FRED for '63 Vibroverb RI

[drasp]

Howdy! First post.

I'm interested in switching the cheap 1N4007 diodes in the rectifier of my '63 Vibroverb RI to FREDs. I've seen in various places, mention of using the IXYS 11A 1200V FRED available from Digi-Key. I was looking it up to purchase a few & saw that it's not actually listed as "Fast" but instead "Standard" (Standard Recovery > 200mA)

My question is, would the HEXFRED 1200V 16A FRED work better for my situation? It's pn# HFA16PB120-ND @ Digi-Key and listed as "Fast" (Recovery =< 500 ns, > 200mA) for speed. Faster is better in FREDs, right?

[nico.verduin]

What are your expectations of putting other diodes in, in the first place?
Nico

[drasp]

I've read numerous places that replacing the cheap diodes used in most mass-produced s.s. rectifiers with FREDs can help the tone of a tube amp be more like an amp with a tube rectifier, that is to say, warmer & more natural. I don't believe that FREDs can copy sag, but I think they cut down on the "coldness" of some amps.

If you go here and scroll down to the 3rd question, "What are FREDS, Why Do I Need Them and Where Can I Get Them!?!" you can read some of what I've been hearing. The same page even addresses using FREDs in my amp. After speakers & tubes, the next-most-complained about shortcoming of the '63 Vibroverb was the choice to change to a s.s. rectifier. . .

[Bruce / Mission Amps]

Most of that FRED crap is utter nonsense and just Net driven drivel.
You won't hear ANY significant changes unless you simply talk yourself into it later, to warrant wasting your time doing the mod in the fiurst place.
What you are hearing in the reissue amp is a cheap speaker, cheap tubes, over biased power tubes and probably too many metalized polypropylene capacitors.

[drasp]

Ah-hah! Glad I posted here before ordering FREDs. The internet is goofy.

[nico.verduin]

Most of that FRED crap is utter nonsense and just Net driven drivel.
You won't hear ANY significant changes unless you simply talk yourself into it later, to warrant wasting your time doing the mod in the fiurst place.
What you are hearing in the reissue amp is a cheap speaker, cheap tubes, over biased power tubes and probably too many metalized polypropylene capacitors.

Bruce I agree with you on this one. The only positive thing about the high speed diodes I can think of is that they tend to produce less noise. But You would have to check the power supply rails first with a scope to determine how much there is now. And let's not forget the rather undersized PT in the re-issues. Wouldn't be the first time when the BIAS is better adjusted they tend to get rather hot.
Nico

[Tom Phillips]

Ah-hah! Glad I posted here before ordering FREDs. The internet is goofy.

I think it’s good that you asked first and that you listened to the advice.
The height of the FRED-mania was in 2001-2002. At that time, one of the original articles that started the FRED-mania was posted at http://www.victoriaamp.com/week4.html
That article has since disappeared from the Victoria Amp web site.
We probably have not heard the last of this subject.

Tom

[drasp]

On one hand, I've learned a HUGE number of things from forums & sites on a wide variety of topics. On the other hand, I've learned to take everything with an extra-jumbo mondo-huge block of salt.

[Tom Phillips]

There is also a lot of misinformation published in books and white papers too but the internet enables the quick flow of information direct from the author to anyone who cares to read it with no sanity check or filtering. Now, more than ever, the reader must verify the information through additional research of other sources. It’s also good to question if the information makes any sense in the first place. That’s a difficult task if you are new to the subject but things do start to fall into place as one continues to learn. There are many cases where inaccurate information is passed on and on by people that never had any idea if it was correct. Sometimes, it’s just what they want to believe like “…pass this email on to 10 people and Bill Gates will send you $100.”

Never the less I’d rather have the internet than not. You can still collect a mountain of good information. I especially like the availability of the scanned classic texts. You can uncover 50+ year old information that was re-published by some “guru” in the 1990’s with the claim that he discovered it. I used to get pissed at that. Now I just laugh it off since it can’t be controlled.

Regards,
Tom

[Jag]

“…pass this email on to 10 people and Bill Gates will send you $100.”

You're getting ripped off Tom. Bill's sending me $500. :-)

+1

[Rob Mercure]

Drasp,

I totally agree concerning the FRED comments and want to echo that after checking out the originating site that you provided I find that much of their "advice/expertise" is bogus. I usually just bookmark such sites in case there may be some further info I can glean but after a quick but thorough review this one doesn't even rate that.

Oh, and I play a 1967 V'lux Reverb with the CQ10s - also if you review the current postings, the one about overfiltering in particular, there are some suggestions about how to add a tube rectifier to a non tube setup (well, you may have to interpret slightly) - and one of the easiest ways is using an old TV damper diode.

Rob

[BobW]

This snake oil nonsense (FREDS) was initially perpetuated by kg, Ken Gilbert from the old ampage site.

we had a few heated discussions on it.