Tubing Question (old Fender)

Jon Light · From: Saugerties, NY

A friend (guitarist) asked my advice and I told him 'don't touch a thing -- bring it to your tech'.

He has a SF Deluxe Reverb. It has 6L6 tubes and a SS rectifier. It HAS been professionally set up for this config. It sounds excellent and he is thrilled with it. Double-excellent is that it was mine and I was not using it and was not going to be using it. I gave him a killer deal and he has finally found what he's been looking for.

BUT -- purely out of curiosity, he can't help wondering how it would sound with the sag of a tube rectifier. Because we always wonder 'what if...?'

With a bit of reading I have concluded that running the DR with 6L6's is already pushing some voltage & current specs. Altering the rectifier would require watching the numbers down the line and making sure that things didn't get knocked outside of safe specs. Standard job for a good tech. But definitely making this NOT be a simple plug & play situation.

Any thoughts? What if this were set up properly for 6V6? Would that make SS - tube rectifier swapping more straight forward?

As I said, I told him to leave it be or bring it to his guy, especially since he's loving what he's got.

Jon Light · From: Saugerties, NY

Update:
Per my advice, he asked his tech. Dude said "just pull out the solid state one and put the gz34 in".
'Talk to your tech' will never be bad advice.
That's that.

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

I agree with the tech that subbing a good GZ-34 in place of a solid-state rectifier is no problem. There is very little voltage sag in a GZ-34, so the change in voltages should not be significant.

However, I would probably not say the same thing about subbing a 5U4 in place of a solid-state rectifier without checking out the voltages, bias, etc. 5U4 has significantly more voltage sag. If the power and output transformers are original (or original spec) it probably wouldn't be an issue, but it might change the relationship between the bias and plate voltages. If the transformers are not original - e.g., for something more like Pro Reverb transformers - I would not sub a 5U4 without checking everything out pretty carefully.

Seems to me that subbing a rectifier tube for a solid-state rectifier would, in general, defeat the purpose of setting up a Deluxe Reverb for 6L6 power tubes - which if I were doing it, would be to get more clean headroom and perhaps a bit more volume out of the amp. The solid-state rectifier, in an amp properly set up, would maximize the potential for increased headroom and volume.

You're right - never a bad idea to say, "Talk to the tech before doing anything."

Jon Light · From: Saugerties, NY

Thanks Dave.
Filling in a lot info that was not particularly important in my original question but does indeed relate to some of your observations --

I bought this amp 20 years ago for an excellent price as an orphaned chassis that had been rebuilt and put in a repro cab. I was the one who went SS and 6L6, "steelifying" it. I enjoyed it for a while and then found things I liked better. I cannot vouch for the transformers et al being correct although my understanding was that it had been rebuilt to DR spec.

When I invited my guitarist/friend over this year to check it out (because he was really unhappy with his rig and he had recently been sonically smoked by another guitarist with a DR, he just loved this exactly as it was.

So for now, 6L6 is what it is. And SS recto. I think I may have planted the idea of tube rectifier with a 'hmm...I wonder how it would sound...'

If it were me, I'd like to try a more saggy tube, just to make the experiment more worthwhile.
But I think I'm reading that THEN, maybe the concerns about its affect on bias & voltages might be better founded.

Once again I will send him to his tech with the question "what if I wanted to try something more dramatic like a 5Y3?" (I am thinking, but not positive, that this would be 'more saggy'?)

I'd tell him to just let it be. Except that I'm not one to talk, for all the wondering & wandering that I do about other gear, other options.

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

Jon Light · From: Saugerties, NY

Thanks Dave.

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