What are the DC voltages on the plates? Make sure your R2 (470K ) is there or you'll have no gain.
-Chris
-Chris
i havent touched R2, but I checked the voltages...if I did it right...it seems like I am getting about 127 V from the plate on V1B, but nothing from V1A...
ok, I put the leads from the voltmeter on either side of R2 and R7 respectively, (I tghink that is the proper way to measure voltage) and I get like 50 from V1B and 100 from V1A, something, possibly me is whack!
ok, i was messing around and when I put the volt meter on either side of R2 I get clear great loud sound coming through, does this mean that I need to get rid or R2? or change the value, or just replace it...
HAHA, EUREKA!! I replaced R2, and it works., I have Much fine tuning to do...but I can finally use it haha...main problem is that when I turn the volume past about 7 there is a high pitched hiss...any ideas?
If you 'scope it, your hiss may be oscillation. When the gain gets high enough you can get feedback through grounds, supply .. or the two plates capacitance. The original circuit used a resistor to burn off some gain.
Try a 220K ~ 470K resistor before the master gain control to kill off some gain.
-Chris
Try a 220K ~ 470K resistor before the master gain control to kill off some gain.
-Chris
ok, so the resistor and bypass capacitor (R3 and C3) that I nixed should be put back in, as they would be before the master volume control? When the high pitched hissing goes on the top part of the V2 tube sparks...could this be because it needs to be replaced or just that I need the resistor back...
thanks for all your help btw!!!
thanks for all your help btw!!!
Yes, put the resistor and cap back. Experiment with the cap connected and out. If the tube continues to spark it may be defective. This circuit is well withing the ratings of this tube.
-Chris
-Chris
hey thanks man, I put the 470k resistor back in, and it got rid of the hissing when I krank the volume...but the volume got cut as well (obviously i guess). I think I will try lowering the reistor value till i get max headroom, but no hissing or sparking. The sparking is most likely due to the one output tube being old and crappy, the other tube is a NOS tube that I just put in, and it is fine. Thank you for your help anatech, youve helped this nubie a great deal!😎
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