Closed Output Transformer High Frequency Resonance

Status
Not open for further replies.
Joker

Joker

Inspired
Cliff, could you please expose the output transformer high frequency resonance paramater inside the transformer / advanced section?

I get that most do not like raspy plexis, but some of us do. Would be great if it's left to the player to choose his preference regarding this.
 
Too dangerous. The uniformed user could set it to a value that causes the power amp to oscillate and then we'd be getting support calls.
 
FractalAudio said:
Too dangerous. The uniformed user could set it to a value that causes the power amp to oscillate and then we'd be getting support calls.
Click to expand...

Could you include a dropdown menu or knob which lets the user set the output transfomer high frequency response to maybe 3 or 4 degrees of "modern" settings, for newer, lower quality transfomers, and "vintage" for the old, better spec transfomers?

As far as I know, the status quo is that all OT transformer modeling - no matter if the physical amp did have less than ideal OTs or not -uses ideal OT HF resonance settings. I know many years ago you've also omitted the AC/DC conversion stage modeling, as amp designers would most probably omit it, too, if only they could. In the end, it turned out to be a vital part of the amplifier response.

I'm no expert, but maybe the OT HF resonance might just be, like the AC/DC conversion stage, an ingredient and not an unwanted constraint. Sure, some builders would always choose 60s Dagnalls for all eternity, but I think a good amount of amps is designed and refined around newer OTs and their shortcomings, as they are part of the tone the amp is producing in the end.

I am also aware that not many would like it, but then again, not all people like the standard power amp hardness settings so they choose something that fits their tonal preference.
 
Just as an addendum for those who are not accustomed to this concept and don't know the impact it might have on an amp's tone. It accounts for some of the difference between this (close to ideal):



and this (not so ideal/raspier high end):



I like both very much, but lean slightly more towards the metal panel plexi in the clips above...
 
Joker said:
Could you include a dropdown menu or knob which lets the user set the output transfomer high frequency response to maybe 3 or 4 degrees of "modern" settings, for newer, lower quality transfomers, and "vintage" for the old, better spec transfomers?

As far as I know, the status quo is that all OT transformer modeling - no matter if the physical amp did have less than ideal OTs or not -uses ideal OT HF resonance settings. I know many years ago you've also omitted the AC/DC conversion stage modeling, as amp designers would most probably omit it, too, if only they could. In the end, it turned out to be a vital part of the amplifier response.

I'm no expert, but maybe the OT HF resonance might just be, like the AC/DC conversion stage, an ingredient and not an unwanted constraint. Sure, some builders would always choose 60s Dagnalls for all eternity, but I think a good amount of amps is designed and refined around newer OTs and their shortcomings, as they are part of the tone the amp is producing in the end.

I am also aware that not many would like it, but then again, not all people like the standard power amp hardness settings so they choose something that fits their tonal preference.
Click to expand...
I don't know what "AC/DC Conversion Stage" is. The Axe-Fx III models an AC power supply, complete with hum, ripple and ghost notes.
 
FractalAudio said:
I don't know what "AC/DC Conversion Stage" is. The Axe-Fx III models an AC power supply, complete with hum, ripple and ghost notes.
Click to expand...

That's what I meant but failed to articulate correclty. Everything modeled from the wall outlet to the amp's DC circuit. I distinctly remember you bringing it up years ago.

My point was that maybe using less than ideal transformers might not be a designer error, but a conscious choice. Most of it is owed to cost-cutting, I'm sure, but there are certainly also decisions which were based on tonality and the holistic effects each part plays in it.

Maybe it's a bad analogy, butI know that Howard A. Dumble used some radio shack, cheap as hell resistors and capacitors in his designs. Yet here we are in 2020 and looking at 150'000 USD Dumbles. Lesser quality components equal different tone, not always bad tone.

To get back to the specific topic at hand: Would such an OT HF resonance knob/menu make sense for you or are there only drawbacks in your opinion?

If it's not implementable across all amps, as these frequencies might affect some models in a different manner and thus might still cause power amp oscillations, would it at least be possible to include a SLP 1959 model with low-quality OT specs, that could close the gap between the two tone styles shown above in the two videos?
 
I've spent a lot of time measuring amps and finding the resonances of the OT. I don't want to give that information away to would-be competitors by exposing it in the GUI.
 
FractalAudio said:
I've spent a lot of time measuring amps and finding the resonances of the OT. I don't want to give that information away to would-be competitors by exposing it in the GUI.
Click to expand...

Understandable. Would it be possible to use a relative scale such as -3,-2, -1, ideal,+1, +2,+3? Or could some amp modeling engineers out there reverse engineer it from just those 7 options?

Maybe just including a single Plexi model, that features a raspier OT, would be the safest way?
 
AFAIK the model of the newer Plexi in the unit already has a raspier OT modelled as part of it. Have you tried that to see if it gets you any closer to what you're after? If I remember right the new Plexis are the ones labelled 1959SLP, Plexi 100w is the older ones
 
JDR3009 said:
AFAIK the model of the newer Plexi in the unit already has a raspier OT modelled as part of it. Have you tried that to see if it gets you any closer to what you're after? If I remember right the new Plexis are the ones labelled 1959SLP, Plexi 100w is the older ones
Click to expand...

The included SLP 1959 sounds closer to the plexi clip from above than the metal panel clip. It's definitely a step up from the Axe FX II and I'd like it to go even more in that direction. To add more of the raspiness, at will, is all I'm asking for. If it's a deep security concern, I understand that Cliff won't go through with it. It's not worth it to risk countless of hours of hard work only so that unaffiliated parties can benefit from that research.
 
Joker said:
My point was that maybe using less than ideal transformers might not be a designer error, but a conscious choice. Most of it is owed to cost-cutting, I'm sure, but there are certainly also decisions which were based on tonality and the holistic effects each part plays in it.
Click to expand...
Obsolete Electronics sold some meticulously researched and blueprinted old Radio Spares clones. Fantastic sounding units. Simcha Delft in New Zealand did the research and study that resulted in the construction details that made them sound so good. I have one in an amp and two on the shelf awaiting amp builds. Turns out the secret to the sound was one key cost-cutting item....
 
FractalAudio said:
When it comes to MI gear it's almost always "the cheaper the better". Manufacturers are always looking for ways to save money. Sometimes this results in a positive sonic attribute. Most of the time however...
Click to expand...
And these days, it's even worse. People pull up Amazon, Reverb, or whatever, and they jump on whatever's the cheapest.
 
FractalAudio said:
Too dangerous. The uniformed user could set it to a value that causes the power amp to oscillate and then we'd be getting support calls.
Click to expand...

I seem to be good at being that uninformed user who can find oscillations. I actually kind of like them as a glimpse into instabilities and nonlinearities.

If Cliff created an "FAS Oscillotronix" amp model that could create relatively unpredictable frequency oscillations, chirps, burps, pops, noise, rumbles, etc, I'd be all over it as a cool "analog" synthesizer (minus red meter lighting up).

Joker said:
Would it be possible to use a relative scale such as -3,-2, -1, ideal,+1, +2,+3?
Click to expand...

-10 to 10 Raspiness
 
Status
Not open for further replies.
Back
Top Bottom