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Speaker Drive vs Motor Drive...

FractalAudio

Administrator
Fractal Audio Systems
Moderator
As far as speaker drive and motor drive, I assume speaker drive adds the distortion character of a hard pushed speaker to the mix, and motor drive adds the compression character of a hard pushed speaker to the mix. ?
Yes. Speaker Drive models the magnetic compression (which is actually distortion) that occurs due to the nonlinear speaker excursion vs. applied voltage. Motor Drive models the change in power transfer due to heating of the voice coil. When the voice coil heats up the speaker sensitivity decreases, in some cases quite dramatically.
 

deathbyguitar

Experienced
If I'm understanding this correctly,this eliminates my one caveat about using CabLab for recordings instead of the onboard cab block. Fan-fucking-tastic.
 

Desmo808

Experienced
So what I've done for the final release is put Motor Drive in BOTH the Amp block and the Cab block.
Forgive me, I'm a bit of a knob with these things. :oops:

What happens if say I put motor drive in the AMP block on 6, and motor drive in CAB block on 7, will that net me a motor drive of 13? Or does one take precedence over the other?
 

lp59

Experienced
Oh, and when using the Motor Drive in the Amp block it's before the output Level control so you don't have to worry about the behavior changing when you adjust the Level knob.
Brilliant. We won't have to level our presets again after applying Motor Drive.
 

200man

Experienced
Yes. Speaker Drive models the magnetic compression (which is actually distortion) that occurs due to the nonlinear speaker excursion vs. applied voltage...
There is this concept of underhung and overhung voice coils...no joke. ;)
Does the speaker drive actually model the response of a voice coil moving thru a magnetic flux that may change with excursion depending on the voice coil design?
 

Rex

Legend!
Yes. Speaker Drive models the magnetic compression (which is actually distortion) that occurs due to the nonlinear speaker excursion vs. applied voltage. Motor Drive models the change in power transfer due to heating of the voice coil. When the voice coil heats up the speaker sensitivity decreases, in some cases quite dramatically.
Thanks for breaking that down for us, @FractalAudio . Who would've thought that a little laggy, level-dependent compression would make such a difference in feel?
 

AlGrenadine

Axe-Master
So what I've done for the final release is put Motor Drive in BOTH the Amp block and the Cab block. If you're strictly FRFR then you can use the Amp block. If you are using a conventional guitar cab or a hybrid configuration (convention cab for monitoring and direct to FOH) then you can use the Cab block.

Doing it in the Amp block also has the advantage that the speaker resonance information in the Amp block is used to calculate the frequency dependent heating whereas the Cab block uses a fixed set of data that is representative of a typical speaker.

Finally I've made the time constant adjustable. I did some more calculations and measurements and found that a typical guitar speaker is actually lower than what I had previously calculated because thinner wire is used than I was assuming. Regardless you can now set the thermal time constant to get whatever response rate feels best.
Best of both worlds, excellent !
 

benvigil

Experienced
So what I've done for the final release is put Motor Drive in BOTH the Amp block and the Cab block. If you're strictly FRFR then you can use the Amp block. If you are using a conventional guitar cab or a hybrid configuration (convention cab for monitoring and direct to FOH) then you can use the Cab block.

Doing it in the Amp block also has the advantage that the speaker resonance information in the Amp block is used to calculate the frequency dependent heating whereas the Cab block uses a fixed set of data that is representative of a typical speaker.
Great solution.
 

DrNick

Inspired
I did some more calculations and measurements and found that a typical guitar speaker is actually lower than what I had previously calculated because thinner wire is used than I was assuming. Regardless you can now set the thermal time constant to get whatever response rate feels best.
You're going to run out of things to measure and model. I fully expect to see a knob with choices like "Tolex" and "Tweed" and "That fuzzy stuff" by Quantum 10.

Seriously though, I worry about how you'll occupy your time. I picture your wife coming home to you measuring the capacitance of your cats or something.
 

guitar32

Inspired
Brilliant +1
Cliff - the new optical + motor drive is a game-changer for performing with backing tracks, which also makes it much more plug/play in the studio. I've hunted the dynamics I have now for 19 years. I'm actually having a hard time accepting it's as good as it is. Thanks a million!
What do you mean by "optical"? Do you mean the new optical compressors? If so what settings do you use to get the best results? I'm playing around with it but still haven't come up with a ideal setting.
 

Rex

Legend!
What do you mean by "optical"? Do you mean the new optical compressors? If so what settings do you use to get the best results? I'm playing around with it but still haven't come up with a ideal setting.
Yes, he means the optical compressors. Search the forum, and you'll find settings that some people have used.
 

Jimmytwotimes

Experienced
So what I'm understanding here is the for people who are using a traditional guitar cabinet ( non frfr), should not be messing with either of these parameters in the amp block, and leaving them at 0, or whatever the default value is - correct ?
 

Rex

Legend!
So what I'm understanding here is the for people who are using a traditional guitar cabinet ( non frfr), should not be messing with either of these parameters in the amp block, and leaving them at 0, or whatever the default value is - correct ?
Correct...unless you like what you hear when you try it. :)

You should be getting motor and speaker drive effects from your real speakers, so for accuracy, leave it at zero. As for what pleases you, anything goes.
 

zenaxe

Fractal Fanatic
whatever the default value is - correct ?
As Rex notes, you want them at zero as a starting point. Speaker drive defaults non-zero now, though; so you will want to edit that every time you reset an amp block. You may also want to try to adjust LF resonance for your physical cab while you are there.
 

simeon

Axe-Master
Yes. Speaker Drive models the magnetic compression (which is actually distortion) that occurs due to the nonlinear speaker excursion vs. applied voltage. Motor Drive models the change in power transfer due to heating of the voice coil. When the voice coil heats up the speaker sensitivity decreases, in some cases quite dramatically.
right, so these are actually modelling different things...but they both result in compression. should we use both at once for absolute authenticity?
 

DLC86

Power User
right, so these are actually modelling different things...but they both result in compression. should we use both at once for absolute authenticity?
I suppose so. I usually use speaker drive at around 0.5 because it makes the sound more reactive and alive to my ears, especially on the lowest notes.

Anyway I have a doubt regarding the authenticity of the algorhythms after reading a few papers about speaker power compression. Almost all of those talk about a thermal time constant of several seconds (like 10 or 15) for a typical woofer design, not the milliseconds the axe defaults to.
I usually trust Cliff's work but I wonder why there's all this difference or if I missed something.
 
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