Cathode biased

[jestaudio]

Hi folks, playing around with a few bits on a build going no where fast lol, has anyone tried cathode biasing a dumble power section and what sort of results did you get
Cheers in advance

[10thTx]

I built the Tweed Overdrive Special, the Tweed BluezMeister and the D'Mars ODS all cathode biased.

No, they are not true Dumbles ........ but are D-inspired.

Physconoodler (in Canada) has built a Dumble clone cathode biased and spoke favorably about it.

DaGeezer has built a Dumblish "sort of" clone that is cathode biased. It's one of the sweetest amps I've ever heard, IMO.

Check out the Twin Ultra-Phoenix clip here (OD later in clip):
https://soundcloud.com/dageezer

The Tweed BluezMeister is in a tweed style cab about the size of a 5E3.
http://www.soundclick.com/player/single ... i&newref=1

With respect, 10thtx

[Luthierwnc]

Never done it with a D-build but it is pretty easy to make an amp switchable cathode/fixed bias. I usually do it with tweeds.

The schematic on top can be done with a SPST on-on switch. It doesn't bother me but this circuit does ground the bias voltage to the chassis. I do use a two-watt bleed resistor on the tail of the bias pot, though. The diagram below leaves the bias circuit open in cathode mode.

If real estate is scarce or you don't want to drill extra holes, you can use the Standby switch. Get a heavy-duty DPDT on-off-on switch. On one side, run the HV to the pole, connect the throws together and run them to the rail. On the other side of the switch, ground the pole and connect the throws to the cathodes and bias/grid leak resistors respectively. The middle position is standby and up or down is the fixed/cathode choice.

sh