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Matched Tubes ???

Discussion in 'Amps and Cabs [BG]' started by Tom Neves, Jul 25, 2000.


  1. Anyone believe in the importance of matched Power tubes?
    Be it duo's quad's sextet's.
    There seems to be some varying opinions.
    There are some who say it doesn't make much difference in musical equipment, after all back in the 50's and 60's, Fender Ampeg, Gibson didn't go through the bother and we all love the way those amps sound. Maybe this accounted for the suttle differences between amps.
    Do you guys think this is over rated hype or valuable for the amps efficiency?
    Bass Players.........Whew, what a Bunch !!! [​IMG]

    [This message has been edited by Tom Neves (edited July 25, 2000).]

    [This message has been edited by Tom Neves (edited July 25, 2000).]
     
  2. Matched tubes are good to have, from an electronics standpoint--more clean power. I don't freak out about it though. The biggest difference I hear is when one side of a push-pull output stage is drawing more current than the other side, then you get a lot of 120 Hz hum from the power supply to the speaker. The degree to which the tubes are unmatched probably does account for part of the output signal sound, because the distortion harmonics that tubes are known for (even-order) are canceled out in a push pull output stage "if" the 2 sides are perfectly matched.

    Interesting, but I wouldn't lose sleep about matching except on a monster like an SVT.

    Having said all that, I do buy matched tubes when I buy tubes. And if I'm digging through my pile of used tubes, I keep swapping out 'til I get an approximate match.

    Chris
     
  3. snapper

    snapper

    May 16, 2000
    Well, I'm certainly no expert, but I have been reading a lot about tube amps lately. From what I understand, although tubes were not sold as "matched" in the 50s and 60s, they were manufactured to close tolerances. Tubes that didn't meet spec were destroyed. These days tube manufacturers don't do such extensive weeding out; it's up to the purchaser or reseller to match them.

    The Tube Amp Debugging page contains a lot of good information about these subjects. Here is a link to the page on biasing:
    http://www.geofex.com/ampdbug/biasing.htm

    Note that tubes that are biased incorrectly (or severely mismatched) can cause major problems in your amp. The fuse might not protect it from damage. So, unless your amp has individual bias controls for each tube (which it probably doesn't unless you modded it that way), getting matched sets can prevent a lot of problems. You still need to set the bias.

    Of course, you don't have to get "groovy" tubes to get matched sets. Most tube dealers will sell matched sets without doubling (or tripling) the price. If you lurk around Ampage (www.ampage.org) or alt.guitar.amps, you will soon find out which tube dealers have good reputations.

    --snapper