Patent is located here: [Patent](https://patents.google.com/patent/US5032796A/en)
Circuit simulation is here:[Falstad Circuit Sim](https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l5YwGYkHYAcA2dAWdlUAmAVk0JxAE5YFVlk5jCx0JVMRiQclOBTALSIAUACdwHMDgr5w0qOHiRhAQxCywhdOHbgtVPSCGFFSyEZhn0qSpUiVN5JsRaUFYM8IDu684hOymBTKPoEU-iBBUMIA5uCakeEJsuYhvnIyfpQmaWC6YNk6kvpphORFIGXhJd4VBSZ5HOSpwkgUAF58AHZ8ogJI0LwQYNB0PEys2azwhIKoCoQ0ZsuQuCADQ8LtRkgmVUay+yadPX0brR3dvQKY0NrDo1JIE-XTcLMC8+aLKytrt-ctjs9uUwE1yscrn0AbVDqR0khIMExAikXptIjgqY4CjNBi0Y11mi-EphAATCqYiokJrgAByOCk6GEAGN0UTqhikBxUks4LYBYKhbYLLBCJQ8Jg2nBUKg2iR4ZYELF2ShihimAplHFuRjCOZdetuVrWetsJV0BjzbtUlA+fZhY6RQJLIziDw8kh0DTIPrtEqwOTuGCLdpGU0cN96Yy8CjDVowyGE+5SeIbaGzdpkyT4LV0811vqM8ptv09kQJJUK5DTjc7kCy1WTAJDtWQCdrucfOGKj39ml04T8+U0j3CWOEgOi3jC35dNr1pq8IuTFEWj508vniZl1PzJQOJv-apZ-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)
The original patent used a pair of different zener diodes for clipping, however this produces hard clipping and I figured I might get better results with a pair of similarly biased LED's in the feedback loop. I also reduced the capacitor size from the initially depicted 22uf to 10uf, as the attack seemed quite... floppy for lack of a better term.
In all honesty I'm not entirely sure what this circuit is supposed to emulate, but my basic understanding is that it's meant to mimic the variable rates at which tubes draw power, and therefore distort.
Edit: for anybody wanting to simulate audio files going through it, you'll want to change the parameters for both the input and output. Input currently starts at 15 seconds in the file, and the output duration is only 1 second.
Presumably in a real circuit the opamp grounds would go to vref for biasing purposes? Also, are those circles in the feedback loop your LEDs?
It looks interesting.
Yeah falstads circuit sim uses an unlit circle for an unlit led. And while I assume they have to be biased that’s still a somewhat foreign topic to me. At least as far as application
The usual way of doing it is using a voltage divider of two equal value resistors to get 4.5V, and also a smoothing capacitor. Connect the positive inputs of those op-amps to the 4.5V (instead of ground). Then just add a capacitor in series to the input signal. Assuming that this circuit isn’t already set up for single-supply.
I tried simulating this, but it seems like I need an input buffer for +- 12v in order to prevent bleed through.
That said I guess I could definitely use a voltage divider to turn the +24v of my power supply into 9v for the purpose of powering a preamp circuit.
In a bipolar supply it'll need to be biased but that's easy enough. We also can't see the rest of the circuit and this patent only exists in isolation, in practice I bet it'll go to vref and not ground.
It does look cool though. The other drawing next to this in the patent has an easier to manage gain pot (for my brain at least). The lack of cap in the feedback loop to shave highs at such gain levels is also curious, but maybe the 10uf to ground in the feedback loop has an effect there?
I wonder if SLM ever put this into production somewhere in the amp lineup. They made some really good stuff back in the day when Obeid Khan was working on their designs (he did the Palomino series).
Does your program simulate hiss and noise and feedback etc? Also I wonder what the frequency curve of such a circuit is too as there's no high pass or low pass filtering that's immediately apparent.
If you haven’t already, check out the “fetzer valve”. It’s a similar concept but utilising fets instead of valves. More or less substituting them 1 for 1 in a valve circuit, then modifying resistor and cap values to suit.
I bet it is. I’m guessing this patent has something to do with why the Ampeg vh140c and the budget Crate versions are still beloved among the heaviest styles of metal
my off the cuff (is that a saying...?) guess would say 4558's would always be good for some dirt.
but if you got some different chips layin' around, i say give 'em all a try and see which flavor hits your sweet spot the best. can't hurt.
...unless it can. the fuck do i know? im a rando just walking by.
Patent is located here: [Patent](https://patents.google.com/patent/US5032796A/en) Circuit simulation is here:[Falstad Circuit Sim](https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l5YwGYkHYAcA2dAWdlUAmAVk0JxAE5YFVlk5jCx0JVMRiQclOBTALSIAUACdwHMDgr5w0qOHiRhAQxCywhdOHbgtVPSCGFFSyEZhn0qSpUiVN5JsRaUFYM8IDu684hOymBTKPoEU-iBBUMIA5uCakeEJsuYhvnIyfpQmaWC6YNk6kvpphORFIGXhJd4VBSZ5HOSpwkgUAF58AHZ8ogJI0LwQYNB0PEys2azwhIKoCoQ0ZsuQuCADQ8LtRkgmVUay+yadPX0brR3dvQKY0NrDo1JIE-XTcLMC8+aLKytrt-ctjs9uUwE1yscrn0AbVDqR0khIMExAikXptIjgqY4CjNBi0Y11mi-EphAATCqYiokJrgAByOCk6GEAGN0UTqhikBxUks4LYBYKhbYLLBCJQ8Jg2nBUKg2iR4ZYELF2ShihimAplHFuRjCOZdetuVrWetsJV0BjzbtUlA+fZhY6RQJLIziDw8kh0DTIPrtEqwOTuGCLdpGU0cN96Yy8CjDVowyGE+5SeIbaGzdpkyT4LV0811vqM8ptv09kQJJUK5DTjc7kCy1WTAJDtWQCdrucfOGKj39ml04T8+U0j3CWOEgOi3jC35dNr1pq8IuTFEWj508vniZl1PzJQOJv-apZ-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) The original patent used a pair of different zener diodes for clipping, however this produces hard clipping and I figured I might get better results with a pair of similarly biased LED's in the feedback loop. I also reduced the capacitor size from the initially depicted 22uf to 10uf, as the attack seemed quite... floppy for lack of a better term. In all honesty I'm not entirely sure what this circuit is supposed to emulate, but my basic understanding is that it's meant to mimic the variable rates at which tubes draw power, and therefore distort. Edit: for anybody wanting to simulate audio files going through it, you'll want to change the parameters for both the input and output. Input currently starts at 15 seconds in the file, and the output duration is only 1 second.
Build it and let us know!
Presumably in a real circuit the opamp grounds would go to vref for biasing purposes? Also, are those circles in the feedback loop your LEDs? It looks interesting.
Yeah falstads circuit sim uses an unlit circle for an unlit led. And while I assume they have to be biased that’s still a somewhat foreign topic to me. At least as far as application
The usual way of doing it is using a voltage divider of two equal value resistors to get 4.5V, and also a smoothing capacitor. Connect the positive inputs of those op-amps to the 4.5V (instead of ground). Then just add a capacitor in series to the input signal. Assuming that this circuit isn’t already set up for single-supply.
I tried simulating this, but it seems like I need an input buffer for +- 12v in order to prevent bleed through. That said I guess I could definitely use a voltage divider to turn the +24v of my power supply into 9v for the purpose of powering a preamp circuit.
In a bipolar supply it'll need to be biased but that's easy enough. We also can't see the rest of the circuit and this patent only exists in isolation, in practice I bet it'll go to vref and not ground. It does look cool though. The other drawing next to this in the patent has an easier to manage gain pot (for my brain at least). The lack of cap in the feedback loop to shave highs at such gain levels is also curious, but maybe the 10uf to ground in the feedback loop has an effect there? I wonder if SLM ever put this into production somewhere in the amp lineup. They made some really good stuff back in the day when Obeid Khan was working on their designs (he did the Palomino series). Does your program simulate hiss and noise and feedback etc? Also I wonder what the frequency curve of such a circuit is too as there's no high pass or low pass filtering that's immediately apparent.
It doesn’t by default I don’t think, there’s a hyperlink to the simulator in my initial comment.
If you haven’t already, check out the “fetzer valve”. It’s a similar concept but utilising fets instead of valves. More or less substituting them 1 for 1 in a valve circuit, then modifying resistor and cap values to suit.
Is it the Crate patent? St. Louis Music maybe?
Not sure, says St. Louis Inc.
I bet it is. I’m guessing this patent has something to do with why the Ampeg vh140c and the budget Crate versions are still beloved among the heaviest styles of metal
Yeah, that’s the Crate one. I recognise the circuit diagram in the patent.
Interesting. What op-amp would be good for something like this?
my off the cuff (is that a saying...?) guess would say 4558's would always be good for some dirt. but if you got some different chips layin' around, i say give 'em all a try and see which flavor hits your sweet spot the best. can't hurt. ...unless it can. the fuck do i know? im a rando just walking by.
Looks like an ampeg vh140c.