Power amp modeling

[vino_buono]

This is inspired by the thread on NDSP pre and power amp models, but I thought it deserved its own thread.

I find power amp modeling to be an area where relatively few solutions are available. There are a lot of preamps one can buy (employing tubes or transistors) and they can be used with a real power amp (there's plenty of them!). But if I want to use my preamp without generating real power, there are a lot less options. Here's the results of my own research.

- Power amp into reactive load: many do this and it works for them; I find it slightly disturbing to generate power to amp a signal, and then dissipate that same power. Not a green option

- With modelers, neither Helix nor Fractal have models of "just" power amps. Obviously one can use the preamp into an amp model and eq the preamp to be relatively flat, but it's more work than I'd like. Plus the preamp will still color the tone a bit. This is what I am currently doing.

- Or one can use an IR of a power amp, such as those @James Freeman provided. I tried the approach. It does sound good, but it does lack the "compression/sag" of a real power amp. For me, I like it with a JCM800, less so with a Plexi

- Or one can use a device such as Torpedo Cab M+, Nux Solid Studio, Engl Cabloader, Mooer Radar, which have a power amp simulation. From what I have read, the power amp simulation in those devices is realtively simple, not fully linear like an IR, but not fully realistic either.

- A profiling device? I have no experience with those, but I imagine a Kemper, NDSP, Tonex could profile just the power amp? This could be a sensible solution. At least the Tonex is not so expensive and would probably make for a very good power amp.

All the solutions above are digital. Now, if I spend money on a great analog preamp, it also makes sense to have a fully analog chain. The only device I have found that emulates a power amp at low power is the Axiom PAE-1 (new version PAE-2 in the works). It is essentially a transistor-based low-power emulation of a power amp, which can be configured in a very flexible way. It has very good (but few) reviews on TGP.

I guess what I fail to understand is whether the scarcity of analog solutions to power amp emulation is because there is really no need of those, because it is difficult to pull off from a technical point of view, or whatever else. What do you think?

 

[laxu]

If you want to play a preamp through a guitar cab, you need a poweramp so no need for a simulation.

If you have digital modeling, it usually already has poweramp modeling so again no point.

A poweramp sim doesn't really fit into a lot of scenarios other than analog preamps. The preamps might have some form of this built in, I believe the Victory models that have a poweramp do, Friedman IR-X has something. Whether it's any good I don't know.

But ultimately it's a pretty niche category for a specific user so I'm not surprised the options are few. There's also the Ignite Amps TPA-1 poweramp sim VST plugin if you want to give that a spin. I once tried it with a Bogner Goldfinger's preamp from fx loop send and I thought it worked pretty decently.

I've tried my Strymon Riverside as a preamp. It's a tube preamp-ish analog/digital drive pedal. Studio Rats has a good video on it using it direct to IRs. To me it sounds better if I put the Strymon Iridium set clean in between, so there's definitely something to amp/poweramp simulation in this scenario. But it's a bit of a niche one because the Riverside can't drive an actual poweramp on its own, I once tried Riverside -> DIY Hudson Broadcast @ 27V to increase output -> Fryette PS-100 -> 4x10 cab and that sounded like a pretty glorious Marshall-ish amp!

 

[SKU]

There is one scenario where you want to use something like Synergy amps but rather than using a tube power amp you want to use a cheaper "linear" SS PA with a tube power amp sim of your choice. Or maybe you want to use your fully analog rig with IRs and only have IRz ( which is basically an EQ ) be the digitalz portion of your chain.
TBH I doubt any of these analog solid state power amp sims can simulate a tube power amp but still ... there's place for innovation. Really curious about the PAE too.

 

[vino_buono]

A poweramp sim doesn't really fit into a lot of scenarios other than analog preamps.

Correct. But I see a few use cases for that. 1) pedal preamp into power amp emulation. 2) Amp send into power amp emulation. In both cases it would be nice to mix and match the preampo with different power amps to get new tones. Isn't that the reason why @James Freeman asked for separate preamps and poweramps in the Helix? This would be the same, but analog. But yes, maybe it's a niche.

Now what would REALLY bother me is that I spend my money on the PAE pedal, only for Line6 to provide separate poweramps in the next firmware...

 

[ballhawk]

Really curious about the PAE too.

I own the PAE-1. I've experimented with it in the loop of my Catalyst 100, in the loop and in front of the quilter superblock US (surprisingly seemed to work better in front). I have a few more tests to do with it, especially with the valvenergy M and V type preamp pedals which I like very much.

To clarify for those who may not know, it is a 9v emulator pedal NOT a power amp.

It does work well IME. It adds some heft and tube-like quality to the signal chain. Really sounded great in the input of the quilter with a modded Boss OD-3 feeding it. Lots of options. Find out more at https://axiomeffects.com/collections/frontpage/products/power-amp-emulator-pae-1

I wish Line6 would take some of the rack power amp only offerings (mesa 20/20 and 50/50, Carvin ts100, Peavey 50/50, etc.) and model them.
Maybe it's just a question of demand .

Now what would REALLY bother me is that I spend my money on the PAE pedal, only for Line6 to provide separate poweramps in the next firmware.

Or worse put them in their next mini box and lure us in to buy it but they wouldn't do that....would they?

 

[Slammin Mofo]

I love preamp/poweramp setups because they allow you to mix and match tones that otherwise would not be possible. They also sound different than full amps with integrated pre- and poweramp sections. Isolated preamps and poweramps have to use their own respective power supplies and this alters the tone more than people might think at first. Running poweramps into a load might not make economical sense, but if you want the tube poweramp coloration, which can change the tone dramatically, it's one of your only options.

At the end of the day, it's just different colors in our tonal pallette.

One can do just fine without ever touching preamps and poweramps, but, as a rack fanatic, I like both worlds equally.

I also excplicitly made my recent poweramp pack because I saw a distinct lack of digital poweramp options. I really wish more companies would offer high-quality algorithmic poweramp models or more people would capture their poweramp sections. It's fun trying out a Marshall style preamp into a 6V6 poweramp just to see what happens and that's simply not possible with full amp captures.

Poweramp sims are also great for pedal based rigs, you can record into your DAW with the drive pedals and still not lose too much in the way of organic tones.

 

[MirrorProfiles]

I really wish more companies would offer high-quality algorithmic poweramp models

+1 on this, but especially for algorithmic poweramp models that have all the options to adjust SIC behaviours and IR’s together. Would be awesome to run a real amp’s FX loop into a plugin handling the poweramp+cab interaction and IR together.

 

[djd100]

Fractal has all the tools available to create great tube power amp sims...

You can neutralize the Amp Block's preamp for practical purposes by using the Tube Pre or a Clean Amp Model and keeping the preamp section as linear as possible...

a) Minimize the front-end Gain and Input Trim.
b) Make that gain up with the Master Trim and Master Volume to taste.
c) Bias the preamp like the Tube Pre (or not...).
d) Use the Null Tonestack.
e) Turn off the Cathode Follower.
f) Turn off Preamp Sag.

...and finally, tune it how you like as needed with the power amp, power tube, and power supply params, plus the preamp and power amp biasing, power tube selection, and preamp triode freqs (plate bypass caps). You can actually do a lot, and get perfectly workable power amp sims this way. I prefer to use a Amp Model that relates to my Tube Preamp, and then dial in the Tube Pre's preamp parameters and the above changes vs adding the power amp parameters to the Tube Pre model, but either will work. I've been doing this for my Tube Preamps since the Gen 1 Ultra, works great and gets pretty close (closer than the Two Notes and other generic power sections, though they also can work quite well!), and most importantly it eliminates the heat, weight, and sweet spot SPL limitations of the real deal.

If using a Fractal model with multiple Amp Blocks, you can use one as a preamp (turn off the power section), the other as a tube power amp (see above).

Most guitar oriented rack mount tube power amps were just a driver/buffer stage, followed by a PI and the power section, that's it, no tone shaping aside from the first stage's coupling caps and NFB (presence and depth etc). You can fake the first stage's coupling caps with the Amp Block's Input EQ's for some Mesa's that rolled off the low end quite a bit, and use the Presence and Depth controls. You also have the Output EQ as well, which can be placed either pre or post.

Good luck!

 

[SeeD]

Yeah, I hope we will see more poweramp options in all the modelers, as it s fun to mix and match stuff.
The ToneX can only do 1 `capture` inside the pedal ( you could do more inside a DAW) , and the same with Kemper ( but only 1 )
This is were the Quad Cortex is a cool device, as it can do capture+capture+capture and so on in the same preset. This makes more sense when mixing and matching preamps and poweramps.



Here you can hear that changing the poweramp captures make a lot of changes to the sound
PS: Both the Synergy VAI capture and the Friedman SS poweramp capture was made by Slammin MOFO I made captures of his captures ( welcome to 2024 haha)

 

[Whizzinby]

The ToneX can only do 1 `capture` inside the pedal ( you could do more inside a DAW) , and the same with Kemper ( but only 1 )
This is were the Quad Cortex is a cool device, as it can do capture+capture+capture and so on in the same preset. This makes more sense when mixing and matching preamps and poweramps.



Here you can hear that changing the poweramp captures make a lot of changes to the sound
PS: Both the Synergy VAI capture and the Friedman SS poweramp capture was made by Slammin MOFO I made captures of his captures ( welcome to 2024 haha)

Nice. Almost makes me want a Dual Cortex.

 

[GTR37]

Nice. Almost makes me want a Dual Cortex.

Your dual cortex will happen they just hit me up to do a survey and question
The want to talk to owners of the FM3 especially and HX stomp , Headrush MX5 ( so you can see where this going)
They were posting for people on the fb group to join

 

[SKU]

Your dual cortex will happen they just hit me up to do a survey and question
The want to talk to owners of the FM3 especially and HX stomp , Headrush MX5 ( so you can see where this going)
They were posting for people on the fb group to join

WHAT ABOUT PEOPLE LIKE ME WHO WANT AN OCTOCORTEX?
You know the people who build a product are engineers when they name it after the number of processors it uses.

 

[JT]

A static capture of a power amp without any sort of 1:1 correlation to said power amp controls to allow for dialing in said power amp "accurately" is a big nothingburger for me. A rabbit hole that doesn't need to exist.



aka me=

 

[SKU]

A static capture of a power amp without any sort of 1:1 correlation to said power amp controls to allow for dialing in said power amp "accurately" is a big nothingburger for me. A rabbit hole that doesn't need to exist.



aka me=

Other than presence and rarely resonance what other controls does a power amp have besides Volume?

 

[JT]

Other than presence and rarely resonance what other controls does a power amp have besides Volume?

For me; it seems like the delineation between pre and power section is a bit murky. And the interaction between said sections murky as well. So it becomes a thing where I'm like 'how accurate is this modeled preamp and modeled power amp that are being treated as separate things on top of the fact that we're not talking a bout a real life disconnect between 2 normally tied together systems; we're talking about an emulated disconnect between two emulated systems"


Way too many mental gymnastics in this discussion for my dumb brain.

 

[SKU]

For me; it seems like the delineation between pre and power section is a bit murky. And the interaction between said sections murky as well. So it becomes a thing where I'm like 'how accurate is this modeled preamp and modeled power amp that are being treated as separate things on top of the fact that we're not talking a bout a real life disconnect between 2 normally tied together systems; we're talking about an emulated disconnect between two emulated systems"


Way too many mental gymnastics in this discussion for my dumb brain.

This makes sense ...

 

[SeeD]

For me; it seems like the delineation between pre and power section is a bit murky. And the interaction between said sections murky as well. So it becomes a thing where I'm like 'how accurate is this modeled preamp and modeled power amp that are being treated as separate things on top of the fact that we're not talking a bout a real life disconnect between 2 normally tied together systems; we're talking about an emulated disconnect between two emulated systems"


Way too many mental gymnastics in this discussion for my dumb brain.

But a modeled amp is ok ?
Fractal is making modeles all the time, as is Line6, NDSP.
I think we can get a good model of anything these days. The tech is there

 

[JT]

But a modeled amp is ok ?

Yes.

 

[jellodog]

Other than presence and rarely resonance what other controls does a power amp have besides Volume?

Wapoosh?

 

[SeeD]

Yes.