electronics class in college, I would very much appreciate if you could share the components you used, specially the OpAmp, since all the OpAmp I own strugles with such low voltages. Thank you.

[@victorsantanpagay5811]

Wow it's very simple at the same it's very effective good work sir

[@aduedc]

This works great for symmetric wave forms, which is most of the cases. Now, imagine you have a wave form which has negative peaks and no positive peaks, then the peak detector will never turn on. To solve this problem you need to place absolute value circuit before the peak detector, which could be as simple as full wave 4 diode rectifier circuit or its opamp equivalent.

[@DiVoidationStudio]

This is the best stuff about electrotechnical principles in music. This beats all that I've learned for several years in my engineering university. Just excellent and very inspiring! Thank you!

[@payloh_3328]

Agreed awesome stuff

[@hamlob]

This is the best video I have ever seen

[@ls-nj8kw]

As someone who recently started designing his own Eurorack Synth from scratch (first VCO PCB is getting manufactured atm :) ), this was a very helpful video! I'm definitely going to check out your other vids. And I really like your style (at least in this video, haven't seen another one, yet)!

[@Blah53455]

DUDE SUPER SLOW CLAP, what and amazing video, i will be sharing this over and over again brother, I love the way you even went in depth on the parts you ended up changing . This just doesn't just show you something , it shows you why you chose to coarse correctly . What an amazing video. I'm so pumped to see your others .

[@DjDoggDad]

Figuring out how to make a sidechaininng compressor has been on my radar of projects i'd like to do and then stumbled across this awesome video! Thank you so much!

[@JonDeth]

This is great and straight forward. There's so many ways to achieve compression that seeing a specific scheme broken down into an actual tutorial with the lab and circuit gives those of us interested an example of a clear pathway for our own designs. Because I am specifically desiring one for guitar ATM, I can see from your circuit a way to incorporate this theory of operation into a feedback path to buck some of my input buffer when the circuit sees an excess. As I understand it, you're demonstrating the implementation of multiple methods of compression for an overall more dynamic circuit and performance. *Anyway, this will definitely help me with the design I have had rolling around in my head.*