More compression in an OD?

[jimosity]

Say I have something like a TS-9 or a Fulldrive and want more compression out of it; what would I change?
Diode clipping? If so, how can I get MORE compression than that alone would provide?  Any suggestions on something variable?

[raulgrell]

I remember seeing a schematic once of an MXR dist+ witth some sort of arrangement of a JFET in its feedback loop that the author claimed made it more compressed... IIRC, it was (after some filtering and level control) signal to the gate, drain to 9V and source to one of the op amp inputs; all of this in parallel to the original loop... I lost the schem though, and it seems the original site is down...

I think it was a design by alfonso hermida...

[ianmgull]

If you have a stock TS9 there will be to Si diodes in the clipping section. Replacing these with Ge diodes will lower the forward voltage and give you a bit more compression in the process.

[darron]

If you have a stock TS9 there will be to Si diodes in the clipping section. Replacing these with Ge diodes will lower the forward voltage and give you a bit more compression in the process.

or take it twice as far with some 1n5819s if you are trying that, but that will loose volume. maybe not the sort of answer you are going for.

[petemoore]

  What's the OD ?
 Yupp, the TS I've been mod-a switchings on now has diode selector and fatness lift switches.
 Ge's would be harder clipping/lower output, and that would equate to reduced signal dynamics [or compression].
 A similar deal is to add a booster in front to bring the signal voltage up higher, also resulting in harder clipping, reduced dynamics, but the output will seem a little louder.

[Mark Hammer]

The problem with many of the suggested approaches is that compression = clipping.  If you don't care about that, just crank up the damn gain until everything clips.  If you want the tone of moderate clipping but with less dynamic range, than you have to adopt another approach.  I'm not sure those other approaches are any less complicated than simply sticking a compressor in front of the clipping pedal.

[liquids]

Edit:  Mark beat me to it.  

1N5819s are schottkys, and my understanding is that they should be pretty close to GE diodes in their 'forward voltage,' generally speaking.  Barring other differences, GEs often do have a certain 'mojo factor' to them in cases where that is what the 'original' used.     I try to stick to working with Schottkys, primarily because they're cheaper....GEs are rarely worth the $1+ a pair more in cost, let alone the trouble of working with them -- I find them break extremely easily, for one.   For many uses, the Schottkys are better all around.   The major factor you will hear in any diode-in-feedback-loop clipping clipping circuit is attributed to the forward voltages of the diodes, rather than the type.

Anyhow, all those mods will add not just more compression, but a harder-clipped signal.  Are you already maxing out your gain control?  If not, than you may truly just want a compressor...

Anyhow, use a DMM and measure the forward voltages of what you have - Silicon, GE, Schottky.  your Silicons should be between .5v-.7v on the DMM.   Ges and Schottkys will be between .15v-.3v.   For more compression, you want lower overall forward voltage....so if your starting with a pair of SI diodes, the next step down would likely be 2 Schottkys/GEs (again use the DMM with the specific diodes you are using to verify this) or mix and match them.  Then the next step down is using just 1 Schottky/Ge, for even more compressed clipping, but more clipping.  less forward voltage will also result in less output volume, comparatively.  

That being said, I personally think slamming the input of the clipping stage with a boost, or 'stacking' by hitting it with a mu-amp/mini-booster/SRPP/mosfet boost stage, for example, is a better way to add 'compression,' if by compression you mean sweeter, more singing sustain, or 'stack' two TS circuits, or any other OD...lots of possibilities.

Keep in mind all of the above - diode changes or booster--> TS will add more clipping/distortion, not just compression.    If you only want more compressed feel, not more clipping or extreme amounts of sustain, You might just want to build a compressor.

[darron]

it's a good question though, what is it that adds a more compressive sound to the output of an overdrive/distortion without adding more clipping.

schottkys cosy a fortune here, more than Ge diodes do, but they conduct sometimes that extra 0.1 v lower lol. they are much much more durable and have a more predictable response speed.

if you wanted more distortion+compression though i'd just ramp the opamp to run harder.