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Axe-Fx III Firmware Version 5.05

York Audio

Experienced
@FractalAudio Is the preamp high cut frequency setting part of the amp’s circuitry, or is that or is that tuned by preference? The reason I’m asking is because I’ve been having a hard time getting the sizzle of my 90’s Marshall DSL with the amp models, but then I took the BE C45 and set the high cut all the way up and now they’re almost indistinguishable.

It was a nice eureka moment to see that I could absolutely nail my raw DSL tones with the Axe, but it just made me curious if that setting is part of each model’s accuracy, or if it’s a matter of player’s preference.
 

jefferski

Fractal Fanatic
More and more I'm starting to suspect that "Cliff" is actually a brilliantly-written piece of AI code that has become self-aware and tireless in its pursuit of tonal bliss for the masses. I mean seriously, how many human people do you know that work this hard and release new software any time of day, any day of the week? :rolleyes:

Thanks, "Cliff"! :D
And like Data, he likes cats... hmmm.
 

York Audio

Experienced
@FractalAudio Is the preamp high cut frequency setting part of the amp’s circuitry, or is that or is that tuned by preference? The reason I’m asking is because I’ve been having a hard time getting the sizzle of my 90’s Marshall DSL with the amp models, but then I took the BE C45 and set the high cut all the way up and now they’re almost indistinguishable.

It was a nice eureka moment to see that I could absolutely nail my raw DSL tones with the Axe, but it just made me curious if that setting is part of each model’s accuracy, or if it’s a matter of player’s preference.
Here's my clip of the test.

It's a seamless clip. Half is the Marshall through a Zilla Fatboy with a single 57 and the other half is the Friedman BE C45 with the preamp high frequency cut all the way up and an IR shot of the same mic-up. The knobs on the real amp and the model are pretty much the same. I'm sure if I spent more time on it, I could get them even closer, but this was just a quick test to see if I could get in the ballpark. The only EQ is a high pass at 80 Hz.

It's scary how accurate 5.05 is.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
@FractalAudio Is the preamp high cut frequency setting part of the amp’s circuitry, or is that or is that tuned by preference? The reason I’m asking is because I’ve been having a hard time getting the sizzle of my 90’s Marshall DSL with the amp models, but then I took the BE C45 and set the high cut all the way up and now they’re almost indistinguishable.

It was a nice eureka moment to see that I could absolutely nail my raw DSL tones with the Axe, but it just made me curious if that setting is part of each model’s accuracy, or if it’s a matter of player’s preference.
The high cut frequency is due to the snubber cap in the PI. Friedman's use 100 pF (or more) for the snubber cap. A DSL only uses 47 pF so, yes, you would need to double the high cut frequency to match.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Any other aliens out there who understand this sentence? o_O
A snubber is a network used to reduce high frequencies. The term is a bit misused in tube amps. Typically a snubber is used to absorb transients in power circuits (like when a switch opens/closes).

In a tube amp the "snubber cap" is a capacitor across the plates of the phase inverter (PI). This reduces the gain of the power amp at high frequencies. It was originally used to prevent the power amp from oscillating. Some modern amps employ large values for tone shaping.
 

Randalljax

Fractal Fanatic
A snubber is a network used to reduce high frequencies. The term is a bit misused in tube amps. Typically a snubber is used to absorb transients in power circuits (like when a switch opens/closes).

In a tube amp the "snubber cap" is a capacitor across the plates of the phase inverter (PI). This reduces the gain of the power amp at high frequencies. It was originally used to prevent the power amp from oscillating. Some modern amps employ large values for tone shaping.
Is this what is meant by filtering in the power section
 

George Koerich

Inspired
Any other aliens out there who understand this sentence? o_O
Haha...
I always think about how those who are from any non-engineering field get most of his explanations :D:D:D. Even for those who are educated in the electrical/computer engineering is not usually easy to fully understand o_Oo_Oo_O, because he talks about the darkness tricks of amp design and this is a very specific field.
 

shireeshb

New Member
A snubber is a network used to reduce high frequencies. The term is a bit misused in tube amps. Typically a snubber is used to absorb transients in power circuits (like when a switch opens/closes).

In a tube amp the "snubber cap" is a capacitor across the plates of the phase inverter (PI). This reduces the gain of the power amp at high frequencies. It was originally used to prevent the power amp from oscillating. Some modern amps employ large values for tone shaping.
You know... this is yet another fantastic thing about the folks at FAS. Cliff takes time to in-service the community on this kind of stuff. Just another way he shows his commitment to the community of FAS product users.

Thanks Cliff! You have few equals.
 

George Koerich

Inspired
A snubber is a network used to reduce high frequencies. The term is a bit misused in tube amps. Typically a snubber is used to absorb transients in power circuits (like when a switch opens/closes).

In a tube amp the "snubber cap" is a capacitor across the plates of the phase inverter (PI). This reduces the gain of the power amp at high frequencies. It was originally used to prevent the power amp from oscillating. Some modern amps employ large values for tone shaping.
If only half the PI triode is working at time, this "snubber cap" would work the same if it was in parallel with the plate resistor and it's only between plates to save money, right?
 

Baldadi

Inspired
A snubber is a network used to reduce high frequencies. The term is a bit misused in tube amps. Typically a snubber is used to absorb transients in power circuits (like when a switch opens/closes).

In a tube amp the "snubber cap" is a capacitor across the plates of the phase inverter (PI). This reduces the gain of the power amp at high frequencies. It was originally used to prevent the power amp from oscillating. Some modern amps employ large values for tone shaping.
Thx Cliff, for taking the time to explain the snubber magic to this non-engineering-background musician - actually it's worse... I work in marketing (and analytics) :)... however, I always love to learn new things, and you making the effort to explain this to me and the whole community here is fantastic. Now I have to stop writing quickly and find that "Tube amp engineering for dummies" book so that I can actually understand better why my AxeFx3 sounds so good...

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DLC86

Power User
A snubber is a network used to reduce high frequencies. The term is a bit misused in tube amps. Typically a snubber is used to absorb transients in power circuits (like when a switch opens/closes).

In a tube amp the "snubber cap" is a capacitor across the plates of the phase inverter (PI). This reduces the gain of the power amp at high frequencies. It was originally used to prevent the power amp from oscillating. Some modern amps employ large values for tone shaping.
I assume it's the same concept as a popular fuzz face mod where a 100pf cap is soldered to the transistors' legs to prevent oscillation, and it also rolls off some highs.
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
If only half the PI triode is working at time, this "snubber cap" would work the same if it was in parallel with the plate resistor and it's only between plates to save money, right?
It's cheaper and easier to use a single cap between the plates. Remember old amps were PTP so they just put the cap right across the terminals on the tube. It's basically the same thing as a cap off each plate to ground (or to B+).
 

Daron Macke

New Member
Awesome...thanks so much FAS!

Also, thanks for the additional info regarding "snubbers"...totally foreign to me, but super cool to read about.
 

stink

Inspired
OK, I've ALWAYS like the sound of a Boogie as long as someone else was playing it, in my hands, I always thought they sounded like shit.... until the JP2C ... holy shitballs!!!! this is now my favorite amp. The Soldano was my go to amp because I love them IRL, the JP2C has now taken its place.

@FractalAudio , I have no idea how you do it but that amplifier model is pure magic! I suspect you truly are from another dimension...
 

phil92

Inspired
Yep, I don’t know what it is, bit the JP2c has some magical dimensionality going on.
I love the Mark IV, both real and model, but it felt almost flat going back to it.

I also noticed the CPU usage goes up quite a bit with this one.
Is there anything special going on in the modeling of that amp?
 
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