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IR vs parametric EQ

gdgross

Veteran
guys i did some eq matching (in protools) on my acoustic instruments, using an eq match feature to make the DI signal sound as close to the mic'd signal as possible. I know some people bake these into an IR.

Is there any advantage to doing that, compared to just adding a parametric eq block (assuming I have enough bands/slope etc options as the eqs in my pro tools.

Thanks!
 

Atte

Inspired
But IRs have a length, which would be the room of recording or something , so the eq would be much drier.
 

Sixstring

Axe-Master
From what I can remember, pretty sure the longer the I/R sample leignth is (200 ms) the greater the lowend information will be.
 

Dave76

Inspired
Fractal's "Normal" resolution IR is 1024-points across the frequency spectrum. I believe the GEQ block tops out at 10 bands and the PEQ at 5. You aren't going to get nearly the same result using an EQ block instead of an IR. The IR also captures phase response that you wouldn't be able to reproduce with the EQ blocks.
 
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barhrecords

Axe-Master
guys i did some eq matching (in protools) on my acoustic instruments, using an eq match feature to make the DI signal sound as close to the mic'd signal as possible. I know some people bake these into an IR.

Is there any advantage to doing that, compared to just adding a parametric eq block (assuming I have enough bands/slope etc options as the eqs in my pro tools.

Thanks!
The advantage would be an IR could result in a tighter match eq curve. A PEQ would have fewer "points" in the EQ curve and probably wouldn't be as accurate a match as using an IR.

It might sound "good enough", via a listening test, to use a PEQ though. In that case, the extra work of using an IR would be moot.
 

gdgross

Veteran
Thanks guys, i figured they are the same in this case.

Actually shooting an IR in real life would bake in the room tone, but in this case it's just an eq match, which *sort of* gets at the room if it has any tonal characteristics, but doesn't address the any time effects.
 

vick1000

Inspired
IRs are just an EQ/Filter, but when creating them, they are "infinitely" more variable. Depending on the IR, they can be replicated with any EQ that has enough range. In the digital realm, it's almost moot. The purpose of an IR is replication of everything between the power amp and recording interface, without the guesswork of an EQ.
 

Ludwig77

New here
So if I want to roll off say 100-150 hz on the low end and maybe 10k and above on the high, can I do this on the IR and SAVE using an extra EQ block and get the same results?
 

mr_fender

Fractal Fanatic
It does, but this just changes the EQ curve, it doesn't generate any room reflections.
With convolution, yes it can. The waves get multiplied together, so each sample of the incoming signal can generate data for the full length of the IR wave. You end up with "smearing" in the time domain. That's how convolution reverb works. It's basically the same process except reverb IRs are typically much longer, like several seconds or more, to capture much later reflections. Room reflections in cab IR's are usually not as obvious because they are usually close mic'd. The direct sound from the speaker cone ends up being way louder than the room reflections because the mic is only a few inches away. It sort of drowns them out.
 

Rex

Legend!
- PEQs and GEQs don’t have enough frequency bands to accurately simulate a real cab. Back in the day, modelers actually used EQs to simulate guitar cabs. It sounded approximately like a cab, but not nearly as accurate and detailed.

- Longer IRS will capture the low end of the cab response in greater detail.

- You don’t have to worry about capturing the room sound in your IR. When you close-mic a cab, the direct sound from the speaker dominates everything else, and room reflections get buried by the direct sound.
 
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