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Thread: Replacing Amplifier Tubes With Wet Hands

  1. #1
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    Replacing Amplifier Tubes With Wet Hands

    Hi All. I have a 50 watt Crate VFX 5112 V Series 50 watt amplifier. I got the amp for free a long time ago and its tubes are going. So I'm replacing them. I put on a pair of rubber gloves, made sure I wasn't fiddling with any capacitors, and pulled the old tubes. The following video shows the process (on a similar 30 watt amp) I went through to remove the tubes.

    https://www.youtube.com/watch?v=qb-TbLjgC5c

    The tubes from my 50 watt amp are different from the ones from the video. I pulled the following tubes from my amp:

    2 X Groove Tube GTEL34R (Power tubes)
    4 X Groove Tube 12AX7EH (pre-amp tubes)

    My question is, can I just order these same tubes, plug them in the empty sockets, and go on my merry way? Or is there any kind of tweaking involved in swapping in new tubes? Also, my old tubes are made in Russia. I'd prefer to boycott Russian products. I'm wondering if there are alternative/possibly better/possibly cheaper tubes I can use as replacements. Any suggestions or tips are appreciated.

  2. #2
    Forum Member dirtdog's Avatar
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    Re: Replacing Amplifier Tubes With Wet Hands

    I'd go with JJ tubes as replacements. Slovak, not Russian. They make EL34s and 12AX7s. I used JJs in both my old Hot Rod Deluxe and DRRI amps and they worked as well or better than Groove Tubes or Sovteks.

    Generally speaking, yes, you can just do a straight swap. No special tools needed.

    However, I know with the power tubes (EL34 in your case), you'd want a matched pair and there's sometimes some biasing adjustments needed (not sure how that's implemented on a Crate). Preamp tubes like the 12AX7 don't need to be fine tuned like that.

    If you're not sure, take it to a tech.

    If you do it yourself, make sure your hands are DRY, for the love of Pete! ;-)

  3. #3
    Forum Member Don's Avatar
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    Re: Replacing Amplifier Tubes With Wet Hands

    The bias should be checked when replacing power tubes.

  4. #4
    Forum Member DanTheBluesMan's Avatar
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    Re: Replacing Amplifier Tubes With Wet Hands

    unless the preamp tubes are microphonic, you probably won't need to replace them. They don't wear nearly as fast as power tubes. There are many 50 year old amps with their original preamp tubes that sound fine.

    then again, the tubes made 50 plus years ago were more solidly built than today's tubes.
    "Live and learn and flip the burns"

  5. #5
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    Re: Replacing Amplifier Tubes With Wet Hands

    Thanks everyone. My amp used to play beautifully at really low volume, but it has started hissing static. The static is not the end of the world, but it does get on my nerves. Unfortunately, I'm unemployed at the moment so I'm thinking about just sticking the old tubes back in until there's some economic clarity again. This was after I checked on replacement tube prices . They are a bit of a luxury item so I've decided to hold off on 'em. The advice about keeping the pre-amp tubes was good. I wish I knew how to find out which tubes were actually causing the static and then just cherry pick a replacement for it. Anyway, taking it to a repair shop sounds expensive. So I'm going to stay in a holding pattern for now. I need to look into biasing too. Thanks for the tips.

    By the way, I decided not to replace the tubes with disembodied hands. Too much trouble.
    Last edited by Toast; 10-29-2020 at 05:25 PM.

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