Impulse Response Issues

[DJHastings]

Hi, I like to use REW to correct headphones' stereo balance and frequency response using two mono impulse responses exported as a single stereo IR. I have questions about the process I use.

- When I'm creating the impulse responses, it often becomes necessary to use trace arithmetic to multiply a frequency response with a pure impulse. The problem I run into is that frequency responses are usually 20 Hz to 20 kHz, but pure impulses generated from the EQ tab are a function of sample rate and so usually range from 1 Hz to 24 kHz or something like that. When you multiply these two together, you get junk responses in both amplitude and phase below 20 Hz and above 20 kHz. How should I address this issue so that when I multiply an FR with a pure impulse, I simply get a result that ranges between 20 Hz to 20 kHz?

- another issue I've run into is that, when exporting a stereo IR using two mono IRs, REW will tell me that the export is halted because the IRs are of a different length. This is true even if I set their windows to be the same width. How do I resolve this issue?

- what is the correct way to convolve a corrective frequency response into a signal such that amplitude and phase are correct in the result?

 

[John Mulcahy]

When I'm creating the impulse responses, it often becomes necessary to use trace arithmetic to multiply a frequency response with a pure impulse.

Why would you do that? Are you using it to force an IR to be generated from magnitude data? That would be better done using "Generate minimum phase", which would let you add tails to extend the response.

another issue I've run into is that, when exporting a stereo IR using two mono IRs, REW will tell me that the export is halted because the IRs are of a different length. This is true even if I set their windows to be the same width. How do I resolve this issue?

You could use the action that trims the IRs to the window.