More gain from OCD

[ferdinandstrat]

OK so here is the schematic for the OCD

What do you think is the best way to add more gain to this that wont affect the sound all that much?

Increase R5? R9? Bypass R6? Though I think the last one will affect the tone though

[antonis]

Just start decreasing R8 down to 10k..
(without altering C6 value, HPF corner frequency is raised up to 160Hz from 41Hz..)

If you wish to maintain original corner frequency, increase C6 value by the ratio of R8_new/39k

P.S.
Increasing R5 should have minimal effect on first stage gain due to 1M Gian pot value..
Bypassing R6 might result into IC1A heavily loading with all touching effects..

[Fancy Lime]

You want gain, not volume, right? If so, decrease R4 by the factor by which you want to increase the gain and increase C3 by the same factor. So, for example, for 10 times the gain, you would have R4=220 Ohm and C3=680nF.

Andy

[GGBB]

Increase the gain pot to 2M. Or if you don't care about low gain sounds, increase R5 to whatever gives you the lowest gain that you would use. For example, if you always have the gain control at 12:00 or above, measure it's resistance at that setting and add that to R5 (a typical A1M pot at 12:00 would be ~100k).

This will not change the sound character.

Decreasing R4 and increasing C3 will accomplish the same goal but may change character slightly because the values might not scale perfectly to keep the high pass cutoff frequency the same. You might also need to scale C2.

Decreasing R8 will probably change the character of the distortion as it will introduce more op-amp distortion. Stock gain of the second stage is ~4.85 applied to the signal that is clipped after the first stage to about +1V/-0.7V. This seems already "on the edge" of clipping, so raising gain of the second stage will introduce even more harsh clipping by the op-amp rails. You might like this, you might not.

[Steben]

Increase the gain pot to 2M. Or if you don't care about low gain sounds, increase R5 to whatever gives you the lowest gain that you would use. For example, if you always have the gain control at 12:00 or above, measure it's resistance at that setting and add that to R5 (a typical A1M pot at 12:00 would be ~100k).

This will not change the sound character.

Decreasing R4 and increasing C3 will accomplish the same goal but may change character slightly because the values might not scale perfectly to keep the high pass cutoff frequency the same. You might also need to scale C2.

Decreasing R8 will probably change the character of the distortion as it will introduce more op-amp distortion. Stock gain of the second stage is ~4.85 applied to the signal that is clipped after the first stage to about +1V/-0.7V. This seems already "on the edge" of clipping, so raising gain of the second stage will introduce even more harsh clipping by the op-amp rails. You might like this, you might not.

Some of that slight opamp clipping will be a crucial element in the OCD sound. So it will indeed come to taste whether one likes more gain in stage 1 or 2 ... or both.

[Mark Hammer]

OK so here is the schematic for the OCD

What do you think is the best way to add more gain to this that wont affect the sound all that much?

Increase R5? R9? Bypass R6? Though I think the last one will affect the tone though

You want more "gain" but don't want to affect the sound?  I don't get it.  Is it not loud enough?  It HAS gobs of gain.  More than enough to push any amp over the edge.

If your goal is to be able to get more volume at lowest Gain knob settings, then simply insert some resistance (e.g., 100-220R) between the clipping section and Vb to raise the clipping threshold a bit without changing the nature of the clipping.

[GGBB]

Some of that slight opamp clipping will be a crucial element in the OCD sound.

The key word there is "slight." I'm not sure there's much clipping in the second stage if any. I wonder if it was designed with just enough gain to avoid clipping or to introduce slight clipping. The effect would depend heavily on supply voltage - low battery will have more distortion, go up to 12V or higher and probably none. In this video https://www.youtube.com/watch?v=eMFqVPLWyAM I can hear a difference between "sag" and 9V but not really any difference between 9V and 18V. YMMV. I have not come across debate about or preference for running the OCD at lower voltages for more second stage distortion (or mods to accomplish the same). In any case, increasing distortion in the second stage is probably "detrimental" to the sound character but personal taste will vary.

[Mark Hammer]

IC1A has more than enough potential gain to exceed the maximum voltage swing of the op-amp.

[antonis]

With all the respect fellows, in a two stage gain overdrive with hard clipping configuration between stages it should be more wise to "share" overal gain..
(one can have 1st stage gain of 50 followed by 2nd stage gain of 2 but I personally prefer two stages of x10 each..)

[Fancy Lime]

Maybe now is as good a time as any to ask if the OP is sure that 53db in the first stage are really not enough. And if so, what signal is going in and what do you want to come out, sonically? I have a hard time imagining a situation where 53db would not be enough gain that doesn't also make me wonder if an OCD is really the weapon of choice here. I for one like the OCD for it's lower gain sounds. For high gain, I would choose something else or stack several pedals. That is of course personal preference, I'm just trying to point out that we might need a bit more information to help you to the best of our abilities.

Andy

[antonis]

Maybe now is as good a time as any to ask if the OP is sure that 53db in the first stage are really not enough.

I totally agree with you Andy but we have to esteem OP's fancies..
(in the mean of offering practically feasibly custom solution..)

[Fancy Lime]

Maybe now is as good a time as any to ask if the OP is sure that 53db in the first stage are really not enough.

I totally agree with you Andy but we have to esteem OP's fancies..
(in the mean of offering practically feasibly custom solution..)

Well, I don't need to tell you that I approve of all kinds of fancies. I am in fact quite the fancier of fanciful ideas. But if we knew more precisely what tones would catch the OPs fancy, we could provide more useful help, I fancy.


Andy

[antonis]

Anything fancy known and understood by more than one person, as a matter of course, automatically ceases from being fancy anymore..

[ferdinandstrat]

Maybe now is as good a time as any to ask if the OP is sure that 53db in the first stage are really not enough.

I totally agree with you Andy but we have to esteem OP's fancies..
(in the mean of offering practically feasibly custom solution..)

But you guys know more than me(most likely), to me the mods are likely to sound good regardless

Maybe now is as good a time as any to ask if the OP is sure that 53db in the first stage are really not enough. And if so, what signal is going in and what do you want to come out, sonically? I have a hard time imagining a situation where 53db would not be enough gain that doesn't also make me wonder if an OCD is really the weapon of choice here. I for one like the OCD for it's lower gain sounds. For high gain, I would choose something else or stack several pedals. That is of course personal preference, I'm just trying to point out that we might need a bit more information to help you to the best of our abilities.

Andy

OK I seem to have forgotten that the OCD is capable of high gain sounds, cos I heard demos and it can in fact chug

[Steben]

There is always a Rat to study for really high gain.
The one with slew rate fancy 

Seriously, I think a booster in front is something to consider. It doesn't alter the original OCD circuit.

[Mark Hammer]

There is always a Rat to study for really high gain.
The one with slew rate fancy 

Seriously, I think a booster in front is something to consider. It doesn't alter the original OCD circuit.

That's why I like to include a booster in the same enclosure BUT also include an order-flipper toggle, so that the booster can either change the output level or push the input harder.

[Fancy Lime]