50w ODS style amp help

[Mikeroesoft]

I have a 50w ODS style amp. The amp came with TAD 6L6s and I was changing them out for some NOS Sylvanias. I powered up the amp to re-bias using the bias port, and I do not have enough range on the bias pot. The resistor on the bias pot is a 10k and it goes from the bias pot to ground on a terminal strip. The user manual says to bias around 0.060 for both tubes and lowest I can get is 0.084 which is likely way to hot. Can someone help point in the right direction?

I understand the dangers of working inside the amp. I haven't done a lot of tinkering, but I have done a little and I am interested in learning more.

[John_P_WI]

If you had a schematic it would be easier to help... but try changing the 10k resistor from the pot to ground to a 15k or 20k resistor.

[Mikeroesoft]

I do not have the schematic, but I could post a gut shot. The amp is a 50w Two-Rock TS1. I spoke to Two-Rock yesterday and they suggested I change out the 10k resistor for a 7.5k or 5k (1/4 or 1/2 watt). I did that today, but it had the opposite effect. I sent them an email today and I am waiting to hear back....I just thought I'd throw it out here as I know there is tons of knowledge on this page. I noticed that almost all of the ODS schematics indicate that Dumble used a 27k resistor...I do not know if the TS1 employs the same bias circuit though.

[vibratoking]

I think JPWI got it right.

[M Fowler]

Does your bias pot arrangement look like this picture?

Increase the resistor to 22k or as close a value you have.

John_P_WI If you had a schematic it would be easier to help... but try changing the 10k resistor from the pot to ground to a 15k or 20k resistor.

[Mikeroesoft]

I am not sure how to post a pic here, but the photo posted above looks quite similar to what I have. I tried a 10k and a 8.2k in series to try an get a better idea of what I need, and it brought the combined value from 0.084 down to 0.074, so I am going to head out tomorrow and get an assortment of resistors, but I think I am going to try a 27k as I wouldn't mind having the extra wiggle room. Thanks so much for everyone who has helped out and contributed

[M Fowler]

Good call get some and keep trying until you get it where you can adjust as needed.

[Mikeroesoft]

I found success with a 33k resistor. It got me in the range I needed. The amp sounds better than ever now. A surprise worth noting, the best sounding V1 tube I have found so far is the new production Gold Lion 12AX7.