Best for mods/gut 'n build: AC4TV or Valve Jr?

Discussion in 'Amp Central Station' started by Whatizitman, Oct 9, 2019.

  1. Whatizitman

    Whatizitman Friend of Leo's

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    I have a tiny bit of birthday cash, and can prolly pick up one of either. Vox combo, or VJ head. I'm pretty close to deciding whether to pull the trigger on either, but there's no hurry.

    I'd prefer a gut and handwire project, keeping transformers and tubes and such. Rather stay away from a PCB, but no biggie either way. I suppose they aren't that different in design (12ax7, EL84, SS rec). I have a cab with 12inch greenie, and I think both amps OTs have 16ohm capability. I'd prefer just a head, but the size of the vox isn't much bigger than a small head.

    I totally missed the VJr mod craze from back when, but I'm aware enough of the typical mods and builds (mini plexi, baby will, etc...). Less aware of AC4TV ideas.

    Thoughts?
     
  2. gusfinley

    gusfinley Tele-Holic

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    The AC4TV doesn't have a lot of panel space to work with.

    I had thoughts of converting one to a Top Boost based circuit when they first came out, but there just wasn't enought space on the panel to do anything interesting with it. In the end I picked up a AC4C1-BL and put a hadwired Top-boost circuit in it.

    The Valve Juniors had more panel space are probably better suited to mods.
     
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  3. Speedy454

    Speedy454 Tele-Holic

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    I still have one VJ head, and at one time had several. I spent a ton of time messing with them. In my experience, nothing really changed the tone until I did 2 things...
    Replaced the output transformer and added a Fender style bass + treble tone stack. The stock output transformer limited the frequency response and tone of the amp to such an extent that nothing I did really changed the tone to any significant extent. Mine were all V3 that had the proper impedance transformer from the factory.
    The cost of a good output transformer will be about 50% of the value of the amp, but it is the first thing you want to do on a VJ.

    If you want to hand wire something, I wouldn't start with a working VJ. By the time you are finished, all that will be left is the chassis and maybe the power transformer. You will probably replace everything else in your journey towards a hand wired build. Even the PCB mounted tube sockets do not lend themselves readily to being chassis mounted for a hand wired build.

    I still use that VJ with the good transformer, good tubes and Princeton style tone stack. Swap a few components and you could have a Vox style tone stack.

    Your tiny bit of cash could easily drop into this bottomless pit if you are not careful.

    But on a positive note, you could end up with a nice class A 5 watt that will easily drive a 2X12 cabinet loud enough to get on your neighbors bad side. My 2X12 cabinet is loaded with Texas Heats. Very efficient. Very loud. Even at 5 watts.
     
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  4. Whatizitman

    Whatizitman Friend of Leo's

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    Nice points. Thanks!

    I'm itching for a handwired project, and this at least is low entry cost-wise. Transformers.... That's the main issue. I know I can use the stock OT. It just wouldn't be much different sound wise. But my intentions are more about the learning aspect of building at this point.

    I'd really like to make something with a BF tonestack. I just would rather not do anything with a PCB. But I could also handle just doing some basic modding while I'm saving up for good transformers or a kit, etc...

    The VJr appeals to me for a build since it's already a head. A typical handbuilt project will need a cab build or buy, and that ain't cheap for a good one. My tolex skills are....well... poor. I built the 1x12 I will use the amp with.

    Princeton-ish tone into my 1x12 would just be icing on the cake.
     
  5. Whatizitman

    Whatizitman Friend of Leo's

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    A guy offered me a really good trade for his BJ tweed, so I guess no big projects for a while. I don’t think it’s been modded, though.....
     
  6. LightningPhil

    LightningPhil TDPRI Member

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    This is a good idea. Rip apart an amp and hand wire the carcass. I have a bassbreaker I despise. The plan forms...
     
  7. gusfinley

    gusfinley Tele-Holic

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    I've done it to two Pathfinder 15 amps and one AC4C1-BL!
     
  8. Fourstringclover

    Fourstringclover TDPRI Member

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    It may be too much work....
    but you could just sell the BJ amp chassis to cover some of the cost of transformers, put in a new chassis and wire it up into whatever. Most all amps with PCB's have board mounted tube sockets, so those would have to go anyways I imagine. At least youd have plenty of room to work in then.

    This ptp rewiring stuff intrigues me though. I have nice copper chassis out of an old wire recorder I would like to do this with. It's got 5 octal sockets, preamp is on a shock mount, plus a majic eye tube witch may have to go unfortunately.

    @gusfinley & @LightningPhil/

    Did you two build the amps like they were
    before? An use the same transformers?

    Just curious

    I have a few old handwired amps, and there is somthing special sounding about p2p wiring I belive. Plus being much easier to work on
     
  9. LightningPhil

    LightningPhil TDPRI Member

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    Not done yet, but will be keeping original transformers. Certainly won’t keep the tone the same though.
     
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  10. gusfinley

    gusfinley Tele-Holic

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    On the Pathfinders, I sold the chassis to a forum member and installed a new chassis - it was solid state so there was no reusing the old transformers. Though I did reuse vintage transformers on the new chassis.

    On the AC4C1-BL I reused the transformers. This amp was so small that this barely worked and I had to built a sub-chassis to mount the tubes to. I would love to try this again in the AC4C1-12 and see if I could find a better place to mount the transformers with 2" of extra width in the cabinet.


    It looked like this before:

    [​IMG]
     
    Last edited: Oct 13, 2019
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  11. VintageSG

    VintageSG Friend of Leo's Ad Free Member

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    There's an old joke about a tourist asking a yokel directions to a town, and the reply being 'Well, if I wanted to get there, I wouldn't start from here'

    The AC4TV has good transformers, but it is an awkward shape inside. The cabinet is cute enough, but limits the speaker. I found running it as a head improved the sound the most, closely followed by opening the rear to form a 'mostly open' cab, but this is hampered by the awkward shape of the chassis.

    The Valve Junior head would give you a far more flexible expanse of real estate to play with.
     
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  12. Whatizitman

    Whatizitman Friend of Leo's

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    Well, the vox got sold, I think. But it seems from the replies that a valve jr is better for gut-n-build. I have a lead on a couple of vintage amps for good prices, so plans may change. But the VJ is still on the table if it doesn’t plan out.

    It’s been a good amp-related vacation so far. Hoping my luck continues today, cuz it’s back to work grind tomorrow. Yuck.
     
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