Why do master volumes on some amps work better than on others?

Discussion in 'Amps and Cabs' started by LaXu, Jan 29, 2006.


  1. LaXu

    LaXu Member

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    Inspired by the Maven Peal thread I started to wonder, how come some amps have master volumes that are close to useless and others that sound pretty good? For example most Marshalls have pretty crap master volumes, the amps sound thin and way trebly at lower volumes. On the other hand I found that the master volumes on for example the Orange Rockerverb and Mesa Lone Star worked quite well. Even though those amps still sound better at higher volumes, the tone was quite pleasing at low volume too. So what do some manufacturers do differently with the master volume? What ingredients make a good master volume?

    Just for the hell of it, lets exclude "specialty" things like Power Scaling and the Maven Peal stuff from the discussion and concentrate on more "normal" MVs.
     
  2. Rusty G.

    Rusty G. Member

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    I think most master volumes work better for high gain amps, because you're looking for pre-amp fizz with high gain. With that said, the master volume on my Matchless DC 30 works great even though it's a med gain amp.
     
  3. Ripfence

    Ripfence Member

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    I could be wrong but I think a lot of it has to do with where the manufacturer places the MV in the signal chain. It could be pre or post phase inverter for example.
     
  4. LaXu

    LaXu Member

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    Smacketybump.
     
  5. Randy

    Randy Member

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    Most of the high gainers I've tried sound great at low volumes. One exception was the Splawn Quickrod. For some reason it sounded choked with the master down low.

    I only mention it because I had tried running an outboard preamp (Engl E570) into the effects return on several high gain MV amps. The Splawn was the only one who's MV didn't effect the volume of the amp with a preamp plugged in. Maybe that's more to do with the placement of the loop but that's what I noticed anyway. I should also mention that the Splawn sounded better then all the others running the preamp that way. Substantially better.
     
  6. drbob1

    drbob1 Silver Supporting Member

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    The Matchless uses a wierd post-PI MV, where it mixes a little of the two sides of the push pull together (so they cancel out) allowing the whole preamp/PI unit to be pushed hard. I believe the Park "Rock Head" has a post-PI MV? Most of the other Marshall ones are pre-PI and really only work to take off a few dB before they start tone sucking. No question amps that rely on preamp distortion for much of their tone work better with MVs but even Mesas sound better somewhat cranked. There's a cool thread on Naylor amps that points out how combining the MV with a loudness feature to increase bass and treble as you cut volume results in a more pleasing sound. Lots of interesting ideas out there...
     
  7. Robert1950

    Robert1950 Member

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    Now this is the type of thread I learn something from. Keep it going!
     
  8. LaXu

    LaXu Member

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    What he said.

    It could indeed be that on amps that sound very pleasing with the master volume down the preamp is voiced very well and the amp's tone depends more on that rather than cooking the power tubes.
     
  9. pfrischmann

    pfrischmann Member

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    I'm going to throw this out there and hope one of the Marshall experts concurs or corrects.

    The best MV's I've heard always seem to be post P.I. In a Marshall, which is where I most need a M.V., distorting the P.I. has a lot to do with the sound, so sticking the MV between the P.I. and the power tubes rather than between the preamp and the P.I. makes a huge difference.

    Better to just crank it though......:D
     
  10. Voodoo Amps

    Voodoo Amps Member

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    Inspired by the Maven Peal thread I started to wonder, how come some amps have master volumes that are close to useless and others that sound pretty good? For example most Marshalls have pretty crap master volumes, the amps sound thin and way trebly at lower volumes. On the other hand I found that the master volumes on for example the Orange Rockerverb and Mesa Lone Star worked quite well. Even though those amps still sound better at higher volumes, the tone was quite pleasing at low volume too. So what do some manufacturers do differently with the master volume? What ingredients make a good master volume?

    Without getting overly techie; It depends on the type of amp, exactly what master volume is being installed and where it's being installed in the circuit (which heavily depends on the type of amp).

    For example; If you are using an amp with 2 gain stages then it would make sense to install a post phase inverter master volume. There are several post PI masters to choose from and only a couple sound good while the rest sound very thin when set lower (in my opinion). Some use added caps, some do not, some use dual ganged pots, some do not, etc. Either way the reason you would install a master volume after the phase inverter tube is so that you can get the distortion commonly associated with vintage style amps.

    If you have an amp with 3 or more gain stages (JCM800 2204/2203 to modern high gain) then the gain is generally being generated in the preamp and not the phase inverter tube. Can the phase inverter tube still break up? Yes of course it can however it's usually not desirable to have a lot of preamp and phase inverter distortion at the same time as it usually results in mud. Naturally there are exceptions but over all I'm generalizing to keep the post fairly short as you could write a book on this (ha, ha)


    Hope it helps & have a great day! :)
    Trace
     
  11. clothwiring

    clothwiring Supporting Member

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    Trace, I've played Bonamassa's 50 Watt JTM Reissue that I believe you modified, it sounded great.
     

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