Hi
I finisched to assembly my 1987 Amp Marshall Model following SDM layout : http://home.comcast.net/~jbjdav26/1987r17.jpg" onclick="window.open(this.href);return false;, and larry grounding spec.
The amp is really nice and tone seems to be ok, no hiss or hum.
Nevertheless I have a problem biasing V1 and V2
My B+ value is 444 V DC and I've calculated a bias value of 39mA but It is stop to 27mA with bias pot completely open.
Do you have an idea to help me ?
Many thanks
Massimo
Help biasing my 1987
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massimo
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Help biasing my 1987
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gloeidraad
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Re: Help biasing my 1987
Hello Massimo,you have bad output tubes or you can decrease the value of the serieresistor from the biaspot.
Then the bias voltage will be lower and then you have more current.
Try a 39k or 33k.
Erik
Then the bias voltage will be lower and then you have more current.
Try a 39k or 33k.
Erik
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massimo
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Re: Help biasing my 1987
Hello erik
Thanks for your tip! I try to use 33k resistor and seems to be OK!!
Many Thanks for your help!!
1987 it's very amazing tone... Now after 2204 and 1987 which is the next?
Cheers
Massimo
Thanks for your tip! I try to use 33k resistor and seems to be OK!!
Many Thanks for your help!!
1987 it's very amazing tone... Now after 2204 and 1987 which is the next?
Cheers
Massimo
http://www.youtube.com/user/maxiblues73" onclick="window.open(this.href);return false;