Sorry Martin.
I just figured that out after I posted this. My printer broke and I omitted that when I copied your schem.
Am working on making that change now.
Thank You
bias question
Moderators: pompeiisneaks, Colossal
Re: bias question
Not sure if this will help but I installed dual bias pots on my D'lite and my 100w ODS clone.
a) this is the stock single bias
b) this is the equivalent dual bias
This circuit works well for me.
a) this is the stock single bias
b) this is the equivalent dual bias
This circuit works well for me.
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Tom
Don't let that smoke out!
Don't let that smoke out!
-
martin manning
- Posts: 14308
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Re: bias question
HH, a small change to the circuit I posted (new version posted above)... if you move the 22u caps from the top of the bias pots to the wipers you'll get a bit better isolation of the trem signal when its "off".
Re: bias question
OK Martin -
We are progressing now.
I have worked on several of these "conversions". This amp was a signal generator for example.
It is great to get a chassis and usable tranny sets for free. But test equipment is usually square in shape, where guitar amp chassis' are normally long and kind of narrow.
As well as being a bit small, the chassis also makes you bunch up all the circuits. I always have to use both sides of the chassis, and barely have enough room to cram all the parts in the available real estate.
So making changes can be difficult and time consuming is what I am trying to say.
Anyway.....
it all seems to be right. One pot only goes to -25.0 VDC while the other goes to -45.0 VDC. Looks like I had a 47k mixed in with my 4k7 resistors. I am sure THAT will prove to be the problem solver. Both pots play now. Will get another 4k7 resistor in there soon. Then I will move on with checking out the amp with the other tubes. So far I have stopped with the rectifier.
The tube sockets seem to have "normal" unloaded voltage present. Do not be surprised if I am back here later. Guess this amp will never be more than a prototype... if I can refer to MY work in those terms.
AGAIN
Thank You (everybody) For All The Help
NO WAY I could have done this without TAG
God Bless
(for now)
We are progressing now.
I have worked on several of these "conversions". This amp was a signal generator for example.
It is great to get a chassis and usable tranny sets for free. But test equipment is usually square in shape, where guitar amp chassis' are normally long and kind of narrow.
As well as being a bit small, the chassis also makes you bunch up all the circuits. I always have to use both sides of the chassis, and barely have enough room to cram all the parts in the available real estate.
So making changes can be difficult and time consuming is what I am trying to say.
Anyway.....
it all seems to be right. One pot only goes to -25.0 VDC while the other goes to -45.0 VDC. Looks like I had a 47k mixed in with my 4k7 resistors. I am sure THAT will prove to be the problem solver. Both pots play now. Will get another 4k7 resistor in there soon. Then I will move on with checking out the amp with the other tubes. So far I have stopped with the rectifier.
The tube sockets seem to have "normal" unloaded voltage present. Do not be surprised if I am back here later. Guess this amp will never be more than a prototype... if I can refer to MY work in those terms.
AGAIN
Thank You (everybody) For All The Help
NO WAY I could have done this without TAG
God Bless
(for now)