Engl Savage question: asymmetrical distortion

[eschertron]

Distortion is a form of signal degradation. It is pretty easy to define what a good "clean" signal is, but trying to achieve just the right kind of "broken" can be pretty maddening.

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[Roberto]

Going on with teemuk's thread explanation, another way to reduce IMD without limiting the bandwidth, is to limit the high order harmonics of the various stages by varying their working point. This gives a better response to lower gain settings, where a too narrow bandwidth can sound sterile, and better response to dynamics.

Also, take care that early stage define the frequencies will be overdriven more, while latest give more a eq-shape of the final sound. Think about the Mesa Mark series: treble mid bass equalisation vs final graphic equalisation.

A mod I did on Engls was to reduce the plate resistance on the second lead gain stage (R31): going to 82k or even in extrema ratio to 68k to improve the definition of the lead without changing its character. At around 350V, that configuration (Rk and Ck being the same, or Rk a little higher) that stage will produce strong low order harmonics, and weak high orders. I used alot this trick in my amps too to have a "3 stage feel" on lower gains and a more punchier sound on high gain settings. It works well also on 5 stages like the 5150 saga.

On other amps, more Marshall inspired like Laney VH100R and similar, lowering the supply voltage on the preamp by a 40-50V can obtain the similar results, tonewise.

Take a look at this link (you can add also positive grid curves): Triode / Pentode Loadline Simulator v.1.0 (20161216 www.trioda.com)

[glebert]

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I am deeply honored!

[yldouright]

J M Fahey
Link edited, thanks.