Rectifier tube in B+ string

[LeftyStrat]

Getting crazy here. I'm playing around with the idea of a multichannel tube preamp. PS silicon rectified, parallel supply strings for each channel. Any reason I couldn't put a rectifier tube in the string for one channel?

I suppose another approach would be to have parallel rectification, and run strings from the appropriate silicon/tube rect for individual channels.

Or maybe there's not enough current draw to matter with just preamp tubes?

Ok, relay to switch between silicon/tube rectification with mini power amp? Perhaps a dropping Zener to keep the voltages close?

Thinking out loud here (which is sometimes a dangerous thing).

[Reeltarded]

Without power you just need a saggy as all Hell supply, no?

How complicated!

Maybe a relay in the power section dumps an SI rectifier across a big resistor AND a pot that could be squishy pretend tube that actually does what you wish a tube did anyhow.

You could swtich from a bus that does your module switching, basically using jumpers for on or off.

Seems.

I still think a soaked up low power 6V6 rear end on that thing is the best idea because it's mine. hah

[LeftyStrat]

I mostly prefer the 'in-your-face' response of silicon, but there is sometimes room for sag like this in a Marshall context:

http://www.cs.cmu.edu/~ehn/ax84/sounds/Jtm45_2.mp3

I built several JTM45's, but never got one to sag like that.

It would be fun to have switchable sag for any preamp channel.

[LeftyStrat]

I suppose I could try one of the London Power Sag kits. But as I understand it, these are closer to compressors.

[Leo_Gnardo]

Spare the rectifier tube. Try a grid-leak circuit for your preamp, with a low-ish hi V supply maybe 75-100V, and a fairly large R between that & your first triode's plate, say 470K.

"Squash" IS compression, however you get it, fancy MOSFET circuit or otherwise. And it's a wonderful thing to have. Not to knock the London Power circuit, I just haven't tried it yet & I do like what a grid-leak does.

[martin manning]

I think a compressor is what you would need to get a sag effect. Being made up of class-A stages, the preamp current draw is on average constant.

[LeftyStrat]

But as I understand it, the sag from a rectifier tube is different than a resistor. The resistor is linear. The recto tube isn't.

Is this not correct? Also, most guitar pedal compressors are feedback based, rather than parallel side band where the reduction can be more than the input.

[LeftyStrat]

I think a compressor is what you would need to get a sag effect. Being made up of class-A stages, the preamp current draw is on average constant.

Doh! You're right Martin (as usual). This is what I never liked single ended power amps. There's no advantage to a tube rectifier in class A.