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Low Cut, High Cut


The cutoff frequency of most filters is at the -3 dB point in the curve. A 6 dB/octave (aka 1st order) filter will roll off an additional 6 dB signal each octave beyond the cutoff frequency. A 12 dB/octave filter (aka 2nd order) would roll off 12 dB per octave.

For example, a 6 dB/octave high pass (low cut) filter set at 1 kHz would give you:

above 1 kHz = pretty much flat.
1 kHz = -3 dB
500 Hz = -9 dB
250 Hz = -15 dB
125 Hz = -21 dB
62.5 Hz = -27 dB
31.25 Hz = -33 dB

a 12 dB/octave high pass (low cut) filter set at 1 kHz would give you:

above 1 kHz = pretty much flat.
1 kHz = -3 dB
500 Hz = -15 dB
250 Hz = -27 dB
125 Hz = -39 dB
62.5 Hz = -51 dB
31.25 Hz = -63 dB

As you can see the 12 dB/octave filter drops off much faster even though they are both set to the same cutoff frequency.


New Member
Just found this post. Bass player coming over from the Stomp to the FM 3.

Jon Willis has a shit ton of techhy info for bass mod,ing,t hat can be applied, IMO, to any modeler (Dr. Tome’s Secret Helix lab).

So I’ve gone with cuts at 64 and 5 to 6k to taste. Steep slope, either 18 or 24 db. I play a 4 string, so low E is approximately 41hz. The cut at 64 does wonders gig volume, whether you forum direct to FOH, or into a power amp and cab on stage. Clear, tight lows, with no mud. The bass now sits well in the mix. Stops the “bloom”. Sound men love it. The hi cut gets rid of the sizzle.

And I do it in the amp block, as the Fractal parameter controls are much much better than Helix.

Try it and tell me what you think.

Again, I do this for gig volume in a full band context.


It's a bit more complicated than that. Moving the microphone further away from the cabinet does IMO not produce "amp and cab in the room feeling". The industry standard for guitar tones has been close miked cabinets for pretty much forever.

Once you start pulling the mic away it's less about the actual cabinet and more about the room you're using. Your mic starts to capture more than one speaker simultaneously and all the reflections from the walls, floor and roof etc. Usually what you end up with is something really honky and phasy sounding with a long reverb tail. (Longer than the Axe-Fx IR format) Actually it would make more sense to just shoot room IR's that have nothing to do with the cabinet and use those IR's for an extremely natural reverb but personally I think the reverb block in the Axe-Fx does the job really well.

I think this is something that's really interesting and I'm sure many people would love to try it out but I have a feeling it's something that will not sound as good as the IR's we have now and the majority if not all people will agree. It's all speculation though. I love IR based reverbs so I'm sure it'll sound awesome but it's not going to be a night and day difference between a high quality reverb.
And using an anechoic room is prohibitively expensive and may not give the right results either.


A far-field measurement is more than just pulling the mic back. You need to perform this measurement in a sufficiently large space so that there are no reflections from the walls and ceiling until AFTER the direct signal is obtained. The microphone, usually a measurement mic like an Earthworks, is setup to make a "ground plane" measurement. This means putting the mic capsule almost touching the floor. The signal captured by the mic is then the direct path first and any reflections occur later in time and can be removed. Another option is an anechoic chamber but that's even more impractical due to the scarcity of such chambers and the associated cost.

It's still no panacea though as what we hear in the room is a combination of direct and reflected sound. A far-field IR captures just the direct sound but when we listen to a guitar cab we are hearing the direct sound plus a reflection off the floor (and later reflections from the walls and ceiling). That's partly why a cab on the floor sounds different than raising it up on a stand or tilting it back. As you raise or tilt the cab the floor reflection path length changes.

Personally I doubt we'll ever get IRs that sound exactly like listening to a cab "in the room". If you want that sound, IMO, then use a traditional cab. Our products were the first to allow the user to send a signal with cab modeling to FOH and tap off before the cab modeling and send that to a traditional cab. Best of both worlds.

For me personally I just use the high and low cuts and I get great tones through my studio monitors. This is what they've been doing in recording studios for decades and there's no denying how great the guitar tones can be.
Are you still using the same kind of settings today? 80hz low cut, 7500khz high cut w/12dB/octave?
Also, what studio monitors were you using then / using now? Do you dial tones in on monitors around the 90dB area?

Hope you don’t mind me asking; just curious of your current workflow and monitoring. 🙂
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