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Complete Tube Replacement for Vox AC15C1

Discussion in 'Amp Central Station' started by MaggieMay, Jun 1, 2020.

  1. MaggieMay

    MaggieMay NEW MEMBER!

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    I'm looking to do a total tube replacement for my Vox AC15C1 amp. I got the amp about a year and a half ago brand new and loved the amp when I first got it. However, it's been giving me staticky/popping sounds intermittently and the overall tone has seemed to decrease. The volume will also give out mid playing. I bought the amp from Sweetwater and contacted them regarding this a few months ago since it's still under warranty. They sent me one pre amp tube to replace. Once I did, I could immediately hear and improvement in the sound. Since changing just one made that good of a difference, I now want to replace the entire set.

    I really like the classic Vox sound. The tone I'm looking for is a clean, full tone, that has a bit of grit when pushed. I don't want anything too tinny.

    I've narrowed down the preamp tubes to a Genalex Gold Lion 12AX7 Gold Pin Preamp Tube or maybe the Mesa-Boogie 12AX7 Preamp Tubes. (Power tubes would be either Genalex or Mesa-Boggie EL-84's).

    What do you recommend? Any help would be appreciated, I'm kind of at a loss as to what to choose. Thanks in advance!
     
  2. richiek65

    richiek65 Friend of Leo's

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    Welcome!

    You'll get a million varying responses!
    Mullard always get lots of praise. I have the same amp (except the C2 version) after a year or so it started sounding hot and spiky so I replaced the V1 with a Mullard, but I really can't hear the difference.

    Singer in my band just bought the same amp as yours and it sounded very warm and lush when I heard it last week so I think mine may be up for some more new valves too.

    I'll be watching the responses here with interest!
     
  3. Fretting out

    Fretting out Poster Extraordinaire

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    As mentioned above there’s gonna be many different answers
    I changed all of mine with jj’s And it sounded fine afterwards

    I’m a non believer in having to get the most expensive or nos tubes

    And all modern tubes are most likely to be made in only a handful of places
     
  4. loco gringo

    loco gringo Tele-Holic Gold Supporter

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  5. VintageSG

    VintageSG Friend of Leo's Ad Free Member

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    For the power valves, hunt down a pair of NOS Soviet 6p14p-EV or -K. They sound great, and can withstand levels of abuse that only a combo can dish out with ease. Beware of expensive imitations. Other than that, Sovtek or JJ seem to work and last quite well.

    Pre-amp valves. There aren't many factories left now. The Genalex/Mullard/Tung-Sol reissues are brand exercises. New Sensor ( Russian ), Shuguang ( Chinese ) and JJ ( Czech ) are about the only ones left. Whatever you buy, it'll be made by one of them. For new production, Sovtek/EHX will get the job done.

    https://www.thetubestore.com/product/1821

    Hmm, rebranding the 6p14p-EV and raising the price by $25, but it does sort of validate the valve.
     
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  6. stnmtthw

    stnmtthw Friend of Leo's

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    I changed all of mine to JJs as well. No issues, and now my AC15C1 is my favorite amp.

    I do encourage everyone with one of these amps to replace the tubes with whatever brand you like. The stock tubes are garbage in an otherwise wonderful amp.
     
  7. Matthias

    Matthias Friend of Leo's Gold Supporter

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    I put JJs in my Blues Junior. They sound good.

    I had the same or similar volume issue on my AC4TV. Either it's the tubes they're using or the pots. I never worked out which. I gave it to a family member with the caveat they might need to fix one or the other!
     
  8. Paul G.

    Paul G. Friend of Leo's

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    I like Sovtek 12Ax7s, quiet and reliable. I like JJ EL84, but sometimes they're microphonic. I've had good luck with Tung Sol, Electro Harmonix, Sovtek and Mullard new production. Your AC15 runs your EL84s hard and I would think of them as a replacement item, like brake pads on your car, and not get real spendy with them. If you don't mind spending more, I find the Groove Tubes are pretty rugged.
     
  9. stnmtthw

    stnmtthw Friend of Leo's

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    I changed all of mine to JJs as well. No issues, and now my AC15C1 is my favorite amp.

    I do encourage everyone with one of these amps to replace the tubes with whatever brand you like. The stock tubes are garbage in an otherwise wonderful amp.
     
  10. stnmtthw

    stnmtthw Friend of Leo's

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    It's the tubes. My daughter has an AC4 with the same issue that my AC15 was experiencing.

    I usually save parts that I pull out of whatever I'm working on (cars, guitars, amps, whatever) but in the case of those no name stock tubes, I threw them in the trash right away.
     
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  11. SPUDCASTER

    SPUDCASTER Poster Extraordinaire Gold Supporter

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    Running Mullards in the preamp section and JJ's in the power section. The Mullards now because I ran into some NOS 12AX7's for a good price.

    Eurotubes for the JJ's. They have full sets of JJ's for the AC15 too. Several choices. Great guys to deal with. Reasonable prices.

    The JJ's always seemed fine. No issues.
     
  12. marshman

    marshman Poster Extraordinaire Silver Supporter

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    Just about every EL84 amp runs the power tubes hard, and Vox is certainly known for that. You can expect the power tubes to last a year or so in heavy use conditions. As noted, don't get too worked up abut fancy modern brands, but by the same token, pairs of new EL84s aren't very expensive, so maybe you can try a few out.

    Preamp tubes are generally under a lot less stress, and good ones should last thousands of hours. But there's a lot more potential for flavor variety, as well. I would take some time and a few bucks to find a really nice sounding 12AX7 for V1, as it will literally 'set the tone' for the rest of the signal path.
     
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  13. Wally

    Wally Telefied Ad Free Member

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    Welcome, Maggie May. I have to ask if the problems with static noise and volume drop out went away with the replacement of one tube? If so, you may have simply have had a dirty tube socket. The intermittent nature of the problems would point to this rather than a bad tube, ime.
    Also, if you replaced the V1 tube, that tube change will have more of a difference in sound than any other position. If one is curious about the difference of that tube, one could trade tubes in V1 and V2 to see what difference is made. fwiw, the Golden Lion is a Russian made tube. A Boogie can be a Russian tube...made in the same factory.
    what tube was sent to you as a replacement? If it is a Mesa branded tube, what codes are on the tube? A Mesa 12AX7 might also be a JJ or a Chinese tube. Fwiw, Ruby Tubes are rebranded tubes, as well. It behoov3s a person to know what one is buying beyond the silk screened logo.
     
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  14. AAT65

    AAT65 Poster Extraordinaire

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    I ran my AC15C1 on the stock tubes for a year, and it sounded pretty good just with those. After a year though I noticed it had lost some sparkle, and was becoming more inconsistent - volume would seem to drop after an hour or so of playing for instance (or maybe it just lost more high-end and couldn’t be heard so well in the rehearsals).
    I replaced the tubes (valves) with a set of JJs from an online supplier in the UK (ampvalves.co.uk) — ECC83s, one balanced to use in the phase inverter, and matched EL84s. No complaints about those at all, the amp roared back to life.
     
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  15. Wally

    Wally Telefied Ad Free Member

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    And....Depending on hours of use, a year and a half might be all one can get out of modern EL84s before that start to decline. I too have had no problems with JJ EL84s and 12AX7s.
     
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  16. acVox

    acVox TDPRI Member

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    I'm referring exclusively to power amp valves in classic Vox amp's, though the principle applies to all..

    Its helpful to realise that current production Vox amp's are carefully voiced during their development phase using all the currently available EL 84 valves on the market to establish which of these gives the best tone at the lowest cost. Hardly controversial, as this is the practice of all manufacturers. It includes the most expensive and exclusive amp's you can think of. It's why current amp's sound so good with current production valves.

    This is one of the reasons that a pair of late 1950's Mullard EL84,s fitted in your modern Vox, having just cost you a weeks wages leave you wondering where all that money went, for so little gain, after being promised so much.. Its not your fault. These valves are lauded for their legendary tone but only in the amp's of the same period.

    The flip side of this coin comes when I attempted, in an ill informed thrift drive, to fit a quad of new production EL84 valves in my vintage AC30 only for an instant redplate, glass melting display saved only by fuses going off like popcorn.. ..

    Its irrelevant who the manufacturer was, but only a set of 1960's Philips EL84,s returned peace,both harmonic and melodic to my long suffering AC30..
    I need vintage power amp valves for a vintage amp for the same reason you need current production valves for a current production amp. They were designed to work together.
     
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  17. TokyoPortrait

    TokyoPortrait Friend of Leo's

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    Hi.

    Here's another place you can look. Watford Valves in the UK. You can get individual valves from a large range of brands, but they also sell various kits and the like.

    I've used them once. I read some mixed reviews after I ordered, but what I got works just fine. Shipped to Japan pretty quickly too. They market cryogenically treated valves as well, which is a contentious and debated topic, and this does make me wonder a little about their other marketing claims. Anyway, I got the AC4HW1 version of the set in the link below. I don't really know if they capture the glory of retro toanz, but they definitely sound different, and to my ears, better than the stock ones they replaced.

    https://watfordvalves.com/product_detail.asp?id=3805

    Anyway, just another option to consider.

    Pax/
    Dean
     
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  18. Collin D Plonker

    Collin D Plonker Tele-Afflicted

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    Genalex Gold Lion are super expensive and have the highest gain. Millard's are much cheaper with almost as much gain.
     
    Last edited: Jun 2, 2020
  19. 3-Chord-Genius

    3-Chord-Genius Poster Extraordinaire

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    JJ's in the power section, Tung Sol in the preamp. Can't go wrong.
     
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  20. Collin D Plonker

    Collin D Plonker Tele-Afflicted

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    I put JJs in my AC10 but didn't like the preamp tubes-- too much headroom. So I left JJs for power tubes and changed preamp to Millard. Sounds great now.
     
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