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Author Topic: Compressor Mods  (Read 10945 times)

phatt

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Compressor Mods
« on: December 23, 2010, 09:24:55 AM »

Hi fellow tone tweakers,
 
It seems it's a love/hate thing with Compressors, some like some don't.

My main experiences are with the dreaded CS2. (hated it and sold it,, noisey as hell)
Also still own a Quadraverb GT. (poor me) It's preamp systems where also a horrabillas experience.

My CS2 was a long time ago and I have learnt a lot since those days so I thought I
should at least test some ideas and see what really goes on inside these circuits.
Heck why not,,I've got an LM3080 chip in the junk pile somewhere.

I've always found Compressors more trouble than they are worth but after hearing a neato trick using a CS2 in front of TS9,,,
Wow really did improve sustain and bingo it sounded a lot less like a compressor.
Well you learn something new everyday.
Obviously it got me thinking about Comp circuits again.

Now I'll cut to chase.
Needless to say out came the breadboard and after a few weeks of breadboarding many
ideas I've found a few things you might like to know. None of these tricks will fix the clean sound of these comps but may improve the OD sound if used *IN Front* of Distortion units,, Obviously after Distortion won't work as well.
If you are into a lot of funk rythums then I admit clean comp is a usefull tool
but Still Noise is usually the enemy.

The Pumping action.
After much headscratching it dawned on me that the clamping action is not a matter of speed but *DEPTH*, it's far too much.

I Fixed Pumping action by *Changing diodes to LEDs*.
A switch could be used here for standard (hard) and led (soft) comp.

This raises the comp point and although you loose a bit of clamping it still retains a fair amount of sustain which helps to overcome that dreaded humph mumph you get with most Comp circuits. (Very nice I like)

The switch on the caps changes the recovery time.
2u2= fast, 10uF= slow. Can't make up my mind about that part yet.

**NOISE**,, As said a huge issue. (on all but the rare expensive studio racks
systems)
It seems that everyone just copys the other's ideas with a few changes and throw it on the market. Even Bootweakers don't seem to try hard to solve some of the noise issues found in some classic circuits.
Heck,, maybe I'm alone in my quest to build quiter circuits.  :lmao:

So lower noise was the priority, the *must fix* otherwise it's just going to end up
landfill and I'm wasting my time. ::)

Now being this unit plays around with a lot of gain I can't say I've made it *Noiseless* but I believe I've dramatically improved on the CS2 styled Compressor circuit.

Tokai made one similar to Boss CS2 unit and it apparently had a better S/N so I mixed up some ideas from a whole pile of schematics and then I just kept tweaking things.

So yes I'm very impressed,, With the Sustain full up and Attack slow it works well
with my distortion units.

With the Leds engaged it has already fooled me a couple of times so it would be hard to tell if it colours the sound. Obviously run clean it still retains the classic CS2 comp sound if that is your thing but I'll hazzad a guess and say it will NOT be as noisy and hissy.

Of course if you wind up the level it will still deliver some hiss but I'm assuming you all know not to use the Compressor output as a master volume,  :trouble.
I doubt you would need to turn up the level much as this unit still has heaps of headroom. (A 50k level pot may work just as well here)

So if you wish to get more from your distortion units this may be an improvement.
At the least I've created a working circuit that may give others with better insight some ideas to work with.

When time permits *I will* be building this circuit. The Danger is to keep on tweaking but I doubt I could improve it further without resorting to much more complex circuits.
Have fun with it, Chrissy Cheers from Phil.
« Last Edit: December 23, 2010, 09:38:15 AM by phatt »
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joecool85

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Re: Compressor Mods
« Reply #1 on: December 23, 2010, 10:16:13 AM »

Keep us posted after you build it.  I've not used many compressors but this looks like one I might like quite a bit.
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J M Fahey

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Re: Compressor Mods
« Reply #2 on: December 23, 2010, 10:21:20 AM »

Looks very good.
I *think* I have a 3080 too.
Where? ... God knows !!!
As a first step, the schematic was duly saved into the special "Phatt" file, together with Phatt-tone, Phatt-Dist , Phatt-presence and last but not least, the glorious Phatt-Reverb.
Yes, I've dabbled into Compressors too (still do) and agree that the *biggest* PITA is getting the correct control signal.
Pumping is deadly.
Congratulations.
EDIT: dear Phil, can't you please save your schematics as .gif or .png instead of .jpg?
The last format is useless here because it was invented for colour pictures and *on purpose* blurs images to hide pixelization.
See that lines, circles, etc. have a "ghost" image around them because of this.
Try it, you'll see a big improvement.
« Last Edit: December 23, 2010, 10:28:16 AM by J M Fahey »
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joecool85

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Re: Compressor Mods
« Reply #3 on: December 23, 2010, 10:38:01 AM »

EDIT: dear Phil, can't you please save your schematics as .gif or .png instead of .jpg?
The last format is useless here because it was invented for colour pictures and *on purpose* blurs images to hide pixelization.
See that lines, circles, etc. have a "ghost" image around them because of this.
Try it, you'll see a big improvement.

Or try a better jpg compression.  As a webmaster and developer, I appreciate the jpg for all it's worth and agree it can be ugly if poorly compressed, but when properly made they look great.  I don't know what he's using for software though and if there aren't any settings, normally jpg gets the shaft and you have to use a .png for high quality work.
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phatt

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Re: Compressor Mods
« Reply #4 on: December 25, 2010, 08:56:08 AM »

Hi folks,
         Yep I've never been able to get my head around all these different formats so Time for me to look into it further.

Sadly coming from an industrial background I missed out on basic Computer skills so a lot of this technoligy goes over my head I'm afraid.
Floppin hang it all ,,I'm Sooo old school I've still got Cassette players and Turntables.
I doubt I could even switch on an iPud. HaHa.

My first few Schematic's from the net took up about 10 pages of an old dot printer for
one schematic which had to be joined together with sticky tape.  :grr
But I've been using IrfanView since some enlightened person put me onto it which
allows one to resize things to fit on normal A4 paper.
That was a big big help. <3)
I've been using IView ever since but now I'm *up-loading* files I obviously need to
look deeper into the finer points,,,So thanks those helpful tips there maybe some improvement in the new year.

I've posted what I hope is a better effort.
Please note a small booboo. ***R13 should be 5k***
I paralelled two 10k as 4k7 is not quite right. The offsets are obviously quite touchy and
without knowing exact DC offsets it's hard to know exactly where to set bias points
so a trial and error working up and down until you find it.

The input to the LM3080 is about as low as you go for SNR but the output may still
need work as the sustain knob still presents a fair amount of hiss when the Amp is
cranked up to live gig levels.
(not bad but enough to be annoying,,
I'll except a Compressor but I'll burn in hell before I use a noise gate)

I might throw it all in a make shift jiffy box and give it a test run at the next Club gig.
Phil.
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joecool85

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Re: Compressor Mods
« Reply #5 on: December 26, 2010, 10:54:46 AM »

Phil, that file looks MUCH better.  Thanks for posting it.
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J M Fahey

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Re: Compressor Mods
« Reply #6 on: December 26, 2010, 03:26:34 PM »

Hey !! That's cleaner , *and* smaller (40K vs 70K)
Congratulations.
Anyway I knew you were the nerdy type: cassettes !!! , what's wrong with 8 channel tapes , huh ?? :grr
And when we go dancing on the beach with all the guys and gals together, we have a portable, battery powered 45 RPM record player .
How's that ??  :tu:
And we sneak some beers too, although we're under 21.
Naughty boys. :trouble
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phatt

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Re: Compressor Mods
« Reply #7 on: December 29, 2010, 08:31:00 AM »

Hi JMF,
A bit of trivia for you,
Did you know that 8Tracks never caught on in the land downunder whereas cassettes where a huge hit.

My LM3080 has died  :'( so that brings all progress to a grinding halt.

For the time being I relented and purchased a cheap S/hand Marshall pedal.
The *Ed 1 compressor* as it's called.
Same chip and very similar circuit that I've posted which of course still has the inherint hiss problem if you up the sustain and level.
With the level held low it's useable,, so will see how long I can stop myself from tampering with it. :lmao:
Hum?? I wonder how a couple of leds would work in that circuit.

Did find some interesting circuits while searching the net.
As to your comment about *Control Voltage* being an issue,, well 2 stood out and looked rather interesting.
*Pearl* Make one and the *DOD 525* looked trick.

Also *DOD Attacker* I did partly test but that is about the time the chip lost its magic smoke. I have a feeling that the control pin5 is a problem if you short it,, but I'll never know exactly what happened :grr
Cheers Phil.
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J M Fahey

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Re: Compressor Mods
« Reply #8 on: December 30, 2010, 01:06:09 AM »

Quote
the land downunder
:o :o
You mean ... Argentina ??? ;)
We have the southernmost city in the World  8)
Just Google Ushuaia :o
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phatt

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Re: Compressor Mods
« Reply #9 on: February 06, 2011, 06:48:39 AM »

Well guys,, it's bin a hard road :'(

A lot of the circuits floating around are really dud,, but light at the end of the tunnel.

I will never visit *Ushuaia* but I just may end up buliding a compressor,, Winky.

After thinking I blew up the LM3080 chip it came back to life after I found the *Blackfinger Schematic by EH*

Wow it works though it has no real controls except for comp.
It's very quite compared to other circuits and I've built a few in the last few months.

Will have a modded schematic in a few days if all goes well.

there are obviously a few *black finger* schematics floating around and they are different but we will see which ones works well after a bit more testing.

*Mictester* at FSB is a rather clever chap and has helped me get a grip on how these things work.

This one although it has limitations does not use the LM3080 chip in the signal path.
Helps keep the noise down by a big margin.  I liked it before I even BB built it.

Have been playing it all day and it's kinda nice,,, not as much Comp as the ED but far less noisey.

Now the trick is to see if I can get it to work from a single supply ,, another task,,, oh well life goes on.
Phil.
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askwho69

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Re: Compressor Mods
« Reply #10 on: February 07, 2011, 12:54:02 AM »

I think i will stop looking for compressor :tu: digging this up:D
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phatt

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Re: Compressor Mods
« Reply #11 on: February 07, 2011, 08:04:14 AM »

I finally got a working schematic.
Bear in mind this is all on the BBoard and still siffting through some ideas but this at least will work as shown.

It was Glitching or clamping hard off in a cyclic LFO kind of way but added R7 (1m2) seemed to sort the random hickup problem.

The Aim is to get this working very well,,,understand it enough to then be able to establish if it could be modified to run on a single supply.
So wish me luck.

Note for Askwho,, be aware these are tricky circuits and I strongly recommend you test these circuits before building them.
Cheers, Phil.
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askwho69

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Re: Compressor Mods
« Reply #12 on: February 08, 2011, 12:13:36 AM »

Thanks Phatt  :lmao: you have Phatt heart  ;D
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J M Fahey

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Re: Compressor Mods
« Reply #13 on: February 17, 2011, 06:30:02 PM »

Looks good, but I was dismayed when asked for LM3080's.
Looks like they are not made any more; NOS omes command from $15 to $30 each !!!!!!!!!!!!!  :duh :loco
Which is the modern replacement? (there must be some, although the ones I found so far were miniature SOIC and the like)
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DJPhil

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Re: Compressor Mods
« Reply #14 on: February 17, 2011, 07:29:18 PM »

Looks good, but I was dismayed when asked for LM3080's.
Looks like they are not made any more; NOS omes command from $15 to $30 each !!!!!!!!!!!!!  :duh :loco
Which is the modern replacement? (there must be some, although the ones I found so far were miniature SOIC and the like)
I poked around a bit and it seems there's not many OTAs made anymore. You might consider the Japan Radio Corporation's version of the LM13700 (Mouser link and datasheet). It's a dual, but it's only a dollar (here in the US anyhow). At that price you could leave the second half of the chip idle and still win out. I haven't done a detailed peek at the specs, but the original 13700 was used in synths, compressors, and LFOs for phasers for many years.
JRC has saved my bacon a few times, as they make more than a few older chips that aren't really easy to find. I'm a big fan of their LM386 clone (NJM386) as it comes in DIP, SOIC, and SIL (!).
Hope that helps. :)

Edit: Fixed a typo
« Last Edit: February 18, 2011, 04:08:50 AM by DJPhil »
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