Rocket with 6V6s - Anyone built one?

[RJ Guitars]

Rich,

Cool amp and great inspiration!!!

I have been doing some of the obligatory digging on this topic and of course it's been hashed around before. Here is one other thread with some good stuff...

https://tubeamparchive.com/viewtopic.php?t=3432

I was specifically looking for a good starting point for the Cathode bias resistor value on pair of 6V6's. Does 250 Ohms seem reasonable??

rj

[rfgordon]

rj,
On that amp I used one of Matt's (musicalpowersupplies.com) 325V PTs, which, iirc, put about 405VDC on the plates. So I think I used a 270 ohm RK for the power tubes. It might have been 300 ohm, though, I don't remember, and the pic doesn't show it. That big voltage gate the amp tons of punch! Unfortunately, Matt's sold out of those PTs, and has been for a while now.

[skyboltone]

Rich,

Cool amp and great inspiration!!!

I have been doing some of the obligatory digging on this topic and of course it's been hashed around before. Here is one other thread with some good stuff...

https://tubeamparchive.com/viewtopic.php?t=3432

I was specifically looking for a good starting point for the Cathode bias resistor value on pair of 6V6's. Does 250 Ohms seem reasonable??

rj

Hey Rich, try an adjustable just for grins. A wirewound 500 ohm will allow you to run them hot or mid or cold. Just a thought.

[rfgordon]

skyboltone,
There you go giving me more ideas again! I suppose I could also put a minimum-safe value R in series with a wirewound pot, to get a more customer-proof arrangement. Hmmmm, now you've really got me thinking.

BTW, still diggin' that Carlton LP. Thanks again.

[RJ Guitars]

Does anybody have a strong reason toward preservation or deviation from the dropping resistor values used in all the Trainwreck amps, when building a 6V6 cathode biased Rocket?

The 18.2K - 9.1K - 9.1K combination seems like it works well so no argument with success where the technology has been proven. Just wondering if 9.1K - 4.5K - 4.5K or any other combination of resistors with that same ratio would cause a problem since the "ideal" end voltages at all the B+ nodes has yet to be established for a hybrid build idea like this?

Curious what light the wise and savvy might have to shed on this?

rj

[dave g]

I would probably run the PI at a higher voltage because 6V6s have less gain than EL84s, so to get a similar amount of drive from the output tubes you're going to need a larger voltage swing coming from the PI.

I would try to get your PI voltage to around 280v, while keeping the preamp around 200v.

If you are running normal rocket voltages, try something around
10k - 22k - 9.1k

I might also consider changing the PI tail to around 20k and the cathode resistor to around 500-800R

[Zippy]

I might also consider changing the PI tail to around 20k and the cathode resistor to around 500-800R

Ref.: The AB763 blackface Deluxe Reverb uses 22k/470R with a 12AT7.