Tube Rectifiers and Sound Quality

Discussion in 'Audio Hardware' started by avanti1960, Jun 2, 2021.

  1. avanti1960

    avanti1960 Forum Resident Thread Starter

    Location:
    Chicago metro, USA
    Having a preamp with a tube rectifier spec 5AR4 / GZ34 I do notice a difference in sound quality between the stock Sovtek and a NOS Amperex.
    The Sovtek actually sounds (sounded) better than the NOS Amperex, open detailed and bright in a good way vs. a darker, more opaque sound from the NOS tube.
    Unfortunately the Sovtek somehow failed taking two fuses with it, living up to a reputation as being less reliable.
    Lots of recomendation for NOS Mullards but very little about how they sound.
    Can you please share your comments about reliable 5AR4 tube rectifiers and how they affect the sound?
    Thanks in advance.
     
  2. KT88

    KT88 Senior Member

    Rectifiers are a gateway for power to the circuit, so they can vary in their ability to provide power in terms of its speed and its limits. Really what you would hear or "feel" would be the quality of the bass, ie how sudden it can be, and how clean. Since your circuit seems to require more power, or your speakers do, then you might want to replace the tube rectifier with a solid state one. That will raise the B+ slightly, so you need to know more about your amp (as would I) to really swap it or modify the amp slightly to accept it.

    Since higher frequencies don't really require so much power, those frequencies are way less effected by the rectifier choice. The rectifiers don't really have a sound of their own since the signal does not pass through them. However, you may hear the bass response change and the power there can modulate the whole amplifier output, making the mids sound gushier than snappy as they might be to remain more faithful to the original. In short, an under powered amp can have you listening to the amp as much as the recording.
    -Bill
     
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  3. allied333

    allied333 Audiophile

    Location:
    FL
    The best sounding GZ34 is Mullard.
     
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  4. Well said.
    Two words come to mind re SS v factory: sag & lag.
     
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  5. vinylsolution

    vinylsolution Forum Resident

    Location:
    Denver, CO, USA
    I have an original Hagerman Cornet (phono preamp) with the 5AR4 (Jim H. himself built this one, it has a TAD 5AR4 in it).

    I felt the urge to roll it for fun, and I found a nice vintage Mullard (Blackburn by date code, 3rd week of February 1960) GZ34.
    I am awaiting arrival still, so I can compare with the native tube.

    I agree in principle with what was stated above, and am not expecting huge sonic differences. But remain hopeful.

    It has vintage Telefunken tubes (12AU7 / 12AX7's) as well, so decided to have the whole chain be vintage.

    FWIW, I have a full set of the Genelex Gold Lions for it too, should I have future failure.
     
  6. Khorn

    Khorn Dynagrunt Obversarian

    I’m waiting for my new preamp to arrive with a “stock” 5AR4 rectifier tube. I don’t know what they are but I’ll run them for a while and see how well I like the provided stock tube’s sound before making any tube moves.
     
  7. Tone?

    Tone? Forum Resident

    Location:
    San Francisco

    If a tube rectifier in a stereo amp functions the same as a guitar amp, ( which I am familiar with), why would these be used instead of SS rectifiers?
    Tube rectifiers in guitar amps make the power section slightly compress and sag. Which in guitar amps sometimes is desirable to get more of a soft bluesy sound.
    I have a guitar tube amp with a rectifier. Depending on the tube you put it, it will sag less or more.
    But I still don’t understand why this would be incorporated in a stereo tube amp. why would you want your stereo amp to sag and have bloaty low end ?

    thanks !
     
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  8. vinylkid58

    vinylkid58 Forum Resident

    Location:
    Victoria, B.C.
    The OP is talking about his preamp, not an amplifier with a power stage. A preamp draws a fraction of the amperage from the PS that a full amp does. Sag is not an issue with a preamp.

    jeff
     
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  9. allied333

    allied333 Audiophile

    Location:
    FL
    Voltage sag? GZ34 is a cathode based rectifier. Sag is very little, perhaps a few volts on an amp that has at least 50% idle current and about nil on a preamp. 275 to 450 volt amps with a few volts sag is not detected by your ears. The main power supply input capacitor drops more voltage anyways.
     
    Last edited: Jun 2, 2021
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  10. avanti1960

    avanti1960 Forum Resident Thread Starter

    Location:
    Chicago metro, USA
    thanks, can you add a little more detail on how it affects the sound?
     
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  11. allied333

    allied333 Audiophile

    Location:
    FL
    I can't explain it beyond it sounds most clear & open. All I know is I tried about every 5AR4/GZ34 and Mullard is best. You have to take my word on it.

    BTW- this is vintage Mullard, not the new re-issue that makes no reference to being a new manufactured tube. Box looks too good to be vintage and does not state NOS. You may have to pay $100 for vintage. Also, used tested strong is ok as I never found a weak vintage Mullard that lasts at least 50K hours.
     
    Last edited: Jun 2, 2021
  12. Razakoz

    Razakoz Forum Resident

    Location:
    Utah
    Because it's good for your other tubes to give them a soft start. With a ss recifier you get full b+ immediately, which is hard on the other components. Btw, another great option is the gz33 made by mullard.
     
  13. avanti1960

    avanti1960 Forum Resident Thread Starter

    Location:
    Chicago metro, USA
    yes! that is what i am looking for, thanks. more open vs the amperex which sounds bassier, darker and opaque.
     
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  14. allied333

    allied333 Audiophile

    Location:
    FL
    The Mullard will be the last rectifier you will ever purchase. Some here state I do not know tubes such as stratmangler, but I been playing with tubes for 40 years and owned over 10,000 NOS audio tubes. Even rare Genelex and other European and about heard them all.
     
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  15. WildPhydeaux

    WildPhydeaux Forum Resident

    Location:
    Canuckistan
    Comments like these are entirely unsatisfying when one is trying to determine what they will get for money spent... and completely understandable since I find my self in exactly the same situation when describing the change from a new, generic rectifier to a quality vintage one.

    As the OP knows, I have the same preamp. I changed the stock rectifier for a vintage Mullard and was immediately pleased by what I perceived as a more "natural" sound, more lively, more presence, more PRAT - all meaningless words to my way of thinking, but nevertheless the sound was noticeably more pleasing for reasons I can't articulate. Critics will naturally assert expectation bias, and I concede there is no reasonable way to refute that.

    Research will reveal there is a strong audiophile preference for the Mullard GZ34, though not universally so, and the earlier f31 is slightly preferred over the f32, though only slightly. Others contend the very early f31 with metal base is the best, though they generally concede the slight audible difference isn't worth the monetary difference.

    Note that this change is the limit of my experience - I've not tried multiple rectifiers in multiple components. And I happened to stumble onto a couple used f31 (not metal base) for a reasonable cost when I first started looking. I have not sought out additional options, as I'm pleased with what I have.

    By all accounts, these vintage rectifiers tend to be long-lived and the new production have proven to be surprisingly short lived. So even if you hear zero difference with vintage, at least you'll hear it longer.

    Cheers,
    Robert
     
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  16. allied333

    allied333 Audiophile

    Location:
    FL
    Err, if unsatisfying comments (recommendation) from me, why are you still talking Mullard GZ34 Robert?
     
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  17. Khorn

    Khorn Dynagrunt Obversarian

    Would the identical rectifier tubes operate optimally in different preamps? Would they exhibit the same attributes even in preamps with different circuit topological layouts? If not it might require infinite rolling for optimization.
     
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  18. Ontheone

    Ontheone Poorly Understood Member

    Location:
    Indianapolis
    I replaced the stock JJ EZ81 rectifier in my phono pre with a late 50's Mullard UK square getter EZ81. Very nice improvement to sonic "weight" and impact. As far as NOS tube rolling is concerned this is a pretty inexpensive upgrade.
     
  19. allied333

    allied333 Audiophile

    Location:
    FL
    I would say so same performance in any preamp. To hear the minute differences such as metal base vs plastic base Mullard GZ34, you need the best amps and speakers and a good pair of trained ears.
     
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  20. Tone?

    Tone? Forum Resident

    Location:
    San Francisco

    Thanks , just learning on how this applies to stereo amps and preamps
     
  21. KT88

    KT88 Senior Member

    That's a good point, yet the OP states that he hears a difference between two different tube rectifiers. There must be some sag and compression. SS rectification would fix that, plus be a big insurance policy against circuit damage due to rectifier failure. The Mullard is known to have very good vacuum and so reliability, but it still isn't as tight as SS diodes.
    -Bill
     
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  22. KT88

    KT88 Senior Member

    Many tube Hi-Fi products have a soft start feature built-in. Rogue Audio amps and preamps feature a controlled warm-up stage. Just as tube guitar amps often incorporate a standby switch.
    -Bill
     
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  23. Khorn

    Khorn Dynagrunt Obversarian

    Good to know. So basically a preamp at my level wouldn’t exhibit the fine differences between different tubes. What level of equipment would be required to hear differences before bothering to roll tubes?
     
  24. WildPhydeaux

    WildPhydeaux Forum Resident

    Location:
    Canuckistan
    Sorry, it was not meant to be negative against what you wrote at all - it was my poor choice of words. I just meant that I agree with you entirely in that it's hard to describe specifically why the sound is better - it just is. Since neither you or I can articulate a detailed description of the change, a buyer may find "trust me" or "you will definitely like it" or other such endorsements somewhat unsatisfying to support a purchase.

    I agree with you entirely, that the vintage Mullard is excellent and I have no trouble believing, based on your extensive experience, that it may well be "the best". I'm certainly not looking for a different rectifier for my preamp...

    Sorry for the confusion.

    Cheers,
    Robert
     
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  25. allied333

    allied333 Audiophile

    Location:
    FL
    Actually common diodes make a lot of noise and will result in far worst sound. However, CIS Cree Schottky diodes have zero switching noise and perform just like a tube. 6-8 amp TO-220 case rated at 600 volts works. No heatsink required for tube amps with the low current draw.

    As why certain rectifiers perform better is not exactly known, but it likely has to do with switching noise, not voltage sag. All an amp is, is a modulated power supply. Poor power supply design results in poor sound.
     
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