6L6 and ss recto in Deluxe Reverb: need more filtering?

[slidincharlie (Carlo P)]

I converted my SF Deluxe Reverb to solid state rectifier (the 'no-sag' Weber WS-1 copper cap) and 6L6GC power tubes.
Is it now necessary to increase the main filter caps?
I believe I've read so in one of G. Weber's books, but I can't find that reference any longer.
TIA.

[MWJB]

If you're still running 450v rated caps (plate & screen voltages can't be far off that now?) then yes it would be a good idea to rewire your first stage filters like a bigger Fender, 2x100uf 350v/450v in series, each bypassed with a 220K 1W resistor.

It's not like the 450v caps are going to blow next time you turn the amp on, they'll probably trundle on fine for years & are rated for some over voltage at turn on, but I think the recommended set up sounds better. A bit of headroom on the screen supply cap wouldn't go a miss, you should be able to find a suitable sized 500v cap for here (TAD/F&T).

[slidincharlie (Carlo P)]

Thanks MWJB.
Bigger SF Fender amps have two 70@350V caps in series before the standby switch. My SF Deluxe Reverb has got two 16@450V caps in parallel after the standby switch. Should I replace the two 16uF caps with two 70uF caps and keep them after the standby switch?

[Enzo]

The whole issue Carlo, is the voltage. What is you B+ voltage up to now? The standby switch is irrelevant.

[MWJB]

I'd forget the 70uf @ 350 caps, 100uf @ 350v/450v will be much easier to find in a size that will fit in the slightly smaller Deluxe cap pan (Sprague 100/350s will be a headache if they fit at all), you should also be able to find caps small enough to piggyback the 220K on to, simplyfying the wiring. Remember to double check any jumper wires under the cap board, it's likely that you will have jumpers at both ends of the caps, you only want the jumper that links them in series (otherwise your B+ will be shorted to ground - double check with a continuity test).

If you had a GZ34, wiring to before the standby would give the recto an easier life - makes no difference with 5U4/SS/Copper cap.

[slidincharlie (Carlo P)]

Thank you Enzo and MWJB.

First, an answer to Enzo:
the B+ right off the 5U4GB is 433 VDC. The filter caps in this amp of mine are 475V rated Sprague Atoms.

Then a few questions, considering the current 6L6GC + ss rectifier setup and the 475V filter caps:
- can the 433V B+ be an issue in this amp?
- is it still advisable to increase the capacitance of the first filter stage tone-wise?
- is it still advisable to increase the VDC rating of the screen supply filter?

[PRNDL]

I converted my SF Deluxe Reverb to solid state rectifier (the 'no-sag' Weber WS-1 copper cap) and 6L6GC power tubes.

Besides the increased voltage, you're also increasing the output power from 20 to 30 watts, which means you'd need power and output transformers with higher ratings.

BTW - some people like to run 6V6's at high voltages, which was not uncommon in the old days (as long as the bias is set right). Of course, some tubes can't handle it. The upside is you keep that special 6V6 tone and distortion.

[slidincharlie (Carlo P)]

!!! I'd never heard that the 6L6 "upgrade" for a 6V6 amp would require beefier trannies... should I fear for the stock trannies?
Anyway I can perceive some increased power... maybe one notch on the volume dial... but it does not sound as double louder as it was before...

[PRNDL]

According to several sources, you don't need to upgrade the transformers.

Sorry ... I tend to error on the side of caution.

[Enzo]

If your B+ is 433v, your 475v caps are just fine. No need to make up series caps.

[MWJB]

Hi Enzo,

Carlo says that 433v is with the 5U4GB and that he wants to use an SS rectifier, might add 30v or more depending on current draw? No need to make up series caps from a reliability aspect necesarily, but in comparisons I find they sound better that way.

[slidincharlie (Carlo P)]

Carlo says that 433v is with the 5U4GB and that he wants to use an SS rectifier, might add 30v or more depending on current draw? No need to make up series caps from a reliability aspect necesarily, but in comparisons I find they sound better that way.

Guys I made a mistake, sorry!
The B+ is 433v right off the ss rectifier.
Thus according to Enzo there's no need to replace those 475v caps reliability-wise.

BUT... What should I expect tone-wise with two seriers large caps? Tighter bottom end? If there is a possibility of better tone (and a tighter bottom end would sound like a good upgrade to me), I think I'll try the series caps as soon as I have a chance to order them online.

[MWJB]

In that case, just as Enzo says, 475v rating will be fine with 433v with the SS.

The series caps tend to be better defined, less mushy. For a noticably tighter bottom end response you would need to increase the uf value, 2x220uf @ 350v (100uf total) for the mains, 40-50uf at the screens?