Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: GreaseBall on December 14, 2020, 05:45:24 pm
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I've just finished building my first ever tube amp. I'm nothing of an electrician but I know a little about soldering :smiley:. It works, clean tones are really nice but the overdriven sound is quite harsh and trebley sounding. I just thought that maybe someone more experienced than me could throw an eye on this build. I used the Hammond 291BEX power transformer.
I'd appreciate any feedback, thank in you in advance guys
(https://i.imgur.com/owfkuoc.jpg)
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Your voltages are way high for a 5E3. The output tubes are idling over 34 watts! Could be part of your issue. You can drop the voltages by using a real NOS 5Y3, unless this is already the case.
Are you using a 12AY7 for V1?
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Yes, I'm using 12AY7 for v1. So the rectifier could be the problem? It's a TAD 5Y3GT
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How much AC voltage do you measure on pins 4 and 6 of the rectifier tube?
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It's 335V AC between ground and pins 4 and 6. My wall voltage is 230V if it makes any difference.
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Ok, I've changed the rectifier to JJ 5Y3S and now it seems to be fine.
B+1: 360 vdc
B+2: 320 vdc
B+3: 237 vdc
My amp sounds significantly smoother now, much more like I would want it to sound.
I think there was something wrong with the rectifier I've had before, there's 5U4M written on it, so I don't know if it was the right tube.
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How about a bigger value for 6V6's bias resistor ?
I often use Zeners diode stack to have a lower B+ voltage.
https://robrobinette.com/Generic_Tube_Amp_Mods.htm#B+1_Voltage
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Ok, I've changed the rectifier to JJ 5Y3S and now it seems to be fine.
B+1: 360 vdc
B+2: 320 vdc
B+3: 237 vdc
My amp sounds significantly smoother now, much more like I would want it to sound.
I think there was something wrong with the rectifier I've had before, there's 5U4M written on it, so I don't know if it was the right tube.
That's almost exactly what I measure in my 5E3. Enjoy it!