looking to DIY a really "obvious" compressor

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Hi... title sort of says it. I want to build a compressor for live use on guitar, but I want a really obvious sounding compressor to get sounds like the auto gain control on an old tape deck or when you set the ratio really high on a compression plug-in. I know usually the idea is to have a smooth "transparent" comp, but I want the opposite.

One sound I like about compression plugins is that if you set the attack pretty short and the ratio high and the threshold low, you can get that sort of lo-fi old desktop cassette tape recorder sound - mild distortion, pumping, breaking up. That's the sound I want.

I've messed around with comp plugins a lot as I have worked as a recording engineer, but I am pretty much 100% ignorant when it comes to the stomp box comps that are out there.

[majormono]

That seems to call for the classic orange squeezer with its enormous swell, it really flattens the signal when you set the bias for the FET accordingly (which people seem to have problems with quite often - I would use a multiturn trim for this and have no problems). It is really more an effect on its own, often described as "dip and swell". Either way, it is such an easy build with the tonepad PCB that it is always worth a try if you haven't already.

[Thomeeque]

Dyna/Ross can be pretty "obvious" too T.

[jessej]

I think it would be interesting to see a schematic for a ALC (Automatic Level Control) from some 80's tape recorded too.

I remember recording song ideas to this Panasonic boombox with a built-in mic back then and I always got an awesome acoustic sound because of the lousy compressor...
As for how I recall the sound, it was not like any ross/mxr/etc I've ever heard, but then again, it might have been all things combined, crap tape and shitty speakers etc.

[Pakaloabob]

I have read great things about the Orange Squeezer, so I built one. Like majormono mentioned, I have been having a hard time biasing the transistor. In the Tonepad build reports somebody said that changing the diode had the affect of allowing more or less control of the sound through the bias pot. Anyway, I haven't gotten the sound that I want yet. Barely detectable effect. I am hopeful it is just the biasing although I could have ruined some of the components during soldering. Maybe someone else has built the Squeezer and compared to another compressor and will prove me wrong.

[petemoore]

  I like 'clunky' compression sounds too !
 Dynacomp/Ross [I left some of the LP filtering out more like Ross] has a capacitor that fills and empties, part of what controls comp-ramping. Making this capacitor larger, and diddling with the fill/drain-rate resistors around it...I'd have to look at the schematic, but it's the 'funny lookin' [not part of the power supply filtering or signal path] electrolytic.
 @@Rate, this changed the ramp up/down characteristics and amount of deep-duck available. Slight ramp-wobble may be noticable at extreme comp setting...also cool, but seems to flatten up pretty close to 'normal' when the comp knob gets turned back...between that and the volume control, nice 'normal' to 'abnormal' compression uses.
  Two capacitors sharing, or one hogging the position, could be put on a switch, allowing original/modded value choices.
 The other one is just a DOD250 with 'a' green LED driving some photocell, sluggish and clunky, which is also cool, doesn't exactly do the unnoticable compression that you'd notice [soon leans toward sluggish as compression is turned up, more like boost when ''compression'' is turned down [the 'compression' knob is essentially ''a gain knob early in circuit'' [before the LED Driver. It's pretty simple and was easy/available for me to plunk together, it's not the worlds most famous compressor, but a little compression [for the more typical compressor uses, such as keep a phaser or other effect circuit topped-up, but not overloaded] or more noticable to 'clunky' ramps [which can enhance certain rythms] is what I answered when I asked 'what do I want a compressor to do besides boost?'

[Top Top]

I think it would be interesting to see a schematic for a ALC (Automatic Level Control) from some 80's tape recorded too.

I remember recording song ideas to this Panasonic boombox with a built-in mic back then and I always got an awesome acoustic sound because of the lousy compressor...
As for how I recall the sound, it was not like any ross/mxr/etc I've ever heard, but then again, it might have been all things combined, crap tape and sh*tty speakers etc.

You might be surprised how close you can get to that sound with a compressor plugin set just right - low threshold, very low attack, ratio maxed out. Especially if you put a short/small room reverb before it, you can get very similar sound to that crappy condenser with auto gain control of those boombox/dictaphone machines. I use this sometimes if I use a sampled instrument in a track but I want to roughen it up a little to make it sound more "real" (as contradictory as that seems). Sounds great on piano - you can get that nice lo-fi living room piano sound.

But it would be cool to be able to get that sound on my stuff live too.

Is there anywhere with extensive clips of different DIY comps in different settings?

[Mich P]

This one maybe ?
http://fuzzcentral.ssguitar.com/ross.php
Mich P.

[majormono]

As many others, I have build compressors of all types (you know... Dyna, Ross, several optos, OS) and the only one that goes really nasty is the OS. The OTA based ones do always remain musical, even when they are set to smash (well, this is highly subjective obviously). The first Squeezers I built had the usual problems with biasing, but the multiturn trim really made the difference, before I was too thinkig that this simply won't ever work but now it's squash city. If you have the OS still at hand, just try and exchange the trim, maybe that does the trick already and it is just a few cents.

[solderman]

Hi... title sort of says it. I want to build a compressor for live use on guitar, but I want a really obvious sounding compressor to get sounds like the auto gain control on an old tape deck or when you set the ratio really high on a compression plug-in. I know usually the idea is to have a smooth "transparent" comp, but I want the opposite.

One sound I like about compression plugins is that if you set the attack pretty short and the ratio high and the threshold low, you can get that sort of lo-fi old desktop cassette tape recorder sound - mild distortion, pumping, breaking up. That's the sound I want.

I've messed around with comp plugins a lot as I have worked as a recording engineer, but I am pretty much 100% ignorant when it comes to the stomp box comps that are out there.

Hi try this one, The Carlin Comp.
I have bread board it and it has sort of the fetchers you are looking for i think. I have etched the PCB from my layout but missplaced it some ware and cant find it, means I sort of have not verified it. and since a lot of other project has made me forget it. Guess I have to start looking 
http://solderman.fatabur.se/future_project.htm

[majormono]

Gee, me again. Since this is a matter of subjective hearing, I searched and found a little testfile I made when twiddling with my OS, so you know what I'm talking about. It's just a little bassline, played crappy and uneven (no, I could really do better, but didn't care for this matter ;-). It goes bypassed, short release, long release; recorded in one shot but normalized in sections. If you take a look at the waveform, you can see that it does not only sound but also look quite squashed. There a some mods done to it (one is obviously a release switch), but basically it's a Tonepad PCB. This frees me from trying to describe what I mean.

http://drop.io/OS_SquashSeries

[wavley]

The Arion compressor, while kind of a POS is great for this lo-fi sound, actually it's the ONLY thing it's good at

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This thread certainly has some interesting info which is helpful... but I can't say I am any closer to choosing one... pretty much every compressor has been suggested so far 

[Ben N]

The squishiest compressor I ever used (briefly) was the DOD 280. It sounded almost like a swell effect.

[guitarman89]

The squishiest compressor I ever used (briefly) was the DOD 280. It sounded almost like a swell effect.

I agree with you, but i want to try these OS, i'm so curious. Many people think that is the best compressor out of there and it is so simple to fill a rainy day without problem...

[Philippe]

That seems to call for the classic orange squeezer with its enormous swell

Ditto. Consider building one of these. It's more of an effect than a transparent volume limiter. The bias adjustment dictates the range of squashing to increased dip & swell, & finally to some moderate distortion as the volume control is increased. You can opt for a 'set & forget' bias trimpot or run with an external potentiometer if you prefer.

[Ben N]

OK, I have had very limited contact with them and have never built one, ut the rep of the OS is, if anything, the opposite: that it can be so subtle (in terms of compression effect) that you don't know it is on. No doubt it can be tweaked for a more "obvious" effect, but from the get-go, the other suggestions seem more one point.

[Top Top]

OK, I have had very limited contact with them and have never built one, ut the rep of the OS is, if anything, the opposite: that it can be so subtle (in terms of compression effect) that you don't know it is on. No doubt it can be tweaked for a more "obvious" effect, but from the get-go, the other suggestions seem more one point.

I am gathering this from this thread and many that I have searched... but on the other hand, getting exactly opposite as well. I wonder if it has to do with the biasing which seems to be a bit tricky.

[petemoore]

  A couple OS's here...looks easy but the Jfets are 'twisty', starting with a layout recommended...@@R@te, the OS's are sweet and IME quite subtle, I could tell that it is not just a booster when...
  it was keeping the amp "up but not over", sounded quite nice like booster, barely tell it's compressing
  it was feeding and envelope follower or Fuzz, by taking a 'hair off the top'
  Nice sound and all but barely noticable other than boosting for the most part.
  There are Orange Squeezer+ type schematics/layouts IIRC, mods to make the OS a bit more powerful compression.
  I'd start with an OTA or Photocell:
  Ross if you like the highs and the hiss don't get too bad or bother, Dyna has extra filtering, starting with a Dyna/Ross board recommended.
  Photocell job is pretty easy though, it's pretty easy to flip the parts in and get ducky compressions.
  Looking at how they work or just building a couple different types...some are better at others when it comes to low frequency Vs. high frequencies Vs. triggering the compression effect.

[Mark Hammer]

The cardinal characteristic of cassette-deck limiters and "AGC/ALC" circuits is the long recovery time.  In other words, toss a transient at them, and the squish is applied for a while after the transient has long since passed.  So, just about any compressor can do what you want, simply by figuring out how to maximize recovery time.

The stock Dynacomp/Ross comes with a relatively long recovery time, set by the 150k resistor between V+ and the 10uf smoothing cap.  generally, what you see as "Attack" controls on compressor pedals uses a very similar circuit and translates that 150k into a 10k minimum resistance plus a pot in series.  Making yourself a Dynacomp clone with a 180k or even 220k resistor will most assuredly provide a sluggishly slow recovery time.

In the case of the Orange Squeezer, the stock design has a very fast recovery time, which is fundamental to its reputation as "transparent".  By increasing the 4u7 cap to ground to 10uf, and increasing the 100k resistor to ground to 470k, you will slow down the recovery time considerably, and subsequent notes played after the first one following a brief period of silence will be suppressed/squished noticeably.