Amp power consumption / GZ32

[sbirkenstock]

Hi everybody,
I found some NOS GZ32 in my collection and I wonder if I can use them in a push/pull 6L6 amp.
I mostly use Vibrolux type power transfomer, putting out 2*325 volt.
So the GZ32 can handle the voltage, my power transformer can easily handle the slightly higher filament current (compared to a GZ34).
So the only difference I found it the lower "max mA" rating of the GZ32 vz the GZ34.

How would I measure the "max mA" in my amp?
And if it exceeds the GZ32 maximum, what would happen? Would it just "sag" or would something blow up?

I attached the Philips GZ32 datasheet.
Can somebody give me an explanation what "Condensor" vs "Choke" input means?

cheers,
Stephan

[tubeswell]

How would I measure the "max mA" in my amp?

Put a mains power meter in series with the mains socket and your amp and switch the amp on and measure the current.

https://www.amazon.com/TS-836A-Energy-V ... 629&sr=1-3

[brewdude]

That seems like your going to be measuring heater current that way(?).

[martin manning]

Easy enough to subtract the heater current from the total. There will be some losses in the PT that are unaccounted, but close enough, I think.

On the GZ32 data sheet pg. 2 (figure A) is capacitor input and pg. 3 (figure B) is choke input. Virtually all guitar amps are capacitor input.

[didit]

Hello -

Should all be fine. Similar to a 5V4. More voltage drop versus GZ34. Just be cautious with sizing of that initial filter capacitor. For reference see the specs of this Hammond Vibrolux replacement == https://www.hammfg.com/files/parts/pdf/290CX.pdf.

Best .. Ian

[tubeswell]

How would I measure the "max mA" in my amp?

Put a mains power meter in series with the mains socket and your amp and switch the amp on and measure the current.

https://www.amazon.com/TS-836A-Energy-V ... 629&sr=1-3

That seems like your going to be measuring heater current that way(?).

Subtract the VA on each other winding, and you got the VA on the winding you want to look at. (Mains VA = Heater VA + Rectifier VA + HT VA)

The VA on the heater and rectifier windings is easy to work out (voltage x total current draw in each case) e.g.
for a GZ32 rectifier = 10VA (5Vac @ 2A https://frank.pocnet.net/sheets/030/g/GZ32.pdf Note: Some datasheets cite 2.3A, which would make it 11.5VA)
for 2 x 6L6s and 3 x 12AX7s and a 150mA lamp wired for 6.3V in parallel = 18VA (6.3Vac @ 2.85A)

If HT winding is 325-0-325Vac, and measured Mains VA = 62, (say 120Vac @ 0.517A* in the US or say 230Vac @ 0.269A* in the UK), then:

If your GZ32 is a 2A filament , then HT current = (62 - 10 - 18)/325 = 0.114A (which would be about right for an amp with a B+ of 420V with a GZ32 and 3 x 12AX7a and 2 x 6L6GCs in fixed bias)

If your GZ32 is a 2.3A filament , then HT current = (62 - 11.5 - 18)/325 = 0.1A

*i.e. what you measure on your power meter

[sbirkenstock]

Thank you guys!
I do have a mains power meter, but those things are slow acting.
I can do the calculation when the amp is in idle.
But how far is it away if I play a hard E chord?
Idle vs max?
Best regards,

Stephan

[sbirkenstock]

Another question / idea:
if I solder in lets say a 100 ohm resistor before the main filter caps I could measure the voltage drop and calculate everything from there.
Just that I have pulsating DC.
Can I measure the volatage drop with a multimeter set to DC or AC?
Best regards,

Stephan

[tubeswell]

Thank you guys!
I do have a mains power meter, but those things are slow acting.
I can do the calculation when the amp is in idle.
But how far is it away if I play a hard E chord?
Idle vs max?
Best regards,

Stephan

One way of doing it would be to use a dummy load and a signal jenny, inject a variety of signals (40Hz, 1kHz, 5kHz and white noise etc) and sine wave vs square wave, at a constant amplitude into the amp and measure current on your power meter.