help with Crate Vintage Club 50 (schem)

JC@ · 10-18-2007, 10:39 PM

Hi, I would need a schem for this amp.
If that is not possible, maybe someone can tell me the components that conform the bias supply. I can't see any pot, so I guess it is a "non adjustable" bias circuit.
Thanks.

Enzo · 10-19-2007, 01:32 AM

Isn't that amp cathode biased?

Measure resistance - with power off of course - from the cathodes to ground. If you get zero ohms, it is fixed bias, but if you get a resistance, it is cathodic.

In the fixed bias ones, R77,78 set the bias. Since the upper resistor is only 150 ohms, both would have to be changed to make it adjustable. It is not adjustable stock.

JC@ · 10-19-2007, 01:51 AM

Thanks Enzo, I'll check that.

JC@ · 10-21-2007, 09:17 PM

Enzo, it is fixed bias.
Well same thing as with the ac30 here.
361 volts on the plates, and if we consider this amp class A, I mean if it is, then 33 mA per tube is ok, but shall I live it there or should I change the bias circuit to run the tubes cooler?

Enzo · 10-22-2007, 03:32 AM

The stock amp works, I wouldn't change it unless I had a purpose.

Send me an email and I will send the drawings What exact model is on the serial number plate? Include that.

tmenzo at msn dot com

JC@ · 10-23-2007, 02:51 PM

I had login problems for a couple of days..
Enzo, I can't see any serial number, I mean there isn't a plate or any reference to model anywhere inside or outside this amp. Not even a paper sticker.

Anyhow.. I'm leaving it stock

10-18-2007, 10:39 PM	#1
JC@ Senior Member Join Date: May 2006 Posts: 369	help with Crate Vintage Club 50 (schem) Hi, I would need a schem for this amp. If that is not possible, maybe someone can tell me the components that conform the bias supply. I can't see any pot, so I guess it is a "non adjustable" bias circuit. Thanks.

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10-19-2007, 01:32 AM	#2
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Isn't that amp cathode biased? Measure resistance - with power off of course - from the cathodes to ground. If you get zero ohms, it is fixed bias, but if you get a resistance, it is cathodic. In the fixed bias ones, R77,78 set the bias. Since the upper resistor is only 150 ohms, both would have to be changed to make it adjustable. It is not adjustable stock.

10-19-2007, 01:51 AM	#3
JC@ Senior Member Join Date: May 2006 Posts: 369	Thanks Enzo, I'll check that.

10-21-2007, 09:17 PM	#4
JC@ Senior Member Join Date: May 2006 Posts: 369	Enzo, it is fixed bias. Well same thing as with the ac30 here. 361 volts on the plates, and if we consider this amp class A, I mean if it is, then 33 mA per tube is ok, but shall I live it there or should I change the bias circuit to run the tubes cooler?

10-22-2007, 03:32 AM	#5
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	The stock amp works, I wouldn't change it unless I had a purpose. Send me an email and I will send the drawings What exact model is on the serial number plate? Include that. tmenzo at msn dot com

10-23-2007, 02:51 PM	#6
JC@ Senior Member Join Date: May 2006 Posts: 369	I had login problems for a couple of days.. Enzo, I can't see any serial number, I mean there isn't a plate or any reference to model anywhere inside or outside this amp. Not even a paper sticker. Anyhow.. I'm leaving it stock

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