Overdrive Deluxe amp

[Smokebreak]

Anyone had one of the copies come across their bench yet? I'd like to get to the bottom of this one. I came across some posts on TGP that confirmed that plugging in the clean input disengages the "OD circuitry", so we can assume the OD channel involves an added stage upfront, switched of by the clean input jack. Also saw reference of "Substituting a 12at7 in the PI", so it almost certainly has the Marshall PI w 12ax7 arrangement like the UP amps. As far as the rest of the preamp, I'd always assumed it was Fender topology, but maybe not? Maybe it's a Marshall thing with a CF and the tone stack after that, with the reverb and trem inserted in odd places....

[Smokebreak]

I guess another theory could be that the OD input just has the FET dealio in front of an otherwised tweaked ab73.
If anyone has any theories, or has thought about this amp's topology, I'm all ears!

[ChopSauce]

That amp seems to be definitely puzzling...

It's a shame that it seems to be impossible to know who built it.

I'd also like to know about your sources because I've seen these:

https://ampgarage.com/forum/viewtopic.php?t=9400

https://ampgarage.com/forum/viewtopic.php?t=11873

https://ampgarage.com/forum/viewtopic.php?t=4175

(etc) http://ampgarage.com/forum/app.php/goog ... itesearch=

but never read about an OD input, plus the "similar" yet without reverb & trem. seemingly original Dumble amp head (3rd link) show no FET...

[Smokebreak]

Oh yea I had kind of forgot about the whole "fake " thing.
Sebago is one of the 2 folks that were making the clones of the original in the video, there's some info here : http://www.sebagosound.com/index.php?id=74
and then https://www.overdrivedeluxe.com/ was also making one.
Here's the comment by Bill @ Sebago about the OD input https://www.thegearpage.net/board/index ... t-24565444

As far as the 100W Overdrive Deluxe messy looking head, I actually built that twice...once as a 50W and once as a 20W, and while they are fantastic amps, they are essentially 2nd gen low plate amps, and not the Overdrive Deluxe in question. I say that not bc of the verb and trem, but they just had a completely different feel and sound. I could be wrong, but I don't think the topolgy is the same as the ODS amps, with the 2 clean and 2 OD stages.

However, it could be a tweaked vibrato channel of a Deluxe reverb, done up with UP values for the clean side, Marshall tone stack, etc..........with V1 used as 2 gain stages up front, for the OD input/side, making the topology kinda like a plate driven JCM800 at that point, in OD mode. Of course all of this with a Marshall PI .
So, kinda the opposite of the usual ODS 2clean + 2OD arrangement, which would explain why the amp sounds so different than the ODS series.

[ChopSauce]

There's nothing at all to validate the FET theory that I could read, still.

Also, according to the discussions on this forum, it seems that the vibrato has nothing to do with the usual blackface one.

I you don't mind, also: what about the references to the "ultraphonix" mods that I could read about on the Sebago website?
(I was tempted to write "just out of curiosity" but the point is I am reluctant to follow you on the "Marshall side")

[Smokebreak]

Yea the FET idea was just a thought, as I'm convinced whatever is going on with the OD is happening in the first stage.

As far as the Ultraphonix mods, while that is a general term, it usually always involves a 33K slope/22n/22n/250p tone stack(Marshall), and a 5F6A phase inverter configuration with a 12ax7, which also became a Marshall thing.
However the usual Fender toplogy remains. I've done this in multiple amps, and the result is this warm, thick,rich clean sound. So I think it's a safe assumption that this is the "clean" part of the Overdrive Deluxe, given

My other Marshall idea was that the OD input would engage 2 stages before the Fender topology. I tried this last night , with a 2k7/.68 first stage, and 10K 2nd stage, both with 100K plates, feeding the "clean" amp. Both stages were heavily attenuated , but it didn't have the right feel. One gain stage, up front ,added to the clean stage got closer.

Of course we must remember, assuming the story is correct, that the amp Dumble built was modded by someone else to produce what it is today, so being super familiar with D style circuits/mods may go out the window!

[Smokebreak]

Anyone get an overdrive deluxe on their bench yet? Any new info?

[bepone]

IMO this was only one amp and chances that someone will have it at home are close to 0. i think it is a combination of guitar, speaker, 1x12" cabinet and boosted deluxe reverb. so if you are interesting in it it is faster to buy ALTEC speaker (417=? ) and play with the tremolo and overdrive to get close results. it is not impossible. this "hollowish" part of the sound is form the 1x12", probably on guitar are switched both pickups (sw. in the middle position), LP type..for my taste sound is missing "body" in it

[Mr. dB]

That still sounds like an LDR trem to me.

[aab0mb]

It’s like a cascaded Plexi topology. We’ll have to guess on a lot of values and little things here and there.

Preamp looks easy enough to decipher the topology.

[Aaron]

Slowly making way through the schematic. This is where I'm at so far.
Assume it has errors, has not been tested.

Thanks,
Aaron

***REVISED SCHEMATIC***

[j0k3335]

Slowly making way through the schematic. This is where I'm at so far.
Assume it has errors, a little bit more to go.

Thanks,
Aaron

thanks ! real interesting

[aab0mb]

Double post

[aab0mb]

Slowly making way through the schematic. This is where I'm at so far.
Assume it has errors, a little bit more to go.

Thanks,
Aaron

Thanks a ton for making this! I’ve been staring at the pics for a couple days and I think you have the majority of it nailed down. Super exciting.

Couple things:

There’s a cap connected to the treble cap entrance. Is the rock/jazz switch possibly being used as what we usually know as the mid boost function instead of typical rock/jazz configuration? Extra capacitance across the treble cap activated by the switch?

I wonder if there’s something like a 1M grid reference resistor hiding around the low input Jack that we can’t see. Would that low input work well without grid ref?

Bright cap is labeled 180j 1kV

[aab0mb]

Double post