Who invented resonance circuit in some high gain amps?

[halebox]

I see it on Camerons, EVH 5150, Barons. Who started it? Its a cool feature

 

[DAMIAN The MAN]

I don't remember heard about it until the PV 5150 came out in 1991, but my memory is way too selective.

 

[chunktone]

I don't remember heard about it until the PV 5150 came out in 1991, but my memory is way too selective.

That's what I was thinking too. Must be the guy who developed the 5150 with EVH. I forget his name. He also designed the XXX.

 

[sahlomonic]

I don't remember heard about it until the PV 5150 came out in 1991, but my memory is way too selective.

That's what I was thinking too. Must be the guy who developed the 5150 with EVH. I forget his name. He also designed the XXX.

James Brown. Badass amp designer. Did a lot of the Peavey stuff, then went on to Kustom for a few years, now does his own thing (AmpTweaker).

I know Soldano has that feature, though it's called Depth on those amps, but I'm not sure when Soldano started offering it.

 

[baron55]

Actually been used for 50 years! But in most applications it was a fixed value so it was not adjustable. It is a simple filter on the negative feedback supply. Been used widely on many tube amps.

Bogners, use the fixed values on the Ubers, and XTC. Basically what the Excursion does, but you are changing values (basically preset depth)

 

[tak]

Pretty sure the first VHT 2150 power amp I purchased had depth knobs (same thing?). I think this was late 80's, maybe '90?

 

[Kelly]

Steve Fryette.

 

[FourT6and2]

It's been around for a long time. But I've seen people state that Fryette invented it back in like 1988.

 

[Dave L]

Rivera had the Focus knob back in 86-87.

 

[stephen sawall]

Steve Fryette.

I believe Steve is the one.

 

[tschrama]

Because he was building amps is the 50's?

 

[tech21man]

Well if you think that it is exactly the "same" principal with the pressence circuit you can't actually give credit to an amp designer for an invention. I first noticed it in peavey. You could play with caps all day and also have mid-yada something ance if you want etc in the power amp, which it all breaks down when you overdrive and are left without useable gain (the ...it doesn't do anything after a point thing).


Fryette is awesome though (and a genious of sort) the way he handles negative feedback and the phase shifts that it causes all the way back he is feeding it into the preamp. Usually it ends up in the phase inverter calculating three major phase shifts "poles" (transformer, power tubes, PI) which are not predictable easily. Oh and he writes awesome stuff on his PCBs!

If you only care about the tonal advantages instead of the dynamic sort of aspect of it a good eq, especially parametric in a good loop is much much more usefull in my opinion and you can actually take it out whenever you want.

You can go all control crazy in many places in an amp but it can become more of a hindrance than an advantage. Imagine: controllable bias in the preamp tubes, pressence (in the cathode) in every one of them, mid sweep extra, variable negative feedback control, selectable tonestack values, input gain, gain (distortion), two master volumes, master defeat, selectable bias settings for one type of power tubes (cold warm etc a-la dv mark or fender supersonic 100), pressonance, gain pot for two preamp tubes (a-la deliverance), negative feedback defeat (recto modern or mark IV extreme), tonestack defeat (a-la fuchs ODS), bright caps, triode/pentode/half power switch on the power amp or whatever the designer can think of.


You end up with a do it all spaceship without actually having a certain identity of sorts which can be a good thing for the tweaker and maybe a nightmare when you gig! And pray that nothing breaks or drifts because good luck trouble shooting it!

 

[FourT6and2]

Well if you think that it is exactly the "same" principal with the pressence circuit you can't actually give credit to an amp designer for an invention. I first noticed it in peavey. You could play with caps all day and also have mid-yada something ance if you want etc in the power amp, which it all breaks down when you overdrive and are left without useable gain (the ...it doesn't do anything after a point thing).


Fryette is awesome though (and a genious of sort) the way he handles negative feedback and the phase shifts that it causes all the way back he is feeding it into the preamp. Usually it ends up in the phase inverter calculating three major phase shifts "poles" (transformer, power tubes, PI) which are not predictable easily. Oh and he writes awesome stuff on his PCBs!

If you only care about the tonal advantages instead of the dynamic sort of aspect of it a good eq, especially parametric in a good loop is much much more usefull in my opinion and you can actually take it out whenever you want.

You can go all control crazy in many places in an amp but it can become more of a hindrance than an advantage. Imagine: controllable bias in the preamp tubes, pressence (in the cathode) in every one of them, mid sweep extra, variable negative feedback control, selectable tonestack values, input gain, gain (distortion), two master volumes, master defeat, selectable bias settings for one type of power tubes (cold warm etc a-la dv mark or fender supersonic 100), pressonance, gain pot for two preamp tubes (a-la deliverance), negative feedback defeat (recto modern or mark IV extreme), tonestack defeat (a-la fuchs ODS), bright caps, triode/pentode/half power switch on the power amp or whatever the designer can think of.


You end up with a do it all spaceship without actually having a certain identity of sorts which can be a good thing for the tweaker and maybe a nightmare when you gig! And pray that nothing breaks or drifts because good luck trouble shooting it!

Agreed. For me at least, simple is better. I don't need all sorts of adjustable points in the circuit. But what I do like are the standard power amp controls like Depth and Presence. My Peters amps have adjustable NFB as well, which is pretty great and changes the feel of the amp more drastically. Other than that, a standard tone stack EQ section is all I need and want.

I've had amps with more controls and I spent more time tweaking than playing. It was detrimental. That's why I stayed away from the Bogner XTC.

 

[Bozo-Breath]

Because he was building amps is the 50's?

No, only since the 60's. Nobody was really doing anything with feedback before the early to mid 80's except having it or not having it, with the exception of some esoteric Hi-Fi gear, which was an early passion of mine.

The Seymour Duncan Convertible amp had variable damping which actually did vary the output impedance slightly, so more or less true to its intended function. To most though, it sounded more like variable presence than anything. Rivera introduced his TBR amp around 1987 I believe with the Focus control which was simply variable feedback.

So the "Depth" or Resonance" control that everyone uses today is different than those above and did not exist on any product before the introduction of the 2150 Power Amp, the design of which is based on my original Pittbull prototype from 1987, and started shipping in 1989 - two years before PV released their 5150 with the identical circuit. This circuit is essentially a variable high-pass filter in the feedback loop and can be used in series or in parallel with a low-pass feedback network typically used to linearize the frequency response of a power amplifier. Its purpose is to allow the amplifiers output stage to become more reactive at the resonant frequency of the speaker/cab combination connected to it, and to control the intensity of that reactance. Essentially, a low frequency Presence control.

Like all inventions, it is founded on prior art and adds to it. I didn't patent it because I wanted it to exist in the public domain. I didn't feel it was going to bring a windfall of income and frankly I didn't care about that at the time. I just wanted credit for having developed it and I never thought for a minute that someone would knowingly apply for and be granted a patent on public domain as one of the aforementioned companies had done. So though I am disappointed that someone chose to take undue credit for my original idea, the fact is, it did become an industry standard and I am proud of that.

I suppose that the (now expired) patents un-enforceability due to provable prior use in commerce, is evident in the fact that I've never seen or heard about anyone ever being forced to cease and desist on this Depth or Resonance circuit in any format by the holder of the patent. That to me simply underscores that they had no qualms about taking credit for something they didn't originate.

Cheers,

Steven Fryette

 

[stephen sawall]

Thanks for clarification Steve....

 

[Audiowonderland]

I don't remember heard about it until the PV 5150 came out in 1991, but my memory is way too selective.

This..

 

[tschrama]

Because he was building amps is the 50's?

No, only since the 60's. Nobody was really doing anything with feedback before the early to mid 80's except having it or not having it, with the exception of some esoteric Hi-Fi gear.....
Steven Fryette

Methods of selective feedback to alter the transfer function are much older, in a more general electronics context. That was the gist of my reply.

But within the context of guitar amplifiers, I am amazed to hear it from the first person to introduce it ! It sure got a lot of following in many brands. Mesa power amp from the early 90's have it, like 395, 500, although th 295, and 400 don't have it. Was Mesa following your design?

I do doubt a resonance control would be accepted by the patent office. As it is just a new application of prior art. Was the presence circuit ever patented?

 

[Bozo-Breath]

Because he was building amps is the 50's?

No, only since the 60's. Nobody was really doing anything with feedback before the early to mid 80's except having it or not having it, with the exception of some esoteric Hi-Fi gear.....
Steven Fryette

Methods of selective feedback to alter the transfer function are much older, in a more general electronics context. That was the gist of my reply.

But within the context of guitar amplifiers, I am amazed to hear it from the first person to introduce it ! It sure got a lot of following in many brands. Mesa power amp from the early 90's have it, like 395, 500, although th 295, and 400 don't have it. Was Mesa following your design?

I do doubt a resonance control would be accepted by the patent office. As it is just a new application of prior art. Was the presence circuit ever patented?

Mesa does not use this scheme. All of the feedback filters I have seen of theirs (and I worked on a lot of their gear back in the day) are focused on high frequency manipulation. The one case I recall that deals wit low end (the 2/90 deep mod IIRC) is a larger cathode cap strapped across the input stage cathode resistor.

Re: Patentability of my design, it would appear that you overlooked my comment about this above, as obviously the USPTO found it a valid premise. Had I known that such an application had been made, I would have filed an objection at the time, and then you would have been correct