Transformer recommendations for my 20-watt 6V6 JTM45 build

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by DCH, Jan 12, 2018 at 6:01 PM.


  1. DCH

    DCH Supporting Member

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    Hi all,
    I completed a significantly modded JTM45 head a while back, and I like it a lot, but I'm finding it's somewhat redundant among my amps, which include a couple of other 50-watt M-styles that I tend to play more.

    I'm thinking I'll mod it to a 20-watt amp for kicks.

    I used a low-voltage PT in the first place, so it gets around 400 VDC on the plates of the output tubes with a GZ34, so I've tried it with 6V6s already, biased up correctly, and do like that sound - but I'm figuring it would be even better driving the right 6V6-intended OT, and I'd love to save several pounds too by using the smaller V-spec'd transformers and maybe put the chassis in a 1x12 combo.

    Any thoughts on transformers to go for?

    The OT is the real puzzle. Most are replicas of or replacements for Fender Deluxes (either tweed or BF DR), but I'd love to find one that was made with a more Marshally tone in mind.

    For the PT, I'd like to shoot for anywhere between 375 to 400 on the plates of the 6V6s with a GZ34, but I can always use a 5R4 to soften one delivering higher voltages, or an SS plug to firm up a PT delivering lower voltages.

    I'm not really enthusiastic to spend Mercury Mags type prices on them, either, and in truth I don't think you need to do so to get a good sounding transformer. Maybe more like Heyboer or Classic Tone?

    Thanks in advance for any suggestions.
     
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  2. sickboy79

    sickboy79 Member

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    I'm a big fan of Mercury Magnetics. I have them in a few amps (some as OEM equipment). Classic Tone/Magnetic Components is hard to beat as well. I'd also recommend checking out Heybour and Pacific.
     
  3. paulg

    paulg Supporting Member

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    I’ve had the urge to replace the tweed Deluxe OT in my 20 wt Plexi clone. I’m looking to the Allen heavy duty Deluxe trans.
     
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  4. Avatar Tech

    Avatar Tech Member

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    Either Classic Tone or Heyboer would be my preference to Mercury.
     
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  5. pdf64

    pdf64 Member

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    Your existing OT is likely to be just fine for use with 6V6.
    With KT66 or 6L6 types and its saggy HT idling at 400V, I doubt the amp would put out even 30 watts anyway.

    But the RS Deluxe OT catalogue listing suggests the 6k6 primary arrangement for EL34 and KT66, and the 8k or 9k primary arrangement for 6L6, 6V6 and EL84.
     
    Last edited: Jan 13, 2018 at 5:26 AM
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  6. DCH

    DCH Supporting Member

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    Thanks, all. The suggestions are much appreciated.

    I'm still kinda' wondering, however, if anyone has direct experience with a specific OT and PT set that they really liked in a 20-watt Plexi or JTM type build with 6V6s.

    I considered the Classic Tone that TimmyP links to, but I believe that's mainly a replacement for an 18-watter type with EL84s? It would work with 6V6s, but again, hoping someone will say, "Man, I loved xxxx with mine..."

    pdf64: thanks. Yeah, as in my OP I have used 6V6s in it just as it is, but I'm thinking I'd rather have a dedicated 6V6 OT that would saturate correctly with the load from the less-powerful tubes, and by replacing both PT and OT I can also save several pounds in weight, which will mean a lot to me if I put this into a combo.
     
  7. 00JETT

    00JETT Member

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    Grab a Marshall style 18watt set from classic tone. The PT and OT will work great with 6v6s. I’ve used them for this before. Great results
     
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  8. DCH

    DCH Supporting Member

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    Thanks 00JETT, much appreciated
     
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  9. Avatar Tech

    Avatar Tech Member

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    Got links to any more of that catalogue?
     
  10. pdf64

    pdf64 Member

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    Sorry, no, google found that page for me on the Marstran forum.
    I saved it just in case that site, like vintageamps.com, disappears.
     
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  11. wyatt

    wyatt Member

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    A 8K primary Tweed Deluxe OT will be great. Not that I belief that OTs are Marshall- or Fender-voiced in the least, but a Tweed or Brown Deluxe is "Marshall tone" in spades.

    But I agree a good Heyboer or similar 18-watter OT would be just as ideal.
     
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  12. DCH

    DCH Supporting Member

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