Tweed clones - Post P.I. Master or Attenuation?

Discussion in 'Shock Brother's DIY Amps' started by jsnwhite619, Oct 12, 2021.

  1. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Who here has tried both? Or either if you want to share your results. It struck me today that we have the 1/4 power & 1/10 power attenuation mods using the big resistors on the back end to tame the volume. And there's the master volume mods - I tried the Pre P.I. master a few years ago and took it out that week, just didn't care for it. But I never tried the Post P.I. version.

    Anyway, I guess I'm asking "What differences are in master volume and speaker attenuation in these old circuits?" How close is the tone from one to the other? I was wondering that even if you didn't want an extra pot to deal with, couldn't you use a switch with set resistor values for a "1/2 power or 1/4 power" option, and how would that compare to using a resistor on the speaker end that has to be so much bigger and more expensive, and deal with heat sink, wattage, etc.

    How much are the non-LTP phase inverter Tweed amps driving the power tubes? Would a overdriven preamp and power tube Master be close enough in the end as an attenuator behind the power section and easier/safer in the end?
     
  2. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    I prefer the attenuator on the 5E3.
     
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  3. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Anything that jumped out to you about either way? I know that sounds and tones can be hard to describe in words, and a lot really can come from the "feel" of the amp. But any comments on why?
     
  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    It seems the character of the 5E3 changes more when the master volume is dialed down. I can't get as close to *the* 5E3 distorted sound at lower volumes with a MV.

    Speculating...
    Maybe it is because the 5E3 power tubes are providing the bulk of the distortion. Any type of MV will dial out signal voltage to the power tubes so, to me, a MV acts similar to, not exact but similar to, turning down the signal at the volume control of the amp or the guitar.
     
  5. printer2

    printer2 Poster Extraordinaire

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    "Would a overdriven preamp and power tube Master be close enough in the end as an attenuator behind the power section and easier/safer in the end?"

    It this a master volume before the power tubes? Normally called a post phase inverter master volume.

    If the master volume is behind a Cathodyne phase inverter it is not going to do much compared to a master volume before the triode as the section is mainly clean.
     
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  6. graybeard65

    graybeard65 Tele-Meister

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    I use an attenuator on a 5E3, and love the sounds on tap within that little beast. It will tick nearly all of the boxes with just three knobs and four inputs. I hate to say so, but without the attenuator, my experience with the 5E3 is that for the grit that I like, it's not a living room amp.

    I have zero experience with any sort of MV mod on the d-lux...but will happily say that before the attenuator, I didn't especially like the 5E3 as a rehearsal amp - but now I use mine all the time.

    YMMV, all the usual and customary disclaimers.
     
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