Looking at my signal generator I noticed wow I can really slow things down

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Now I'm wondering if I could construct the clamping circuit shown connect meters and actually see in real time voltages changing ala capacitor charging and discharging in real time 
Also put probes across the diode to watch when it gets busy 

Now I wonder is 0.03 hz gonna still be too fast to see 🙈

Or

Is the signal generator actually gonna deliver that low

The MosValve 500 has an interesting take on it. There is a voltage amplification stage which runs on significantly wider power rails than the output stage. Negative feedback is taken from the voltage amplification stage, not the speaker output.

That should have two effects: one is that the impedance of the MOSFET output devices is not hidden from the speakers; i.e. it raises the output impedance a bit ("tube like").

Secondly, the MOSFETS will clip long before the VAS does and their clipping is outside of the NFB loop. Clipping being out of the NFB loop means that we don't get the hard clipping where the output is forced to stay linear until the very limit; the output stage is "allowed" to produce nonlinearities before clipping. This is again like a tube output stage without NFB.

Yes, in SS aamps power  amp is just a BIG Op Amp, and clips as such, boring.

A few SS buikders such as Peavey Transtube, Pritchard, Quilter, Roland Blues Cube have power amps emulating tubes, but they are the exception.

So I got to thinking wow maybe I have a (fixed) bipolar power supply at my house

And I do  it's called a Peavey Audition Chorus 

Looking at the schematic it looks like if a bridge rectifier is constructed from four diodes then
-neg voltage can be obtained from the node in between the anodes
-positive voltage can be obtained from the node in between the cathodes

So I'm looking forward to making a circuit like that and checking it out 

Like this 

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Now that WOULD RULE 

The first problem out the gate

Why can't variable DC power supplies have positive and negative

Like my function generator does

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As of now I'm trying to dream up something I can take an ordinary say 0-20V DC power supply and convert it to a symmetrical -20 to +20 DC power supply

Now I learned earlier that to make a waveform like a sin wave go up (add DC) just put the DC in series so that is not so hard for me to comprehend

But how does Hickock put neg DC in series in all at the control of a single knob

I need to look at some amp schematics and stuff where they have a pos and neg rail that shouldn't be so hard

But how to bring them together without an explosion 💥

So I'm thinking ok get a neg rail and a pos rail and maybe put a variable resistor between them

But that sounds like a disaster  shorting pos and neg rails

I haven't ruled out taking the lid off of the Hickock to see how they did it because I can't find a schematic 

I really want to play around with
-diode limiters
-cutoff limiting
-clamping circuits
-separator circuits
-voltage multipliers
-voltage limiters


And all that where the input is a signal and the circuit consists of not much more than a diode, a resistor, and a capacitor 

Should be cool

Then down the line introducing DC and zener diodes and transistors etc

I think the first item of business is gonna be constructing this circuit

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But instead of introducing AC I want to use DC for the signal and attempt to measure test and observe each step observing how the output responds to the input. The book gives a play by play but I've read it slowly a thousand times and I can nod my head and go oh hell yeah that's how it works sign me up  but I'd rather see it in slow static motion 

Obviously some of the time I'll have to be slowly increasing or decreasing the DC and paying attention

Speaking of paying attention I think I just realized I better start with AC and find a good combo of capacitance and resistance to produce a nice outcome.

 

Quote from: J M Fahey on August 16, 2026, 08:53:57 PMThe attenuator is the real thing, it is flat, sends to speaker an attenuated but accurate version of amp output but most important, it preserves power tube distortion which is warm and full.

Master volume does not, power amp works clean contributing little, all distortion you have is preamp distortion, thin and buzzy.

Besides, attenuator keeps power pentode distortion, MV keeps Triode distortion, very different.

I would argue that on most solid state amps, the end result is very similar when comparing master volume to attenuator.  Like you said though, tubes are a different story where you can get significant (and pleasant) power amp distortion which you lose when you turn down a master volume.

The biggest difference conceptually is location in the circuit.  MV sits between preamp and power amp.  Attenuator sits between power amp and speaker.

Interestingly, I had some of these kicking around (no idea how I came to have them, but I've had them for YEARS) and am using them for an RGB controller.  It's only running 9v, but I had no other use for them and they work well.

Quote from: saturated on August 17, 2026, 01:18:11 AMYes sir thanks I admit the part about the carbon went over my head

Maybe it's like a variable resistor? Idk

Yes, it IS a sound actuated variable resistor.
Inside it has carbon which is resistive like all materials so if you apply meter probes terminal to terminal you will get a reading.
Typically between 300 and 600 ohms.
If it were a slid block, it would be fixed but it´compressed carbon dust.
Grains make POOR contact with each other , imagine grains of sand, they would not touch flat face to flat face, there is none, but at random tips so resistance is higher than in a solid block.
Did I say "poor contact"?

But if you sandwich it between 2 metal plates and PRESS them together, they make better contact and resistance lowers.
When you stop pressure resistance rises.
So yes, it is a pressure sensitive variable resistor.

If you make plates thin and flexible, Audio pressure will vary resistance.

If you apply voltage (typically 48V in old school phone lines) and put a speaker (earphone) voice coil in series, that audio modulated current will make speaker VC move and you will hear sound.

Quality is horrible, "telephone sound", but you can understand it.

Microphone and earphone can be many miles away, so TELE (far away) PHONE (sound)

Worldwide phones were based on that until the 60s or 70s and even today, if you plug an old phone into a line, it will work.

Notice there are no electronics involved, no tubes or transistors 

Our elders were incredibly clever.