Orange Squeezer Mods

[aziltz]

Thinking about the Orange Squeezer, I'm about to build one using Theo Hartman's External Bias Mod.

http://www.guitarjamdaily.com/index.php/insiders/1932-pedal-insider-control-freak-part-2

But, I also like what I hear from Mark Hammer's Compression/Gain Control used in the Tangerine Squeeze.  Example,



My question is regarding using both.  Mark's Compression/Sustain Control takes the Stock Level of compression and lets you back off quite a bit. 

Does Hartman's Bias Control act the same way, or is it more like a Ratio Control?  Can anyone attest to this?  I know its a popular addition.

[Mark Hammer]

They end up doing more or less the same thing, which is varying how much resistance change there is in the "ground leg" of our virtual pot i response to an input transient.  You can either accomplish that by changing the resistance to ground via Hartman's approach (which is also valid), or you can accomplish it by varying how much envelope signal is produced in response to an input transient.

For my part, I lean towards the second method, because the first one does not necessarily allow you to shape what frequencies the envelope "favours".  But if you don't need the unit to give any frequency preferences in terms of what it responds to, one method works as well as the other.

Again, I remind folks that the feel and compressin action of the unit depends on both the input leg of the "vrtual pot" (the 82k resistor on a stock OS), and the ground leg of that same attenuator circuit (the FET and trimpot/s).  When you have a resistive divider, and dynamically vary the resistance of one side of it, the impact changes to the ground leg resistance has on the signal level will depend partly on the value of the input leg.  If that 82k was, say 47k, you would need to swing way down low on the ground leg to produce noticeable attenuation (since the FET starts out being a high off-resistance).  If it was 150k, then even modest changes to the FET drain-source resistance would start to produce audible attenuation.

[aziltz]

Thanks for that explanation Mark. I was hoping you'd jump in there. 

[MattXIV]

I've been messing around with the OS as well and trying to get a control that can go above stock compression with minimal additional noise.  The 3 options I've been looking at are:

1.  Replacing the 82k with a pot and a fixed resistor.
2.  Adding a pot to increase or decrease the gain of the op amp.
3.  Using the other half of the op amp to amplify the signal before the diode a la Mark's design.

Any thoughts?  3 seems the best option at this point, but I'd like to avoid running up the part count anymore than I need to.

[aziltz]

after building Hartman's Mod tonight to turn down the compression via the Bias, I've concluded that Mark's control is much better, much more practical.

The thing with Hartman's control is, if you adjust it, and then smack the strings hard, the FET "readjusts" itself somehow and there is a huge clamping, just for a moment.  Then everything is even and good.  This happens whether you are turning up or down.

If you want more compression, separate the two sides of the op amp and adjust the gain driving the diode, so that it doesn't give you more output when you turn up the compression.