The Power of Pre-EQ

I'm guessing Seymour Duncan and Dimarzio are in on this conspiracy, the reason most if not all but Mesa and Dumble do not have pre gain EQ's. It's either a pay off or a snyper at the ready, waiting to be sure a monkey wrench goes into any idea of an amp maker getting any ideas of creating and mass producing an amp with pre-gain EQ. Otherwise they'd become obsolete once folks figure out they can recreate their favorite pickups by twisting a few knobs. ;) I'm on the fence with pre EQ, sometimes I use it sometimes not. Like if a guitar is putting out flubby bass I'll use pre EQ to get rid of it, same goes for taming shrill highs. Boosting mids is also a good way of pushing an amp that doesn't have much gain over the top. To me though, adding too much EQ kind of spoils the relationship between guitar-pickups-pots-cable-amp-cable-speakers, and the characteristics your nice maple and mahogany tonewoods and expensive pickups become trivial. o_O

Just my two cents, I'm not saying one way is better than the other, do what sounds good to you. After all, we are all individuals and hear things differently than one another. Music would be boring if we all sounded the same. Unless you sound like me, the most interesting man in the world. :p

:)
 
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As outlined in the MIMIC white-paper the fundamental paradigm of distorted guitar tone is EQ -> Distortion -> EQ. For higher gain tones the post-EQ is typically the tone stack and the Presence and Depth controls, when available. Therefore the user has access to the post-EQ but no control over the pre-EQ. One notable exception to this rule is the Mesa Mark series of amplifiers where the tone stack is located before the distortion.

I suppose the ultimate amplifier would be one with dedicated pre-EQ and post-EQ controls although I can imagine many guitar players with looks of bewilderment when presented with such an amp. Indeed I believe there was an amp years ago that had separate input and output graphic EQs. I'm thinking it was made by Seymour Duncan but it was a long time ago so I'm not really sure. I don't believe it was terribly successful.

So as we delve into the realms of higher gain tones we are the mercy of the amp designer and his choice of pre-EQ. The standard practice is to cut the lows before the distortion stages. There are various approaches to this: small coupling caps, partially bypassed cathodes, etc. These are simple methods and given the relatively simple nature of tube amps all we can really expect. Other popular pre-EQ techniques are shelving filters, i.e. the Marshall 470K, 470pF network and networks which roll off highs.

The pre-EQ, along with the post-EQ, shapes the tone when the amount of distortion is low. As the distortion increases the tone becomes more dependent upon the post-EQ. Anyone who has adjusted a Mesa Mark series amp will attest to the seeming ineffectiveness of the tone controls at higher gains. They will also attest to the affect the tone controls have on the feel.

So... the pre-EQ is an important part of the overall tone equation. We guitarists tend to focus upon the post-EQ and put graphic or parametric EQs after the amp but we neglect the pre-EQ. Therefore it is worthwhile to experiment with pre-EQ. The simplest approach to start with is using a graphic EQ before the amp block. Note how boosting or cutting certain bands affects the tone and feel. Note how the effect changes as the gain is increased or decreased.

One popular studio technique in the 80's was to put a parametric EQ before an amp and boost a narrow band of frequencies. This gives a slight mid-emphasis to the sound and can be useful in helping the guitars stand out in a mix. This technique seems to have been lost over the years. Years ago Micheal Sweet from Stryper showed me the frequencies he used and IIRC he boosted around 800 Hz about 6 dB. I don't remember the Q but I would start around 1.4. Incidentally the frequencies he were boosting are just about the same as the frequencies that are cut by the tone stack. So when playing softly the net result is a flatter EQ. As you play harder the input EQ becomes less effective and the tone becomes more scooped.

Pre-EQ can make amps sound warmer, or tighten the bass. It can be used to increase brightness without becoming harsh. Pre-EQ is also very useful with amps on the verge of breakup or mildly overdriven. Experiment with boosting frequencies to give your leads a more vocal character or make them more unique.
Thanks for the detailed information, do we have a list where we can see which amps (fractal Axe fx) have pre eq and which have post gain eqs, like how you mentioned regarding mesa where tone stack is before gain stage. This I am sure will help us all. Thanks.
 
Yes. That’s what it’s there for.

Question on this. I was reading this thread today and tried Cliff's settings. Wow, I can't believe I missed this before. Makes a huge difference in sound! Especially driving the output level of the filter block up a bit. Which leads to my question...

If I do the EQ settings in the Amp Input EQ section instead of a Filter block. What else is needed to achieve what the Filter block level was doing? Or do you still need a filter block just for that?
 
If I do the EQ settings in the Amp Input EQ section instead of a Filter block. What else is needed to achieve what the Filter block level was doing? Or do you still need a filter block just for that?
If you just want to drive the amp harder across the spectrum, user the Input Trim parameter in the Amp block.
 
As outlined in the MIMIC white-paper the fundamental paradigm of distorted guitar tone is EQ -> Distortion -> EQ. For higher gain tones the post-EQ is typically the tone stack and the Presence and Depth controls, when available. Therefore the user has access to the post-EQ but no control over the pre-EQ. One notable exception to this rule is the Mesa Mark series of amplifiers where the tone stack is located before the distortion.

I suppose the ultimate amplifier would be one with dedicated pre-EQ and post-EQ controls although I can imagine many guitar players with looks of bewilderment when presented with such an amp. Indeed I believe there was an amp years ago that had separate input and output graphic EQs. I'm thinking it was made by Seymour Duncan but it was a long time ago so I'm not really sure. I don't believe it was terribly successful.

So as we delve into the realms of higher gain tones we are the mercy of the amp designer and his choice of pre-EQ. The standard practice is to cut the lows before the distortion stages. There are various approaches to this: small coupling caps, partially bypassed cathodes, etc. These are simple methods and given the relatively simple nature of tube amps all we can really expect. Other popular pre-EQ techniques are shelving filters, i.e. the Marshall 470K, 470pF network and networks which roll off highs.

The pre-EQ, along with the post-EQ, shapes the tone when the amount of distortion is low. As the distortion increases the tone becomes more dependent upon the post-EQ. Anyone who has adjusted a Mesa Mark series amp will attest to the seeming ineffectiveness of the tone controls at higher gains. They will also attest to the affect the tone controls have on the feel.

So... the pre-EQ is an important part of the overall tone equation. We guitarists tend to focus upon the post-EQ and put graphic or parametric EQs after the amp but we neglect the pre-EQ. Therefore it is worthwhile to experiment with pre-EQ. The simplest approach to start with is using a graphic EQ before the amp block. Note how boosting or cutting certain bands affects the tone and feel. Note how the effect changes as the gain is increased or decreased.

One popular studio technique in the 80's was to put a parametric EQ before an amp and boost a narrow band of frequencies. This gives a slight mid-emphasis to the sound and can be useful in helping the guitars stand out in a mix. This technique seems to have been lost over the years. Years ago Micheal Sweet from Stryper showed me the frequencies he used and IIRC he boosted around 800 Hz about 6 dB. I don't remember the Q but I would start around 1.4. Incidentally the frequencies he were boosting are just about the same as the frequencies that are cut by the tone stack. So when playing softly the net result is a flatter EQ. As you play harder the input EQ becomes less effective and the tone becomes more scooped.

Pre-EQ can make amps sound warmer, or tighten the bass. It can be used to increase brightness without becoming harsh. Pre-EQ is also very useful with amps on the verge of breakup or mildly overdriven. Experiment with boosting frequencies to give your leads a more vocal character or make them more unique.

PEQ on the amp block really helped me mold a realistic amp tone.
 
IMO, it is posts like the original one here that has FAS standing out, far and above other systems. The most interesting dynamic to me is the transparent mentorship, and its organic nature that seems to occur to some degree with each owner. Yeah, that's it, OWNER, and not just a customer. That's what I feel like.
 
And who can forget Tom Scholz, I remember almost falling off my chair the first time I heard the tones on the first Boston album. He used multiple stages of EQ and compression in his chain to get those sounds. Or old school guitarist using a 7 band Boss EQ in front of a pushed 50 Watt Marshall as a shaped drive pedal. The possibilities are endless by using pre and post EQ.
 
I love this stuff. Wondering if there is any way to approximate an ideal (memory-less) non-linear operator in the III so you could experiment with this without being affected by intrinsic coloring and dynamic response of the various amp models. Something like pre-EQ -> Sigmoid -> post-EQ -> Cab IR, ideally with options for the non-linear operator so you can isolate its impact as well - odd vs even harmonics etc.

Ideas anyone? Perhaps one of the more transparent drive models could be used to approximate this?
 
And who can forget Tom Scholz, I remember almost falling off my chair the first time I heard the tones on the first Boston album. He used multiple stages of EQ and compression in his chain to get those sounds. Or old school guitarist using a 7 band Boss EQ in front of a pushed 50 Watt Marshall as a shaped drive pedal. The possibilities are endless by using pre and post EQ.
@FractalAudio go and knock on the door of Tom Scholz to make him convert to Fractal products :)
 
I love this stuff. Wondering if there is any way to approximate an ideal (memory-less) non-linear operator in the III so you could experiment with this without being affected by intrinsic coloring and dynamic response of the various amp models. Something like pre-EQ -> Sigmoid -> post-EQ -> Cab IR, ideally with options for the non-linear operator so you can isolate its impact as well - odd vs even harmonics etc.

Ideas anyone? Perhaps one of the more transparent drive models could be used to approximate this?
That's approximately the Kemper model. Fractal has gone with circuit modeling instead. I can't say whether they'd offer that in the future.

And you're right: you can experiment with this using existing blocks. You could even use the Amp models instead of drives. Playing with Bias on the class-A models will give you some control over the even/odd harmonic mix.
 
That's approximately the Kemper model. Fractal has gone with circuit modeling instead. I can't say whether they'd offer that in the future.
I hear you, and don't get me wrong I think Fractal's approach is the way to go. I'm interested in this purely from an geekish experimentation point of view. Curious if I can get my ear to recognize the impact of each element.
And you're right: you can experiment with this using existing blocks. You could even use the Amp models instead of drives. Playing with Bias on the class-A models will give you some control over the even/odd harmonic mix.
Will definitely play with this. I was thinking in the direction of drives because they shouldn't have much dynamic compression and may be easier to tweak for flat eq? Trying to separate variables.. Thanks for the suggestion on tweaking the bias.
 
One of the least CPU hungry EQ fixes that are available is the PEQ and Filter blocks. Here are a bunch of blocks that I've accumulated and would like to share with all the Fractal Boys and Girls. They can be used anywhere in the chain you see fit. Try em out and have fun, Part 1 I can only load 10 blocks max. Parts 2, 3 and maybe 4 to follow. These are in II XL + format, use FRACTOOL to convert to your platform. Cheers, Perry
 

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One of the least CPU hungry EQ fixes that are available is the PEQ and Filter blocks. Here are a bunch of blocks that I've accumulated and would like to share with all the Fractal Boys and Girls. They can be used anywhere in the chain you see fit. Try em out and have fun, Part 1 I can only load 10 blocks max. Parts 2, 3 and maybe 4 to follow. These are in II XL + format, use FRACTOOL to convert to your platform. Cheers, Perry
WOW please describe them a bit so we know what's the idea of each one or when you use them. THANKS.
 
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