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|1/27/2000 6:28 PM|
||Tweed bias tweak|
Hi, '59 Tremolux is running hot:
37-40 ma idle current. 2 NOS RCA 6V6GT's, NOS
Syl. 5U4GB rectifier. What would be the best way
to bring this down? Would tweaking the bias supply
resistors ie: changing the 56k to 68k or so
work? Is there a way to lower the plate voltage with
a different rectifier?
Thanks in advance for any advice,
|1/27/2000 9:22 PM|
Yep. You'll have to tweak the values of the fixed resistors in the bias supply to get yourself a little more negative voltage on those control grids. I installed a trimpot in mine.
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|1/27/2000 9:32 PM|
John, thanks. Did you replace one of the resistors with
the pot or place it in series with the resistor.
|1/28/2000 5:47 AM|
I placed it in series.
|1/28/2000 5:10 PM|
||More general bias pot questions|
I've been wondering about these tweed bias pots I hear so much about. What value does one usually use? Also, do you just use two terminals kinda like a variable resistor? What sort of Wattage rating? Linear or Log?
Inquiring minds want to know.
|1/28/2000 11:06 PM|
Hello Inquiring Minds, I haven't done this yet
but I would try using a trimpot in a rheostat type
fashion: tie the wiper to one end of the pot and
put the two ends in series with the resistor that
you want to raise the value of. I guess it depends
on the values of the bias supply's resistors as to
what value of pot would be best to use. On the 5G9
Tremolux (56K & 82K) I would put a 25K pot in series
with the 56K resistor.
|1/28/2000 11:10 PM|
Oh yeah, at least 1/2W, linear.
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