Matching Low Cut in Cab to Low Res Frequency in Amp Block?

Mateo11

Mateo11

Inspired
Do any of you guys do this? I keep thinking I read it somewhere but not sure exactly sure to be honest.

Example: Amp Block under "Speaker" Tab has Low Res Freq at 100. Do you match your Low Cut then in the Cab block to 100?

I still just use my ears but have found I generally end up very close in that area anyways.......curious if any of you guys do this?
 
It does make a difference, sometimes quite significant: to have the resonant frequency (amp block speaker page) to match the speaker IR (also for an actual cabinet). Ideally, this is below the frequency of the lowest fundamental of the instrument (82hz low E on guitar).

*If your resonant frequency is at 100hz: that seems rather high - more like for an 8" or 10" speaker. Typically, 12" speakers have a resonant frequency around 75hz, and will sound much better and more balanced over their entire range. I'd get that right first. Otherwise it may exhibit a persistent honk at 100hz and its overtone series (since it will emphasize a range where guitars typically already have a frequency bump).

The cab roll off, as Yek points out, is different: but is still very important. It took me a while to figure out that more aggressively attenuating the highs and lows (-6db/octave in the cab block) around 4500hz (as low as 3900hz or as high as 12k) and the low cut: (generally between 80hz and 180hz) - depending on amp, guitar and genre - were the key to getting the tone to really open up, and for FRFR/IR to more closely match the sound of real cabinets I enjoy.

As there are so many variables: doing it by ear is de rigueur.

*EDIT: Correction to above: distinction between cabinet and speaker resonance:

Speaker resonance (amp speaker page) is for the interactive nature of the power amp with the speaker, and will be specific to the speaker, or a system of them wired together. It does make a difference to have this accurately set when using an external cabinet or with an an IR for a speaker that has a substantially different resonance than the default.

Cabinet resonance: the acoustic resonance of the system of a speaker in a cabinet is addressed by the low cut in the cab block and other EQ manipulations.

*YMMV: Note: I typically use speakers in the 75-89hz range - perhaps a bit out of gamut from the norm.
 
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artzeal said:
It does make a difference, sometimes quite significant: to have the resonant frequency (amp block speaker page) to match the speaker IR (also for an actual cabinet). Ideally, this is below the frequency of the lowest fundamental of the instrument (82hz low E on guitar).

If your resonant frequency is at 100hz: that seems rather high - more like for an 8" or 10" speaker. Typically, 12" speakers have a resonant frequency around 75hz, and will sound much better and more balanced over their entire range. I'd get that right first. Otherwise it may exhibit a persistent honk at 100hz and its overtone series (since it will emphasize a range where guitars typically already have a frequency bump).

The cab roll off, as Yek points out, is different: but is still very important. It took me a while to figure out that more aggressively attenuating the highs and lows (-6db/octave in the cab block) around 4500hz (as low as 3900hz or as high as 12k) and the low cut: (generally between 80hz and 180hz) - depending on amp, guitar and genre - were the key to getting the tone to really open up, and for FRFR/IR to more closely match the sound of real cabinets I enjoy.

As there are so many variables: doing it by ear is de rigueur.
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Thanks for the reply. Some of the amp models (for example the Bogner Shiva and many others) default at 110 hz for the Low Res Frequency. I did read that the amp block defaults to the correct Low Res Freq Hz for it's intended cab/speaker. So while some of the Low Res Freq settings in the Amp block are quite high my understanding is that it is set correctly for its intended speaker/cab. Of course this would need to be adjusted depending on which speaker you choose like you said.

I will definitely say though that I have found as well that the Cab Block tweaking has been the magic ingredient for me getting a preset to go from sounds good to sounds amazing.

I generally do about the same cuts as you mentioned (80hz-160hz) for the Low Cut and for the High Cut I've gone as low as 3500hz but generally fall somewhere between 8000hz and 4000hz. This seems (to my ears) to make the amp model sound like you said more like a real guitar cab.

The one thing I didn't understand though is you said you do a -6db/octave in the cab block. Are you referring to changing the Filter Slope from 12db to 6db in the cab block? Thanks!
 
I have always wondered why one had to even mess with it? If the cab IR and low resonance freq. in the amp block have to change when you use a different amp or cab block then aren't you forever having to find the happy place for the two?
 
artzeal said:
It does make a difference, sometimes quite significant: to have the resonant frequency (amp block speaker page) to match the speaker IR (also for an actual cabinet). Ideally, this is below the frequency of the lowest fundamental of the instrument (82hz low E on guitar).

If your resonant frequency is at 100hz: that seems rather high - more like for an 8" or 10" speaker. Typically, 12" speakers have a resonant frequency around 75hz, and will sound much better and more balanced over their entire range. I'd get that right first. Otherwise it may exhibit a persistent honk at 100hz and its overtone series (since it will emphasize a range where guitars typically already have a frequency bump).

The cab roll off, as Yek points out, is different: but is still very important. It took me a while to figure out that more aggressively attenuating the highs and lows (-6db/octave in the cab block) around 4500hz (as low as 3900hz or as high as 12k) and the low cut: (generally between 80hz and 180hz) - depending on amp, guitar and genre - were the key to getting the tone to really open up, and for FRFR/IR to more closely match the sound of real cabinets I enjoy.

As there are so many variables: doing it by ear is de rigueur.
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Many of the amp models have a Low Res frequency between 100-110Hz.

Remember that this is the resonant frequency of the CAB not the speaker... There is a difference :)
 
Sixstring said:
If the cab IR and low resonance freq. in the amp block have to change when you use a different amp or cab block then aren't you forever having to find the happy place for the two?
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The “happy place” for the low frequency resonance is wherever you think it sounds best, and that’s going to vary as the Amp and cab change. For every parameter, the Axe has to load some default value. I think the value for the cab associated with the amp model is a good choice for that default.
 
unix-guy said:
Many of the amp models have a Low Res frequency between 100-110Hz.
Remember that this is the resonant frequency of the CAB not the speaker... There is a difference :)
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Whoops: I stand corrected: I hurriedly knocked out my previous post and failed to make the important distinction between cabinet and speaker resonance: I've revised that statement above. FWIW, the five types of actual speakers I have; Celestions, Eminence, have speaker resonances of 75hz, 75hz, 75hz, 85hz, 89hz. Whether used with an actual cabinet, or when using the IR of that same speaker with FRFR: they sound a bit better with speaker resonance in the amp speaker page set to match the actual value. No doubt many speakers are in the 100hz range, but I guess the ones I prefer are a bit lower.

In any case, I go with the FAS defaults until I think my cab choice may have gone far afield.
 
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Mateo11 said:
....The one thing I didn't understand though is you said you do a -6db/octave in the cab block. Are you referring to changing the Filter Slope from 12db to 6db in the cab block? Thanks!
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Yes: the filter slope: -6db attenuation to my ear seems to roll off naturally like an actual cabinet; leaves some air in the higher frequencies. I can see where -12db might be better for some mixes, or help to control stage wash.
 
artzeal said:
Yes: the filter slope: -6db attenuation to my ear seems to roll off naturally like an actual cabinet; leaves some air in the higher frequencies. I can see where -12db might be better for some mixes, or help to control stage wash.
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Thank you! I will have to try that out. I honestly never messed with that parameter much before.
 
artzeal said:
Whoops: I stand corrected: I hurriedly knocked out my previous post and failed to make the important distinction between cabinet and speaker resonance: I've revised that statement above. FWIW, the five types of actual speakers I have; Celestions, Eminence, have speaker resonances of 75hz, 75hz, 75hz, 85hz, 89hz. Whether used with an actual cabinet, or when using the IR of that same speaker with FRFR: they sound a bit better with speaker resonance in the amp speaker page set to match the actual value. No doubt many speakers are in the 100hz range, but I guess the ones I prefer are a bit lower.

In any case, I go with the FAS defaults until I think my cab choice may have gone far afield.
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Except "better" is a matter of taste...

The primary IR I use came from cabIR.eu and is from an Orange 4x12 with g12H30 speakers. They measured the frequency at 108Hz.

Also, my assumption is that the values Fractal uses for each amp are relative to the associated cab used when it was modeled.
 
artzeal said:
FWIW, the five types of actual speakers I have; Celestions, Eminence, have speaker resonances of 75hz, 75hz, 75hz, 85hz, 89hz. Whether used with an actual cabinet, or when using the IR of that same speaker with FRFR: they sound a bit better with speaker resonance in the amp speaker page set to match the actual value. No doubt many speakers are in the 100hz range, but I guess the ones I prefer are a bit lower.
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The resonant frequency of a particular speaker is its free-air resonance — the resonance when the speaker is suspended in the air, with no baffle or cabinet. I don’t know anyone who plays that way. :)

As soon as you mount a speaker into a cabinet, the resonant frequency shifts upward, usually above 100 Hz.
 
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+1. Go by the speaker cabinet's resonant frequency, not the speaker's spec'd resonant frequency. The speaker is just part of the system. The baffle and enclosure play a big part too, particularly in the low frequencies.
 
mr_fender said:
+1. Go by the speaker cabinet's resonant frequency, not the speaker's spec'd resonant frequency. The speaker is just part of the system. The baffle and enclosure play a big part too, particularly in the low frequencies.
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This. +1
 
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