Confusion regarding IR

[markus]

Hey guys. Another couple of questions re. Impulses. Are these always gathered with a poweramp driving the speaker? I know I've downloaded a few that specify a JJ tubed poweramp. There is also one on the axechange (Noarin?) that specifies a Soldano poweramp. Do you guys typically turn off the Axe poweramp sims when using these types of IR's? I've noticed that when I use some of these, I immediately have to shelve at 140-200 Hz from 5-10 db, whereas when I turn the Axe sag to 0, I don't have to shelve anymore.

I realize that I probably shouldn't worry too much, and should just use my ears, but I'm curious to what others are doing.

Thanks,

Mark

 

[Jay Mitchell]

Hey guys. Another couple of questions re. Impulses. Are these always gathered with a poweramp driving the speaker?

Something has to provide the signal to the speaker. That something is, without exception, a power amp. I think you meant to ask if there is a tube amp driving the speaker, right?

I know I've downloaded a few that specify a JJ tubed poweramp. There is also one on the axechange (Noarin?) that specifies a Soldano poweramp. Do you guys typically turn off the Axe poweramp sims when using these types of IR's?

An impulse response cannot contain the nonlinear (distortion/compression) effects of the behavior of a power amp or speaker. It can only contain linear effects (e.g., frequency response). There is no way to replace a power amp sim with an IR.

 

[markus]

Something has to provide the signal to the speaker. That something is, without exception, a power amp. I think you meant to ask if there is a tube amp driving the speaker, right?

Absolutely, Jay. I definitely meant tube amp.

An impulse response cannot contain the nonlinear (distortion/compression) effects of the behavior of a power amp or speaker. It can only contain linear effects (e.g., frequency response). There is no way to replace a power amp sim with an IR.

Thanks for clarifying that. Although, I'm amazed at the differences between some of these IRs. Some have HUGE peaks at 150ish Hz (17 dB) while others seem more manageable at 10dB or so. Assuming these were the same speakers, I assume it would be the cab resonance that would affect this frequency?

Anyway, thanks for the response and any other info, Jay. Your help is much appreciated!

Mark

 

[xrist04]

Some things may account for some of the differences, like mic placement, mic type, etc.

 

[javajunkie]

Some things may account for some of the differences, like mic placement, mic type, etc.

Not to mention post-processing.

 

[Clawfinger]

I did some IR's the other week with a Krank rev+ as poweramp (6550 tubes), and the difference compared to the QSC SS poweramp I usually use, is ridiculous. It sounds like it's been scooped like an old Norwegian black metal album. I suggest using Guitar amp-made impulses with preamps, unless the scoop is a welcomed feature.

 

[markus]

I did some IR's the other week with a Krank rev+ as poweramp (6550 tubes), and the difference compared to the QSC SS poweramp I usually use, is ridiculous. It sounds like it's been scooped like an old Norwegian black metal album. I suggest using Guitar amp-made impulses with preamps, unless the scoop is a welcomed feature.

So, you say I should try to avoid IR's that use a tube poweramp to drive the speaker?

Oh, and thanks for all the comments, fellas! The knowledge I gain around this place is invaluable.

Mark

 

[Clawfinger]

I did some IR's the other week with a Krank rev+ as poweramp (6550 tubes), and the difference compared to the QSC SS poweramp I usually use, is ridiculous. It sounds like it's been scooped like an old Norwegian black metal album. I suggest using Guitar amp-made impulses with preamps, unless the scoop is a welcomed feature.

So, you say I should try to avoid IR's that use a tube poweramp to drive the speaker?

Well, the eq is different, and as you wrote, a different eq is necessary to get what you want. There are no rules, just go with what makes you happy.

 

[markus]

I did some IR's the other week with a Krank rev+ as poweramp (6550 tubes), and the difference compared to the QSC SS poweramp I usually use, is ridiculous. It sounds like it's been scooped like an old Norwegian black metal album. I suggest using Guitar amp-made impulses with preamps, unless the scoop is a welcomed feature.

So, you say I should try to avoid IR's that use a tube poweramp to drive the speaker?

Well, the eq is different, and as you wrote, a different eq is necessary to get what you want. There are no rules, just go with what makes you happy.

Hehe...ok, sounds good. Thanks for the advice.

You know, I'm glad I downloaded all these other IR's, as it gives me more stuff to play with, but I'm angry that I downloaded all these other IR's, because it gives me more stuff to play with! I can't settle on one thing. :mrgreen:

Mark

 

[Clawfinger]

You know, I'm glad I downloaded all these other IR's, as it gives me more stuff to play with, but I'm angry that I downloaded all these other IR's, because it gives me more stuff to play with! I can't settle on one thing. :mrgreen:

Mark

Been there done that.

The big problem is that each and every IR on the internet (maybe with an exception of the modeler IR's) are made with a sweet spot in mind. But to be able to recreate that, one would need the whole signal chain AND the hands playing the guitar/bass. Always look for IR's that are made with similar equipment as you'd use yourself. As an example, I've reamped an LTD Viper w. EMG81's and the character of the guitar made my EMG81 equipped Prophecy sound like a sumo wrestler on steroids. I had to re-tweak the drive, amp and mic placement, and after three sessions I'm not quite there yet.

You could start with an IR that contains the cab you're interested in, and use ONLY that for a while. With that approach, you'll get better in tweaking the "important" stuff. If you have to crank something to get your sound, maybe it's time to reconsider another IR. A guitar sound don't need a +/-15db tweak.

Good luck man.