Triode mod for my JCM 800

Discussion in 'The Workbench' started by Dwayne Eash, May 21, 2020.

  1. ampmadscientist

    ampmadscientist Well-Known Member

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    I figure a low power amp cranked up all the way-
    is better that a high power amp dumbed down with a master volume or attenuator.
    It sounds better and that's been my philosophy of lower wattage amps.

    So I lower the wattage, and tweak to get the best sound in triode.
    I play it wide open.

    True pentode sounds different. But to my ears, triode sounds more articulate.
    Triode is more "hi fi" sounding to my ears.
     
  2. Dwayne Eash

    Dwayne Eash Active Member

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    I wish I did. hehe But I have other passions besides music, and they lack funding too.

    You suggest spare mechanical tuners, and amps. That's nice, but elaborate.

    Tube amps do not usually break down but once every decade or two. And since I'm not a working musician, why bother with that great added expense, when you can fix things yourself when they eventually do break down? Plus, in the mean time, that money is needed for food and medicine and shelter, so sorry, needs win out over wants.

    Because money is on a tight budget over here, be happy you apparently have enough money to have what you want, but I struggle to have what I need. But also, just because you are probably doing better financially than I am, doesn't mean we are not both badly oppressed, financially and from pollution.

    ~~~

    You have my dream rig, a fire breathing JCM 800 50 watt, and a modern take on the old plexi, a 20 watt studio version of a Plexi, which I believe happens to includes an effects loop. It must be very nice, to have those two great amps on tap.

    Maybe one day, but frankly, I can't imagine how long it would take for me to afford having two great tube amps, instead of just one. But they rent to use our own national money supply for perpetual debt enslavement, which is a tax on us all.

    That's kinda like one person having two cars, just in case one car breaks down. LOL Most don't do that for the economics of it all. Maybe after one of my invention designs becomes financially successful, then I could finally have all the sonic goodies.

    ~~~

    I'm not holding my breath, but I do have some good ideas that deserve to be researched and tested.

    I can't afford spare amps and tuners, far too much of an unnecessary risk to justify. So I fix the one I can mostly afford to own.
     
    Last edited: May 22, 2020
  3. Dwayne Eash

    Dwayne Eash Active Member

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    I do too. I like the idea of a smaller tube amp cranked up so you don't need lots of power attenuation in the first place. However, I have yet to find a great sounding lower powered amp that sounds like a JCM 800 for example, but at 3 watts instead of 50 or a 100.

    So the tone and sonic character, means more to me than low wattage tube amps do, but I really like the idea of a low wattage JCM 800. But unfortunately, due to nonexistence, although I love the idea of low wattage tube amps, I'm stricken with the same problem I started out with.

    My best option, is to attenuate this amp, the best way possible. I'm only going from MV 5 to MV 3 and I'm good. Not an impossible task, even on a budget.
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    There is the new 20W version of JCM 800.
     
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  5. Dwayne Eash

    Dwayne Eash Active Member

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    Right on. But from what I can tell, it's not much quieter than my rig. And I paid less for my rig than that mini rig, and my rig is the original icon, and it sounds like a dream come true, when it's all dialed in. But the power tubes are probably not biased right. IDK.

    I am glad they have a lower powered version, and I hear they did a good job with it sonically too. But it's still too loud for home playing, at the 5 watt low power setting, to go for cranked power tube saturation. One guy said it was waaay too loud to try that at home, so don't be too certain about that amp's low power mode, it's still very loud.
     
    Last edited: May 22, 2020
  6. ampmadscientist

    ampmadscientist Well-Known Member

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    Yes 5 watts is pretty loud. 18 watts blows my ears out.
     
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  7. _Steve

    _Steve New Member

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    I bought the plexi version of that amp (the SV20H) and it's astonishing just how loud the 5W mode is. But it does work better through an attenuator than its big brother does because you don't have to attenuate nearly as much. In theory you could try to mod your power amp to the SV20/SC20 spec. This would preserve something like the original tone far better than a blunt VVR and also drop your output power by way more. It would be a lot more invasive however and im not sure how it would work with the original tranny. Also note that the SV20/SC20 are cathode biased. You'd need to really know what you are doing.

    You can also reduce the volume by using 10" speakers rather than 12s, but i know you're trying to not spend money. At bedroom (attenuated) levels im actually preferring the sound of a jerry-rigged 2x10 over my 2x12.
     
    Last edited: May 22, 2020
  8. stickyfinger

    stickyfinger Well-Known Member

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    Triode sounds like a blanket over the speaker cab. Maybe it sounds ok with a Tele or Strat but over all I find them to have no use and no extra value to a amp purchase. A quality attenuator is what I use with every amp I own. JVM, 2204, JMP you name it. I use a Rockcrusher but a Power Station, Alex ect will work just as well. Its a good investment and retains the tone the best.
     
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  9. thetragichero

    thetragichero Well-Known Member

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    that is a rather broad brush you're painting with there
     
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  10. Flat5th

    Flat5th Member

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    I never really heard a pentode/triode switch that didn't kill tone along with the volume. Some of these guys are right. Forget that mod and figure out another way to cut your volume. Everyone suggests power attunuators. That's probably a much better idea. I have a couple of boutiques with pent./tri. switches and I never use them because they stifle tone when they cut the volume.
    Go buy a hot plate or whatever attenuator guys on the forum would suggest for a Marshall.
     
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  11. pedecamp

    pedecamp Well-Known Member

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    Do you have fluxtone speakers?
     
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  12. pedecamp

    pedecamp Well-Known Member

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    Take a look at the Mojotone Studio One amp and tell me what you think. Its a 2 channel 1 watt JCM800 with some gain mods. This might be a good project for you.

    https://www.mojotone.com/kits/MojotoneAmpKits_x/Mojotone-Studio-1-Kit
     
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  13. Travis398

    Travis398 Well-Known Member

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  14. Dwayne Eash

    Dwayne Eash Active Member

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    So much sonic goodness, but it's expensive! After seeing this technology, the first video of it, I was hooked instantly. You are addressing ampmadscientist. I bet he'd like several, interested to hear his answer.

    I do not have a fluxtone speaker, no, I had no idea they existed until days ago. I would love to have one.

    This is the sonic goodness we have all been waiting for!!! I love it. I gotta have it. Lets hope I wont die before I can afford to buy one! Hurry up and wait, the story of my life.

    I might could have the key to the universe, but, since I can't build and test it, who cares, it's just an idea. I have rarely seen such excellence, and the results speaks for themselves. Very impressive, and in theory, should be the best attenuation available. I figure, after expensive startup manufacturing costs are absorbed, the technology is not that exotic and expensive, so I imagine the price should become more and more affordable.

    Maybe everyone should support other makers to emerge, making the same quality, but at a lower price. Best in sound attenuation, can hold an artificially high price, because the demand is so high by the best in the field. And the best in the field, are making enough money that the decision is a no brainier.

    If I was touring, I absolutely would have these Fluxtones in my rig, no doubt about it.

    Great name, great product, best tone preservation, simply amazing. Brad Paisley's demo locked it in for me, his is the best demo I've seen, but I would like to see a hard rock to early metal guy, do the same thing with an amp like mine, JCM 800.

    It was stunning when Brad went to half and then to bedroom level, and the tone remained the same. As he says, it's the same amp sound, but it's like your just walking further and further away from the amp. It simply gets quieter and quieter.

    After watching those videos, I feel like I've just seen the hand of god or something. hehe This is a great thing for the tube amp purist.
     
    Last edited: May 25, 2020 at 11:57 AM
  15. Dwayne Eash

    Dwayne Eash Active Member

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    Very nice. I love the idea of lower wattage tube amps so its naturally easier to push them into power tube overdrive, without ear splitting volume. It is pretty close, but I would prefer the Marshall's 20 watt versions, with 5 watt low power options. Seems like from what I have heard, they are better sounding amps, more resembling the original classic amps.

    2 channel is a nice concept. Looks like it has lots of potential, and I might like it better than my first impression, if viewed in person, or had a different demonstration. IDK. But I see this as being Marshall like, but not a mini clone of a JMP Master SL or a JCM 800.

    I am learning I was correct to buy a great classic tube amp, even if it was way too loud to sound good at home without some kind of sound attenuation. I am picky about tone and sonic character.

    So my challenge remains the same, to quite down my fire breathing beast of a rig, in the best way possible, for the least money. Call me a bit of a tone hound :hippie: or a classic amp purist :agreed: if you want. IDK, I just go by what pleases my ears, and my inner guitarist. hehe
    :slash:
     
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  16. ampmadscientist

    ampmadscientist Well-Known Member

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    OK I will post schematics to change it to triode.
    Or, it can have a triode pentode switch.

    Sound of triode
    I hear some people say they don't like triode.
    But I tweak the amp to sound good with triode.
    I think a lot of people speak in generalizations and assumptions without really understanding.
     
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  17. Dwayne Eash

    Dwayne Eash Active Member

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    That would be great. In general, I am picky and prefer the better quality sound, and part of that is a lower powered amp, easier to send into power tube saturation and overdrive.

    I am a rookie at E34 overdrive, but having recently tasted it, I need it! Sooo goood!!! It starts happening strongest at 6 on the MV. The amp really opens up and sounds radical with singing overtones. I have doubts about the pentode triode power thing, but it's possible that's what the little amps from Marshall does to get low power, although you don't tend to hear guitarists talk about them sounding thin or not Marshall enough on low power mode.

    So if they are using petode triode switch to achieve lower power mode, then maybe there are ways of making the slightly lacking triode sound, better somehow. IDK.
     
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