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Power Transformer for AX84 Hi-Octane with LND150 FX-Loop

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iefes:
I wouldn't worry too much about the max-voltage of the EL84s plates. There are many amplifiers out there which run at anode voltages way above 300V. For example, the Mesa Boogie Studio .22 runs the EL84s at 390V on the plates, Fenders Blues Junior at 330V. My Carmen Ghia inspired amp also runs over 300V without problems.
So if you're not dependent on the lower plate-voltage (soundwise or for whatever reason) I'd just use the larger transformer and run the tubes at these higher voltages.  ;)

kvdmeulen900:

--- Zitat von: iefes am  2.02.2021 20:19 ---I wouldn't worry too much about the max-voltage of the EL84s plates. There are many amplifiers out there which run at anode voltages way above 300V. For example, the Mesa Boogie Studio .22 runs the EL84s at 390V on the plates, Fenders Blues Junior at 330V. My Carmen Ghia inspired amp also runs over 300V without problems.
So if you're not dependent on the lower plate-voltage (soundwise or for whatever reason) I'd just use the larger transformer and run the tubes at these higher voltages.  ;)

--- Ende Zitat ---

390V, hot damn. I bet that Mesa burns through tubes rather quickly then.
Is there anything I should take into account regarding the higher voltage? For instance, should I up the power rating on the screen resistor from 1W to 2W?

EDIT:
I also wonder what effect the higher voltage will have on the sound of the amp. Will the poweramp behave differently in terms of overdrive?

dimashek:
Higher Voltage makes sence for push-pull amps to get more power out of 2 small tubes, biasing it very cold
For SE amp, like yours - higher Voltage will give a bit more output, but will increase the power dissipation as well. So you'll need to low down the bias current. = less output on other halfwave.

Laurent:
Hi,

With about 280-290V plate voltage on the plates of a EL84 in SE, that will work without troubles. If you go higher, as Dimashek says, the dissipation will rise so biasing colder will be needed. Moreover if you increase the plate voltage too much, you will need to have a higher reflected impedance on the primary of the output transformer, which may make the sound muffled compared to less reflected impedance.
So keep plate voltage around 250-285V and everything will be fine. In the shop, the small RKT 30VA of the shop should be your best bet.
Cheers,
Laurent

iefes:
I didn't realize you're planning a SE amp, apologies for that!  :facepalm:  I should have read your entry post more carefully.
In this case I'm with dimashek and Laurent  :topjob:

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