Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Raymond P. on November 23, 2017, 08:11:52 AM

Title: Voltage Mismatch [resolved]
Post by: Raymond P. on November 23, 2017, 08:11:52 AM

Hello,


Just finished my Crack (w/o Speedball) and had a great time building it. It's my first amp kit and first tube amp. Resistances and voltages are within spec. I've been listening to it, and it sounds fine as far as I can tell. There is something I'm curious about though. I noticed there are voltage mismatches between terminals 1 and 5, and between 7 and 9. Does that indicate potential problems that could surface in the future? What would cause the mismatches? Tubes?


T1: 83.9V
T2: 172.3V
T3: 0V
T4: 172.2V
T5: 80.8V


T6: 0V
T7: 107.9V
T8: 0V
T9: 106.1V
T10: 0V


A3: 1.59V
A8: 1.59V


Thanks!
Raymond

Title: Re: Voltage Mismatch
Post by: Paul Birkeland on November 23, 2017, 08:19:43 AM

The voltages at terminals 1 and 5 depend on the 12AU7.  Yours vary by about 4%, this isn't anything to be concerned about.  If you had 65V at T1 and 120V at T5, then you would want to dig a little deeper.

The voltages at T7 and T9 are heavily influenced by the voltages at T1 and T5, but these also look nicely matched.

-PB

Title: Re: Voltage Mismatch
Post by: Raymond P. on November 23, 2017, 11:28:35 AM

Thanks, Paul.