SS -> Tube Rectifier in Bassman 50

[boyer]

Hey everyone,

Great site you have here Can't believe I didn't get onto it sooner.

So, I have a later model Bassman 50, which I've partially blackfaced (all the important stuff anyway) and partially modded in other ways.

I've been seriously considering using a tube rectifier.

In your opinion will the voltage from the 5U4 (~50V less, am I correct?) be too low, keeping in mind that I'd like to maintain a fair amount of the clean at lower volumes, and have it compress as it gets louder.

Has anyone attempted this before? I haven't been able to locate anything online.

Does Hammond (or anyone for that matter...) make a 5V only transfo I can add so I can run the heaters, or would I be better off tracking down a similar PT but with a 5V winding?

Also, having only grown up using and working on Fenders, Traynors and Garnets, I have no idea how M-boogie preform SS to tube rectifier switching. Do they have a "soft" switch, or just something like a DPDT relay that switches hard? Does it just switch in the diodes over the tube, or does it take the tube out of circuit?

[Bruce / Mission Amps]

Hey everyone,

Great site you have here Can't believe I didn't get onto it sooner.

So, I have a later model Bassman 50, which I've partially blackfaced (all the important stuff anyway) and partially modded in other ways.

I've been seriously considering using a tube rectifier.

In your opinion will the voltage from the 5U4 (~50V less, am I correct?) be too low, keeping in mind that I'd like to maintain a fair amount of the clean at lower volumes, and have it compress as it gets louder.

Has anyone attempted this before? I haven't been able to locate anything online.

Does Hammond (or anyone for that matter...) make a 5V only transfo I can add so I can run the heaters, or would I be better off tracking down a similar PT but with a 5V winding?

Also, having only grown up using and working on Fenders, Traynors and Garnets, I have no idea how M-boogie preform SS to tube rectifier switching. Do they have a "soft" switch, or just something like a DPDT relay that switches hard? Does it just switch in the diodes over the tube, or does it take the tube out of circuit?

Put a 120 to 150 ohm, 15w-20w resistor in series with the B+ lead from the cathodes of your B+ rectifiers and before the first filter cap.
Rebias the power tubes to about 16-17 watts each.
Try it and see if you like the way that sounds.
That will be similar to what a tube rectifier will sound like in this amp.

[boyer]

Great suggestion Bruce, thanks!

The more I think about it, the more of a PITA it would be to add a tube rectifier. This could be the ticket.