Question about IRs for the amp modeling and axe fx crowd

[Jan___]

OK so there's something about amp modeling (software and hardware) and IRs that I am having some trouble wrapping my OCD head around. It's about the power amp part of the IR and amp modeler.

1. The IR:
So basically you can have IRs that have been "shot" with either a tube or a solid state power amp. Some people (e.g. Cliff Chase) think it's generally best to use a neutral solid state power amp to create IRs. At the same time, a lot of the IRs everyone here is using and liking are created with a tube power amp (oftentimes a 6505).

2. The amp modeler:
Most amp modelers model the whole amp, i.e. preamp + power amp. There are some that just model the preamp and some that have an "optional" power amp (like the Axe FX), but most seem to have the tube amp baked in, like for example Amplitube.

Now here comes the part that confuses me:

Whenever I play an IR that was "shot" with a solid state power amp it sounds kind of shitty… too much mids, not enough oomph, etc. not really "clear" or "open", just flat, boring and sucky. I am exaggerating, but you get the idea.

Now I have a LOT of IRs (redwirez, old and new ownhammer, some from the forum here, etc.). The ones I consistently like the most are those shot with a tube amp. BUT: this is also the case when I use an amp model that already has a tube amp baked in. Shouldn't it bee "too much power amp" in that scenario?? This way you would basically get 2x tube amp, but it doesn't sound wrong. What does sound wrong to me is using a "full amp" with just a "Solid state IR". However, if I just use a pre-amp (like the TSE ) with a "tube amp IR" that sounds fine to me.

So in some way it seems to me that a "full amp amp model" is not able to compensate for the solid-stateness of an SS IR. The other way around works fine though. What the heck is going on here? To me it starts to seem like shooting IRs with solid state amps is generally just not cool. At least for a rock/metal type tone.

OK so I'm sorry for the long post but I am really curious what you guys think about this, and more importantly: what do you do?

Cheers
Jan

 

[deLuther]

Solid state amps also can have strong negative feedback like on tube amps with same impedance curve, of course not all, but not all SS amps is "neutral". Someone can reduce negative feedback on tube amp to have more flat impedance curve.

 

[Jan___]

Hey man thanks for your reply. I knew that tube amps differ in terms of how neutral they are but I wasn't aware about that with solid state amps. Especially with regard to impedance curve.

Still I wonder what people do with regard to solid state vs tube IRs...

 

[deLuther]

I`m have two solid-state amps, one with negative feedback and one without, first one have "tube-like" curve, second have almost Hi-Fi curve

 

[Flow Of Time]

I also noticed this, although, in my opinion, it then sounds better with the powerampsim turned off.. Have you compared the X50 with powerampsim on/off? Major difference My guess would be, that those solit state poweramps either DO colour the sound and/or, that contemporary powerampmodelling isn't as accurate as what you capture with an ir.

PS: I don't have any technical knowledge about this matter, so my statement could be utter bullshit ^-^

 

[deLuther]

Of course there is major difference between sound from preamp (i.e. X50 with PA turned off) and from PA (you can capture this signal parallel to cab), even SS PA with flat impedance curve have slight coloration.

 

[Mago]

well you can try for yourself to see if that really is the issue.

Markus did an incredible job here with his impulses
http://cabs.kalthallen.de/

and iirc he made impulses of the SAME MIC POSTITION but with different power amps (tube and SS if Im not mistaken)
so you can hear for yourself how the poweramp affects the sound or not. cause its not easy/impossible to say if you have impuleses where the other parameters vary a lot.

IMO most impulses through "metal" amps shouldnt color the sound too much, cause the poweramp most of the time isnt an essential part of the sound of the amp...not like with a jcm800, that sounds different when cranked.
With that I mean that most of those modern heads don't make as much of a sound difference above a certain level than old shool amps.
Minus of course stuff like resonance and presence settings than effect the power amp stage, like the 5150s do.
Also minus the fact that the 5150 gets honky as hell if you set it too loud.
Kind of special beast that thingy haha


Personally I like to use whatever...if it sounds good then I'll do it. Have used sims without poweramp and with poweramp sims, regardless of if the IR was made with a SS ir Tube head...whatever sounds good in the particular situation really.
I'd rather be glad that I'll have a lot of things to fuck with in the digital realm than having to do something a certain way "just because".

 

[Soul Forlorn]

Whenever I play an IR that was "shot" with a solid state power amp it sounds kind of shitty… too much mids, not enough oomph, etc. not really "clear" or "open", just flat, boring and sucky. I am exaggerating, but you get the idea.

Now I have a LOT of IRs (redwirez, old and new ownhammer, some from the forum here, etc.). The ones I consistently like the most are those shot with a tube amp.

I can't explain why but I'm in the same boat as you. I consistently prefer IRs that were shot with a tube amp over the stock ones in the Axe, Redwirez, OH, etc. for high-gain tones.

I've wondered about the same things as you but I just go with whatever works. For me that's IRs shot with tube amps and tone matches.

 

[Jan___]

Guys, thanks very much for your replies!

deLuther: thanks, that's definitely interesting. I can't run the X50 (I have a Mac) but I know what you mean!

Flow Of Time: haha, I don't think it's BS. No I don't have the X50 but I am curious to try that out when it'll be released for Mac.

Mago: I know the Kalthallen cabs, but thanks for the link! I have tried it out with the new ownhammer IRs (which are really nice by the way) - that's what's "sealed the deal" for me on liking the tube ones better. It's interesting what though you said about most metal amps… I really want to shoot some IRs with my different tube amps and see what the difference will be. Maybe next time I'm in a proper studio. And yeah, you're right - I probably overthink stuff. But it's fun to try and understand stuff like this. You definitely have a point in just using whatever works though haha.

Soul Forlorn: thanks for the affirmation. Yeah man same here, I also (try to) just go with what works. I just had this feeling and wanted to see if I'm completely nuts.


@all: happy I'm at least not the only one who has noticed this haha. Part of why I ask is I was thinking about getting an Axe FX or Kemper. I am much more drawn to the Axe but with the Kemper at least it's kind of everything baked into one profile and I wouldn't have to think about IRs… guess I'll just have to see if I can try 'em both.

 

[deLuther]

Yoy can try Ignite Amps TPA-1 instead of X50 PA.
http://www.igniteamps.com/audio-plug-ins

 

[deLuther]

There is another topic about IRs - different approaches to retrieving process.
Many IRs are made with Voxengo Deconvolver, different modes can give you slightly different, but audible, results.
Test sine sweep in this tool starts from 45 Hz, so you can have abrupt low end response:
http://www.ultimatemetal.com/forum/...olution-methodology-test-sample-impulses.html
I`m use my own sweep generator and deconvolution for IRs.

There is also additional approaches: using white noise instead of sine sweep or by using tone matching between line amp and miced signals.
Some short test between miced and two kinds or IRs (sweep and matched):
http://soundcloud.com/deluther/22102013_v1
Larger test, including noise IRs, to come soon.

 

[RiF]

I don't have much of an answer to the "why" question, but I shot an IR from my cab through the fx-return of my Dual Rec and applied that one to a Recto model from Amplitube.
The end result is VEEEERRRY similar to the Dual Rec miced through the real cabinet (I probably could not tell it in a blind test in a mix). It sounds a little more static of course, but no hint of "double poweramp" in the chain. I have to add that my Dual Rec had been quite cranked up when I shot it, so there's a fair amount of power amp flavour in the IR.

But I never heard the sound change when I turn up the power amp volume in Amplitube, but when I crank my Dual Rec (through a Palmer PDI-03, I don't want to clean up the bloody mess in my backyard from all the dead birds that fell from the sky...), the sound changes significantly to a more honky, mid focussed and less open sound. I can see none of that in Amplitube.

 

[deLuther]

Some test I`m made for myself, with comparison to miced signal:


Both power amps are solid state, but KMG 5 has strong negative feedback like on tube amps.

 

[Jan___]

Some test I`m made for myself, with comparison to miced signal:

Awesome man, thanks! I'll check em out when I get home.

 

[Jan___]

I don't have much of an answer to the "why" question, but I shot an IR from my cab through the fx-return of my Dual Rec and applied that one to a Recto model from Amplitube.
The end result is VEEEERRRY similar to the Dual Rec miced through the real cabinet (I probably could not tell it in a blind test in a mix). It sounds a little more static of course, but no hint of "double poweramp" in the chain. I have to add that my Dual Rec had been quite cranked up when I shot it, so there's a fair amount of power amp flavour in the IR.

But I never heard the sound change when I turn up the power amp volume in Amplitube, but when I crank my Dual Rec (through a Palmer PDI-03, I don't want to clean up the bloody mess in my backyard from all the dead birds that fell from the sky...), the sound changes significantly to a more honky, mid focussed and less open sound. I can see none of that in Amplitube.

LOL @ the birds. Well that's an interesting point... definitely gottta run some more experiments myself next weekend. But I agree, if they have power amp modeling in their amps it doesn't seem very pronounced in that regard.

Edit: which doesn't mean I don't like them, I actually like their newer amps quite a bit.

 

[Jan___]

Some test I`m made for myself...

Hey dude just had a quick listen to this. Definitely super interesting, thanks for sharing! Yeah this is definitely something like the difference I was hearing and referring to. Might be about the negative feedback then... as I said, interesting! Thanks

 

[onqel]

In the ampsim it all depends on how the poweramp is modeled.. if it's modeled with respect to the real amp there would most likely be negative feedback in the poweramp... that would give you twice the frequency response if you try to setup your ampsim with the same settings as the real poweramp.. a presence at 10 (e.g 6dB boost) on both real amp (impulse) and ampsim would in theory give you a 12dB boost.. The tube poweramp is usually strong in harmonics, so disabling the poweramp model will cause some of them be lost (if it's modeled well), but keeping the poweramp model will most likely force you to use different settings than the real amp

 

[deLuther]

Gyus on other forum prefered Randall implulses from the test with X50 due to flat impedance curve

 

[Jan___]

Again, guys, many thanks for your replies. A lot to think about and experiment with further. I am currently travelling but might upload a few tests when I am back home. Cheers