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What real amp is the FAS Modern based on?

DFauvre

Inspired
I am a writer, guitarist, and music producer. Big fan of the Fractal. I've spent weeks dialing in the new tones for my next album. One of my favorite tones is the FAS Modern amp block.

I'd like to buy the real amp this was based on. Or amps.

What amp or amps was the FAS Modern based on?

Thanks!
David
 

2112

Fractal Fanatic
All the FAS amp models are idealised versions of real amps or original designs. FAS Modern is an idealised Recto. Check the fractal wiki or yek's amp guide for more.

From the Fractal Wiki
Fractal Audio:

  1. "This model is my interpretation of the ideal modern metal tone. In the digital realm we are not constrained by the limitations that face tube amp designers so we are free to implement designs that would be nearly impossible with a tube amp. The Axe-Fx II modeling includes a variety of general purpose filters that I can place anywhere in the signal path. So I put some second-order filters in there to tighten up the tone. Implementing second-order filters in a real tube amp is difficult and costly so is rarely seen."
 

DFauvre

Inspired
great answer. If I wanted to recreate this tone with a real amp, what would you recommend? A recto? Which model? And how do I replicate the 'filters' he's talking about?
 

DFauvre

Inspired
what do you mean by, 'An Axe-Fx with an added power section ---IS--- a real amp.' are you talking about adding a power amp between the Fractal and a real cab?
 

Budda

Fractal Fanatic
what do you mean by, 'An Axe-Fx with an added power section ---IS--- a real amp.' are you talking about adding a power amp between the Fractal and a real cab?

Most likely yes.

I'm not sure what would be involced with making a real recto sound like this model, but a dual or triple reborn model is probably the place to start.
 

rossipedia

Experienced
great answer. If I wanted to recreate this tone with a real amp, what would you recommend? A recto? Which model? And how do I replicate the 'filters' he's talking about?
If you mean, "how do you replicate this tone with an analog amp" then see this part:

Implementing second-order filters in a real tube amp is difficult and costly so is rarely seen.

It's possible, but probably requires more time and money than it's worth.
 

IronSean

Experienced
After a little bit of quick googling, depending on the circuit second order filtering doesn't seem that hard or complex if you really wanted to do it yourself. To make a second order low cut/high pass, you just duplicate the low cut RC (resistor capacitor) circuit again, basically applying the same low cut twice, doubling the slope of the roll-off. Hence, second-order.

Now, that's still an additional two components which have to be ordered, and assembled, and take up space. I could see why many amp designers would just change a value to have the low cut start at a higher frequency instead of duplicating it to get a steeper cut. And consider that high gain amps might have a dozen of these around doubling them up adds up in terms of cost and complexity. and more complex filters could need even more added to get second order effects there.

So I agree with Cliff that it's more costly and adds complexity, so most amp designers considering their amps on production scales would avoid them. It's also a bit annoying to add them to existing amps, because there won't be physical space laid out for the extra components. But it's a pretty attainable goal if you know what you're doing, don't mind it looking a little janky when you point to point wire a bit of circuit above the circuit board, and want to mod some into an amp yourself.

That said, if you wanted to try and build a FAS Modern it would be a lot easier if you were Cliff and knew which extra filters were added where. And even then, building an amp on the level of a Mesa Boogie Recto is a pretty big undertaking even before you go customizing it.

So for the OP, your easiest bed is to find a Mesa Rectifier series amp that sounds close, and make use of some combination of pre (before the amp), in the loop, and post EQ to try and get close.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
After a little bit of quick googling, depending on the circuit second order filtering doesn't seem that hard or complex if you really wanted to do it yourself. To make a second order low cut/high pass, you just duplicate the low cut RC (resistor capacitor) circuit again, basically applying the same low cut twice, doubling the slope of the roll-off. Hence, second-order.

You cannot create a 2nd-order filter with complex coefficients that way. You are limited to your coefficients being constrained to the real axis. IOW your Q cannot exceed 0.5. FAS Modern uses filters with a Q higher than 0.5.
 

skunc

Experienced
he shared his setup in a thread not too long ago. I can't remember where I saw it. Matrix power IIRC.
 
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