Overdrive stage?

[badoumba]

Hi

I just went through some different generic readings about guitar amps and they all explain that the best overdrive happens when the power stage is saturated, preamp stage saturation prividing a unpleasant fuzzy sound. Looking at some dedicated books, they mention that overdrive happens in a cascading pream stage with several valves in series.

As lentioned in a previous post, I try to build an amplifier providing a sound similar to Kingsley for blues (check this video from my friend Sam Vilo - http://www.youtube.com/watch?v=Xe9fYJQ7Wyw). How/where should overdrive be designed for achieving such sound?

Thanks in advance[/url]

[brewdude]

I don't know anything about that Kingsley amp, but if he is using it with the 2 channels cascaded in series, I would expect that the tone is utilizing preamp distortion.

Then again I suppose one could run the 1st channel at a low setting and the 2nd channel up bit higher to utilize PA distortion.

By the way, I think that your premise stating that pre-amp distortion is unpleasant and fuzzy, is an over generalization and in fact one can great overdriven tones out the preamp. The Dumble ODS is a fine example of an amp designed to provide pre-amp distortion that is smooth and warm, not unpleasant and fuzzy.

[da Geezer]

As lentioned in a previous post, I try to build an amplifier providing a sound similar to Kingsley for blues (check this video from my friend Sam Vilo - http://www.youtube.com/watch?v=Xe9fYJQ7Wyw). How/where should overdrive be designed for achieving such sound?[/url]

IMO, that OD tone is mostly being generated in the preamp, by cascading the 1st channel into the 2nd......look at the Dumble ODS schematics for ideas

Very nice tone, BTW

$0.02

Geezer

[da Geezer]

http://kingsleyamplifiers.com/products/amps/14/

4xEL84 cathode biased
12ax7 inverter
2x 12ax7 preamp
Tube recto

When the gain mode is run "series", all 4x triodes are cascaded into each other.....very Dumble-ish topology in the pre

Vox-ish in the power section

G

[10thTx]

I wonder if it could be anything like this? Sort of some Voxish topology with Dumblish OD & cathode biased & tube recto.

With respect, 10thtx

[da Geezer]

Yes, I think so, but without the cathode follower

I also can't figure out about the tone stack....the literature says it has a tone control shared by both channels, but all the pictures I find have a TMB on both channels(?)
Maybe there are several different incarnations of this amp??

G

[badoumba]

Thanks guys

I am pretty new in this area and it's still a challenge for me to read these schematics. As I can see, the top 12AY stage can be put in series with the 5751 lower stage before entering the power stage. Is this correct?

[10thTx]

it has a tone control shared by both channels

I read that to be that is has "a" (one) tone stack shared by both channels............

meaning that the clean channel tone stack is shared by the overdrive because of the clean going into the od?

Yes, clean is in series with od.

With respect, 10thtx

[badoumba]

Thank you guys for your comments and explanations about Kingsley topology. I learned enough to start my design sketch!