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  1. JohnH

    Vintage Modern LDM VS Studio Vintage

    Thanks for those vids! Ive been hanging out for such a comparison for several years. Out of those, both sound great, but I don't think I need both and Im very happy to run with my VM
  2. JohnH

    Simple Attenuators - Design And Testing

    Unwinding an inductor coil: 1mH to 0.9mH Nothing better to do on a Saturday morning, so I decided to unwind an air-cored inductor. The 8 Ohm version of the M2 attenuator calls for a 0.9mH inductor. But many standard ranges only offer 0.82mH or 1.0mH. To be honest, its not really critical, a...
  3. JohnH

    Thoughts on the Marshall JCM2000 DSL401?

    I still have one and I like it very much. But they are notorious for heat-related issues that build up over time, and they are hard to work on. Mines from 2005 and needed a serious do-over a few years ago, and now it's got some new issues. A given 401 could be more than 20 years old. I don't...
  4. JohnH

    Simple Attenuators - Design And Testing

    I looked up that SVT! it's a BEAST! If you want to attenuate because of better tone up high, all the design theory should work but built with Stage 1 like an industrial substation. Speakon connectors instead of jacks, thick gauge for the coil and uprated resistors, probably divided in multiples...
  5. JohnH

    Simple Attenuators - Design And Testing

    hi @KIL0 and welcome to our thread. For the HRD, if you need a 16 Ohm load, you can build a 16 Ohm M2 and use it with either a 16 or 8 cab, or in principle, an 8 Ohm Torpedo. But when I looked up HRD's specs, It looked to have an 8 Ohm output rather than 16Ohm?, also ok with two cabs for a 4...
  6. JohnH

    Completed JohnH Attenuators?

    Hi Gene, these new units look really good - great work!. Im proud of them too! Getting to a place where we have such a well executed and proven design continues to be a great ride. I really enjoy the collaboration and none of us would be here on our own! Onward!
  7. JohnH

    Simple Attenuators - Design And Testing

    hi @PelliX , I can pick up the question about the Webers. With a good circuit model of a full speaker, we can model most passive attenuators in Spice. Here's my Weber Mini-mass analysis: On the schematic at the bottom, a full speaker is modelled, and at the top the mini-mass driving a...
  8. JohnH

    Simple Attenuators - Design And Testing

    ok sounds fine. No issue with steel for the screws for other than the coil and you have that covered. Can you check resistance of the fan as measured by a meter?
  9. JohnH

    Simple Attenuators - Design And Testing

    Looks like a great bit of product design and production engineering! What's your coil-mounting arrangement? Any space to offset it a few mm up off the base? Also, since you've got a credible looking fan, shall we try to take the next step with developing an amp-driven self-powered...
  10. JohnH

    Origin 50 vs 2266 Vintage Modern

    It's hard to find some comparisons like this. Origin, VM and also SV20 although different are to some extent all designed to 'scratch the same itch' for 'vintage-y tone. Most people wouldn't have access to more than one in that ballpark. I do love my VM combo though. I can recommend it as a...
  11. JohnH

    Simple Attenuators - Design And Testing

    Hi @Gene Ballzz , that looks really great! (I think I'd keep wanting to turn it over to admire the grills!) And I see it's getting the neat 8-16 tweak on the output with the 39ohm. I'll get a schematic diagram to show that.
  12. JohnH

    Simple Attenuators - Design And Testing

    Our designs use switched stages, for a few reasons: Passive attenuator designs based on pots or Lpads may or may not sound good enough or acceptable, but as you note, there typically is indeed some tonal difference across the dial. In the basic examples it sucks! But M2 and its related...
  13. JohnH

    Simple Attenuators - Design And Testing

    LOL, yeah maybe but...really just NO!
  14. JohnH

    Simple Attenuators - Design And Testing

    Hj @Gene Ballzz Here's the double version, described in post #1731 on page 87 There's a couple of ways to do this, depending whether each half is an 8 or a 16 ohm circuit.(8 ohm halves shown here) It's also possible to do 4, 8 and 16 out of two 8 ohm circuits, but switches with the right...
  15. JohnH

    Simple Attenuators - Design And Testing

    Hi Gene, no prob, I'll post the double-barrel one again when I get on a computer.
  16. JohnH

    Simple Attenuators - Design And Testing

    hi @colchar , all good advice posted above! If you can identify an amp output impedance that will work across the amps that you have or might like, then you can build an M2 for that, and the attenuator can let you run either 8 or 16 Ohm cabs safely, and with good tone. If you like heads, I think...
  17. JohnH

    Simple Attenuators - Design And Testing

    In principal you feed a rectifier circuit, that feeds a dc fan. Search online for rhe Marshall Powerbrake circuit. But in practice it would take ecoeriment to get the right values and components that work for you. So I wouldn't launch right into it yet.
  18. JohnH

    Simple Attenuators - Design And Testing

    hi @xiaozi0624 On page 112 I drew a layout and schematic for an M2 with line-out, which might help. But you can also take a line out just from the attenuator output, either with a pot to control it, or directly provided you set the attenuation level to a suitable level for your DAW. Ive done...
  19. JohnH

    Use Marshall PB100 Power Brake alongside Bugera PS1 Power Soak

    That's right. At the time of the JCM 800's there wasnt anything as effective as an IR to get you a good DI sound, and raw would sound bad. Hence many might note it as unusable. But worth trying now with new IR tech!
  20. JohnH

    So I finally got a Plexi tattoo'd on my arm....let me know what you think!

    It's cool! But if you ever need an intravenous drip, should they plug it into your Lo input or your Hi input?


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