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It's a (push-pull) tube power amp emulation. The steering diodes clip signal peaks and also introduce crossover distortion above certain threshold. Outcome is similar to push-pull tube power amp...

I could be off track here, but I think the driver arrangement is not only a bootstrap but a short circuit protection as well: Increased current draw of the finals will 'starve' the driver collector...

...And if you sketch out the circuit(s) from which those resistors are from it might help to determine their component values. If not exactly, then at least a close-enough values.

Sometimes you...

Try contacting Elk Electronic Industries instead. After all, that is the company who manufactured these amps for Fender Japan, Ltd., which - BTW - was entirely different business entity than the...

I realize there are two different ”schools” concerning tube audio design. One school basically recognizes something like a triode tube as the most ideal linear amplification device ever. This school...

Yes, a good video. Few years ago I posted some links to oscilloscope plots of a saturating output transformer to another one of these threads. The videos displays pretty much the same effects.
...

I was looking for that schematic for research few years ago. Eventually bought it online from somewhere.
It was a very advanced solid-state amp by '82 standards. And is even today.

Correct. It is indeed a soft limiter they employed in some revisions of the JC-series amps (including JC-120) and in some bass amps of the same era (BA-series, can’t remember?)
Open loop...

I agree, no need to dismiss this topic even though it's not particularly something of my own interest (although I pretty much started out this whole electronics hobby by something one could consider...

This is another vital detail in understanding tube overdrive circuitry: As a rough rule of thumb, the grid begins to conduct (and its impedance drastically decreases) whenever grid voltage turns more...

Exactly. In that ENGL amp pretty much all preamp gain stages are generic common cathode circuits, therefore they all "look almost the same" because they follow a standard circuit topology.

The...

If I interpret the schematic correctly, gain stage around V2b is NOT responsible for Crunch II. In fact it is bypassed in Crunch II mode and amployed only in Lead mode. Crunch I is basically on that...

Some guitar amps that use cascode: Vox V125 Lead, Ibanez Starfield series, Marshall 9001 preamp, to name a few. Of course they are bass amps but Aguilar’s DB750 and DB659 also employ multitude of...

It is not the distortion circuit. It is an electrical switch.

Notice different polarity of the FETs; one conducts when the other doesn't - and vice versa.

The electrical switch selects signal...

This.

If the baffle is "dadoed" to the cabinet structure then only way of disassembling it is tearing the cabinet apart.

It's a Peavey circuit, naturally.

As said, those diodes do not distinctly affect "grid clipping" (and associated effects) because they basically just replace the grid conduction (and associated...

There is a cathode resistor. It is that 15K resistor that connects the cathodes to the negative voltage supply.

BTW, "bias supply" is only the one titled "F". The only common thing with PI supply...

Yes, plates dissipate heat by radiation. The envelope, on other hand, by convection. Radiation is more effective the higher the temperature difference is, therefore a cooled envelope aids radiation....

Amps with high Z output (which isn’t necessarily just a tube amp characteristic) will create higher voltage potential across terminals of higher impedance load than across terminals of lower...

In the late 1970's and early 1980's their bass amps started to have pretty heavy competitors by the likes of A.M.P., Gallien&Krueger, SWR, Eden, Hartke, Trace Elliot, etc. Many of these companies...

Absolutely not. I think the whole idea is ridiculous, it's those higher order harmonics we need to worry about more.

Push-pull power stages inherently produce mainly odd order distortion, and many...

The amp already features a short circuit protection. It's a crude VI-limiter -type circuit, which steers drive current away from the driver transistors when high-enough output current is detected....

And I wouldn't be surprised if the input stages were actually "xeroxed" from a design where low frequency modulation is introduced in input stages, with bias voltage modulation, after which the LF...

For perfomance of ancient valve technology nothing really beats it. But there are VERY good reasons why one also likes to get rid of that ancient valve technology.

Besides the obvious benefits of...

To be fair, at least the KBO Dynamics design uses many more "monitored" inputs than just cathode current. If I remember correctly, it monitors plate voltage and grid bias voltage as well. With more...

The inexpensive ones are often low power too. Not much headroom for cleans so cleans channel is voiced for overdriven tones as well.

CA3046 chip is just a transistor array, basically five "discrete" transistors contained in a DIP package. Two have their emitters internally connected and I assume at least those transistors of the...

Miles Platting schematics can be found here: Index of /tubes/MilesPlatting/Schematics