alternative overdrive architecture

[pula58]

I was thinking about a build where the overdrive channel gets its input from the preamp V1A anode. Then, there is no tone stack until the output of the OD section.

So, the clean channel would be:

gain -> tone stack-> gain

and the OD would be:
gain -> gain -> gain -> tone stack

has anyone ever tried this..results?

thanks!

P.

[noworrybeefcurry]

That sounds like a really interesting concept, id love to know what the results are.

[rsalinger]

I could be wrong... and obiously I know that this is like compering a fine Bordeux to Grape Kool-Aid, but I think that Peavey used this architecture in their Classic series.

Cheers,
Rob

[odourboy]

That's not unlike what you get with a Bluesmaster stack with PAB engaged - with the added benefit (?) of an extra attenuation/gain stage.

[butwhatif]

demeter

[max_lwedge]

In the 90s, I modded a BF Showman with dedicated clean and OD as you suggest, pre-TW and Dumble days. Short answer is it resembles a BM with stack lift PAB. OTOH, with this OD you’re not concerned with how it sounds clean or how it sounds with a pre-OD stack, so your tweaking may go new places.

My normal (clean) channel was closer to Trainwreck (without the cold clipper) than Fender BF. I had LDR switching between the channels and for series shunt on the OD input. Used vibrato jacks for foot switches. It sounded great, and the amp is still the owner’s favorite. It likes single coils pretty well. I tweaked a lot before I got happy though.

My experience since building D style amps has been that the mix of treble, mid and bass and all the subtleties of high/low plate, bypass caps and all going into the final OD stage make a huge difference on the OD tone. With the post OD tone stack only, you can tweak up the levels to the power amp ala HRM, but the touch that the player feels and the harmonics in the OD are relatively set by what happens before the OD. The search for that perfect blend explains why D amps came in all of those 1st, 2nd 3rd gen and Skyliner versions.

The post OD stack only has a distinct aggressive sound because the mids are basically full on. Think of Marshall, Soldano, Bogner, and even the Tweed Deluxe. There are still a lot of things to tweak with plate voltages and resistors, bypass caps, cold clipped stages, entrance networks, whether you push either the 2nd and/or 3rd stage into or close to clipping, how much bass you pass, grid stoppers, snubbers and so on.

I added a footswitch to cut the some mids before volume pot. This is actually an old Gibson mid-circuit. Find the mid setting you like on the trimmer, I hit on about 100k. This gives you a pre-amp cut (PAC) and gives you a mellower OD. It probably should be on a relay, but I actually used a passive footswitch when I did it with no issues.

Please post if you give it a go.

[tictac]

This is how I do it...

I have this boost footswitchable plus you can set the gain you want with an internal trimmer.

You can easily get into Boogie terretory with this setup plus I think it's easier to implement than the PAB boost.

TT

[Structo]

Doesn't that become sort of a mid boost with the .002uf there?

[tictac]

Yes I suppose you could look at it that way...

Yet the tone stack is bypassed in the boosted mode so it ends up being a single gain stage going into the volume control then into another gain stage...

The mids are boosted but so is the low end and the gain. On my amp I have the trim pot set so the boost volume is slightly higher than the normal clean volume.

TT

[renshen1957]

In the 90s, I modded a BF Showman with dedicated clean and OD as you suggest, pre-TW and Dumble days. Short answer is it resembles a BM with stack lift PAB. OTOH, with this OD you’re not concerned with how it sounds clean or how it sounds with a pre-OD stack, so your tweaking may go new places.

My normal (clean) channel was closer to Trainwreck (without the cold clipper) than Fender BF. I had LDR switching between the channels and for series shunt on the OD input. Used vibrato jacks for foot switches. It sounded great, and the amp is still the owner’s favorite. It likes single coils pretty well. I tweaked a lot before I got happy though.

My experience since building D style amps has been that the mix of treble, mid and bass and all the subtleties of high/low plate, bypass caps and all going into the final OD stage make a huge difference on the OD tone. With the post OD tone stack only, you can tweak up the levels to the power amp ala HRM, but the touch that the player feels and the harmonics in the OD are relatively set by what happens before the OD. The search for that perfect blend explains why D amps came in all of those 1st, 2nd 3rd gen and Skyliner versions.

The post OD stack only has a distinct aggressive sound because the mids are basically full on. Think of Marshall, Soldano, Bogner, and even the Tweed Deluxe. There are still a lot of things to tweak with plate voltages and resistors, bypass caps, cold clipped stages, entrance networks, whether you push either the 2nd and/or 3rd stage into or close to clipping, how much bass you pass, grid stoppers, snubbers and so on.

I added a footswitch to cut the some mids before volume pot. This is actually an old Gibson mid-circuit. Find the mid setting you like on the trimmer, I hit on about 100k. This gives you a pre-amp cut (PAC) and gives you a mellower OD. It probably should be on a relay, but I actually used a passive footswitch when I did it with no issues.

Please post if you give it a go.

Hi,

Tone controls reminds of the Ultra Mix Channel mid control on the Garnet Session Man and Garnet Stencil/Private label amps.

Best Regards,

Steve