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Tube swap on Vox AC 15 C1

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  • Tube swap on Vox AC 15 C1

    Hello everyone,
    I have a Vox AC 15 C1 and I'm pleased with the amp. I'be been reading, however, that the stock tubes suck and that they must be changed. So here are my 2 questions:
    1- does the tube swap make such a big difference?
    2- if I do change the tubes, should I just replace the 2 EL 84s or should I get all 5 tubes changed?

  • #2
    They are probably Shuguangs. I think Shuguangs are fine. I like them better than pretty much anything Russian or JJ. And they mix well with Russians and JJ's as well.

    You can replace all the tubes for maximum effect. If you swap out only the power tubes, I would suggest swapping out the phase inverter as well.

    I recommend old NOS Russian 6P14P-EV's for the power section and a Sovtek LPS for the phase inverter for maximum headroom and width.

    The change won't be drastic, though. Tubes make a small difference.


    • #3
      A tube swap makes some difference, but I think it's often oversold. It's not going to turn a Marshall into a Fender or vice versa. The basic voice of the amp is going to be there no matter what tubes you're running but you might get a little more clarity, less noise, or more bass/mids by swapping tubes. In my experience, preamp tubes will last at least twice as long as power tubes.

      If you're happy with your amp's sound, there really isn't any reason to change the tubes. For home use where you're not bumping an amp around much, tubes can last an awful long time. If you're gigging every week night at high volumes you probably will need to replace power tubes every couple years.
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      • #4
        I kind of suspected there was too much hype on tube swapping. I'm pleased with my amp and I'll probably leave it as it is for now. Thanks for the precious advice!


        • #5
          I will say that it CAN make for a difference in sound, but whether it is a better difference, is the question? The biggest trap of them all is the recent NOS and vintage tube market... Total hogwash. Here is the thing about NOS and vintage tubes. If they lasted 50-60 years to even be able to make it to a respectable retailer, they were a good tube, to begin with. BUTTTT, and it's a big one, there is no guarantee it will sound good. NOS tubes do not inherently sound better than modern production tubes. The ones that sound good, do sound good, just as modern tubes do. Secondly, there is a limited supply and NO TWO NOS TUBES WILL EVER SOUND ALIKE. The supply of NOS tubes is limited and dwindling, furthermore, the pool of tubes left are from several different years of manufacture and perhaps even different stages of development. So the set you find today that sounds amazing will have NO other set of NOS replacements that will sound the same.

          Modern production tubes are no different. They all sound minutely different, and on occasion, you get an oddball one that sounds amazing, just as you come across duds. The big difference is that modern tubes are only made in three factories, so no matter which brand you get, it is made in one of three factories. This means that there is a much greater level of consistency. China-made Shuguang tubes are 100% fine, I just don't like supporting China. JJ's are made by JJ and JJ supplies just about every name you know with tubes to rebrand. Reflektor is the only other factory and just like JJ, they sell mostly tubes that are rebranded. So a modern-day EH tube is made by one of those three companies. If you get a set of Ruby Tubes, it is a tube made in one of those three factories. Groove Tubes, one of those three companies provided that tube for rebranding. Modern tubes are every bit as good as NOS tubes in that they work and perform as intended. NOS tubes do sound different because they are 50-60 years old and made in a different era. NOS tubes sounding better is 100% up to the ear that is listening.


          • #6
            V1 in any tube amp makes the most notable change IME. Power tubes make a change but to a lesser degree than V1, IME. If V1 doesn't move you in the right direction, rolling all the tubes might not be worth it.

            Ewizard has valid points. What I've observed is that certain current rebrands go through the steps to weed out the bad tubes by testing and only selling the ones within a tight tolerance. For example, I have a TAD Shugang 12AX7A-C that is every bit as good as my holy-grail International-branded Mullard 10M I bought in 1978. Mesa, Groove Tube and Ruby are a few others that only seem to distribute/sell the good ones. Meanwhile, a plain white-box Shugang straight from the factory could end up just as harsh sounding as a straight factory Sovtek 12AX7WC.


            • #7
              v1 in most amps yes, since its the first, and usually second, gain stages. in a bf/sf fender most people use the vibrato channel so v2, which is the first and second stages for that channel, would be the one to experiment with


              • #8
                yes, the v1 preamp tube change will change it. i used to have the AC15 C1 and changed it to a Tung sol or Ruby, i forget exactly, but yes it went from harsh to smooth and deep.
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                • #9
                  It may be worth trying a 12AU7 in the PI if you want to increase headroom. I've had success doing that in EL84 amps, but I still don't like them much. I think the biggest difference in tone short of replacing the amp itself is going to come from a speaker swap. It took me a few hundred bucks to learn that in the end, I'm a Greenback guy.