MH's ideal coil and voltage question

[poynt99]

And what does any of that have to do with the present discussion?

[minnie]

  Take two identical batteries,call on EMF,the other CEMF. Put a resistor across
battery EMF,current flows,now introduce battery CEMF, nothing changes,current
still flows.
    It has to be the rate of change that makes the whole thing tick.
            John.

[partzman]

Aren't all JFETs depletion mode?

Yes they are, but it might be an interesting experiment to see what oscillations might exist at the threshold of forward conduction in the pn gate to source junction!

I prefer enhancement mode MOSFETs for my pre-amp designs, hi-fi and guitar/bass.

Yes I can understand why. Higher operating voltage for all the class A preamps would improve the signal to noise ratio with the higher gains that could be achieved plus the wider dynamic range. The jfets used back when had a Vds of ~30v so the signal swings were puny compared to say a 12AX7A or 7025.

I'm sure you are familiar with Crown's technology of using a split power supply in the output section where the load is connected between the center tap of the supplies and ground, and the + and - terminals are driven by complimentary bipolars or mosfets. IOW, the entire high voltage/current supply swings at the audio rate. Unaware of Crown back then, I developed the same technology that I sat on for years before building a company around the idea. The design symmetry allowed easy implementation of current and voltage feedback plus control points for prevention of saturation, soft start, quiescent bias, etc.

pm

[picowatt]

Yes I can understand why. Higher operating voltage for all the class A preamps would improve the signal to noise ratio with the higher gains that could be achieved plus the wider dynamic range.

Dynamic range?  In a guitar amplifier?  Surely you jest...

Back in the day when audiophiles were trying to reconcile the difference between tubes and solid state, or trying to discern the difference between two amplifier's with similar THD but having a different "sound", listening to the attributes of various tone arms and cartridges, and then later on doing A-B comparisons between analog and early digital, guitar players were doing the "crank 'em all up to 10" maneuver on Marshalls and the like. 

Have you ever looked at the waveforms coming out of a Marshall while it's cranking away at ear deafening levels?

Besides clipping just about every stage in the Marshall and saturating the OT, at the levels being played, feedback from the microphonics generated as tubes were rattled to the brink and even the guitar itself, were all contained within an electronic and acoustic feedback loop that was part of a very loud "harmonic generator" or guitar "sound generator".

And if you happened to have a very loud guitar "sound generator" ("amplifier" being a misnomer...) that just did not generate enough harmonics, or was not "edgey" or "fuzzy" enough for you, no worries, all manner of pedals could fix ya' up.

To the woe of every frustrated sound man trying to get a decent live mix and having to deal with stage wash from the axes bleedin' into everything, the words "can you turn it down a bit?" were repeated as if a mantra.

So, with tongue in cheek, and no offense intended toward any guitar players out there, amplifying the sound of the "guitar" has rarely been the desired intention of a guitar "amplifier", but rather it is to use that guitar in the feedback loop of an ear deafeningly loud guitar "sound generator" capable of producing all manner of harmonics.

My apologies to all, I digress...

PW

[poynt99]

Dynamic range?  In a guitar amplifier?  Surely you jest...

For audio "Hi-Fi", yes of course. For the "clean" channel of a guitar or bass amp, yes to a degree.

So, with tongue in cheek, and no offense intended toward any guitar players out there, amplifying the sound of the "guitar" has rarely been the desired intention of a guitar "amplifier", but rather it is to use that guitar in the feedback loop of an ear deafeningly loud guitar "sound generator" capable of producing all manner of harmonics.

The amp is certainly 50% of the guitarist's "tone".

Pre/Pwr tubes and OPT's are obsolete, as I hope to prove in the near future.