5AR4/GZ34 questions

Discussion in 'Amps and Cabs' started by Laurence, Jan 20, 2020.

  1. Laurence

    Laurence Silver Supporting Member

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    Hey,

    I've been aware of this difference for many years, but I don't understand 'why' it is what it is. Why are old/vintage 5AR4/GZ34 tubes so expensive, while newer production 5AR4 tubes are considered cheesy (performance/reliability) and very inexpensive? I think I can understand the opinion of the newer produiction tubes.

    All other octal rectifier tubes commonly used (5UG, 5Y3, 5V4, 5R4, etc.) seem to be reasonably priced as old production.

    What's up with the 5AR4/GZ34?

    Thanks!
     
  2. RAG7890

    RAG7890 Member

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    Supply & demand along with the fact that a good NOS GZ34 will almost last a life time.

    Hunt around, you can get good options without spending a small fortune IMHO.

    The GZ34 is also the most popular Rectifier Tube in Guitar Amps I would think.

    :beer
     
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  3. 120db

    120db Supporting Member

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    Truthfully, I haven't noticed any difference in sound between a NOS Mullard gz34 or new production Russian or Chinese ones. The Mullards and other NOS are just plain more reliable.
     
  4. teefus

    teefus Silver Supporting Member

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    i never felt like the NOS gz34's i used in my valvetechs affected the sound as much as NOS preamo and power amp tubes. i used them mostly because they were bullet proof and lasted a long time.
     
  5. fiveightandten

    fiveightandten Member

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    I don’t know the physical differences. But I do know that I’ve had 5 or 6 new production GZ34s fail on me. I’ve had one old GZ34 fail. It was the *original* rectifier tube in my 1964 AC-50. It failed in 2008 (44 years old).

    The modern ones fail in a few months, a year, a little over a year, any time they want to, really. The old ones just keep going and going and going. Personally, if I have a modern GZ34 in an amp, I replace them annually before they kick it. If I have an old school tube in there, I just leave it.
     
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  6. mallcorn

    mallcorn Member

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    I had a Victoria Double Deluxe and got both rectifier tubes with the amp. I was told the 5AR4 provided the amp with more watts (near 40) where the GZ34 was more around 30. I couldn't tell the difference.
     
  7. BearBryan

    BearBryan Member

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    It’s not about improving tone with NOS rectifiers it is about reliability. Like it was previously stated, the 5ar4/gz34 was/is a popular rectifier so supply and demand.
     
  8. HotBluePlates

    HotBluePlates Member

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    I had no idea old GZ34s were supposed to be "special" except that in the mid-90s Gerald Weber's first book talked up Ken Fischer & Trainwreck amps, and said Ken wouldn't ship one of his Rocket amps unless he could get a Mullard GZ34 to go with it. That was the first time I'd heard anything about European GZ34s and Mullard in particular.

    From them on, I noticed that Mullard GZ34 were very expensive, and even American 5AR4 tubes were relatively cheap (except when they were relabeled Mullards). For a while it seemed that even Amperex and other Philips-brand GZ34s weren't as-expensive as Mullard, though that seemed to turn around at least in the last 10 years or so.

    So from my perspective, it's about hype from a particular source causing the higher price of a particular type & brand. That said, I only use old-production rectifier tubes because I don't trust new rectifiers, and haven't fitted protection diodes to all my amps to save the from a shorted rectifier tube.
     
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  9. zenas

    zenas Member

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    It's simply supply and demand. I've drug home a good bit of old junk to salvage tubes and bits, organs, radios, TVs. The two rectifier tubes you see most often are 5u4s and 5y3s, those two types are common as dirt. I picked up exactly one GZ34/5AR4 in that time, it's a Hammond branded Mullard.
    CBS Fender phased out the GZ34 for a reason. 5u4s were cheaper and other than requiring an extra amp for the filiment and they put out a bit less voltage, they worked just fine. No biggy just order compatible power transformers.
    The GZ34 just was never a popular tube, at least in the States, from what I've seen anyway. Honestly wished Leo would've just went with 5u4s and called it good from the get go. About the only amp Leo made that probably really needed the GZ34 was the high power tweed Twin. That originally had a different rectifier the 83 but was quickly changed to the GZ34. Pretty sure that was the first Fender to use a GZ34.
    After that every Fender with a quad of 5881s or 6L6 had solid state rectifiers. The 5u4 would've been fine in the rest of the lineup. (with proper PTs of course) CBS Fender proved that.
    Anyway I don't believe people in the NOS tube buisness are finding GZ34s in bushel baskets like they do the other more common rectifiers. So you have to pay more.
     
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  10. FuzzyAce

    FuzzyAce Member

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    I actually prefer 5R4 and 5U4 varieties. A 5AR4/GZ34 is fine if you want the most voltage without going ss rectified and I'm sure that's why it's more in demand.
     
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  11. 67super

    67super Member

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    I also use the 5R4 often, it’s a nice cheap alternative. I don’t mind the additional voltage drop, you just bias accordingly.
     
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  12. Laurence

    Laurence Silver Supporting Member

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    I have a couple of spare 5R4GY tubes. I may revert to those. My issue is that two of my Fenders take the 5AR4, drip edge SFPR and '61 Super, and I have a internal struggle paying $100+ for old production (I'm old enough to remember going to the drug store to test and buy tubes). I'll continue shopping.

    I've got loads of 5U4 and 5Y3 spares.

    Thanks!
     
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  13. BFC

    BFC Supporting Member

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    I just picked up a Clark Beaufort Reverb. That’s his take on a blackface Deluxe Reverb. Just noticed it has a 5V4 in place of the 5AR4/GZ34 it calls for on the chart. Sounds absolutely awesome with the 5V4. Great feel. So there’s another viable alternative for cheap.
     
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  14. oneblackened

    oneblackened Member

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    Well, the reason that the GZ34 has the lowest voltage drop across of any of the common hard vacuum rectifiers is because the plate and cathode are spaced very closely. For that reason, manufacturing defects are more likely to cause them to arc over. And, because modern tubes are, shall we say, not as well made as old production ones, they're more likely to arc than 5U4s or other directly heated full-waves which have a wider plate:cathode spacing.

    Realistically I would advise everyone have a tech install protection diodes on rectifier sockets, or even better, just convert the amp to solid state rectification with an appropriate value dropping resistor (GZ34 is ~170R) before the first filter cap. Quick and easy and far more reliable.
     
    Last edited: Jan 21, 2020
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  15. zombiwoof

    zombiwoof Supporting Member

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    5V4 is a great option to GZ34, it's right between a 5U4 and GZ34 in terms of voltage drop, and the filament draw is similar to the GZ34. I put one in my Vintage '65 Princeton Reverb to get the voltage down closer to normal with today's increased wall voltage, and put my vintage Mullard GZ34 away for the future (it was still working as of 2017, 52 years on). The 5R4 is just above the 5Y3 in terms of voltage drop, I used one at home a bit, but for louder applications it was too saggy.
    Al
     
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  16. Laurence

    Laurence Silver Supporting Member

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    Thanks! I've got some 5V4 spares as well.
     
  17. Bluesful

    Bluesful Supporting Member

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    If you have a modern amp with a GZ34 and you grab a NOS GZ34, can you just switch the modern one out for the NOS without having to tinker with anything (bias etc....)?
     
  18. BFC

    BFC Supporting Member

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    It’s probably close enough. I’ve done it plenty of times myself and nothing tragic happened.
     
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  19. big mike

    big mike David Grissom Wannabee Gold Supporting Member

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    Exactly
    It’s a function tube.
    The problem is the current stuff isn’t as reliable IMO. I use a NOS GE in my Greer cam18.
    The marshalls are all solid state
     
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  20. big mike

    big mike David Grissom Wannabee Gold Supporting Member

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    Better to bias. Could be looking at 10-20 volt change in some cases
     

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