Want to Build a Compressor

[Schappy]

I have a Boss Compressor and really dont like the way it sounds.

What are some good DIY compressors?

[auden100]

Pretty much everyone and their dog builds either the Ross/Dynacomp/Keeley Compressor or an Orange Squeezer. You can see details at tonepad. Or just search.

Fuzz Central has a nice work up of the Ross schematic.
http://fuzzcentral.ssguitar.com/ross.php

There's also a compressor section in the schematics/layouts part of the forum. Loads of options there. Pick one!
http://www.diystompboxes.com/smfforum/index.php?board=22.0

The schematics section has 12+ compressors, and the layouts gallery has a boat load more.

[jkokura]

I'm kinda interested in an optical compressor build. I'd also like to try including a blend circuit in a compressor ala barber... If only it were Christmas and Dave were here to share the tone press with us. Sigh.

[mmaatt25]

I built a DOD280 optical compressor using Tonepad's PCB, I didn't like it myself, the attack seemed slow. It had loads of compression available if you wanted it.

I've also built a Ross compressor, again on a Tonepad PCB and an Orange Squeezer on perf. The Ross is cleaner than the OS, that said I like colour/tone the OS adds.  

I found I was using one or the other all the time, so I built them into one box and used a 3pdt to switch between them, I can't bypass them, but as I said I always use one or the other.

So I recommend both

[GibsonGM]

The OS, for me, is more like a dirty booster with some (but not a TON) of compression.   I use mine as a solo boost, lol.  It does sound really good, adds a tad of grit and warmth, IMO, but for a more 'traditional' compression, you might want to try a Ross or something.

[Mark Hammer]

Compressors are a frequently misunderstood, and misapplied, device.  People often use them in ways that simply exaggerate their worst characteristics.  

I'm not accusing you of either of those, but the question needs asking: How do you use yours, and what is it that you don't like?

[armstrom]

Here's a design I adapted from the Q&D compressor. Minor changes (nearly all suggested by Mark) The result was pretty good. Lots of gain available so you can use it as a clean boost if you want.

http://www.mr2-power.com/compressor.pdf

You can see some of my comments on the build here as well: http://www.diystompboxes.com/smfforum/index.php?topic=74507.msg715251#msg715251

[Schappy]

To tell you the truth I dont use my compressor very often at all.

When I do its mainly to get a country clean sound and also for more sustain for soling.

[FlyingZ]

I have built 9 Orange squeezers  and use one myself studio/live.

[Schappy]

Mark,
Im still a little mystified as to the proper use of a compressor. Please give me some info.

I feel the Boss Compressor just colors the tone in a way that is undesirable.

[Hanglow]

I like the flatline for a simple build

schem -http://www.hollis.co.uk/john/flatline.jpg

layouts  are in the gallery, think markm did one or two. there's aslo a vero one floating around

[CynicalMan]

The flatline is nice. It has a slow attack, but it sounds good and sustainey.

[.Mike]

Im still a little mystified as to the proper use of a compressor. Please give me some info.

I highly recommend reading DBX's whitepaper Compression 101: ftp://ftp.dbxpro.com/pub/PDFs/WhitePapers/Compression%20101.pdf

Even though it is for rack units with much more flexibility and indication than any compressor stompbox I have seen, it really puts compression into easily-understood terms.

Edit: Fixed link.

Mike

[FlyingZ]

I feel the Boss Compressor just colors the tone in a way that is undesirable.

The Boss CS-3 has some usefulness in the studio as a limiter. It's a fair audio compressor but not at all optimized for an instrument.

[CynicalMan]

Im still a little mystified as to the proper use of a compressor. Please give me some info.

I highly recommend reading DBX's whitepaper Compression 101 [PDF].

Even though it is for rack units with much more flexibility and indication than any compressor stompbox I have seen, it really puts compression into easily-understood terms.

Mike

That link doesn't work. Go here:
ftp://ftp.dbxpro.com/pub/PDFs/WhitePapers/Compression%20101.pdf

[Mark Hammer]

Mark,
Im still a little mystified as to the proper use of a compressor. Please give me some info.

I feel the Boss Compressor just colors the tone in a way that is undesirable.

Most of the treble lives in the first few hundred milliseconds after your pick/strum.  After that, the small wiggles of the string disappear and all that's left is the fundamental and some lower-order harmonics in any appreciable amount.  Moreover, the treble is essentially riding on top of the fundamental, and is a chunk of what makes those initial peaks as tall as they are.  Because compression is such a non-obvious effect, in comparuison to distortion or filtering, people tend to crank up the amount of compression.  As a result, when one uses lots of compression, there is the impression that the treble has been removed, since the treble presents itself in a way that forces the signal to be instantly reduced by the compressor.  There are two solutions.  One is to mix in a bit of the unaffected signal with the compressed signal, and the other is simply to back off the compression amount so that you get to hear a bit of the initial attack.

So, the "coloring of the tone" that you feel the Boss provides is something you would likely experience with a great many other compressors if they were set for the same amount of compression.

Now, heavy compression, and the apparent treble-cut it provides, can be just the thing if you are driving a pedal or amp to breakup.  If you wish to keep the sparkle of a nice clean tone, though, it's best to use less compression than you think you need.

The other thing to keep in mind with compressors is that they amplify anything they interpret as "soft signal".  Most stompbox compressors do not include any sort of circuitry that would help them to tell the difference between soft picking, and background hiss.  So, if you feed them anything other than a pristine signal, and you stop playing, that hiss will be boosted; moreso if you have the pedal set for heavy compression.

[.Mike]

That link doesn't work. Go here:
ftp://ftp.dbxpro.com/pub/PDFs/WhitePapers/Compression%20101.pdf

Thanks. It worked in the preview, but was changed out when I submitted. 

[Schappy]

With the Boss unit what do the attack and sustain knobs do?

[armstrom]

The sustain knob simply controls how much compression you get. Many compressors use the term "Sustain" rather than "compression ratio" because many guitarists are just looking to get more sustain by using the pedal.

The "attack" knob appears to be a threshold adjustment of some sort. At least that would be my guess from looking at the schematic. "Attack" usually refers to the rate at which the system reacts to a change in signal level, however as far as I know the only good way to increase/decrease the rate at which an RMS level detector reacts is to change its averaging cap. This pot simply acts as a 250k variable resistor between +9V and the input of a JFET so it would seem to be offsetting the output of the RMS level detector before it goes into the VCA.

[Mark Hammer]

"Sustain" is compression amount, and "Attack" is actually recovery time/rate.  The gain is automatically (and rapidly cut) in response to pick attack.  After you pick, the gain is slowly brought back up.  By slowly increasing the gain (and resulting volume) as the actual vibrating string dies out, you get the illusion of a string that is sustaining longer.  It isn't; it just sounds like it is.  If the gain recovers slowly, you get more of that long sustain illusion.  But if the gain stays low for a longer operiod, it also means that the next note you pick (assuming you pick fast enough) will not be at the same output volume as the first note...because the gain is still taking a little "holiday" before it fades back in.  

Because such long gain-recovery takes away from hearing the pick attack of subsequent notes, and because the concept of gain-recovery is too darn complicated to explain to some folks, manufacturers have traditionally labelled that control "Attack".  Boss is not alone in doing so.  They almost all do it.  The thing is, that adjustments to "attack" are not always audible.  You will hear the difference between faster and slower recovery times only when you pick fast clusters of notes.  Pick one note on one string and let it hand around with some finger vibrato, and chances are you will not be able to hear a difference between any setting of the "attack" control.  If you intend to play like Paul Kossoff or Tom Scholz, then slow attack is your friend.  If you plan on chicken-pickin', then you want very fast attack settings.