Oranger Squeezer Bias = Comp?

[nguitar12]

Hi everyone just wonder if the "Bias control" of Oranger Squeezer Compressor equal to the "Comp" control of most compressor pedal? If not how to modify it into a two knob pedal (Comp and Level)?

Project:
http://www.generalguitargadgets.com/effects-projects/compression/dan-armstrong-orange-sqeezer/

[jatalahd]

I am not quite sure what is referred to as "Comp" control, but I will try to answer anyway The four most important parameters that define a compression effect are: threshold level, attack time, release time and compression ratio. In the referred schematic:

http://www.generalguitargadgets.com/pdf/ggg_osq_sc.pdf

the bias control pot (R7) controls the threshold level. When the output voltage exceeds the threshold level (with the JFET pinch-off voltage included), the resistance of the JFET Q2 drops so that the voltage divider formed by R2 and Q2 passes most of the signal to ground instead of output. As such it implements a dynamic compression ratio control.

I have never though about controlling the compression ratio in the Orange Squeezer, but at a quick glance, this could be possible by adding a pot between R2 and the drain of Q2. If the resistance of this added pot would equal R2 (82k), then in the case of exceeding the threshold, the input voltage would be always approximately halved before going through the op-amp. This does not really qualify as a true compression ratio control, but is a simple solution towards it. Here we cannot really know the resistance over Q2, but if Q2 is fully conducting, then its resistance is quite small compared to R2. If I have understood the terms correctly, a better place for compression control would be at output of the op-amp, just before the level detection.

Let's wait and see if others have better ideas.

[GGBB]

Yes and no. Although the bias control does affect compression level, it doesn't provide as much control over "ratio" that one would typically expect from a compression control. The most thoughtful effort I've seen at this was by midwayfair a few years ago: http://www.diystompboxes.com/smfforum/index.php?topic=98682.0. I think he now tends to not bother with it as it doesn't provide enough control to prove useful.

I took another approach for the Orange Smoothie that originally came from Mark Hammer's Tangerine Peeler. It is a more true ratio control, but the build is more complicated than the Orange Squeezer. However, I find the threshold control to be more useful - seems like varying the ratio for guitar compression is not that useful IMO. That being said, the Orange Smoothie can really compress a lot if you want it to.

[nguitar12]

Yes and no. Although the bias control does affect compression level, it doesn't provide as much control over "ratio" that one would typically expect from a compression control. The most thoughtful effort I've seen at this was by midwayfair a few years ago: http://www.diystompboxes.com/smfforum/index.php?topic=98682.0. I think he now tends to not bother with it as it doesn't provide enough control to prove useful.

I took another approach for the Orange Smoothie that originally came from Mark Hammer's Tangerine Peeler. It is a more true ratio control, but the build is more complicated than the Orange Squeezer. However, I find the threshold control to be more useful - seems like varying the ratio for guitar compression is not that useful IMO. That being said, the Orange Smoothie can really compress a lot if you want it to.

Is this compressor perform better than the orange squeezer? If I going to remove all other pots except the Volume and Compress/Ratio. What's the suggested value for the fixed resistor. Also if Rev. 3C the latest version?

Many thanks

[GGBB]

"Better" is subjective. I would describe it as the same sound, more transparent and more versatile. You could build it as a stock squeezer plus comp control - the instructions for that and a whole lot more information is in the build guide I put together which you can download from the first post in that thread. I have a 1.1 version now (slight changes) that will be released soon (read the last few posts of the thread for information). If you want stock squeezer plus comp then 1.1 offers no benefit for you so build 1.0 Rev. 3C.