FM3 Low/High cut vs Preamp section Filters Low/High

In my stock settings for the preloaded Amp patches, they are all defaulted at 20 on the low cut & 20000 on the high cut, but the preamp section shows cuts in the filter section.... sometimes 20 on the low & 10k on the high or 85 low / 11k high, etc. I guess my question is how do these 2 sections interact with one another? On my Ax8, I only remember setting the low/high cut & this is where preloaded presets or other presets I downloaded Had cuts. I’ve tried adjusting both but at some point ear fatigue comes in & you can’t tell the small differences any more. Any ideas on how when to adjust either of these sections?
 
I believe you are asking about the Cab block, which has High/Low cuts for each IR as well as overall High/Low cuts in the Preamp section, which comes after the individual IR cuts.

See the Cab block section in the Blocks Guide here:

That has a block diagram showing the signal flow.
Thanks! So basically the preamp section trumps the the cab blocks low/high since it is after in the signal path ? Or do they interact with one another, & both sections cuts affect the cab output in series?
In general, how would you set your cab block in the FM3 format - only from the preamp, mainly from the cab high/low cuts, or both?
 
Thanks! So basically the preamp section trumps the the cab blocks low/high since it is after in the signal path ? Or do they interact with one another, & both sections cuts affect the cab output in series?
In general, how would you set your cab block in the FM3 format - only from the preamp, mainly from the cab high/low cuts, or both?
Think of it like this... the low and high cuts in the cab block affect the individual IRs in each slot, so you can keep them all wide open or use the frequency range you want for each IR. For instance, you can make a 57-121 mix and clean up the 121’s low end without taking away from from the 57, or if you like the natural top end of the 121 but want to tame the 57 a bit, lower the high cut on the 57. It’s kinda like EQ’ing individual mic channels on a console.

The low and high cut on the preamp page is the master cut that will impact your whole IR mix.

Personally I prefer keeping those set wide open 20-20k, and then backing it down on either side if the tone needs it.
 
Thanks! So basically the preamp section trumps the the cab blocks low/high since it is after in the signal path ? Or do they interact with one another, & both sections cuts affect the cab output in series?
In general, how would you set your cab block in the FM3 format - only from the preamp, mainly from the cab high/low cuts, or both?
It does not "trump" the preamp EQ, the effect of preamp EQ and any EQ after the preamp section is quite different.
It is important where an EQ used in your signal chain; BEFORE or AFTER the distortion is applied (like in the preamp section):

The pre-EQ is applied to the signal before it hits the amp's pre-amp stage.
Then, in the preamp stage, the distortion is added to the signal (assuming that the amp is not fully clean).
Adding distortion will add frequency content to the signal that was not present before.
(the term "adding" distortion is not 100% correct, but that does not matter here)

For example you high-cut frequencies in the pre-amp EQ, let's say above 1 kHz.
With a distorted amp, those above 1 kHz frequencies will be added again in the pre-amp where the distortion is applied.
On the other hand cutting frequencies AFTER the amp block will permanently cut those frequencies from the signal (unless you use a 2nd amp or drive pedal after that).

So that's the main difference: preamp EQ is usually applied BEFORE the distortion, the Cab EQ is usually applied AFTER the distortion.
The preamp EQ shapes the character of your distortion, EQ after the pre-amp (like the cap EQ section) shapes your tone.
Almost every boost/drive pedal makes use of this type of "pre-distortion EQ".
Does that all make any sense? If it sound good - who cares.
 
It does not "trump" the preamp EQ, the effect of preamp EQ and any EQ after the preamp section is quite different.
It is important where an EQ used in your signal chain; BEFORE or AFTER the distortion is applied (like in the preamp section):

The pre-EQ is applied to the signal before it hits the amp's pre-amp stage.
Then, in the preamp stage, the distortion is added to the signal (assuming that the amp is not fully clean).
Adding distortion will add frequency content to the signal that was not present before.
(the term "adding" distortion is not 100% correct, but that does not matter here)

For example you high-cut frequencies in the pre-amp EQ, let's say above 1 kHz.
With a distorted amp, those above 1 kHz frequencies will be added again in the pre-amp where the distortion is applied.
On the other hand cutting frequencies AFTER the amp block will permanently cut those frequencies from the signal (unless you use a 2nd amp or drive pedal after that).

So that's the main difference: preamp EQ is usually applied BEFORE the distortion, the Cab EQ is usually applied AFTER the distortion.
The preamp EQ shapes the character of your distortion, EQ after the pre-amp (like the cap EQ section) shapes your tone.
Almost every boost/drive pedal makes use of this type of "pre-distortion EQ".
Does that all make any sense? If it sound good - who cares.
Thanks! Just to be clear , you are referring to the preamp EQ in the cab block correct? Once I’m sitting in front of FM3 edit, I’m sure it will make more sense visually.
 
Think of it like this... the low and high cuts in the cab block affect the individual IRs in each slot, so you can keep them all wide open or use the frequency range you want for each IR. For instance, you can make a 57-121 mix and clean up the 121’s low end without taking away from from the 57, or if you like the natural top end of the 121 but want to tame the 57 a bit, lower the high cut on the 57. It’s kinda like EQ’ing individual mic channels on a console.

The low and high cut on the preamp page is the master cut that will impact your whole IR mix.

Personally I prefer keeping those set wide open 20-20k, and then backing it down on either side if the tone needs it.
Thanks Justin! So basically you prefer to EQ each IR vs an overall approach in the preamp section? Just clarifying. I see everyone has a different approach based on preloaded Fractal presets to the ones on Axe exchange.
 
Thanks! Just to be clear , you are referring to the preamp EQ in the cab block correct? Once I’m sitting in front of FM3 edit, I’m sure it will make more sense visually.
Ah sorry, I thought you mean the amp's block preamp EQ. With the Cab's preamp it's the same concept, but it may be less obvious:
Here in the cab preamp you can add drive + saturation (distortion) too, similar to the preamp stage of an guitar amp.
That can add harmonic content to the signal (high frequencies) as described before.
In the cab block the EQ in the cab tab comes BEFORE the (potential) cab's preamp distortion, the cab's preamp EQ comes AFTERwards.
The cab's microphone preamp section will usually not be set to distort as much as an guitar-amp preamp does, so the BEFORE and AFTER distortion EQ effect will not be as noticable.
 
Thanks Justin! So basically you prefer to EQ each IR vs an overall approach in the preamp section? Just clarifying. I see everyone has a different approach based on preloaded Fractal presets to the ones on Axe exchange.
No problem! There’s really no “wrong” way to do it, it’s all based on your personal preference and workflow. When you set all cuts off (including setting the default 10k cutoff on the preamp page up to 20k), you’re hearing an accurate representation of the IR and what the mic actually heard on the cab. Your ears may want to cut some lows or highs, and that’s perfectly fine, but I like starting a preset with all cuts off, choosing an IR, and then dialing in the amp. I typically use a pre-mixed IR and may cut lows in the preamp page around 80-120 depending on the tone just to clean up any unwanted rumble, but that’s it.

Sometimes I’ll need to recreate a specific tone, so I’ll use a few mics and tweak their levels and low/high cuts as if I was at the console mixing several mic lines. Maybe I’ll blend a couple mics that sound great, but I want a little more depth, so I’ll blend in a Room or Rear capture and make a more aggressive low or high cut for that one capture just to get the vibe of it without adding unwanted low or high end to the whole picture.

Everyone is different though, and it all depends on which IRs you use. The best advice I can give you is to not overthink it. Your ears will tell you what they want to hear. :)
 
No problem! There’s really no “wrong” way to do it, it’s all based on your personal preference and workflow. When you set all cuts off (including setting the default 10k cutoff on the preamp page up to 20k), you’re hearing an accurate representation of the IR and what the mic actually heard on the cab. Your ears may want to cut some lows or highs, and that’s perfectly fine, but I like starting a preset with all cuts off, choosing an IR, and then dialing in the amp. I typically use a pre-mixed IR and may cut lows in the preamp page around 80-120 depending on the tone just to clean up any unwanted rumble, but that’s it.

Sometimes I’ll need to recreate a specific tone, so I’ll use a few mics and tweak their levels and low/high cuts as if I was at the console mixing several mic lines. Maybe I’ll blend a couple mics that sound great, but I want a little more depth, so I’ll blend in a Room or Rear capture and make a more aggressive low or high cut for that one capture just to get the vibe of it without adding unwanted low or high end to the whole picture.

Everyone is different though, and it all depends on which IRs you use. The best advice I can give you is to not overthink it. Your ears will tell you what they want to hear. :)
Very good info, thanks again!
 
Back
Top Bottom