Power amp models and the lack thereof

[synthpenguin]

Is there a technical reason none of the major modelers have any separate power amp models?

While this might seem like a niche feature to some people, I feel like this is requested enough almost across the board—from Helix to Fractal to TMP (it’s possible on the QC via captures)—that there is demand for it that’s at least comparable to some of the more specialized amp models added to the various platforms over the years. And I’ve seen enough people who, like me, have started using external capture devices purely to be able to do this too.

There are some products that provide this at varying quality levels, like the KMA Endgame (not sure about how good that is), Axiom PAE (an apparently great analog take on the idea), and the Two Notes Opus (which has excellent power amp models, as I’ve recently learned via the GENOME software), but it would be great to be able to do that right in Helix etc instead of having to add another piece of gear (and 1 to 2 more A/D + D/A conversions) just for that feature.

There are workarounds like using full amp models or studio preamp models at specific settings combined with EQ blocks, and they can work okay if you just want the EQ curve, but the second you start pushing them things fall apart (at least on Helix), which becomes even more obvious when comparing it to a NAM or Tonex power amp capture or the Two Notes power amp models and how they respond.

I guess this becomes somewhat moot with the new gen of Helix and upcoming gen of Fractal both adding capture support, but I’m still really curious why this isn’t something any of the major players have done—whether it’s a technical reason, or just that it’s too low of a priority because of (real or perceived) lack of demand.

 

[timbuck3]

Is there a technical reason none of the major modelers have any separate power amp models?

While this might seem like a niche feature to some people, I feel like this is requested enough almost across the board—from Helix to Fractal to TMP (it’s possible on the QC via captures)—that there is demand for it that’s at least comparable to some of the more specialized amp models added to the various platforms over the years. And I’ve seen enough people who, like me, have started using external capture devices purely to be able to do this too.

There are some products that provide this at varying quality levels, like the KMA Endgame (not sure about how good that is), Axiom PAE (an apparently great analog take on the idea), and the Two Notes Opus (which has excellent power amp models, as I’ve recently learned via the GENOME software), but it would be great to be able to do that right in Helix etc instead of having to add another piece of gear (and 1 to 2 more A/D + D/A conversions) just for that feature.

There are workarounds like using full amp models or studio preamp models at specific settings combined with EQ blocks, and they can work okay if you just want the EQ curve, but the second you start pushing them things fall apart (at least on Helix), which becomes even more obvious when comparing it to a NAM or Tonex power amp capture or the Two Notes power amp models and how they respond.

I guess this becomes somewhat moot with the new gen of Helix and upcoming gen of Fractal both adding capture support, but I’m still really curious why this isn’t something any of the major players have done—whether it’s a technical reason, or just that it’s too low of a priority because of (real or perceived) lack of demand.

I thought fractal had some control over power amp types in their units?

 

[TSJMajesty]

I thought fractal had some control over power amp types in their units?

Not wrt picking which one you want to use. Like, if you pull up the Tri Axis preset, you can't then pick a 2:90 to go with it. Cliff has already modelled that Tri Axis with whatever power amp he decided to use.

As far as why you can't pick out whatever power amp you want to pair up with a pre amp, I seem to recall him saying something about the internal code, and something regarding that making him choose to not make that feature possible.

But there are all sorts of parameters available in the power amp section of the amp models- things like tube choices, grid bias, NFB, sag, variac, etc., that I'd imagine you could conjure up pretty much any power amp sound of your choosing. Although you might have to ask the "tweaker gurus" over at FAS Forum how to dial in what you're after.

I sure af don't know what to do with those deep parameters.

I just start with a factory preset that I like the amp sound of, then tweak the controls I'm familiar with to fine-tune it to my taste.

 

[EOengineer]

It would be a significant usability improvement to be able to run separate preamp/poweramp blocks in Stadium. I’d be elated if I could set up one signal chain and just tap a send after my post-preamp fx to go to the 2:90/guitar cab while the other side of that split heads to the Agoura power amp block and virtual cab/mic/FOH.

Currently, I end up having to either duplicate the post fx across paths and hope I don’t screw up the footswitch assignments or send the full amp model to the 2:90, which I don’t love. Separate is better.

All that said, there could be technical hurdles there or it’s too narrow a use case to bother supporting. A possible escape hatch would be for L6 to provide an assortment of power amp captures via proxy that could be combined with the Agoura preamps. Honestly I could live with that solution. I’ve been using homemade caps of some of my tube amps for a year now and it works very well.

 

[Lele]

Is there a technical reason none of the major modelers have any separate power amp models?

If I remember correctly, some Line 6 engineers once explained that there’s a certain level of interaction between the preamp and power amp circuits that’s modeled when you use a full amp model. You lose some of that interaction or it doesn’t behave quite as accurately if you use the preamp and power amp as separate blocks. Maybe that’s also a relatively niche request among users.

 

[Tanax]

Just guessing here.. but I suspect they've probably modeled the amp as a "whole" and can only switch components, not the layout of the model.
Maybe this is something they've looked into for the next-gen versions but I haven't seen much rumors about this at all to be honest.

 

[EOengineer]

If I remember correctly, some Line 6 engineers once explained that there’s a certain level of interaction between the preamp and power amp circuits that’s modeled when you use a full amp model. You lose some of that interaction or it doesn’t behave quite as accurately if you use the preamp and power amp as separate blocks. Maybe that’s also a relatively niche request among users.

There is interaction there but given L6 has figured out inter-block communication with amps & cabs, I doubt maintaining that interaction would be a big hurdle at this point.

 

[Progressive_disclosure]

If you’re running for example a preamp pedal you’re already not getting the preamp-poweramp interaction. I’d be fine with that on old Helix already, just feels like a frustrating deficit in what the hardware can do for me. Hoping for some updates on this for Stadium but yeah, captures work as well so Proxy might be enough.

I’m less frustrated about it now since I got a Tonex One. It does involve some extra conversions along the way so keeping it on one box would def still be preferable.

 

[metropolis_4]

I can’t believe this is still something that doesn’t exist after all these years of people wanting it and asking for it

I always wished there was a power amp model in my AxeFX so I could put a Triaxis in the rack with it

 

[synthpenguin]

If I remember correctly, some Line 6 engineers once explained that there’s a certain level of interaction between the preamp and power amp circuits that’s modeled when you use a full amp model. You lose some of that interaction or it doesn’t behave quite as accurately if you use the preamp and power amp as separate blocks.

For sure, but I think this is also a trade-off people accept in real life with preamps run into separate power amps, so it would be okay.

Just guessing here.. but I suspect they've probably modeled the amp as a "whole" and can only switch components, not the layout of the model.

That makes sense, and I think the solution then would be to specifically model tube power amp rack units.

Alternatively, I’d be fine with a generic / original tube power amp model or two! This is what Line 6 has done with the Studio Tube Pre, not to mention their original amps, so there is precedent there, and Fractal as well. Two Notes takes this approach too, but with configurable power tubes etc (which Fractal could offer too, while maybe Line 6 would offer a couple of variations instead)

 

[synthpenguin]

[fwiw the closest I’ve gotten in Helix to my favorite 6L6 power amp capture is US Princess + two EQ blocks, one before and one after (the pre EQ is essential to getting a more accurate response across the saturation spectrum imo). US Super is great too if you want higher headroom.

I did not really like the various Archetype Clean or Studio Tube Pre-based approaches I’ve seen around and tried. Always felt either brittle or overly processed to me.]

 

[jay mitchell]

Is there a technical reason none of the major modelers have any separate power amp models?

I can only speak to two examples.

1. Years ago, Cliff said he would never provide access to the internal signal chain of the amp blocks in the Axe-Fx - IOW, he would not allow separation of preamp and power amp - because it would facilitate reverse engineering his modeling algorithms.That statement applied to first-gen units. Whether it is still true is an open question.

2. The now-defunct Atomic Amplifire product line does have power amp only models. I have never used them, but they are there.

 

[synthpenguin]

1. Years ago, Cliff said he would never provide access to the internal signal chain of the amp blocks in the Axe-Fx - IOW, he would not allow separation of preamp and power amp - because it would facilitate reverse engineering his modeling algorithms.That statement applied to first-gen units. Whether it is still true is an open question.

Oh, interesting! I can see how that would make sense. I wonder if there is similar reasoning across the board, and that might be why it’s usually not directly answered when asked about either.

 

[Sascha Franck]

As many real amps offer FX loops with power amp returns, I completely fail to understand why power amp models aren't more popular.
Heck, besides being able to run whatever other preamps into them, you might want to insert some effects there, so they can take advance of some power amp chew.

 

[timbuck3]

Not wrt picking which one you want to use. Like, if you pull up the Tri Axis preset, you can't then pick a 2:90 to go with it. Cliff has already modelled that Tri Axis with whatever power amp he decided to use.

As far as why you can't pick out whatever power amp you want to pair up with a pre amp, I seem to recall him saying something about the internal code, and something regarding that making him choose to not make that feature possible.

But there are all sorts of parameters available in the power amp section of the amp models- things like tube choices, grid bias, NFB, sag, variac, etc., that I'd imagine you could conjure up pretty much any power amp sound of your choosing. Although you might have to ask the "tweaker gurus" over at FAS Forum how to dial in what you're after.

I sure af don't know what to do with those deep parameters.

I just start with a factory preset that I like the amp sound of, then tweak the controls I'm familiar with to fine-tune it to my taste.

So by power amp, you mean the tube type power ramp so like the THR 100 or the black star ID core 260s ability to choose the tube type like EL 84 etc. etc.

 

[Sascha Franck]

The now-defunct Atomic Amplifire product line does have power amp only models. I have never used them, but they are there.

They're not bad. Been running some analog preamps through them with very decent results.

 

[timbuck3]

So by power amp, you mean the tube type power ramp so like the THR 100 or the black star ID core 260s ability to choose the tube type like EL 84 etc. etc.

But with a lot more controls, of course, in a power amp like saag and what not

 

[Richard_G]

I'd love to have separate power amp modeling in both my Line 6 and Fractal gear. One use case would be to combine this with my analog preamps and preamp pedals.

 

[Shask]

I can only speak to two examples.

1. Years ago, Cliff said he would never provide access to the internal signal chain of the amp blocks in the Axe-Fx - IOW, he would not allow separation of preamp and power amp - because it would facilitate reverse engineering his modeling algorithms.That statement applied to first-gen units. Whether it is still true is an open question.

2. The now-defunct Atomic Amplifire product line does have power amp only models. I have never used them, but they are there.

That is what I remember. Discussions of providing parts of blocks would make it easier to reverse engineer what was happening.

 

[synthpenguin]

That is what I remember. Discussions of providing parts of blocks would make it easier to reverse engineer what was happening.

It’s interesting, and I guess it doesn’t apply to the preamps if a lot of the magic is in the power amp + power supply side and interplay between both components.