deluxe reverb - can't get plate voltage down

[retrograde]

Hi all. I am a returning member. Been away for some time.

Starting playing with an early '68 deluxe reverb and can't get the plate voltage below 449v without biasing too hot. Required rectifier is GZ34/5AR4. At 430v the current is 40+ mA plate voltage on the preamp tubes is high also 225V+/-

the dropping resistors on the filter caps are within range

Does this sound like a PT problem?

Geoff

[Albert Kreuzer]

Hi Geoff,

how high is the heater voltage?
Maybe you need this:
Vintage Voltage Adapter

Biasing too hot is NOT a good way to knock down plate voltage (don't ask how I know...)

Cheers,
Albert

[retrograde]

Thanks. Interesting concept. Hadn't thought about my 120v+ ac.

I'm not biasing hot. Running 6V6s at 11.5 watts. I just checked to see how much current was required to get the plate voltage down closer to 425v.

[Albert Kreuzer]

I have an old 4 x EL34 amp with 800V on the plates. Mains voltage increased from 220 to 230 Volts in the 90s, making that 845 Volts
Caps were rated at 800V (2 x 400 in series), changed that to 2 x 450 and added a "vintage voltage" 12V transformer to get back to 800...

Solton Conqueror

Cheers,
Albert