Screen frequency / q and mismatch?

edo

edo

Power User
Vendor
I just discovered some advanced parameters in the af3 amp block I had not noticed before: screen freq / q and mismatch. How do they work? Screen freq seems to do nothing other than freezing the axe if set to any extreme. I can hear some difference by tweaking mismatch, does it have to do with odd / even harmonics or what?
 
man i don't know what the beta team is even for, what kind of basic system function check doesn't include at the least a minimum and maximum sweep of all parameters, and in various combinations/iterations...i want to be a beta tester just to see if i can break the thing, it's way to easy lately, i don't even go looking for extremes, i just stumble on a parameter variation it doesn't like that 'most people probably wouldn't do'... it sounds great but it's got some really fragile spots in various places. (who am i kidding, it's kind of exciting...is this going to kill it? lets find out!)
 
shatteredsquare said:
man i don't know what the beta team is even for, what kind of basic system function check doesn't include at the least a minimum and maximum sweep of all parameters, and in various combinations/iterations...i want to be a beta tester just to see if i can break the thing, it's way to easy lately, i don't even go looking for extremes, i just stumble on a parameter variation it doesn't like that 'most people probably wouldn't do'... it sounds great but it's got some really fragile spots in various places. (who am i kidding, it's kind of exciting...is this going to kill it? lets find out!)
Click to expand...
That's absolute bullshit. Name some.
 
FractalAudio said:
That's absolute bullshit. Name some.
Click to expand...

don't get me wrong, this space box is amazing and i love it...not complaining at all...but the instance mentioned above at a min/max setting, the reverb block crash set to low size/time settings (fixed in latest FW), reverb block glitching on size 6.1/6.2, the pitch block glitching (fixed in latest FW). the fix for the reverb block crash was basically just deactivate those size settings below 6.1 or set an internal fixed 250ms pre-delay. i was sad, because the early reflections at super low size is where the magic is! sorry FAS, i am grateful, and no doubt the code for ur stuff is undoubtedly complex since you don't use pre-cooked modules, so i can image it would not be so easy to dig up minute digital conflicts with so much else going on, i will take better quality/efficiency over chinese-mass-produced-cheap-stability any day, plus it's really nitpicking to call those few things issues, the core functionality of the thing is stable as can be and sounds amazing, if you don't get crazy with certain knobs. (note to self: don't talk bad about FAS's baby. ever. :rolleyes:)

edit: Screen Freq isn't freezing my unit... @edo what FW are you on?
edit edit edit...yes it does! screen freq at 1.00, sweep screen Q back and forth and it clicks off and output leds max out, goes silent. reverb block did that a couple times if you moved size up from 1.00 too fast, it would click off like this. this is probably on par with complaining that an amp freezes up if you poked the trace with a paper clip. the white screen gets some extra lines in it when you boot back up doing this.
 
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Just to be clear, I was not focusing on the screen freq bug (otherwise I would have posted in the bug section), but rather on the function and what it does in the range where it works
 
edo said:
Just to be clear, I was not focusing on the screen freq bug (otherwise I would have posted in the bug section), but rather on the function and what it does in the range where it works
Click to expand...

sorry to thread jack. and somehow manage to piss off FAS again.

manual page 61..."Screen Frequency, Screen Q – These set the resonant frequency of the virtual power tubes’ screen filter, and the Q of that filter." some filtering value, i guess maybe the cap they use for that section of the circuit. I bet it doesn't sound like it does anything because the master is too low when you're adjusting it, if the master isn't high enough to be pushing the power section, there probably won't be much audible difference in a little filter value on a power tube cause the tube won't be doing much yet...

it's subtle, but it's doing something. i guess that's one of those big power tube filter caps. Recto 2 Red Modern, master 5.76, screen freq 1.35, screen Q 7.522, I got it to doing some pumping tremolo thing now or something...sounds like a bias trem if you stop playing, it goes to pumping. test monkey is confused.
 
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edo said:
I just discovered some advanced parameters in the af3 amp block I had not noticed before: screen freq / q and mismatch. How do they work? Screen freq seems to do nothing other than freezing the axe if set to any extreme. I can hear some difference by tweaking mismatch, does it have to do with odd / even harmonics or what?
Click to expand...

http://wiki.fractalaudio.com/axefx2/index.php?title=Amp_block#SCREEN_FREQUENCY_.2F_SCREEN_Q

http://wiki.fractalaudio.com/axefx2/index.php?title=Amp_block#POWER_TUBE_MISMATCH
 
shatteredsquare said:
don't get me wrong, this space box is amazing and i love it...not complaining at all...but the instance mentioned above at a min/max setting, the reverb block crash set to low size/time settings (fixed in latest FW), reverb block glitching on size 6.1/6.2, the pitch block glitching (fixed in latest FW). the fix for the reverb block crash was basically just deactivate those size settings below 6.1 or set an internal fixed 250ms pre-delay. i was sad, because the early reflections at super low size is where the magic is! sorry FAS, i am grateful, and no doubt the code for ur stuff is undoubtedly complex since you don't use pre-cooked modules, so i can image it would not be so easy to dig up minute digital conflicts with so much else going on, i will take better quality/efficiency over chinese-mass-produced-cheap-stability any day, plus it's really nitpicking to call those few things issues, the core functionality of the thing is stable as can be and sounds amazing, if you don't get crazy with certain knobs. (note to self: don't talk bad about FAS's baby. ever. :rolleyes:)

edit: Screen Freq isn't freezing my unit... @edo what FW are you on?
edit edit edit...yes it does! screen freq at 1.00, sweep screen Q back and forth and it clicks off and output leds max out, goes silent. reverb block did that a couple times if you moved size up from 1.00 too fast, it would click off like this. this is probably on par with complaining that an amp freezes up if you poked the trace with a paper clip. the white screen gets some extra lines in it when you boot back up doing this.
Click to expand...

https://en.wikipedia.org/wiki/Punctuation
 
yek said:
http://wiki.fractalaudio.com/axefx2/index.php?title=Amp_block#SCREEN_FREQUENCY_.2F_SCREEN_Q

http://wiki.fractalaudio.com/axefx2/index.php?title=Amp_block#POWER_TUBE_MISMATCH
Click to expand...

Thanks @yek , I'd already seen / read those, but I was looking for a practical description rather than a technical one. I don't even know what a power tube screen filter is, so I was hoping to understand what it does to the amp tone as opposed to what it is within the amp! Same thing for the tube mismatch, I understand that 0 represents a perfect match, but what happens with negative vs positive values in terms of tone?
 
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shatteredsquare said:
man i don't know what the beta team is even for, what kind of basic system function check doesn't include at the least a minimum and maximum sweep of all parameters, and in various combinations/iterations...i want to be a beta tester just to see if i can break the thing, it's way to easy lately, i don't even go looking for extremes, i just stumble on a parameter variation it doesn't like that 'most people probably wouldn't do'... it sounds great but it's got some really fragile spots in various places. (who am i kidding, it's kind of exciting...is this going to kill it? lets find out!)
Click to expand...


The attitude that your putting out doesn't seem like its going to do you any favors towards being invited to be a part of the beta team....
 
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edo said:
Thanks @yek , I'd already seen / read those, but I was looking for a practical description rather than a technical one. I don't even know what a power tube screen filter is, so I was hoping to understand what it does to the amp tone as opposed to what it is within the amp! Same thing for the tube mismatch, I understand that 0 represents a perfect match, but what happens with negative vs positive values in terms of tone?
Click to expand...
Mismatch means that one power tube has more gain than the other.
So in a typical push-pull power amp, where each tube amplifies only the negative or positive half of the signal, the result is that the upper or lower half of the wave is bigger and this creates crossover distortion.
If the power amp is pushed you'll have asymmetrical clipping too.

In tone terms think the difference between a TS9 (asymmetrical) and a TS808 (symmetrical)

Ever mounted a non-matched pair of tubes in your amp?
 
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