Solid-state v. tube rectifiers

I see that Holger and Don have gone from tube to solid-state rectifiers for their production power amps.
There are plenty of beyond-my pay-scale arguments for each.
Am wondering if anyone has had experience with both on an otherwise identical amp, and what their impressions are.
Thanks,
Gollum

One issue is reliability ...

peterh wrote:One issue is reliability ...

Peter, I don't mean the difference between the Webers and a Mullard, for example. This involves a whole separate power supply architecture. Sorry to have been less than clear in my question.

One issue is reliability...

.

Solid state rectification is more efficient saving 15-20W of power by not heating the rectifier tube cathode.  Plus there is less voltage drop across the rectifiers in operation so the supply is faster to respond to current demands.  20W is about 9% idle power in the ST-120 so adds up.

Finding the correct diodes to use for low noise is a challenge in some circuits.  The ultra-fast recovery diodes used in switching supplies may cause a lot of diode hash in slow commutation supplies (50 or 60Hz).  In a guitar amp I finally found some older fast soft-recovery diodes that quietened the amp down considerably.  Depends upon the application.

Controlling inrush current is a challenge with straight SS diode rectification.  The filter caps look like a dead short circuit at power on.  A tube rectifier has a characteristic impedance that controls how fast the filter caps can be charged.  But this valve rectifier voltage drop also creates B+ droop during high current demands.  In comparison, SS diodes typically have about 1V forward drop at their rated current.

As for sound difference I don't know and don't have an opinion.  Use what you like best.

I'll go with "whatever sounds best."
There have however been some complex and interesting arguments pro and con given by these board members, including Don Sachs and Holger Schaarschmidt, as well as Andy Bowman at Vintage Tubes, all with their own nuances. Again, I'm not asking about swapping out Webers for Mullards but as to circuit design specific to solid-state rectification in big amps that wouldn't even work with tubes.
Just askin . . .

.

I thought Don favoured tube rectification.

Tube Nube wrote:I thought Don favoured tube rectification.

He does on his preamps but if you look at his new KT-88 he has gone to solid state.
So here are three bright guys differing on what ought to be a dumb question: a diode is a diode is a diode, eh?
Maybe the question is too esoteric.
Since our little market, which ain't Marantz v. McIntosh v. ARC, is so small, none of these guys have any "marketing" reason to tout one over the other. Me, I like the tube rectifier sound just find so just why mess with it? Tested your hearing lately? If you can hear even a hiss at 4k you're awfully young.
Aw, forget I brought it up. It was just an assignment from my kindergarten teacher, Mrs. Keller, who wouldn't hear my answer anyway.

I built my ST120 with UF4007 diodes which cost pocket change. To cushion the blow to the power supply I also use Bob's time delay circuit. Have had no issues with them in over a year of use.

In the past I've gone through more rectifier tubes than I care to remember with my previous Dynaco amps. (ST70, MkIV)

I would also recommend getting a variac for classic tube gear. It might seem optional but if you have high AC voltage then a variac might be just what you need to keep your amp and precious tubes lasting longer.

to my own ears an SS power supply totally kills the sound, especially in a tube preamp. Night and day difference in the sound, like analog VS digital.
But in a power amp IF you use ultra high speed diodes in combination with capacitors and current limiters,
the difference in sound isn't as great as the increase in reliability and long term life.

interesting to read the various comments here. As deepee pointed out, I've pretty much gone all solid state on all my gear.
Reason is stability, reliability, and yes, less noise!
Now some here may disagree with the 'less noise' comment, but to my ears, there has been an improvement in overall unwanted noise of the amp and preamp, max volume, no input, VERY quiet. Again, to my ears, much quieter then when I used tube rectification.
Keep in mind though, sound is extremely subjective.
It is VERY important that the solid state power supply is designed well and using high quality components, there should be absolutely no compromise in that! For power amps, time delay for B+ is an absolute must, and I use about 50s before B+ 'hits' the tubes etc. I also use thermistors to limit inrush current.
I do not use any time delay for the preamps power supply, but again, thermistors are used.
This is all very fine, but for me, irrespective of what my ears tell me, the prove is customer feedback and comments.
Since switching to solid state power supplies, I have had no negative feedback with regards to 'noise', in fact, the opposite is what I hear.
Of special note is the LOMC option phono preamp with a solid state power supply. If there is going to be any 'noise', this would really make itself known, but again, the feedback I've been getting, is that the owner is blown away by the lack of unwanted noise, not to mention the clarity of the music.
I am a solid state power supply convert, others prefer tube rectification. Heck, these differences in preferences, likes, dislikes etc, is what makes this all so interesting, and each to their own!

Im imagining the noise is only heard when no signal is passing through the amp. I wonder if thats accurate?

Back in'92 when I bought my beloved Naim Nait2, I noticed that we could hear, ever ao faintly, a radio station, when the phono setting was selected. The vendor said they could absolutely modify the amp to filter that out, but the negative impact on fidelity would be regretable.

Tube Nube wrote:Im imagining the noise is only heard when no signal is passing through the amp. I wonder if thats accurate?

Back in'92 when I bought my beloved Naim Nait2, I noticed that we could hear, ever ao faintly, a radio station, when the phono setting was selected. The vendor said they could absolutely modify the amp to filter that out, but the negative impact on fidelity would be regretable.

Tube Nube, hope you didn't let them modify it!
My experience with RFI and hum on the phono end has mostly been cable-related, especially if you've got an AC line and a signal line running closely parallel to each other. Ideally they should cross at right-angles -- although the odd preamp tube can decide it's an AM receiver, too.
As to Holger's comments, I've got a plethora of old Mullards and McShane's new Gold Lion 5AR4s for the Big Boppers and the switchover to solid state, albeit tempting, just doesn't make economic sense considering the money tied up in the tube rectifiers. I DO have solid-state rectification in Holger's Janis iteration of the PH-16 and it sounds superb; absolutely black, soundless background, and none of its 6922s have gone into cardiac arrest on start-up -- and I play it a lot. I use a Bendix rectifier in the SP-14, another fantastic tube rectifier if you can find one.
As just about everyone has said, music reproduction is a subjective matter. If it were straight-line arithmetic, there'd be no need for discussion.
-d-