more OD/gain from ratio control

[briane]

Hello all,

I have been playing around tweaking the od in one of my builds, thought I might ask if anyone had any suggestions or experience in pushing the od a tad further towards my goal.

I would like to get a bit more gain out of the ratio control. I often find the drive (od input) is near zero (just enough to pass signal), and the ratio(od return) is cranked to max to get a nice mellow lucious overdrive thats not overly grinding. problem is mainly in wanting the ratio control to go to 11 or 12, not a whole lot more is needed, but some is.

This is on a non-hrm build, basically built off the ODS101 nHRM schematics, 100k drive (labeled level on ODS101...edit) pot, 100k ratio pot, .01/150k out v2a, .005/180k out v2b, and 180k/120k plates on v2, 220k/150k plates on v1. the OD input is through a 220k into a 100k trimmer set about halfway or so. Snubbers are 250p. Pretty standard stuff. The guitar is a nice strat.

any suggestions appreciated.

thought I might try:
1) 250k ratio control (or larger)
2) drop 180k out v2b to 100k or lower, maybe use small bypass cap
3) monkey with plate values. would 220k/150k plates on the od get me closer to my goal?
4) 100k plate on v1a. How would this affect the sound?

currently has .01 on mid cap tone stack.

So if you have tried any of these it would really help to know if they are a step in the right direction. I've cruised through old posts, but this does not seem like something thats been discussed in any detail, or at least not beaten to death yet.

thanks in advance,
brian

[dave g]

I'm not really sure what you're trying to accomplish here, really. The OD level doesn't give you distortion per-se unless you're clipping the power section. You're saying you want a hotter signal coming out of the OD section? You could just turn the master volume up a little more...

If you're after the low gain thing, 100k plates is really the way to go. I personally prefer 100k plates all around, even for higher gain stuff, but that's another story...

[briane]

I should mention the pot I am discussing is labeled in the ODS101 schematic as ratio, its the last 100k pot in the OD before the master volume....Somehow I got in the habit of calling that level...anyways

yeah, separate masters was my first thought....though I am trying to retrofit this build without redoing the faceplate, and I am not yet conviced that a few minor tweaks to the existing circuit might achieve that (I guess the ratio could be replaced with 1m (ie new master), rewire the OD switch for separate masters, add 100k ground reference and that would be the same). But a non-HRm with separate masters just seems like more hardware than is really needed.

Its not more distortion that I am after, its really just more of what already exists....that is to say to get the same OD tone as the ratio control maxed out, but only having to turn it up to say midway. That would allow more range in matching volumes of the switchable channels.

Part of this is it would allow a better matching in equality in volume when switching in and out of OD with the PAB engaged. The idea being to increase the OD rather than reduce the boost, in order to more closely match the two, as the 100k ratio pot seems to run out of range.

Its a subtle thing I admit....thanks for the hints.

[ayan]

I should mention the pot I am discussing is labeled in the ODS101 schematic as ratio, its the last 100k pot in the OD before the master volume....Somehow I got in the habit of calling that level...anyways

yeah, separate masters was my first thought....though I am trying to retrofit this build without redoing the faceplate, and I am not yet conviced that a few minor tweaks to the existing circuit might achieve that (I guess the ratio could be replaced with 1m (ie new master), rewire the OD switch for separate masters, add 100k ground reference and that would be the same). But a non-HRm with separate masters just seems like more hardware than is really needed.

Its not more distortion that I am after, its really just more of what already exists....that is to say to get the same OD tone as the ratio control maxed out, but only having to turn it up to say midway. That would allow more range in matching volumes of the switchable channels.

Part of this is it would allow a better matching in equality in volume when switching in and out of OD with the PAB engaged. The idea being to increase the OD rather than reduce the boost, in order to more closely match the two, as the 100k ratio pot seems to run out of range.

Its a subtle thing I admit....thanks for the hints.

OK, I understand you want more volume out of the overdrive channel. Not a problem, and no need to convert to individual masters. You have a 180K fixed resistor plus a 100K pot, right? You can go with a 33K resistor and a 250K pot instead. That will preserve the frequency response.

Gil

[briane]

You can go with a 33K resistor and a 250K pot instead. That will preserve the frequency response.

super excellent. thanks, just what I was thinking, but did not have the values in mind. I kept thinking this should be just a minor change.

will post back in a day or two after swap out and test.

as always, much appreciated.

[briane]

gil, that worked great, theres now about 2 1/2 times more range in the ratio control.

while at it I also noticed the circuit has a frequency drop out as the level control (labeled so in ODS101) in turned up from low to mid, ie about between 8 & 9'oclock. at 10'oclock the frequency cut opens up, but this also results in a lot more grind. Switching the input resistor to v2b to 150k, and adding a 47 ohm resistor on the level control between pin 1 and ground (ie, grounded through 47ohm) seemed to mostly fix that issue. I suspect thats caused by the amount of resistance the signal sees, and the associated high frequency drop out that should be expected with just under 280k of resistance (which I now have just under 250k with level control near minimum, but not totally grounded).

[ayan]

gil, that worked great, theres now about 2 1/2 times more range in the ratio control.

Great -- of course, I knew it would work out for you as it was something I had looked into years ago.

while at it I also noticed the circuit has a frequency drop out as the level control (labeled so in ODS101) in turned up from low to mid, ie about between 8 & 9'oclock. at 10'oclock the frequency cut opens up, but this also results in a lot more grind. Switching the input resistor to v2b to 150k, and adding a 47 ohm resistor on the level control between pin 1 and ground (ie, grounded through 47ohm) seemed to mostly fix that issue. I suspect thats caused by the amount of resistance the signal sees, and the associated high frequency drop out that should be expected with just under 280k of resistance (which I now have just under 250k with level control near minimum, but not totally grounded).

I am not sure what to say. If the pot is wired correctly, the output of the stage always sees a fixed resistance.... However, the thing is that the tube begins to behave in a non linear fashio as you turn the "level" up, so the sound will perhaps change in a not si predictable way. Quite frankly, I "tune" my amps for the range of ovedrive in which I use them. I someone wants less gain than I do, I would change a couple of things in a certain specific direction. If somone wnated to use the amp with more gain, I would do the opposite. Glad you seemed to have found a solution that works for you.

Cheers,

Gil

[ayan]

gil, that worked great, theres now about 2 1/2 times more range in the ratio control.

Great -- of course, I knew it would work out for you as it was something I had looked into years ago.

while at it I also noticed the circuit has a frequency drop out as the level control (labeled so in ODS101) in turned up from low to mid, ie about between 8 & 9'oclock. at 10'oclock the frequency cut opens up, but this also results in a lot more grind. Switching the input resistor to v2b to 150k, and adding a 47 ohm resistor on the level control between pin 1 and ground (ie, grounded through 47ohm) seemed to mostly fix that issue. I suspect thats caused by the amount of resistance the signal sees, and the associated high frequency drop out that should be expected with just under 280k of resistance (which I now have just under 250k with level control near minimum, but not totally grounded).

I am not sure what to say. If the pot is wired correctly, the output of the stage always sees a fixed resistance.... However, the thing is that the tube begins to behave in a non linear fashio as you turn the "level" up, so the sound will perhaps change in a not si predictable way. Quite frankly, I "tune" my amps for the range of ovedrive in which I use them. I someone wants less gain than I do, I would change a couple of things in a certain specific direction. If somone wnated to use the amp with more gain, I would do the opposite. Glad you seemed to have found a solution that works for you.

Cheers,

Gil