[AGTCooke]

No sound at all. I haven't started troubleshooting yet, but thought someone might be able to pick something off from lolight oking at it.

Attachment 22010

Tubes light up, that's a good sign.

Center LED didn't light up on the first try, soldered in a new one, still no light. Kinda fubarred one of the pads (no longer existant) pulling the original LED out.

Not a drop of sound. No crackle, no pop,

 

[rhester]

Does relay ever kick in? Looks like the BD139 may be backwards.

 

[AGTCooke]

Quote:

Originally Posted by rhester /img/forum/go_quote.gif Does relay ever kick in? Looks like the BD139 may be backwards.

Yesssss! Thank you. New miniMax is online.

 

[tomb]

Glad to hear it!

P.S. Thanks, Max - I've been out of town the last couple of days.

 

[AGTCooke]

Is it possible to get better than 14 gain out of this? It drives my HD515's like nobody's business, but my DT770's could use some more "umf".

 

[tomb]

Quote:

Originally Posted by AGTCooke /img/forum/go_quote.gif Is it possible to get better than 14 gain out of this? It drives my HD515's like nobody's business, but my DT770's could use some more "umf".

No. Except - there are 12AE6's and then there are 12AE6's.

Some tubes have a naturally higher output than others. Testing can reveal some of this, but I've also had some low output tubes seemingly have more gain/slam than others.

Other than that, for high impedance cans, be sure that your bias is correctly adjusted for maximum voltage swing - that would be 1/2 the voltage supply setting (typically 13.5V for each tube). You should check that final bias about 3-4 hours after running. You may find that the bias drops by as much as a full volt, meaning you won't be getting the voltage swing you should.

Not sure that has as much or anything to do with it as do the tubes, though. There's a 12AJ6 that has the proper pinouts and voltages, but its gain is actually 55.(!) A couple of people have tried them and they didn't work in the circuit without constant clipping in the buffer. It might be worth a shot to try if you have a very weak source. No guarantees, though.