• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Need help with tubes problem...

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tomat

Member
Joined 2007
leadbelly said:
You need to give much more detail. This was a working preamp, and then what you did was replace one existing tube with an NOS tube of the same type and it began to act as you described? What preamp model and tube are we discussing?
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yes,that is working preamp,i was using electro harmonix 6sn7 previously,and then i change to rca grey glass 6sn7,the problem begin after that.
i was check the voltage on my preamp ,120v from plate to cathode ,the current is 3ma,filament voltage is 6volt.
i have at least 4 pairs nos rca 6sn7 tubes and they are all have same problem,cracking sound and then make the woofer move like pumping.
i was buying that tubes from trusted vendor in canada,and they said that they was test the all tubes before they ship

thanks
 
T

tomat

Member
Joined 2007
azazello said:
And without preamp, is there the same problem?
Put left out preamp to right in of power amp, and
right out to left in of pow. amp. Is there the same?
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i have change to other tubes,the problem is disappear,so i guess the problems came from the tubes.
my question,can we know if the tubes had a problem without using a tube tester?.cause the tester is expensive
sorry for my poor english

thanks a lot
 
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