ODS101 schematic

[dogears]

The 47pf on the clean master will destroy the tone of the OD due to the treble bleed effect when the OD is on. No cap is best unless you come up with an ingenious way to have the cap when the cleans are selected and have it out when the OD is on.

Also, 100k OD master is wrong even in Non HRM if the amp has seperate masters. The PI needs to look back at 1M. You need to figure out a way to keep the loading accurate on both sides.

[HiGain]

The 47pf on the clean master will destroy the tone of the OD due to the treble bleed effect when the OD is on. No cap is best unless you come up with an ingenious way to have the cap when the cleans are selected and have it out when the OD is on.

Also, 100k OD master is wrong even in Non HRM if the amp has seperate masters. The PI needs to look back at 1M. You need to figure out a way to keep the loading accurate on both sides.

Interesting points. How would people feel about a 500K/500K divider/15pF bright cap after the 100K OD Master?

For the clean master 47pF bright cap, maybe you could use a 3PDT relay rather than a 2PDT to lift the cap off ground in OD mode.

Also, should I put a 100K resistor ahead of the PI input cap?

I've made the other changes above, and will update a final schematic soon.

Jake

[Bob-I]

The 47pf on the clean master will destroy the tone of the OD due to the treble bleed effect when the OD is on. No cap is best unless you come up with an ingenious way to have the cap when the cleans are selected and have it out when the OD is on.

Yes, whe you told me that and I removed the cap the OD opened up much better.

Also, 100k OD master is wrong even in Non HRM if the amp has seperate masters. The PI needs to look back at 1M. You need to figure out a way to keep the loading accurate on both sides.

The point is that the OD out needs to see 100K and the PI in needs to see 1M, very important. A divider might work just fine, never tried it.

[jaysg]

Is it better to show HRM mods or create two separate schematics?

I forget where I got this schematic with the 22M resistors for Boost.

[swt]

Hey scott! that's an interesting point, the one about 1M at the PI. How can that be done with separate masters?. the fact is that i always use the dumbleators, and the return pot is 250k. should i change that to 1M to the PI?.

[HiGain]

[EDIT] I uploaded again. If they look good I'll put them in the files section.

Thanks all, and thanks to Scott for the time.

Jake

OK, here's the updates. Three schematics. HRM, NONHRM, Combined.

Point is to have a basic, clear starting point. Please comment on corrections if you see any.

Thanks, Jake

PS stw: I didn't make CL2 10uF because I wanted to keep it true to the norm, not the exceptions. Although, I'll have to try that mod in my next build. Thanks.

[jaysg]

Nicely done. Q: Are there snubber caps on OD1 and OD2 in the HRM? I thought there weren't.

[swt]

in the HRM the slope resistor has a huge impact on tone, maybe is worth pointing that...i prefer 47k to 56k to the 33k suggested. Also the addition of the treble bleeder trim/cap suggested by scott is worth to mention, just a departure from the original but important as side notes (i guess as important as the metal film resistors, depending on the amp). Thanks for the effort.

[Bob-I]

Nicely done. Q: Are there snubber caps on OD1 and OD2 in the HRM? I thought there weren't.

You are correct. Those snubbers on the HRM should be removed.

[tictac]

Interesting one suggestion to reduce treble (treble bleeder cap) and one suggestion to increase treble (remove snubbers). Maybe if you leave the snubbers in you won't need the treble bleed cap.

My amp switches between HRM and the 80's type OD channel, I like the snubbers (330pf) in both modes.

TT

[HiGain]

OK... I will incorporate these suggestions. I appreciate the input and corrections.

Jake

[HiGain]

I uploaded another version. If they look good to you guys I will put them in the files section. Thanks to Scott for his time and the rest of you guys for helping out.

Jake

[fabiomayo]

That looks great. Thanks for sharing these schems.

I have one question though. Seems like HRM could benefit from at least
one cathode bypass being smaller. Which one? OD2?
The effect of this would be to tame the bass at the OD stage, right?

[fabiomayo]

Ohhh. One more thing... I never heard of that bass cut mod in front of
the OD. Anyone tried to make it switchable? (As if we needed even more
switches well.... I bet we do ) With this mod OD entrance
would be .047uF coupling cap, 10M to ground, another .047uF and to the
low gain OD entrance network. Did I get this right, at all?

[dogears]

Ignore the bass cut mod.... That is not what this is. It is only a simulated clean master load for the OD since the bright cap on the clean master is a treble bleed when the OD is on. By floating the clean master ground (when the OD is on with a 10M) you don't have the bleed. The simulation is to add a 1M to ground from the OD input side of the cap to ground. Jake made a teenie error on this one. All in all a great job though. OD2 does indeed have a 1uf cap as well.