my first tube kit, i need help!! i have problem in 1 channel

knowledge base for the classic Dynaco ST70

Postby mati1979 » Sat May 09, 2009 1:32 pm

yes. in future i can upgrades many components.

ask: in a manual say (setup bias):

After about 20 seconds or so of the tubes
being lit up you should begin to get a reading on your meter. We want to set the bias of each side to 1VDC on the meter, turning the bias potentiometers clockwise will cause the voltage reading to go up and
counterclockwise will cause it to decrease.


i need setup with amp after about 20 seconds or 5` - 10`minutes?
i see 20 sec 0.7V
and then 10` min 0,9V.
how long I have to wait to start the configuration ?
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Postby kheper » Sat May 09, 2009 2:03 pm

mati1979 wrote:yes. in future i can upgrades many components.

ask: in a manual say (setup bias):

After about 20 seconds or so of the tubes
being lit up you should begin to get a reading on your meter. We want to set the bias of each side to 1VDC on the meter, turning the bias potentiometers clockwise will cause the voltage reading to go up and
counterclockwise will cause it to decrease.


i need setup with amp after about 20 seconds or 5` - 10`minutes?
i see 20 sec 0.7V
and then 10` min 0,9V.
how long I have to wait to start the configuration ?


After you turn it on, set it. Then, about an hour later, set it again. You could monitor the bias voltage periodically if you are afraid that it will rise beyond 1V.
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Postby mati1979 » Sat May 09, 2009 2:07 pm

ok.
can i test with signal (from pre) ? or nothing conected to rca in ?
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Postby mati1979 » Sat May 09, 2009 2:08 pm

with a pot full and then 40 min. i see 0,95V.
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Postby kheper » Sat May 09, 2009 2:10 pm

mati1979 wrote:ok.
can i test with signal (from pre) ? or nothing conected to rca in ?


You can set it with shorted input jacks or with the preamp connected but no signal. ie. turn the volume knob down full.
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Postby mati1979 » Sat May 09, 2009 2:17 pm

if in a future i want a replace tubes for other better , this tubes can generate more Volts in bias ?
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Postby kheper » Sat May 09, 2009 2:19 pm

mati1979 wrote:if in a future i want a replace tubes for other better , this tubes can generate more Volts in bias ?


Unless you know what you are doing, do not set the bias any higher on any tube than what the manual specifies, ie. 1 V.
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