PCB for compressor?

[ferrinbonn]

Hey guys. I'd like to build something along the lines of an Xotic SP Compressor or Wampler Ego. I know the FourOne from Madbean has a blend like those two, but it's optical and I don't think the others are.

Anybody build the FourOne and willing to share their experiences? Anybody know of any other PCBs along the lines of the SP or Ego?

[dbp512]

I haven't built the 4:1 yet, nor have I built any other optical compressor, but I heard great things about it. I actually got one in a PIF that I'm looking forward to building. I built a few orange squeezers and ross based, which are very different but nice in their own ways. I'm also planning on building an engineer's thumb, which is supposed to be a bit quieter than the ross.

[matmosphere]

I built a bear hug and love it. It doesn't have a clean blend but you could add one.

[midwayfair]

Don't just jam whatever compressor you like into a blend circuit. You need to make sure that the signals will be in phase at the output. (So you can't just put the Bearhug in the JMK Panner for instance without extra work, not that I think that the Bearhug benefits from a blend circuit given the short decay.) The 4:1 was set up to do the blend right. The fractional extra speed you get with an OTA compressor like what's in the the Wampler over a fast vactrol like the VTL5C1 is not really that meaningful when you're using the clean blend to retain the attack of the note.

If you want to be able to add any compressor (or other pedal) to a blend circuit so you can experiment, read this: http://www.geofex.com/Article_Folders/panner.pdf

[daleykd]

Don't just jam whatever compressor you like into a blend circuit. You need to make sure that the signals will be in phase at the output. (So you can't just put the Bearhug in the JMK Panner for instance without extra work, not that I think that the Bearhug benefits from a blend circuit given the short decay.) The 4:1 was set up to do the blend right. The fractional extra speed you get with an OTA compressor like what's in the the Wampler over a fast vactrol like the VTL5C1 is not really that meaningful when you're using the clean blend to retain the attack of the note.

If you want to be able to add any compressor (or other pedal) to a blend circuit so you can experiment, read this: http://www.geofex.com/Article_Folders/panner.pdf

Jon, did I read an old post of yours correctly in that the Engineer's Thumb doesn't need an added blend?  It already has it using the RATIO pot?

[midwayfair]

Don't just jam whatever compressor you like into a blend circuit. You need to make sure that the signals will be in phase at the output. (So you can't just put the Bearhug in the JMK Panner for instance without extra work, not that I think that the Bearhug benefits from a blend circuit given the short decay.) The 4:1 was set up to do the blend right. The fractional extra speed you get with an OTA compressor like what's in the the Wampler over a fast vactrol like the VTL5C1 is not really that meaningful when you're using the clean blend to retain the attack of the note.

If you want to be able to add any compressor (or other pedal) to a blend circuit so you can experiment, read this: http://www.geofex.com/Article_Folders/panner.pdf

Jon, did I read an old post of yours correctly in that the Engineer's Thumb doesn't need an added blend?  It already has it using the RATIO pot?

Merlin on this subject:

U1a and U3a form a current-controlled gain block. The 100pF feedback capacitor stabilises the circuit at high frequencies. The ratio control works by introducing a fixed feedback resistance in parallel with the OTA, effectivedly blending uncompressed signal with the compressed response.

This does not mean that your dry signal is amplified separately from the compression circuit, and any gain increase introduced by the gain pot can be eaten by the OTA chip, but your gain can never go below unity (minus 10% from the 1K/10K divider at the volume pot) so technically when compressing heavily it works like a blend circuit. There's also a treble bypass to keep from cutting your highs.

But this is sort of like cheating to say that's a blend circuit like what's meant here. I mean, the Bearhug will do the same thing when you hit 1x gain, but I wouldn't call it pre-blended or anything.

I would say I was probably wrong about the ET not benefiting from a blend circuit, but I also don't particularly care for blended compression at the front end of a guitar anyway. (Recording is a different matter. I'm all about blended compression in post.)

[daleykd]

I would say I was probably wrong about the ET not benefiting from a blend circuit, but I also don't particularly care for blended compression at the front end of a guitar anyway. (Recording is a different matter. I'm all about blended compression in post.)

All of your info makes sense.  Thank you!

The only thing I want to confirm, just for my sanity: the ET, like the DynaComp will invert the phase; correct?  Therefore, I'd need a summing opamp and an inverting opamp?