Post cab eq

Dave Moore

Member
I'm curious if most folks are using high and low cuts after the cab (or in the cab block)? It seems to me that the frequency response on the axe is extended a bit on both ends. I'm mostly a clean fender guy so I'm sure this may not apply in all cases, but I find I have to filter out the extreme highs a bit. I also think a lot of the presets benefit from some low shelving after the cab.
 
I'm using the Cab Block to cut 80hz on the low end. That and 80hz on the input EQ in the Amp Block is all that's needed IMO. Sounds stellar this thing together with some preamp drive and saturation together with the EQ in the cab block!
 
Also since Cygnus not needing to use cab EQ as much. Used to have to have a pretty severe cut in highs.

Nowadays I use a pretty big pre cut in the amp block (80-100) and usually leave the cab alone.
 
Take a look at the IR length in the cab block as well. Going from “Max” to “256” does a massive, massive difference when it comes to cleaning up the low end. A “Max” it’s totally out of control on my system. That has more impact than the low cuts actually.
 
Take a look at the IR length in the cab block as well. Going from “Max” to “256” does a massive, massive difference when it comes to cleaning up the low end. A “Max” it’s totally out of control on my system. That has more impact than the low cuts actually.
Interesting!
 
Take a look at the IR length in the cab block as well. Going from “Max” to “256” does a massive, massive difference when it comes to cleaning up the low end. A “Max” it’s totally out of control on my system. That has more impact than the low cuts actually.
The math guys can chime in here, but as I recall, truncating the IR has other undesirable effects.
 
The math guys can chime in here, but as I recall, truncating the IR has other undesirable effects.
Can you elaborate on this? I've never enjoyed my Axe FX III as much as I do now when I realised that shortening the IR really helped taming the very boomy low end. Now it's tight and great. I mainly use OwnHammer 3rd party impulses so I don't know if that makes any difference to the factory IR:s (which partly also consists of OwnHammer IR:s)
 
Can you elaborate on this? I've never enjoyed my Axe FX III as much as I do now when I realised that shortening the IR really helped taming the very boomy low end. Now it's tight and great. I mainly use OwnHammer 3rd party impulses so I don't know if that makes any difference to the factory IR:s (which partly also consists of OwnHammer IR:s)
Thanks for pushing me to be more specific.
And so much for my memory about this, it's actually more complicated than "longer (or shorter) is better", and I'm 100% not an authority.

Here's a smattering of quotes from Cliff; there are some big threads on the subject (search "ir length", user FractalAudio).
About 5.3 ms. The length doesn't determine the amount of bass. It determines the resolution. If there is a sharp resonance in the bass response a short IR will smear that resonance causing it to be wider than it actually is.
I've been experimenting with IR length lately and keep finding that I like a shorter length. So I gave some thought to it and I think the reason is that a shorter IR trims off the early reflections.

As I stated over at The Argument Gear Page:
A 1024 sample IR is over 20 ms. If there is a wall 5 ft. away that puts a reflection smack dab in the middle of the IR. The Redwirez IRs you can see (and hear) the ceiling reflection pretty clearly (ceiling was probably about 8 ft). Using a shorter IR removes that reflection.

I've actually been turning down the IR length lately on my personal patches, typically 512 samples, as I find it makes the IR "clearer". While the push in the industry has been towards longer and longer IRs I'm not sure that's a good thing unless you are careful with your IR capture to ensure that you aren't capturing reflections.

Some IRs, particularly ported bass speakers, may need the longer length to capture the low end with sufficient detail but the average guitar cab is probably fine at 512 or even less samples. Heck, prior to the original Axe-Fx some products were even using 128 samples.

The next time we go into the studio to shoot IRs I'm going to lay the speakers on their backs to try to eliminate the floor reflections. Or maybe just lean them back, say, 45 degrees.
I should add that for this particular IR I believe the ideal length is 512 samples. 256 is too short as there is significant energy beyond that. 1024 is too long as there is a reflection around 550.
FWIW, I almost always reduce IR length on my personal presets. Usually 512 or 1024. I like the lack of reflections.
 
In my experience, hi/lo filters before or inside the amp block do more to change the feeling of the tone. Filters after the amp (in the cab block or a peq) seem to do more about shaping the actual sound of the tone.
 
Thanks for pushing me to be more specific.
And so much for my memory about this, it's actually more complicated than "longer (or shorter) is better", and I'm 100% not an authority.

Here's a smattering of quotes from Cliff; there are some big threads on the subject (search "ir length", user FractalAudio).
Cool! I’ll continue to use 256 though as it sounds killer on my system.
 
The Smoothing parameter for each cab has a similar effect of "blurring" any really sharp peaks in the IR, but it does so for the whole frequency range.
 
I use a PEQ block with steep cuts at 69Hz and 8600Hz on ever preset to get rid of any rumble or zizz. It has my F/M compensation setup built in as well....
 
Interesting about shortening IR length, I was under the impression that longer was better, but I'll definitely give this a try.
 
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