Dumble: why overdrive after preamp?

[pula58]

On eof my favorite sounds is a nice Fender Blackface or Silverface style amp with an overdrive pedal in fron tof it.

I have been looking at the dumble schematics, and generally (the ones I have looked at) the overdrive is fairly late in the signal path, just before the Phase inverter, or just before the effects loop. Why is that?

Did any of Dumbles amplifiers have the overdrive earlier in the signal path?

Are there other amplifiers that have the overdrive earlier in the signal path.

pluses/minuses of having "early" or "late overdive" ??


Thanks!!

P.

[Bob-I]

Dumble claimed that overdrive before the preamp would overload it. I don't know what he meant by that, but the Boogie was the other way around and I prefer the smoothness of the Dumble architecture.

[DonMoose]

Dumble claimed that overdrive before the preamp would overload it. I don't know what he meant by that, but the Boogie was the other way around and I prefer the smoothness of the Dumble architecture.

? IIRC all of the tube amps with built-in tube overdrive sections put the OD after, at least, the first gain stage - having a hard time even thinking of one were the OD isn't after the tone stack. Some Marshalls?

[tictac]

Marshalls, Soldano, Bogner, 5150's, and practically all of the new generation high gain multichannel amps get the distortion going before the tonestack...

tt

[Chris333]

Marshalls, Soldano, Bogner, 5150's, and practically all of the new generation high gain multichannel amps get the distortion going before the tonestack...

tt

Don't forget HRMs!

pluses/minuses of having "early" or "late overdive" ??

I think it takes 4 gain stages to get the kind of overdrive most on this forum like. If you had enough overdrive after two gain stages, why would you bother to add more, unless it was for gain makeup after a tone stack or some such thing?

[Structo]

I think a lot of people don't realize that Dumble used the first two stages for his clean tone.
Then cascaded two more on top of those first two for the OD tone.

His later HRM amps were an attempt to address the lack of a tone stack on the OD tone.

[d95err]

Most "classic" amps (Plexis, Deluxes, Bassmans, Voxes) have their overdrive after the tonestack, by means of phase inverter and poweramp distorsion. My guess is that the Dumble architecture comes from trying to create the sound of a cranked non-master amp, but at a controllable volume level.

I.e. instead of clean preamp->overdriven poweramp (=massive volume), we have clean preamp->OD circuit->master volume->clean poweramp (=controllable volume)

[KT66]

If you look at some of the first amps that had the option of plugging into a Hi-gain jack that added an additional gain stage for the purpose of driving the preamp into heavy distortion, like the early Mesa Boogies, or a Marshall 2203 for example, it is true that the extra stage is added in front of the normal preamp, but the stage that is "overdriving" is a later one. The Dumble method of making the added stages be the ones that are driven in to clipping is actually quite logical and it is surprising to me that a big name company didn't think of it first.

The advantage of doing it this way is that the overdrive section's components can be tailored to best produce distortion in the way that the designer desired. because that's all that it is supposed to do - it does not double as a clean section of the amp. Furthermore, this method also allows the user to control the sound level of the distortion so that it does not have to be at a higher level when the amp is in hi-gain mode.

[wicker]

I rather think that HAD took basic Fender clean channel, then added another one cascade without tone stack, messed with some values, and said - that sh*** sounds good.

[Max]

Most "classic" amps (Plexis, Deluxes, Bassmans, Voxes) have their overdrive after the tonestack, by means of phase inverter and poweramp distorsion. My guess is that the Dumble architecture comes from trying to create the sound of a cranked non-master amp, but at a controllable volume level.

I.e. instead of clean preamp->overdriven poweramp (=massive volume), we have clean preamp->OD circuit->master volume->clean poweramp (=controllable volume)

As Lindley told Guitar Player in a July '77 interview, "I've got a lot of little amps, but on the road, I always use Dumble amps because they never break down. We went about getting the sound in those amps by taking an old Fender Deluxe to Howard Dumble and saying, 'We want this, but bigger and louder.' And Howard got the closest of anybody I've heard."

source: http://personalpages.manchester.ac.uk/s ... /Articles/

Cheers,

Max

[stelligan]

As Lindley told Guitar Player in a July '77 interview, "I've got a lot of little amps, but on the road, I always use Dumble amps because they never break down. We went about getting the sound in those amps by taking an old Fender Deluxe to Howard Dumble and saying, 'We want this, but bigger and louder.' And Howard got the closest of anybody I've heard."

source: http://personalpages.manchester.ac.uk/s ... /Articles/

Cheers,

Max

Bigger and louder......... Me likey, too.

[pula58]

If you look at some of the first amps that had the option of plugging into a Hi-gain jack that added an additional gain stage for the purpose of driving the preamp into heavy distortion, like the early Mesa Boogies, or a Marshall 2203 for example, it is true that the extra stage is added in front of the normal preamp, but the stage that is "overdriving" is a later one. The Dumble method of making the added stages be the ones that are driven in to clipping is actually quite logical and it is surprising to me that a big name company didn't think of it first.

The advantage of doing it this way is that the overdrive section's components can be tailored to best produce distortion in the way that the designer desired. because that's all that it is supposed to do - it does not double as a clean section of the amp. Furthermore, this method also allows the user to control the sound level of the distortion so that it does not have to be at a higher level when the amp is in hi-gain mode.

Ah...that is a good explanation, I see the logic in it now.

Thanks!

P.

[jaysg]

My guess is that the Dumble architecture comes from trying to create the sound of a cranked non-master amp, but at a controllable volume level.

Yeah, my sense is that he was trying to create a triode based distortion that sounded like output tubes cranking away.