A thought/question about cab impulses...

[nwright]

In reading up/trying out cab impulses on tracks, I read people saying that this is only capturing the preamp phase of an amps characteristics.

My though/question would be...If one sends the sine wave through their amp's power amp input at the appropriate level, wouldn't the power amp's tone/colour be imprinted into the impulse generated? So, not only would you get the mic/speaker combo, but you'd also get the tonal effects of the power section of your head?

Of course, you'd be using the power section imprint of just the one used to generate impulses, even if you DI'd guitars from different amps.

Or, am I crazy or this been discussed before?

 

[Mutant]

My though/question would be...If one sends the sine wave through their amp's power amp input at the appropriate level, wouldn't the power amp's tone/colour be imprinted into the impulse generated? So, not only would you get the mic/speaker combo, but you'd also get the tonal effects of the power section of your head?

Yes and no.
You would capture your poweramp's frequency response, but not its tube character.

Or, am I crazy

Yes you are !

this been discussed before?

Possibly.

 

[nwright]

Yes and no.
You would capture your poweramp's frequency response, but not its tube character.

Well, those of us who play non-bias modded 5150's/6505's aren't missing much character then, are we!

 

[Student]

Ideally an impulse would be made with a white noise blast directly into the cabinet and with an absolutely flat mic positioned to emulate the sound of the speaker, but most people would want an impulse of a specific mic at a different sounding position, not to mention they typically don't have an anechoic chamber and so on.

A tone generator capable of white noise, and a transparent amplifier into the cabinet, this would be best when impulsing a mic at a certain position. Also flattest response would be around 80dB SPL at the mic position.

Short answer, no one cares enough about the coloration to really justify a change, it's not broken, so don't fix it.

For the many bedroom studios, the impulses sound good, so we use them, if they're bad, we don't...just trust your ears, or mic the cab.

Keep experimenting, and record record record.

 

[GuitarMaestro]

Yes and no.
You would capture your poweramp's frequency response, but not its tube

???? What nwright proposes is exactly how guitarhack, etc. do their impulses. They go into the fx return, therefore capturing only the character of the power amp section + speaker + mic and bypassing the preamp. The power amp input on all tube heads I saw is basically the same. An input BEFORE the tube power amp. Why do you think it would not capture the tube character?

 

[Mutant]

Why do you think it would not capture the tube character?

Because that is how convolution works.
Convolution is a linear process and tube response is non linear.
Plus convolution works on frequencies and tubes work on amplitudes.

 

[Mutant]

btw Student's post above yours is so full of wisdom he should change his nick to Teacher.

A tone generator capable of white noise, and a transparent amplifier into the cabinet, this would be best when impulsing a mic at a certain position.

 

[GuitarMaestro]

Because that is how convolution works.
Convolution is a linear process and tube response is non linear.
Plus convolution works on frequencies and tubes work on amplitudes.

I dont think it is that easy. A tube poweramp of a guitar head sounds very different than a hifi power amp and you hear that in the impulse very much. The characteristics of the poweramp used for doing the impulse has a big influence and therefore you capture some of the tube character if you use a tube power amp.

But my point was just to make clear to nwright that most impulses passed arround on this board were done through the poweramp of a guitar amp as you kinda made it sound like this is something unusual and bad.

 

[GuitarMaestro]

Because that is how convolution works.
Convolution is a linear process and tube response is non linear.
Plus convolution works on frequencies and tubes work on amplitudes.

I dont think it is that easy. A tube poweramp of a guitar head sounds very different than a hifi power amp and you hear that in the impulse very much. The characteristics of the poweramp used for doing the impulse has a big influence and therefore you capture some of the tube character if you use a tube power amp.

But my point was just to make clear to nwright that most impulses passed arround on this board were done through the poweramp of a guitar amp as you kinda made it sound like this is something unusual and bad.

 

[Mutant]

I dont think it is that easy. A tube poweramp of a guitar head sounds very different than a hifi power amp and you hear that in the impulse very much. The characteristics of the poweramp used for doing the impulse has a big influence and therefore you capture some of the tube character if you use a tube power amp.

A vacum tube adds frequencies (harmonics) - convolution plugin can't do that.

But my point was just to make clear to nwright that most impulses passed arround on this board were done through the poweramp

True dat !

you kinda made it sound like this is something unusual and bad.

False dat !

 

[GuitarMaestro]

A vacum tube adds frequencies (harmonics) - convolution plugin can't do that.

Yeah thats true....nothing like the real thing!
But it's still a big difference if you use a tube amp or something else for making the impulse.