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tube vs solid state rectifier?

Fisherdude said:
With full apologies to all concerned, I will, once again, speak of "that which must never be spoken".

The power supply, whether tube or SS rectified, does two things:

1. It converts the AC supply to the necessary voltages.
2. Rectifies the AC to pulsating DC.

After these two things are done, the next stop is the filter circuit, which does one thing:

1. Converts the pulsating DC to pure DC, thus removing all traces of what happened before.

Let me repeat that. Once the pulsating DC has been converted to pure DC, there is no trace of what happened before that point. What does that mean? It means that it can't possibly matter what the rectifier was made from.

This has nothing to do with good power supply design, including adequate power transformer sizing, and adequate filter network design. Poor power supply design can, and sometimes does, result in a power supply that cannot meet the amplifier and load requirements without sag. This has nothing to do with what the rectifier is made from. The designer obviously knows what rectifier he has chosen, and will determine the necessary circuit values to give the proper output voltages, given the rectifier chosen. This has nothing to do with what the rectifier is made from.

The output of the filter network is pure DC, thus removing all traces of what happened before.
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The voice of sanity. Ill draw up a little circuit with some part numbers when I get home.
 
The only place I could see a benefit of a tube rectumfrier is on a guitar amp, where you may want some power supply sag. You definitely DON"T want any sag on a HiFi amp.
 
It just produces a distortion (like many early Fenders, Marshall, Vox, its a classic 60s sound. The amp is sort of part of the instrument in creating the sound.
 
62caddy said:
How would voltage sag benefit a guitar amplifier?
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Compression(sponge) due to the sag of the PS, overdriving the small signal all the way up to the output tubes and even the speaker/s effect, all depending on the amps power capability and loudness that the player is trying to achieve and their intermixing relationships.. Really good guitar players can "work" a properly setup tube guitar amp like it`s part of their guitar and musical emotional feed back.. It`s really great to watch a really good one(talented) "milking" beautiful tones, when their inspired while testing his/her reworked Fender, Marshal, ect. and enjoying the heck out it.. I guess that`s what`s called "synergy", or sonic woody, if you will, in their world.. Exceptional playing pours forth when it`s all dialed in, as witnessed hundreds times by myself after reworking their amp. Regards, OKB
 
I got into HiFi tube amps when I acquired an old 1962 Electrohome console with a B65Q SE amp stage. It had what I now imagine is the “sponginess” or compression and sag that is described in this thread. Kind of a pleasant change from the SS amps I was used to.

I subsequently collected a couple of old vintage amps that have solid state rectification, and the sound is much cleaner and “transistor”-like, compared to the old Electrohome.

I have been thinking of trying one of the inexpensive Chinese 300B amps with tube rectification. I suppose I am hoping for some of that “sponginess” at loud volumes, although I imagine it might grow tiring after spending many years with very clean and accurate tube amps (a Conn 7868 PP and an old RCA 6BQ5 SE).

Do these Chinese amps have a hint of that quality? Not really looking for comments about not buying cheap Chinese tube amps, but lay ‘em on if you must.
 
doctor fuse said:
I have been thinking of trying one of the inexpensive Chinese 300B amps with tube rectification.
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IMHO, if you're going to try an SE 300b amp, skip the cheap Chinese ones. You really need good output iron (and everything else) for one of these amps. You're not going to get a good Chinese amp unless you pay for decent iron. This includes a good power supply section, which most don't have.

I'm currently listening to a friends custom built SE-UL 6CA7 (EL34) amp, and it's easily as good as most of the 300b amps I've heard in the past.

jeff
 
A good 300B amp isn't going to be cheap. Even if you build it yourself.
All the iron alone including the choke cost me close to $800 back around 2012. And you can spend a lot more on transformers. Then there is the cost of the 300B tubes themselves. I used a Tubelab PCB for my second 300B amp. I stripped out the iron from the first one I built point to point.
I liked the compact aspect of the Tubelab 300B amp. It has a 5AR4 rectifier instead of a SS rectifier. It also has regulated DC heaters.
It's a decent sounding amp, but you can spend a lot more building a
300B SET amp. Those fairly inexpensive Chinese 300B PCB kits, or amps aren't going to sound all that good. The output transformers alone won't be that great. I've used the less expensive Chinese output transformers in two of my amp builds. A SE EL84 amp, and a EL34 SE amp. The EL84 trany's cost a whopping $11 each. The EL34 tranys are sizable and heavy, but still only cost me $34 each. They sound ok, but not great.
 
May I suggest that Doctor Fuse has introduced some confounding variables in his comparison to a single-ended amplifier vs unspecified solid state rectified vintage amplifiers. If these had a similar topography to the Electrohome, I am out of line. If, though, the various vintage amplifiers were of a different output power, push-pull, etc., these factors might override the rectification question. A better test would be to change the Electrohome rectifier to solid state, adjust its output voltage to match that of the rectifier (6CA4?), and then make the comparison.

Better still and certainly impossible to do, find a second so as to perform a double-blind A-B test. (None of us is up to such activities for many reasons, of course.)
 
P78 said:
May I suggest that Doctor Fuse has introduced some confounding variables in his comparison to a single-ended amplifier vs unspecified solid state rectified vintage amplifiers. If these had a similar topography to the Electrohome, I am out of line. If, though, the various vintage amplifiers were of a different output power, push-pull, etc., these factors might override the rectification question. A better test would be to change the Electrohome rectifier to solid state, adjust its output voltage to match that of the rectifier (6CA4?), and then make the comparison.

Better still and certainly impossible to do, find a second so as to perform a double-blind A-B test. (None of us is up to such activities for many reasons, of course.)
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Yes that would be a good test, unfortunately the old Electrohome kicked the bucket a while ago and was passed on. But looking at the schematic it did have a 6X4 rectifier.
 
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