Question about the Mark series graphic EQ modeling

Why did the Mark models tapers change since 2019?
A lot of the wiki links and google searches link to this thread, if there are questions regarding the Mark models tapers it is best they are asked and answered here.

I'm still confused about the IIC+/++/JP2C tapers, the wiki is clear only about the IV model that has all Log10 tonestack.
I have also learned that GEQ settings form the Mark manuals or Metallica studio notes and old images will sound totally off.

First Fractal request ever: Add a Linear(Authentic)/S-Taper switch to the Mark GEQ. :)
 
James Freeman said:
What are the tonestack tapers on the IIC+ and IIC++?


Mark V schematic shows all Log pots just like your Mark IV... maybe the real amp deviates form its schematic?
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There are many different types of "Log pots". Logarithmic potentiometers (more correctly known as audio taper pots) have "tapers". There are 5A, 10A, 20A, 25A, and 30A as well as reverse versions. The most commonly used tapers in guitar amps are 10A and 30A. The taper indicates the percentage of maximum resistance when the pot is halfway. I.e., a 1M 10A pot will be 100K at noon.

A pot labeled as 1MA doesn't indicate the taper and Mesa, in particular, doesn't like to divulge the tapers they're using. When I compared our reference Mark IV to our reference Mark V the tapers of the controls were different.
 
FractalAudio said:
The amp is much more abrupt since it uses linear taper (should use 'S'-taper).
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FractalAudio said:
It’s smoother.
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^These^ (obviously lol - the man knows his stuff!)

On my 2C+ the sliders are much less forgiving than on Fractal's models. Making a very slight adjustment to the 5 band EQ on my amp can be difficult. Sometimes I literally move a slider just a few millimeters and that band changes the output tone quite a bit.

On FAS' 2C+ models I would say the sliders are more refined and predictable than on my physical amp.
 
Rex Rox said:
On my 2C+ the sliders are much less forgiving than on Fractal's models. Making a very slight adjustment to the 5 band EQ on my amp can be difficult. Sometimes I literally move a slider just a few millimeters and that band changes the output tone quite a bit.

On FAS' 2C+ models I would say the sliders are more refined and predictable than on my physical amp.
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I would rather have the authentic experience with the original linear taper sliders than the 'corrected' ones.
That's a recurring observation from owners that have the original amps, so why not provide the original experience in the Fractal as an option?
 
James Freeman said:
I would rather have the authentic experience with the original linear taper sliders than the 'corrected' ones.
That's a recurring observation from owners that have the original amps, so why not provide the original experience in the Fractal as an option?
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I think the point is almost every one is slightly different, so theyd have to model your exact amp. So the better solution is to improve the design and let people use their ears.
 
Here is a practical example that shows the necessity:
https://forum.fractalaudio.com/thre...e-at-donington-1991-sound-with-axe-fx.199104/
I have a great photo of the Mesa settings of Angus Young and would like to copy the settings one-to-one (since 30 years). Currently the only thing that doesn't seem to fit is the Mesa EQ and since my ears are easily tricked/deceived, I'll never know whether I've really reached the 80-90% of tone. Please enable 1:1 transfer with linear controls like the original amplifiers. Thank you!

P.S. 30 years ago I used a lot of time to discuss with my dude about the possibility to simulate a tube amp sound with solid state technology. It's great that you and your team really did it!
 
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Unboxed said:
No, no, no - nothing is ever that simple! We need to measure resistance changes, response curves, and nalyze the frequency response of the amplifier with different potentiometers so we can see the difference!!! /s. :)
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you can lose the /s, because you're exactly right; we do need to measure these things (or someone does) because our perception is subjective. Depending on the context things can sound very different to you even when they are objectively the same.
Then your listening experience will have a major impact on what you notice. To a lot of people a distorted guitar will sound just like any distorted guitar. Even a lot of guitar players are overwhelmed with the possibilities and parameters in the Axe FX. So asking about this stuff is totally valid.

A few people have requested or asked, even pleaded for an additonal Mark GEQ with closer to real world tapers, while I'm happy with adjusting by ear, and I think I have some good results. But why the modeling accuracy ends at the GEQ is beyond me, seems like an arbitrary line.
 
When I bought the AXE FX I thought the modeling accuracy is 100% for all parts of the amps, incl. potentiometers and EQs.
I learned that's not true, but I'm not sure. I thought the resistance can be measured well Fractal will have done this for some positions and filled the rest based on an algorithm. If it's possible, yes please. The issue is, Fractal need to disassemble all parts again, which is a lot of work. But I am sure, this is the step to have a 100% tube amp simulation everybody wants.
I used more or less 30 years plexi amps and I know how they react. From my experience, potentiometer are never 100% correct, but 90%. I often measued them and more than 10% diviation I could not measure. But I don't know it for sure. 90% is better than my ears.
 
I feel slightly misunderheard here. The gist of my post is “a rose by any other name still smells as sweet” — either the sound of an amp in a Fractal works for you or it doesn’t, regardless of the name it’s given or the “real world” amp it is supposedly modeled after.
 
But I want to copy the setting 1:1 and be sure that I got the sound on amp side. The FRFR speaker, IRs and power amp is complex enough to EQ it. I need a part in the line that 90% is working like it should. Currently I don't know if it does it. I like the sound very much but is it the same which is coming with "90%" quality from the original amp? If you say, the potentiometers where not measured or implement as available in the amp, I don't think so. But I can't image it was not done by Fractal. Possibly just not for the Mesa EQs.
 
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Ultimately it's still going to be ears and not eyes that tells you if you're "there". Even with the linear tapers like the hardware, it's still going to be tough to exactly match the settings based on a picture. On the amps, most of the EQ's action is bunched up at the top and bottom of the slider's travel. The middle part of the range doesn't change much and then all the sudden it changes a lot right towards the end of slider travel. In other words, if you're a mm high or low towards the middle, it won't matter much, but a mm off towards the very top or bottom can make a big difference.
 
I'm sure that's right. Today AC/DC uses Plexi setting of potientiometer at 3. Wow, I could not believe it. But tht's what I want. I want to take over the settings from my stars and I want to get the same output on amp output like my stars. Also with the Mesa EQs. I think it's understood. It's just the view of a normal fanatic and guitar player but I'm sure it's not the view of a producer in a studio.
Possibly Fractal can manage both views. All the best!
 
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touch33 said:
I feel slightly misunderheard here. The gist of my post is “a rose by any other name still smells as sweet” — either the sound of an amp in a Fractal works for you or it doesn’t, regardless of the name it’s given or the “real world” amp it is supposedly modeled after.
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sure. But if you go out to buy roses for your S.O., you want to get roses and not kale. Trust me.

In other words, if I am going for a sound that I associate with a Deluxe Reverb I'd like to be able to use that model in the Axe FX and expect a match (and I haven't been disappointed so far), and not having to go through hundreds of amp models until I find one that sounds close.
 
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