Axiom IR loading - just loading an EQ curve and not the actual IR?

[FarmerDave]

I just did some tests with the IR loading function discussed here:
https://www.bluecataudio.com/Blog/tip-o ... itar-cabs/

It sounds very cool, but in my tests is not a 1-1 when compared to another plugin with the same IR loaded.

It appears to me that the Axiom IR loaded simply loads an EQ-curve based on the IR that gets loaded. It's cool that we can save that curve which then seems independent of the IR file. If I remove that IR file and relaunch AXIOM, the IR isn't missing, which further tells me Axiom is just loading an EQ curve.

This is all cool and still sounds very good, but I'm just trying to confirm this is the case, because the curve and the IR it comes from actually sound very different.

[Blue Cat Audio]

It is actually loading the IR (and saves it into the session/preset so you do not need the file anymore). It is a true IR loader and convolution engine. You can even load Reverb IRs in there!

There are two things that could make it sound different:
1. Before loading the IR, make sure that you have a flat EQ, as both the IR and EQ are combined together, and after loading make sure that the mix and shift parameters are set to their defaults.
2. The IR is not truncated at all, whereas some other IR loaders sometimes have a limit in the number of samples they can use. This could affect the tone in the low end (the IR looses it's precision in the lower frequencies when truncated).

[FarmerDave]

Thank you for this confirmation! I kept playing with it and it seems like when I drop it in, the level of the IR is 3db down. When I bring it back up I can much more closely match the other IR loaded in another VST. I'll have to figure out why it was 3db down as I had started with as "default" an EQ curve as possible. Maybe whatever preset was loaded into post-FX was already -3db.

All those tricks I had done, trying to avoid operator error as much as possible. I think it's mostly the level. I should've tried a reverb IR!

This is fantastic news that it's a true IR loader! I can confirm a reverb IR works. Loving this.

Thank you!

[FarmerDave]

On further testing yep, all the EQ, shift, etc., don't reset when an IR gets imported.

Thanks too for your note about how the EQ & the IR get combined! That is a major factor.

I'll make sure from now on to start with the Post-FX preset "Flat" before bringing in an IR.

[Blue Cat Audio]

Yes, some normalization occurs while loading an IR, because they do not all have the same level, so you have to compensate somehow to avoid huge jumps in gain depending on the IR that you load.