kometious astroid 60w build - question about bias resistor

[Roe]

We recorded with this amp yesterday. sounded good with esq and strat

[bnwitt]

I had to increase the 470 bias resistor to 4k7 or 10k to get the right bias range with mullard ri el34s - have anyone else had this problem with a komet or astroid build?

Roe

I'm not sure where the 470 ohm value came from. It should have been 47k to begin with as in the original.

[Roe]

are you positive about this? I know its a 47k between the bias pot and ground. I'm talking about the 470ohm resistor in the astroid layout (it is situated between the blue/red lead from the PT and the diode before the bias pot.)

the comet has become very popular in our studio and rehearsal room: it has been used for:
punk recording (hamer korina special jr and 4x12" w g12t75s)
country recording (strat, esquire; 2x12" with alnicos)
stoner rock rehearsal (335 tuned to C; 4x12" with scumback H75s)
the stoner guitarist says he is gonna get a comet now

[bnwitt]

nik's caps are 100uf. I'll install 4 80uf mallorys soon. (i just have 3 of them now)

I'd leave the 100uf caps in there. Allyn has indicated the 80ufs cause ghost notes.

[bnwitt]

I'm talking about the 470ohm resistor in the astroid layout (it is situated between the blue/red lead from the PT and the diode before the bias pot.)

Sorry Roe, I misunderstood you. The resistor you refer to is a 470 ohm value. So to answer your original question, I haven't had any problem achieving the proper bias range in my asteroid with the original values. What is the value of the resistor after the diode on your board? It doesn't look like a 10k, but maybe those bands that look green to me are really black. Also, what was the range of your negative bias voltage out of the 50kl pot with the 470 ohm resistor?

[Roe]

Hi, I have a 10k after the diode. I used two 10uf caps instead of the original 8uf caps. would that affect something?

the range was quite a bit of with the 470 resistor. I don't remember exactly - think it was something like - 50v at pin 5

[arjepsen]

nik's caps are 100uf. I'll install 4 80uf mallorys soon. (i just have 3 of them now)

I'd leave the 100uf caps in there. Allyn has indicated the 80ufs cause ghost notes.

Would you mind trying to give a deeper explanation of this?
I''ve recently built an asteroid that generally can sound good, but has a buzzy kind of distortion that fades out rather abruptly when it's set at the edge of breakup.
Wonder if my problem is related.

[M Fowler]

I will try get a hold of Barry (bnwitt) so he can answer your question. He frequents Hoffman Forum more often than TAG.

Mark

[Roe]

Try the HD option with 220uf main caps

[arjepsen]

It sounds interesting, but what are the differences between the standard 60 and the HD?
Just solid state rectification, 220uf main caps and nothign more?

[Roe]

exactly. You could also try a compromise. I am using a 220uf in series with a 100uf for a total of 70uf

[Reeltarded]

Roe, what tubes have you run in this amp and which of them have you liked most?

Umm.. I'm unsure if the caps will stick but I did come up with a full set.

I have pairs of Xf2, Xf4, and STR Phillips 6L6GC to pick from. I am really into 6L6s lately, but Dave says this thing is Leslie West on brown acid.

[Synchu]

EH 6CA7 sounding best here.

Niki

[Reeltarded]

But I want to use the 6L6s and it's important to tell me they were most amazing.

You are no help at all.