6V6s in Stiletto Ace?

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Mark II
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6V6s in Stiletto Ace?

Post by groovebelly » Mon Jan 15, 2018 11:03 pm

Can the Ace run 6V6s on Spongy power mode?
I was hoping for the EL34/6V6 option working out even though this amp isn't advertised with this option.
Any experience?
Stiletto Ace Head
Mark V25
Widebody closed back C90
Widebody 3/4 back 1x12 C90
mini rec cab stack

PRS Mira

Mark II
Posts: 104
Joined: Fri Jul 28, 2006 5:58 pm
Location: Europe

Re: 6V6s in Stiletto Ace?

Post by darkbluemurder » Tue Jan 16, 2018 10:15 am

No experience with that particular amp. I also don't have a schematic of that amp but a few general remarks. When considering a power tube substitution, the following points should be considered:

- the new power tube should not require substantially more heater current than the stock one (stock EL 34 1.5A, new 6V6 0.45A - check)
- the new power tube should not be operated above the rated maximum plate voltage. Since we don't know what the plate voltage in that amp is, I would only consider the JJ 6V6 as a potential substitute. It can handle up to 500V plate voltage, and it is unlikely that the Stiletto Ace runs that high - this should be checked however.
- the new power tube should not be operated above the maximum power dissipation (EL34 = 25W, 6V6 = 14W. This means that the bias voltage must be checked. This is a bit tricky in an amp like any Mesa Boogie that does not have adjustable bias.

In summary, it could be done if it is done properly by a competent tech.

I have a 100W Marshall which I modified myself. I once tried a quartet of JJ 6V6s in that amp. This worked fine. Sonic difference at volume settings below power amp compression/clipping was less bass compared to the EL34 - is that what you want?

If what you want is power amp compression/clipping at a lower volume, an attentuator would be the better solution.

Cheers Stephan

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