Vintage compressors reverse engineered with ReaComp

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aquataur
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Vintage compressors reverse engineered with ReaComp

Post by aquataur »

Edit 2022. For the record. I have recently incorporated the subsequent information and much more into a written document on the subject that I have published earlier. This document is about using compressors to instill some sense of loudness early in the mixing state. It uses Reacomp as a versatile compressor engine, and I have worked out several basic task-oriented compressor models besides looking at the vintage icons below and more. Against all odds, I finally published ed.2, and it has become eminently useful. You may want to behold it here. The subsequent information is thus redundant and likely obsolete. It may remain there as a reference and for consitency. .

This is for you folks to try out.

I find compressors hard to understand. They are powerful tools that demand to be understood, or you are at the mercy of boutique plugins or presets.

I suspect very few people understand them thoroughly and thus resort to those units, that are proven to work, such as 1176 and La-2a types. It is ironic that those are half a century old.

Unfortunately, buying those elusive plugins does not make me wiser.
I went to find out what the difference in those units is and what makes them so special. This is what I found till now:

#1) don´t let yourself be fooled: aesthetics
#2) some hard to define analog quirks like tube saturation and subtle coloration. For those who hear the grass grow.
#3) hard and fast electric peculiarities as follows.

* LA-2A uses an optical element (light bulb) to excite the gain reduction. This is very slow. How slow in milliseconds is hard to say, but this acts as an averaging element. The signal is averaged over time. LA2A has a fixed attack time of 10ms, but seems to vary up to 80ms. Auto release seems to work well. A slim knee of <1dB is in order.
The side chain is derived from the main input (detector input).
Edit: the LA-2A seems to be of feedback type too.
Note that in the comparison the threshold has been set some dB lower, since the detector circuit "sees" less.

*1176 uses a FET that is very fast (sub-ms). Also a knee of <1dB (hard knee on 1:20). The detector is fed from the output (feedback type), but this time the signal is not averaged. It is not as fast as a VCA (peak = 0ms), so a few ms are in order.
This units uses classic attack, meaning the curve is heading towards 1:1 at higher excitations again.

This exercise would be meaningless if it was not compared to an "official" 1176 unit. I used the free audiocation compressor that is said to be much like an 1176. Use the same settings and compare for yourself. This unit makes this easy, because you see the figures beside the controls. All tests used a drum part made by EZD.

Note that the audiocation unit cheats (like most others) with their presets according to the motto "louder is perceived better". Aim to set the output compensation painstakingly correct for subjective equal loudness, or the comparison will be unfair.

I also tried Stillwell´s Rocket, also an acclaimed 1176 clone, but this is difficult to compare, since (like before) the presets are hyper-inflated in volume, the controls are unreadable and ambiguous and the meters too slow. Fancy it is though. :roll:

So many of those retro-looking devices are flawed by the fact, that the controls are unreadable on a first look.
You always have to read those. For an equalizer this means, you have to read all of them to see where the tweak is. Centuries of optimization for easy readability and space age handling improvements have bypassed those units.
We humans need a mental map engraved in our brains so to find the relevant parameters easily and efficiently and to recognize differences in one look. All other things may look fancy, but are nothing but distraction if you pay attention.
On top of that, there was no standardization on what knobs show, like attack. They are basically labelled "min to max", which makes them hard to compare, let alone simulate with other units.

Those Rea plugs compete well in this respect and are very powerful.

Verdict: I can hear no darn difference between the 1176-ish setup and the "official" emulation! :D
However, the La2A does sound different (I have no free vst unit to compare). This is mainly down to the different RMS computation window. Play with that, this makes the biggest difference.

It is to be expected (or hoped) that expensive emulations make something better, but if reacomp gets me close to them, I´m in!

Attached you will find two screenshots that show all settings for both presets.
Let us know, what you find, fellow mixers.

have fun,
-helmut
(to be continued...)


Addendum:

A guy here emulates an SSL-G with reacomp:
Attachments
1167ish.jpg
1167ish.jpg (170 KiB) Viewed 30936 times
la2a-ish.jpg
la2a-ish.jpg (164.21 KiB) Viewed 30936 times
Last edited by aquataur on Sun Sep 11, 2022 2:54 am, edited 5 times in total.
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Re: Vintage compressors reverse engineered with ReaComp

Post by aquataur »

More considerations on setting RMS window size for LA-2a-ish mode.

The main control element in this device is a filament lamp.
Bulbs that are line-operated are known to exhibit no flicker. This means 20ms for 50Hz mains supply.
It can thus be expected, that the reaction time of such an element is well beyond 50 ms.
Observations from other people for the LA-2a´s attack time (nominally 10ms) range from 30-80ms. Also, there is no agreed method to measure or quantify this parameter. This supports my theory of 50ms or more. Any faster attack times on our generic simulation device are thus meaningless.

As a matter of fact, the LA-2a was used for leveling, for protecting broadcasts from exceeding certain levels.
Incidentally, VU meters were used for gauging, and those have an integration time of 300ms. I would thus not be surprised if the LA-2a´s integration time was much longer than 50ms.

Coloration of tone:

Compressors do not only squash a signal, they can also be used to change its tonality by reshaping transients.
Any compressor, or, as we should realize by now, rather those critical settigs have the power to contribute to that.

I am keen to hear from others who have expensive boutique plugins, how close the simulation gets.

Yes, there will be subtle tone colorations by tubes, but let´s face it, those units were not made to distort, they were made to be clean. Additions by that will be homeopathic and will most certainly drown in a mix.

So, to be fair, any comparisons should be made within a mix.

I don´t know if the pricey replicas are made so well to the original as to repeat their flaws. For example, both types of compressor are known to exhibit pumping and breathing caused by LF overload. A simple side chain HP filter will cure this.

The LA-2a is said to introduce some hi-mid sparkle. Well, be it either by carving out the inner details of a sound by the way it reshapes transits, or by technical peculiarities, this can be mimicked by a hi-mid shelf afterwards, or indeed, a mirror image lo shelf in the sidechain -- if there is one :wink:
(can you hear me, Mixcraft staff?)

On Metering:

I mentioned in the preceding post that some plugin´s meters are useless. They are too slow. Although it has been repeated (even by myself) like a tibetan prayer roll that listening is better than looking, meters provide an excellent starting point.

I don´t know how accurate reacomp´s meters are, at least they respond to transients that others flatly don´t see.
A geek could also listen to the side chain and make decisions upon that.

A sidestep to vari-mu:

Vari-Mu (such as Fairchild) compressor´s curves appear like an extra wide knee, such as 10dB.
They are fast too, so timings are comparable with FET. They are AFAIK feed forward type, with classic attack.
Anybody willing (or capable) to experiment with those settings? If this works, we´d have all four types, VCA (see SSL in the previous post), FET, Opto, and vari-mu types emulated, which would be the end of excuses for everybody.

* RMS size.
* Knee size.
* classic attack.
* feedforward/feedback.
* go for it!

vca-opto-vari-mu-fet-compressors-when-to-use-which

-helmut
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Re: Vintage compressors reverse engineered with ReaComp

Post by Mark Bliss »

Well you tore off a big bite to chew on here Helmut!

I am not sure I have much to add to the idea, but what the heck, some thoughts anyway......

I think the ReaComp is a great hidden gem, as are a few other plugs in that suite. (such as the ReaEQ.)

I look at compressor plugs as tools, and therefore really consider primarily, how they sound and do the controls suit me.
I like simple straightforward controls that make sense.

Metering.
I think you put it well, that using your ears first and foremost is very important. But.....
I also find that in some cases, such as compressor plugs, having some kind of useful indication of its activity helps me get the results I seek quicker. Far too many compressors have very poor metering or indication IMO.
I find myself comfortable with the line style meter in some compressors, that show the threshold, knee and activity pretty clearly in my mind.
comp meter.jpg
comp meter.jpg (14.34 KiB) Viewed 30869 times
Boutique and vintage emulations.
I have experimented with a few and have to admit I largely "don't get" all the fuss and attention. Most of them have vague controls, and many times there seems to have been more attention paid to the graphics face/skin than the programming and resultant sound. And yes, the insistence on setting the default make up gain too loud is very frustrating when evaluating. I hate that! But if they didn't I guess newbs would ignore them for those that did do that. :roll:
I am guessing there are several types of users who might be drawn to vintage emulations.
One is going to be the (probably rare) user who used the real thing and is comfortable with the controls and knows what to expect them to do.
Another (probably more common) is finding an ego boost or something by possessing such plugs.
Some are probably pretty good. And probably overpriced.

Then there is those of us who are just trying to learn how to use the tools to get the desired results. This poses the question, are we trying to get the results we desire? Or are we trying to get the results we have been told we should be looking for.........

I think the best result may come from:
1: Knowing what we are trying to accomplish.
2: Understanding the basic premise of dynamics and how a compressor basically works.
3: Having some knowledge of how the compressor plug in can be used to get the various results.
4: The knowledge that many of the people trying to teach the above, cant tell you #1, cant explain #2 very clearly and insist on abusing their audio in efforts to explain #3.

So, back to your experiment Helmut, what do YOU think so far? 8)
Stay in tune, Mark

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Re: Vintage compressors reverse engineered with ReaComp

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Ah, this thread was kind of dormant over in this cosy corner :D

The story up til now was:

I recorded some stuff that sounds fine on its own, then find that in context everything is competing with everything.
Some vocals drown in the mix for a few seconds, so I consult the web what people do against that. Naturally, everybody hauls out their proven secret weapons like 1176 and co.

Pro´s probably grew up with stuff like that, and they got things sorted out with them, so they won´t use anything else. Word has slipped about their habits, so retro compressors abound.

However, cookbook recipes on how to set certain devices do not suffice. Levels are different, programme material is different, the context is different, groove is different. So those recipes are of little use.

I was going to find out what is special on those compressors and I did to an extent. I also learned what those parameters mean and in what situations those should be tweaked.

People produce 1:1 re-issues of actual hardware devices. Who knows what everybody hears, your brain is biased.
The key parameters I found will certainly get one a long way.

Some others shroud themselves in mystery by terming their presets "opto" or "fet", which only contributes to more mystery.
I found it much more useful to understand stuff like "rms window" and the like.

I find those presets are no good. If you want to tame a singer, you choose "vocal preset XY", and still don´t know what to tweak or to listen for.

If you know that you want to tame peaks, sure you can use a $$$ Urei look-a-like, but you might also use ReaComp and set the RMS window and attack time accordingly and save big bucks. If you want to level balance a track, set the RMS size bigger, and if you like, set it like a LA-2A would do.

That alleged misterious treble enhancement or sparkle that people claim to hear.... prove it.
I file this under homeopathic.

Or to put it another way, posessing those elusive devices will not make your mix one iota better...
Yes and I agree with you on the ReaPlugs. They are underestimated. Somebody once suggested a trendy skin for their suite... they resisted. British understatement?

-helmut
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Re: Vintage compressors reverse engineered with ReaComp

Post by pipelineaudio »

While we were developing ReaComp, I accidentally ignited a flame war of crazy kickbanning porportions with an extremely similar thread. I'm glad to see how much more reasonable people are here and much much much more glad that someone "gets it" that so much of the compressor characteristics we are familiar with (subconsciously or not) are about the detector
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Re: Vintage compressors reverse engineered with ReaComp

Post by Mark Bliss »

Well, late or not, welcome to the conversation. More recent visitations to the subject at the end of this thread: http://forums.acoustica.com/bbs/viewtop ... 14&t=20470

Many open minds here, a few exceptions as expected.
But we are still searching for the "truth", please go on.......
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Re: Vintage compressors reverse engineered with ReaComp

Post by aquataur »

Welcome pipelineaudio.
I remember your name from the other forum. I also remember the controversy.
See you have changed the fleet. :wink:

Did not realize that you were entangled in the making of reaper plugins.
Maybe you can bring some more light into this discussion.

There used to be some reaper buff that claimed he could emulate all sorts of character compressors. But unfortunately, apart from one or two there was never any follow up.

I wish they had supplied a few presets with it.

Now this is somehow in contradiction to what I have said in the beforementioned thread about presets, but in this case it would be a good learning exercise.

Of course some devices will have unfathomable gew-gaws like tubes and auto-this-and-that (which maybe is homeopathic in contribution) but it will get us close and teach us a thing.

I would not know how and where to start if I were to find out what other (famous) compressors do regarding those parameters.

-helmut
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Re: Vintage compressors reverse engineered with ReaComp

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I read that thread as well. Always looking to dig out the useful details and ignore the nature of some posters. :lol:

I seem to recall the article on the plug in use being a blog, and yes, feeling like the author left the topic hanging, waiting for some additional follow up. Not like that ever happens. :roll:
But I think your (old) posts here caught the good parts of it quite well Helmut. Very much worth the study.

I am always curious about the efforts to emulate old hardware, and wondering about the value of such efforts.
But so many things are so very subtle.
I am intrigued for instance by talk of the effect of just routing signals through some of these old boxes even with settings turned off. Back to that "bit of sparkle" comment I guess. And also to this Neutrino thing. I thought I had pretty sensitive hearing for the subtle, but I am just not getting it.
And then we come to the ultimate question, what does it matter to the end user listening to your carefully produced song on his "smart" phone speaker.......... 8)
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Re: Vintage compressors reverse engineered with ReaComp

Post by aquataur »

Mark Bliss wrote:But I think your (old) posts here caught the good parts of it quite well Helmut. Very much worth the study.
That is satisfying.

And then you asked the forbidden question:
Mark Bliss wrote:(...) what does it matter to the end user (...)?
(Sigh).

This reminds me of my father´s 70th birthday. We did a whole rigmarole about this. Music, eating, dance, big fireworks at midnight and all.

My brother did the filming, the brother´law in excess of 500 fotos.
I made a beautiful film out if it, with script and narrator, good film music, funny trailer and take-outs. Weeks of work.
Needless to say, nobody took notice. They were all bored looking at this. Spoiled by action-laden Hollywood stuff and overly distracted by the day´s chore.

This repeated lateron with the music I had recorded too, and other things

This taught me, do it for yourself.

And another little thing to remember: Sgt. Peppers. This was done on a 4 track unit with repeated bouncing. I am sure they did nothing more than some gain riding with a good ear, maybe some crude spring reverb. Are we getting lost in technicality, seriously? Is the mountain of things we have not conquered yet in front of us humbling us so much as to giving up trying?

-helmut
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Re: Vintage compressors reverse engineered with ReaComp

Post by aquataur »

New insights have changed the situation. Please read the edit in my first post.
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Re: Vintage compressors reverse engineered with ReaComp

Post by Mark Bliss »

Good to see you back around Helmut, will be peeking at your additions!
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Re: Vintage compressors reverse engineered with ReaComp

Post by aquataur »

Thank you Mark. Good to view you too.

Against all odds, I managed to solve the conundrum.
Ed. 2 is out (link on top) and I find it useful myself. Hey, I have written my own help manual.
Keep revisting that page, this is work in progress.
Let me know if anything needs more attention.

Have fun,
-Helmut
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Re: Vintage compressors reverse engineered with ReaComp

Post by aquataur »

Another year has passed. We are still at it.

As mentioned in my .pdf document (see original topic), Reacomp (and all other free = non-Reaper plugs) have not been updated for several years. So reacomp free might slowly be phased out due to increasing incompatiblities and quirks. This is very misfortunate, since one would be willing to pay, if this were the motivation that kept them from updating it.
So I was looking for a similar platform that was equally generic, meaning configurable.
I think I found it with Melda´s (free!) M-Compressor.
mcompressor.jpg
mcompressor.jpg (717.59 KiB) Viewed 10307 times
(Note the graph window is detached, more on this later)

For a free plugin (if you can ignore the nag line on the bottom) this is astounding.

So what is lacking compared to the palette of controls reacomp offers:
*look-ahead ("pre-comp") as mentioned
*(vintage) feedback mode (it is presumed feed-forward, i.e. the SC is input-derived)

So it can do practically all emulations or task-specific models I outlined in the write-up, apart from the following exceptions:
*ducking
*parallel
because it does not have look-ahead. Edit: see on the bottom
They do supply a limiter preset, but how well this works without look-ahead remains to be judged.

However, what this plugin does have is a phenomenal persistence or history display (they call it time display), as shown on the picture, which can be used alternatively to the common input/output/reduction meter. This is ultra configurable in a menu.

It also has an input gain control (which makes an alleged gain plugin in front of reacomp obsolete) and it has an output control that is not entangled with the gain reduction as it is on reacomp, meaning again saving a gain plugin afterwards.

The main limitation of the unregistered (free) version I discovered is that you cannot resize the plugin window in case you want a bigger time view, but, as shown in the picture, you can detach it and resize to any dimension you want.

From a sonic view, I do not hear (with my aged and highly untrained ears) any difference for equal settings between reacomp and M-Compressor, but the vastly increased display options are very useful. So for everyday tasks you want to perform with authority, this appears another perfect candidate and it has potential to push reacomp from the throne.

I recommend giving it a swing (pun indended).

Edit
I wrote another paper that explains how to add faux look-ahead to your compressor
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