NOS GE 5AR4 copper post rectifier tube

Discussion in 'Glowing Bottle Tube Amp Forum' started by Cornpone, Jul 21, 2018.

  1. Cornpone

    Cornpone TDPRI Member

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    Hi all, long time lurker, first time poster. Does anybody have any experience with a GE 5AR4 copper post rectifier tube? GE code: IR 188-5. Not much information to be found online (maybe I just don’t know where to look). It may be going in my Genz-Benz BP30 2x12. Any insight is much obliged. Thank y’all!
     
    Last edited: Jul 22, 2018
  2. BluesOwl

    BluesOwl Tele-Holic

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    They are great! Used one 'forever' in a Matchless
     
  3. Cornpone

    Cornpone TDPRI Member

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    I appreciate the reply! Looking forward to seeing how it affects the amplifiers overall characteristics. I bought it "just for sport" as they say, I'll report back when I install it. Cheers!
     
  4. Wally

    Wally Telefied Ad Free Member

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    Cornpone, if you want to know the effects; take voltage and bias measurements before and after changing the rectifier. Compare the two sets of numbers. Then, set the bias to the same plate dissipation point...and compare voltages and sound.
    Any other comparison is lacking in a basis for comparison, ime.
     
  5. Old Tele man

    Old Tele man Friend of Leo's

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    Thinking that changing the rectifier will change your tone is like thinking that changing your gasoline will change your driving ability.
     
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  6. Cornpone

    Cornpone TDPRI Member

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    Duly noted Wally, thank you
     
  7. Wally

    Wally Telefied Ad Free Member

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    The only ways a rectifier changes the sound of an amp is if there is a difference in the voltage drop between the replacement tube and the tube it is replacing and/or if the biasing is not done to assure the same plate dissipation.
     
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  8. alnicopu

    alnicopu Friend of Leo's

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    This^ A good example is when I changed out a gz34 in my SF Princeton Reverb for a 5v4. My filament voltages were pretty good but the rail was a good bit above the schematic specs with the gz34 and the 5v4 took it down to pretty darn close. Where did the excess go? Across the new rect. Since p=IE, the I (current) may have to be adjusted up to get the same dissipation when the E (voltage) goes down. I was lucky, I didn’t have to change the bias resistor. It put everything right in range with the original value.

    Don’t mean to insult anyone’s intelligence. I used to teach this stuff and I sometimes comment as though its new to folks.
     
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  9. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    :lol::lol::lol::lol:

    What everyone else is saying translates as - if it changes voltages you *may* hear a difference. Beyond that a rectifier does nothing. It has no magic tone sauce. It is purely a functional part.

    If two rectifiers have identical specs but one is 3x the price the only consideration is - will it last 3x as long?
     
  10. ocduff

    ocduff TDPRI Member

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    I have a NOS 5a4 Ge as the OP. '61 date. Red script - sexy tube. 188-5 denotes Owensboro, Kentucky facility. There's likely a trench of heavy metal lining to bottom of the Ohio river on down to Paducah from that factory. ;)

    Guys, to say a rectifier only supplies voltage is understating things. Some can hold the opinion that two rectifiers that supply equal voltage (I have 5V4 and gz34 that supply same amount) that have drastically different effects on the way an amp feels and responds.

    Those saying there is no difference between rectifier tubes of the same type have not heard a Blackburn made Mullard f31 gz34. Or f32. Or not critically listened with an open mind.

    It's the only rectifier tube I'd risk saying publicly in a forum full of knowledgeable people, some with opinions quite precious to them, that makes a difference in the way an amp sounds, responds, and breaks up.

    And I am not replaying internet chatter I've heard elsewhere, nor did that info worm its way into my head. In fact I don't recall others saying what I'm saying here: rectifier tubes of the same type can sound different.

    It's an opinion, no more and no less, but I hear a difference when I plug in a Mullard gz34.

    They add character to an amp - a Pleasant character.
     
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  11. Les Paul lover

    Les Paul lover Tele-Meister

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    Isn't the black pearl designed for a GZ34?


    By the way, if you want to play with valves that have a notable effect on tone with the black pearl......

    I've changed the EL84 for Russian NOS 6P14P EV valves. They sound fabulous, lovely rich smooth top end, full rounded bass and everything in between. They really have made a difference. Costs abiut the same as a set of JJs. These military valves are designed to last 5000 to 10000h too, as opposed to 500 to 1000h for regular EL84, and can take plate voltages of 500v. Good thing as the black pearl runs super hot.

    Another very significant change I've done. I've popped in some NOS RFT ECC83 in V1 and V2. I've bought them cheap from Russia rebranded as RSD valves. RFT 12xx7 series have a very specific construction, unique to them (plate design is very different). These ECC83/ 12AX7 have brought on a more significant crunch, with more edge to it, which I like very much.

    I've also tried some 60s tunsgram (again, rebranded as RSD bought from russia), and those are superb too, though stay cleaner and smoother. Again those came with the metal tag in the plates which is specific from tunsgram preamp valves.

    I preferred the edge of the RFT design in that amp though, so they stayed in.
     
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  12. Les Paul lover

    Les Paul lover Tele-Meister

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    By the way, both preamp valves (RFT and tungsram) have a base sound that is richer, fuller than standard JJ, EH or Sovtek preamp valves, with a smoother, more pronounced high end, and make the amp sound a bit thicker and fuller. Richer low end too.

    They cost me around $20 each, which I find to be extremely good value compared to modern production valves.
     
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  13. Les Paul lover

    Les Paul lover Tele-Meister

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    Ah.... I'd forgotten that 5AR4 is the other name for a GZ34......
     
  14. Cornpone

    Cornpone TDPRI Member

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    Thank you all for the replies! I’m no expert, but I think I can sense a change in the overall ‘feel’ of the amplifier, in a good way. It just seems to sound a little better in some way that I’m at a loss to describe. It replaced a Tung-Sol that was originally in there. There’s not anything wrong with it, I’m just in the process of retubing with nice NOS tubes purely for fun and experimentation (before they get even more expensive) I became curious about rectifier tubes while laying in bed one night lol. Apologies for the late response, had to head out of town for work. Thank you all!
     
  15. Wally

    Wally Telefied Ad Free Member

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    Did you take voltage and bias measurements before and after?
     
  16. Cornpone

    Cornpone TDPRI Member

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    I haven’t had the time yet. I had a day to play with it then had to leave town for work. Will report back. Thank you Wally
     
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