Rectifier Bias Board buzz

[Blues Hound]

I just finished building a 100-watt Bluesmaster this weekend, and when powering it up I noticed a buzzing sound coming from the rectifier/bias board.

Checked the voltages from the board to the bias pot, has a range of -53 to -38 VDC, B+1 is 503VDC, but there is a buzzing noise I have not heard before, checked my 102 and it's quiet.

I am using the same PT that's in the 102 amp I built, it's a custom Heyboer.

Took the board apart, diodes are good, electrolytic caps are good, .01 ceramic caps are good, changed the ceramic caps, still buzzing.

Any suggestions are appreciated.

[ijedouglas]

Connect the 102 (good) PT to the Bluesmaster (bad) rectifier board. If it still buzzes then there is something in your rectifier board. If it's quiet, it's your Bluesmaster PT.

[Blues Hound]

I was thinking that this morning.

Thanks

[Blues Hound]

All sorted out, resoldered the ground connection at the bias pot, she is alive.

470 VDC at the plates, biased at 35.1 mA on the JJ 6L6s

V1a at 206 VDC (Mullard 12AX7)
V1b at 208 VDC

V2a at 196 VDC (GE 5751)
V2b at 198 VDC

PI 280 VDC at the 91k and 260 VDC at the 110k (JJ 12AX7LPS)

Will post a new build thread over the weekend.

Thanks,
Steve

[ijedouglas]

Great! How does it sound?

Your voltages seem a little high on V1, low on V2 and low on V3. Try swapping V1 and V2. Try aim or 200-205 on V1, 200 on V2 and 300 on V3

[Blues Hound]

Sounds very good.

Felt that voltages at V1 were a little high, but only 10 volts, and the clean side is very nice.

I tried several tubes in V1, V2 and V3, finding the NOS GE 5751 was best tone wise for V2 and the Mullard 12AX7 for V1, PI tube is a JJ 12AX7LPS that has closely balanced triodes.

Balancing the Boost/Overdrive to Clean took a little while to dial in but sorted it out.

Seems to favor humbuckers on the OD channel and sounds great.

Happy Friday everyone