Replacing ss diodes in my bass amp.

[Bob M.]

Hi,
I have a 2x 6L6 (low powered) bass amp that I want to replace/renew the rectifier with solid state diodes. I have two types in stock right: 1N5406 and UF5408. My B+ is about 490~495 Vdc and I'm currently using 7581A versions of the 6L6. What are some opinions for the best diodes choice of the ones that I have right now?
I use this bass amp for recording and low volume gigs, like coffeehouses, etc. and, of course, I have other bass amps for other applications.

Thanks,

Bob M.

[nickb]

A B+ of almost 500V implies a PIV rating for diodes of well over twice that. If you were to use two of your UF5408 stock diodes in series that will give you 1600v which is a good margin. That means four diodes in total, two to replace each half of the tube rectifier.

The diodes will drop less volts than the tube so your B+ could be significantly higher. This means you need to verify capacitor voltages. Also, 6L6 power dissipation will go up so will have to increase the bias voltage to reduce the current. That in turn might give you more crossover distortion.

As you can see, this might get complicated given you have a high B+ to start with.

[Jazz P Bass]

To add: the preamp voltages will also rise.

[TimmyP1955]

Unless you play it loud, you won't notice a difference. If you play it loud it will (presumably) sag a little less, but the power difference will be negligible. Leave it as it is - running the tubes within a reliable range.

[drewl]

What amp is it?
I had an Oliver (made by the guy who developed the Ampeg Portoflex amps) that was similar.
Not super loud but sounded great.