Getting Started on SSS 002

[Vertigo]

I made the change, but it's going the wrong direction.

The voltage coming out of the bias board is -382V. Once it goes through the 820K resistor, I measure -45.1V.

Control Grid ~ -40V
Cathode ~50mv with the pot at zero resistance and getting closer to 60mv as I add resistance.

I have a 118K in place of the 130K on the voltage divider to ground. If I swap it out for a 130, it should send more negative voltage to the grids...am I understanding this correctly?

Edit: With the 130K in place, I now have -44.9V on the grid and the cathode is measuring 42mV with the pot wide open (no resistance). I'm going to sub in a 150K and see what there is to be learned.

[martin manning]

You have a 1M instead of the 820k, right? that means you will need something bigger than 130k to hit the same point as the 820k/130k. I think 150k might be about right.

[Vertigo]

You have a 1M instead of the 820k, right? that means you will need something bigger than 130k to hit the same point as the 820k/130k. I think 150k might be about right.

No I'm just a bone head and need to fail a lot before I succeed.

I swapped the 1M for an 820K and then proceeded to sum the pot with the 820K and not the 118K that was in the place of the 130.

Every failure is a stone on the path to learning...or something like that. This gives me another opportunity to burn my fingers while fiddling with that damn pot.

[Vertigo]

I think I'm on the verge of wearing out my solder sucker, and the board.

It's looking good now. 35mV on the cathode and -47.5 on the grid.

Time to move on to other things now.

Thank you everyone for your help while I learn things the hard way.

[Vertigo]

question for those who have built an 002...if you turn the preamp to 10, how much crunch are you getting? Mine starts to break up with the knob at about 6 and gets pretty crunchy...not bad, just not what I expected out of this amp and it's making me wonder if I did something wrong.

Also, has anyone done anything useful for the "mid" switch?

[Abe5150]

Thats kind of how mine is too except it starts around 8.5. It’s definitely not clean all the way through. I used Mesa Boogie CTS pots.

[Abe5150]

I think Ryan posted some updates to the layout/schematic that effects the Mid switch.

[rccolgan]

question for those who have built an 002...if you turn the preamp to 10, how much crunch are you getting? Mine starts to break up with the knob at about 6 and gets pretty crunchy...not bad, just not what I expected out of this amp and it's making me wonder if I did something wrong.

Also, has anyone done anything useful for the "mid" switch?

I think I get a little crunch about 1'oclock. I know it tightened up and cleaned the tone with the v1 LNFB from 1m (original) to 100k (corrected). See attached

for the mid switch, I've seen us try .001uf up to 1uf. I believe 1uF has been observed on other amps with the mid accent switch with favorable results.