Can you hear a difference in brands of rectifier tubes?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by kingsxman, Oct 6, 2005.

  1. kingsxman

    kingsxman Silver Supporting Member

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    Recently I recieved a new Budda amp that was damaged in shipping. Budda sent me a replacment amp while I kept the damaged one. In the meantime...I was able to get the damaged one working well enough to gig with it until the new one arrived by replacing the broken Electro Harmonix 5U4 rectifier tube with a Groove Tubes 5U4. When the replacment amp came, with a EH 5U4 installed, out of curiosity I tried both 5U4 rec tubes in the new amp. To my surpise..the GT sounded noticably better. It gave a more detailed sound and a bit crisper. It surprised me by how much difference there was.

    I managed to break my GT tube last night and called a "very reputable vintage dealer" for a replacment. The dealer, somewhat rudely I thought, told me I must be hearing things as there is no way that a tube rectifier can effect your tone because no signal passes through it. Other than making me feel like a fool....it got me wondering if anyone else has experienced hearing differences in brands of rectifier tubes. I know that theoretically there isnt supposed to be a difference...but I SWORE I heard a difference between the GT and the EH 5U4.
     
  2. Reeek

    Reeek Member

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    I think I can. Some types of rectifiers are just better for an amp, especially rectifier tubes that have a slow heater warmup in amps without a standby switch but tone, to me, is certainly a result too. Technically, "they" say you should rebias when changing out rectifier tubes but I don't think it's as dangerous as just slipping in new power bottles.
     
  3. Killa-B

    Killa-B Member

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    I don't think you can hear a difference in tone, but you can definitely hear a difference in amp response (punch, sag, etc.). I believe this has to do with the impedence of the particular rectifer tube you're using. Different makes of rectifier tube certainly make the amp sound different (due to impedence), so why wouldn't tubes of the same model type (5AR4 etc.) sound a bit different between brands that surely vary in impedence and other critical specs?

    Don't listen to people who start trying to make you feel dumb for asking a question. Many of the smartest people I've ever met seem more interested to explain why you're wrong in a particular case rather than make you feel lesser for being incorrect.

    In this case I think you're on to something!!
     
  4. jrigg

    jrigg Gold Supporting Member

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    I definitely hear a difference. Do a search on this subject as a number of debates have already occurred on this subject. Bottom line for me is - if I hear a difference, there is a difference.
     
  5. VaughnC

    VaughnC Supporting Member

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    Theoretically, rectifier tubes of the same type should not affect the sound. However, while I can't hear much difference in tone, I do detect differences is the feel of my amp and how it breathes with different manufacturers rectifier tubes of the same type....especially when comparing modern versions with older NOS types.
     
  6. markdurham

    markdurham Member

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    If you still have both 5U4's put them in and measure the B+ voltage in your amp. I would be surprised if they gave you identical voltages. B+ voltage can vary even between rectifier tubes from the same manufacturer due to manufacturing tolerances. The rectifier tube with the higher B+ voltage at idle will also, most likely, sag less when loaded. Hearing a difference, however slight, is possible.
    Also, both the EH and GT tubes are rebranded from the original manufacturer. Depending on the country of origin they may not be built to the exact specs of a NOS 5U4. As long as they meet or exceed the specs for a 5U4 they can be branded as such. That could account for an audible difference in B+ voltage, sag, and response. I say trust your ears.
    markd
     
  7. Scumback Speakers

    Scumback Speakers Gold Supporting Member

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    Different electrical voltages affect your tone. I know that for a fact. Since that tube is tied to your power tranny to rectify it's voltage...uh...d'oh...but doesn't it follow that you could have different voltages showing up from two different tubes and the amp would sound different?

    Who was the vintage dealer? Just curious...
     
  8. kingsxman

    kingsxman Silver Supporting Member

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    Markduram, where would I find the B+ voltage? I actually had to buy another GT 5U4 becuase I stupidly broke the old one while making a cap change.

    I just put the new GT in and once again I CAN hear a bit of a difference. the GT just makes the amp sound a bit more alive and responsive. It has a bit more bite to the sound but not in a harsh way. A bit more sparkle. Very wild.

    Scumbag, the dealer was Willies Vintage guitars here in St. Paul. Great place, good people. Just surprised to get that treatment at that time. THey're pretty much always top notch.
     
  9. Scumback Speakers

    Scumback Speakers Gold Supporting Member

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    Huh, heard only good things about Willies...so I'm real surprised that they came up with that answer. You'd think they'd want the chance to sell "anything" they could if it was popular...especially for vintage gear buyers looking for "the tone".

    Sheesh...I know I've spent a small fortune on acquiring the tone... you'd think a dealer like that would be, well, a little more "open minded" or better informed. That's what I get for thinking like that...huh? :rolleyes:
     
  10. markdurham

    markdurham Member

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    Measure the DC voltage off pin2 or pin8 of the rectifier tube socket. Or follow the wire connected to one of those pins(usually pin8) to the first filter cap and check the DC voltage there. From your description, I would guess the GT will have a higher B+ voltage.
    markd
     
  11. drbob1

    drbob1 Silver Supporting Member

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    But do it carefully! You're talking 400v of electricity there which can do anything from smoking your meter to killing you!!!!!!
     
  12. TheAmpNerd

    TheAmpNerd Member

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    If you are changing caps and don't know where to find the B+,
    please be very careful. What drBob said.

    Specifically, from Basic Electronics, V1, NAVPERS10087-C:

    ELECTRIC SHOCK
    @ 1mA = shock felt
    @ 10mA = shock severe to paralyze muscles and
    not be able to release from conductor
    @ 100mA = shock is usually fatal if it lasts for one
    second or more.


    In short, don't dick around, be safe, discharge the
    caps in the amp before fooling with it.


    postscript

    Of course being the squids that they are and doing
    anything to get out of chipping paint onboard ship...
    Two paragraphs after the shock warning I
    found the following to be particularly enlightling:

    "IT SHOULD BE NOTED AT THIS POINT THAT THE
    TAKING OF AN INTENTIONAL SHOCK IS PROHIBITED
    BY NAVY REGULATION."

    (the "sea green" should make any squids here feel
    right at home too.
    :AOK
     
  13. Reeek

    Reeek Member

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    LOL! I was a Navy CTT and I honestly can say none of us took deliberate shocks for the thrill ;) :p
     
  14. CarlJ

    CarlJ Guest

    Ahhh, we used to test Rocket Pods by touching the contact and cycling the intervelomiter and feeling the shock since there never were any testers available. :(
     
  15. frank62

    frank62 Member

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    yes, i can hear the difference.. they all respond different. some are "faster" than others. i think this is known as slew rate. i have an old ge gz34 in my deluxe. it is somewhat "slow" and causes a sag or slight delay in the amps respone. i like this. a friend has a nice mullard gz34 and it produces a tighter sound in the same amp. a solid state rectifier is faster and tighter still.
     

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