Matching output tubes neccesary?

Discussion in 'Glowing Bottle Tube Amp Forum' started by spellcaster, Mar 7, 2019.

  1. spellcaster

    spellcaster Tele-Holic

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    I've got a 1970 Twin Reverb chassis that I've been running with two TAD 6L6 output tubes in order to reduce the power. I'm happy with it as is, but have considered adding the second pair of 6L6's in order to sell it. One of the second pair is faulty, so I removed the two inside tubes as a quick fix and ended up liking it that way, but if I sell it, I'd want to make it right. Can I buy a single TAD 6L6 to replace the faulty one without worrying about matching it? I know that years ago, we used to replace tubes without matching them and they seemed to work fine.
     
  2. thegeezer

    thegeezer Tele-Afflicted

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    Everybody worries about it anymore and I buy matched sets but we always used to just stick something in them, didn’t we? Always seemed to sound fine.
     
  3. gusfinley

    gusfinley Tele-Holic

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    There may be some advantages of matching output tubes. Just keep in mind that unless you have matching parts everyone else including your output transformer, you tubes become "unmatched" pretty quickly.
     
  4. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    Bear in mind that TAD doesn't make tubes and you may get another "TAD" 6L6 that's quite different from the other three.
     
    Last edited: Mar 7, 2019
  5. D'tar

    D'tar Friend of Leo's

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    If you have the original box.. They are sometimes marked with a number/code that you could use to get a pretty close enough match. Maybe even marked on the tube itself.
     
  6. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    If you have a multimeter or want to buy one you can get one of those octal socket bias probe things and check the current draw of each tube to confirm that they're close enough.
     
  7. jimash

    jimash Friend of Leo's

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    Isn't that the truth. I do buy matched power tubes and change them all. But I'd never pull two tubes in a Twin. Too scared.
     
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  8. FRANKENJAG

    FRANKENJAG TDPRI Member

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    From the excellent site of @robrob :

    Intentional Phase Inverter Mismatch

    Howard Dumble added a phase inverter balance control to his Tweedle Deetweed Deluxe amplifier. The control allows intentional mismatch between the two phase inverter output signals which generates sweet sounding even order harmonic distortion and intermodulation distortion to fatten up the amp's tone. Anytime harmonic distortion is created intermodulation is also created. The phase inverter balance control lets you thicken your clean tone but also maintain control when pushing the amp hard into overdrive.


    Using mismatched output tubes works the same way.
     
  9. Dukex

    Dukex Tele-Holic

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    I certainly don't know, but Jim at Lil dawg Amps in his Blog states the following for Tube Rolling in the 5e3 D-Lux:

    "You can swap any of the tubes out at any time in any order with the exception of the power tubes which need to be a matched pair."

    I have no idea if this applies to other amps.

    But I'd always rather be safe than sorry.
     
  10. spellcaster

    spellcaster Tele-Holic

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    The tubes are tagged. If I supply those numbers to the vendor, is it possible to get a matched tube?
     
  11. D'tar

    D'tar Friend of Leo's

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    Thats the idea. Ive had tubes doa and been sent a single new tube with same matching code. Biased within 3mA of the others. Also had new matched sets bias 7ma apart.
     
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  12. spellcaster

    spellcaster Tele-Holic

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    Thanks for the info, guys
     
  13. D'tar

    D'tar Friend of Leo's

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    That said tho. I would probably spring for a quad and keep yours for spares.
     
  14. FRANKENJAG

    FRANKENJAG TDPRI Member

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    I wonder if he is referring to swapping within the 12A family of preamp tubes, and warning against swapping different types of power tubes? Then again, the folks who preach matched pairs aren't wrong... it's just that sometimes there are more than one right answer.
     
  15. beyer160

    beyer160 Friend of Leo's

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    That's because years ago in days of old when magic filled the air, tubes were manufactured to a much higher tolerance. You could grab whatever 6L6 they had at the drugstore and swap it into your amp, and it'd be pretty close to whatever else you had in there. Now that western tube manufacturing is a thing of the past and all tubes are made in the Eastern bloc and China now, specs are all over the map. That's why they get matched now- to make sure the current draw of all the tubes in a set are the same so you can bias the amp properly. Mismatched tube sets might sound cool, but they might not.
     
  16. max_twang

    max_twang Tele-Afflicted

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    I actually did this. The people at Antique Electronics Supply (tubesandmore.com) were extremely helpful. I had the ratings of a tube I needed matched and they sent me one that while not identical, was in the ballpark.
     
  17. Buckaroo

    Buckaroo Tele-Meister

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    That is the best choice really. Check the current going through each tube. The bias probe makes it easy.
     
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  18. Buckaroo

    Buckaroo Tele-Meister

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    Well said now! Couldn't be more spot on!!
     
  19. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    Tube QC was totally different in the 60's and 70's, and there is not the same consistency nowadays. Even "rated" tubes like Mesa's and GT's numbered tubes vary FAR more than the printed number would seem to indicated.

    They don't HAVE to be matched, but amps run more efficiently if they are - assuming the driver tube is balanced as well. And somebody will need to check/adjust the bias for the best tone within the tube set's safety range.
     
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  20. dogmeat

    dogmeat Tele-Holic

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    if you don't know what each tube draws it pretty much pointless to worry about matched tubes. if yo want matched outputs you need to match current draws. but realistically... any proper tube you stuff in there will work.
     
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