Amp level vs cab level

ByTheHandOf

ByTheHandOf

Inspired
Att. Cliff: Amp level vs cab level

Hey Guys.

This is more of a question of the technical part of the axefx setup. I am finetuning my various presets, trying to to create some headroom for a boost (to be placed at the very end), and it got me thinking:

Does other blocks react to the input volume they get, the same way the amp block does? Eg. is there a certain level/sweetspot to get the best out of a cab block or a drive block etc? I am considering if i should go through each block individually to check wether they are similar to the completely dry signal levelwise, but don't know if this will do any good or if I'm wasting my time...

I've played around with it a bit by lowering the amp blocks level by 10db, and then raising the cab blocks by 10db. I can't really tell the difference soundwise, but it did get be thinking about the technical part of it. Do any of you guys know (Fractal staff??), if there are any blocks that might clip/distort or react differently if they get too much or too litle input? Though I couldn't really tell when I did the playing around, I can't help bu to think wether any of my blocks do a little bit of distorting, if they are hit too hard by the previous block.

Hope my explanation makes sence, as english is not my first language.
 
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Things that react to level: Compressors, Drive, and cab block if you use motor drive.

Also, if I remember correctly, there is an "emergency shutoff" if you somehow manage to create crazy high levels.
 
Thanx :)

I have added an "att. Cliff" to this topic, as I would love to know the technical side of the gain/level's importance between effects. Some of my older presets still sound to me like there is some vague clipping noises, despite no meters being in the red..
 
I can hear a big difference when gain staging the Drive, Amp, & Cab blocks differently. But maybe it's just psychological, so I would love to know the specific details of how each block reacts to the input they receive as well. For instance, to my ear, if you have Amp level @ +0.0 db and Cab level @ +10, then take cab level to +0.0 and adjust Amp level up to compensate for the lost level (because you turned Cab down), the two gain stages sit in the mix completely differently. Why is that? Or am I just crazy? Maybe both...
 
From the wiki:

[h=2]Cab: position of effects and Cab block[/h]
  • In the "real" analog world it makes a difference if you put effects before or after the speaker cabinet. It's different with the Axe-Fx II.
  • Javajunkie: "You can place the effects loop anywhere in the chain (just add the fx loop block). Unless you are running a stereo cab or 2 mono cabs panned hard L/R, you may want to place stereo effects after the cab. The cab is a linear time invariant effect (unless you add drive) so effects like delay and reverb will sound the same before or after it. As Cliff and others have stated on numerous occasions LTI effects can be placed before and after each other and they will sound the same. Only when placed before or after non-LTI effects (drive, amps, et. al) it really matters. The one caveat there is that some effects are mono, placing effects before and after that makes a difference."
  • Cliff: "The difference in having the cabinet before or after the effects is usually subtle. It depends on how non-linear or time-variant the effect is. For effects like EQ, which are linear and time-invariant, it doesn't matter at all. For slightly time-variant effects like chorus and flanger the difference isn't very pronounced. For highly time-variant effects, like pitch shifting, the difference can be marked."
  • Cliff: "Linear means that the output is related to the input by a straight line: y = mx + b. Filters are example of linear systems. A cabinet IR is a filter. Distortion is an example of a nonlinear system. Linear systems are associative and commutative. Associative means that a * (b * c) = (a * b) * c. Commutative means that a + b = b + a or a * b = b * a. Therefore you can do cab -> eq (a * b) or eq -> cab (b * a). The cab block is "completely" linear if motor drive is non-zero but it is "wide sense stationary" so you can treat it as linear." Source
  • Cliff: "The cab block is level-dependent if the Motor Drive is non-zero. So if you turn up/down the level out of the amp block you may need to compensate by doing the opposite with the Motor Drive." Source
  • Cabinet blocks in parallel rows sound louder than a single Cabinet block. Here's the explanation. Bakerman: "It depends on how you're panning. Assuming a mono signal sent to cabs: Stereo cab w/ Pan L and Pan R fully left & right will be the same output level as 2 mono cabs w/ balance L & R. If pans/balances are centered the 2 mono cabs will be 6 dB louder. Balance elsewhere would be between 0 and 6 dB louder, and balance doesn't correspond 1:1 to pan L/R for the same placement. Balances will need to be further toward -50 or 50." Source


[h=2]Reverb: position[/h]
  • Cliff: "If there isn't distortion or modulation in the delay/reverb then the order is irrelevant since they are then Linear Time Invariant (or shift invariant in digital parlance). If there is a small amount of distortion or modulation then the order is probably still irrelevant. If there is a lot of distortion or modulation then the order may make a difference. However, typically the biggest difference, as noted above, is series vs. parallel since h1(t)*h2(t) is not the same as h1(t)+h2(t). If LTI h1*h2 = h2*h1. It may seem counter-intuitive that the order doesn't matter but try it and you'll be surprised."Source
  • Cliff: "Placing reverb after the cab is the recommended routing. The reverb is stereo. The cab block may be mono so you would lose the stereo field. Both blocks are linear so there is no advantage to placing reverb before the cab." Source
[h=2][/h]
 
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