Significance of 'low' B+ on V1 & V2

[exocet]

Since lurking a lot and making the odd post on this forum I've been bitten by the amp building bug.

I'm slowly starting to understand more about how and why D - Style amps are constructed.

However - when I look at #124 and compare with other reference material I notice that the B+ voltage on V1 and V2 is low (around 190 - 200v). Many Fender designs are around 230 and 280 is pretty common in Marshall amps.

Are the B+ voltages low for a reason (is there an impact on tone?) Or am I looking too close?

Marc

[bluesfendermanblues]

(low) Voltage on V1 and V2 is important, but a lot of factors are of importance in achieving the Dumble tone.

- Preamp tubes (I tried all and ended up with jj 12ax7s)
- Capacitors - the right orange drops (many swear by 6ps or 225)
- Cathode electrolytic caps
- resistors - Dale for plates and carboncomp for signal
- Lead dress - do it like dumble
And the list goes on and on......

Hereto comes the philosophical question; which Dumble amp? - he's made around 300 and not many of them should be alike.

[Guitarman18]

bluesfendermanblues:

- resistors - Dale for plates and carboncomp for signal

Dales for plate, Carbon Film for signal. A peppering of metal film resistors is pretty common in original HAD builds, (eg. on cathodes).

Hope this helps.

Cheers,

Paul.

[marcos]

To answer Marc´s first question: The reason for the lower voltages (compared with Fender designs) is a much smoother, softer distortion.The Fender values are good for real sparkling, clean tones, a bit harsh in overdrive.At the same time, around 200 V is still enough for good clean tones.The difference in tone is quite pronounced, still a lot of room for tweaking.The real Dumbles range from as low as 160 V(V1a) to 220 v (on V2b) ,as far as I know.

[bluesfendermanblues]

bluesfendermanblues:

- resistors - Dale for plates and carboncomp for signal

Dales for plate, Carbon Film for signal. A peppering of metal film resistors is pretty common in original HAD builds, (eg. on cathodes).

Hope this helps.

Cheers,

Paul.

roger that