First Dumble from scratch

[pompeiisneaks]

Very nicely done!

From one Phil to another

~Phil

[philbard]

Thanks for the nice comments everyone.

So far I'm only able to get about 3.5v difference on the PI Plates by adjusting the trimmer, with the V3A being the higher. I've seen this mentioned before on the forum and the suggestion was trying different tubes. Did so with several and this is the best I could get. Any other suggestions as to how to get to 6v? Does it matter that much?

[erwin_ve]

Thanks for the nice comments everyone.

So far I'm only able to get about 3.5v difference on the PI Plates by adjusting the trimmer, with the V3A being the higher. I've seen this mentioned before on the forum and the suggestion was trying different tubes. Did so with several and this is the best I could get. Any other suggestions as to how to get to 6v? Does it matter that much?

You might get better result using a scope, see the topic on the PI balancing. Basically it is the Ampeg SVT procedure without a spectrum analyzer. If a 5k trimpot doesnt do it, you could put a 10k trimpot as a PI balance pot.

Btw nicely build amp; my 2nd ODS wasnt that neat

Erwin

[philbard]

Thanks for the nice comments everyone.

So far I'm only able to get about 3.5v difference on the PI Plates by adjusting the trimmer, with the V3A being the higher. I've seen this mentioned before on the forum and the suggestion was trying different tubes. Did so with several and this is the best I could get. Any other suggestions as to how to get to 6v? Does it matter that much?

You might get better result using a scope, see the topic on the PI balancing. Basically it is the Ampeg SVT procedure without a spectrum analyzer. If a 5k trimpot doesnt do it, you could put a 10k trimpot as a PI balance pot.

Btw nicely build amp; my 2nd ODS wasnt that neat

Erwin

Erwin,

Thanks! I'd seen that topic awhile back but at a time when I had only a basic understanding of Dumble amp circuitry. Just tried it out and it made a HUGE difference in the harmonic content in the OD channel. Better in clean too but more noticeable in OD. Smooth grind and a tonal richness that is exactly what I've been looking to get to. Loving this amp right now even though it still has a way to go until its broken in. Cheers!

[philbard]

All finished up and sounding pretty fine....

Finished.jpg

[pompeiisneaks]

Oh wow so nice! Well done

~Phil

[dbharris]

Looks great, very nice amp you have there!

-Dan