- Post n°1
I rebuilt my Mk III's and noticed a little hum on both. I just assumed it was the transformers, but the more I listen it seems to be coming from my GZ-34's. The amps were pretty much rebuilt stock except for an SDS Labs board in place of the quad cap. I hear no hum from the speakers. I was wondering if it was normal or if they might be getting too much juice from the 50uF section of the SDS board. Do tubes hum even the hum? It is fairly and hard to pin point. Really don't care about the hum just don't want to destroy the NOS tubes.
- Post n°6
harpy wrote: Yes it's the tubes. Would the rectifier tube diode mode sticky apply for the pre-rectify?
Yes, I like to use diodes as 1/2 wave rectifiers ahead of the 5AR4. The "yellow sheet" mod in the sticky is worth doing. How much capacitance do you have on the side of the choke away from the GZ-34?
- Post n°9
I tried switching out rectifier tubes and hum remains. I haven't done the yellow sticky mod yet because I would like to see if I can find the issue. The only thing I can think of is a bad ground on the SDS boards. The green wire is the grounding point and it grounds out where the 3 terminal board where the blue bias cap is. Any other thoughts?