Why some patches take up tons of CPU?

Aeser

Aeser

Inspired
I've been wondering for a while now and hoped maybe one of the experts here could illuminate me as to why some patches that REALLY don't seem like they should, take up a ton of C
U and just about max it out and make me paranoid the thing is gonna crash or freeze or something.

For example the preset I have pictured, yes it is 2 amps and 2 cabs but I've seen tons of people do that and still maintain CPU in the 50's or under whereas mine seems very simple by comparrison yet is ripping through 86%+ of the CPU on my AXE FX III MK II (which REALLY seems like it should be able to handle it.

The preset is a Fender Champ for one amp (a whopping 1 knob IRL on the thing, just volume, 1x8" speaker, 5 Watts, just a volume knob, and it's using a matching 5F1 1x8" Tweed cab block, and the other amp is a Fender Deluxe with a whopping TWO knobs IRL (volume AND Tone, getting fancy!), and it also has a matching 1x12" Deluxe Tweed cab, with a looper block to play stuff while i tween it, a drive block using a VS9 Valve screamer block and a Cry Babe Wah Bock, but it's maxing my AFX out at 86.6%-ish and i do not get why. I have it up on Axe Change too if anybody wanted to download it and fiddle with it/maybe discover why its using SO much CPU?

Thanks!


ChampDeluxe86.png
 
Hahaha nice.

Here's a kitchen sink W/D/W patch I made, running in the Axe-Fx III standard, non-turbo edition at 77.8% CPU:
jXLGMIE.png


note: each cab block is running 4 separate IR's, too. Standard IR's though.
 
Ok I just duplicated your patch as best I could (same amps, 8 dyna cabs, both cab block preamp quality settings set to High with a preamp selected) and only got 75% and change, again on a standard, non-Turbo AFXIII.

edit: what Drive model are you running? I'm swapping around between a few and the highest I'm seeing is 81%, still not enough to trigger the high CPU warning.

I77mNvg.png
 
Aeser said:
I've been wondering for a while now and hoped maybe one of the experts here could illuminate me as to why some patches that REALLY don't seem like they should, take up a ton of C
U and just about max it out and make me paranoid the thing is gonna crash or freeze or something.

For example the preset I have pictured, yes it is 2 amps and 2 cabs but I've seen tons of people do that and still maintain CPU in the 50's or under whereas mine seems very simple by comparrison yet is ripping through 86%+ of the CPU on my AXE FX III MK II (which REALLY seems like it should be able to handle it.

The preset is a Fender Champ for one amp (a whopping 1 knob IRL on the thing, just volume, 1x8" speaker, 5 Watts, just a volume knob, and it's using a matching 5F1 1x8" Tweed cab block, and the other amp is a Fender Deluxe with a whopping TWO knobs IRL (volume AND Tone, getting fancy!), and it also has a matching 1x12" Deluxe Tweed cab, with a looper block to play stuff while i tween it, a drive block using a VS9 Valve screamer block and a Cry Babe Wah Bock, but it's maxing my AFX out at 86.6%-ish and i do not get why. I have it up on Axe Change too if anybody wanted to download it and fiddle with it/maybe discover why its using SO much CPU?

Thanks!


View attachment 147965
Click to expand...

Using all eight IR slots combined in both of the Cab blocks will greatly increase the CPU load. As an experiment, remove one of the Cab blocks to see the affect it has on the CPU.
 
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I don't have a III and I don't know where the Smoothen option is.
Maybe if you are using that on 4 to 8 IRs it could be eating a lot, but guessing you aren't?

Also, as I thought a big part of IR processing has its own chip (not the CPU), I'm surprised it does eat so much.
 
Is it a dumb question to ask why you need 4 cabs?

DynaCabs take up a lot of memory...especially if you use a preamp.

Reduce to 2 dynaCabs per cab block and I bet you'll be OK.

My 2 cents...
 
You're using 4 cabs in each cab block and the preamp model set to High Quality in both as well. That's going to use a lot of CPU.

Soloing a single cab in each Cab block drops the CPU down to 46.5% on my Mark 1 III.

You could try creating a tone match of each those Dynacab mixes and then use them as single legacy user IR's in each instead to save a ton of CPU.
 
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Aeser said:
I've been wondering for a while now and hoped maybe one of the experts here could illuminate me as to why some patches that REALLY don't seem like they should, take up a ton of C
U and just about max it out and make me paranoid the thing is gonna crash or freeze or something.

For example the preset I have pictured, yes it is 2 amps and 2 cabs but I've seen tons of people do that and still maintain CPU in the 50's or under whereas mine seems very simple by comparrison yet is ripping through 86%+ of the CPU on my AXE FX III MK II (which REALLY seems like it should be able to handle it.

The preset is a Fender Champ for one amp (a whopping 1 knob IRL on the thing, just volume, 1x8" speaker, 5 Watts, just a volume knob, and it's using a matching 5F1 1x8" Tweed cab block, and the other amp is a Fender Deluxe with a whopping TWO knobs IRL (volume AND Tone, getting fancy!), and it also has a matching 1x12" Deluxe Tweed cab, with a looper block to play stuff while i tween it, a drive block using a VS9 Valve screamer block and a Cry Babe Wah Bock, but it's maxing my AFX out at 86.6%-ish and i do not get why. I have it up on Axe Change too if anybody wanted to download it and fiddle with it/maybe discover why its using SO much CPU?

Thanks!


View attachment 147965
Click to expand...

This is a good example of what's often thought is not practically possible - yes indeedy, one can easily max out the CPU on Ax3 using very few blocks. But for most, I'd guess such scenarios are outlier examples.

Most of the challenge here is in the cab. I've attached a preset that duplicates your initial Scene1@87%CPU and then gives you very similar subsequent scenes using reduced CPU without eliminating any of the main features you've used or changing any model types. Here's the explanations (I'm using Ax3-mk1):
  • Scene2@64%CPU - Changed IR Lengths from "Max" to 1024. I can discern very little difference between scene1 at "Max" and scene2 at "1024". I know some here can, and thats understandable as many here have better ears than me. Where I get skeptical though is when folks say there's a huge difference between "Max" and other options (depends on ones def of "huge" I guess). I run mine at 512 (would yield 52% in this preset) and love the sound of my presets. FractalAudio once stated here that he actually prefers lower resolutions which tells me that there's nothing inherently wrong with reducing it to gain CPU headroom if you don't consider the added reflections material or desired. Also, if you are running "Air" at 40% like you are, it's hard to imagine you're hearing much of those longer reflections anyway.
  • Scene3@60%CPU - Changed Cab PreMode to "Economy". Again, how much difference do you hear and is it material.
  • Scene4@41%CPU - Simulates Using External IR Mixing/Blending. This scenario simulates what the CPU would be if you mixed IRs externally (ie in CabLab). Now this would mean purchasing 3rd party IRs, but imo well worth the small price relative to Ax3 initial $ outlay given the resultant cpu savings and all the other added features/benefits provided in Fractal or other 3rd pty IR Paks (+ many of the same stock DCs are already available or on the way in CL4 Cab Paks).. A challenge with the stock IRs, even DynaCab, imo, is that there are very few mic mixes (none in the case of DC) which forces folks to mix them on the fly in the preset as you are doing here - works fine, but has a CPU cost. Actually the CPU in this case would be even less with external IR mixing because you could go with 1 stereo input config'd cab with 2 hard panned cab slots filled with external mixes, instead of using 2 cabs.

Other possible savings:
  • Change Looper to 1/2 Speed. For the purpose of tweaking with looper running, recording and playing back at 1/2 is fine for most (me anyway) - savings 2%CPU.
  • Remove the shunts (you don't have to go end to end in the grid) - savings 1%CPU for this preset.
  • The "Room" on the cabs is costing 5.5% (check if you really need it).
  • The Preamp on the cabs is costing 5.5% (check if you really need it).
  • Alignment adjustments on the cabs is costing 1% (check if you really need it).
  • The input gate is on costing 1.5% (check if you really need it).
  • Drives vary widely in CPU usage - others may do a similar job and be more cpu miserly.
Config'd to my usual practice, this preset is running at a lo lo 27.4% with externally mixed IRs and running at 512 with no cabpre or room turned on and no alignment shift (+gate off, no shunts, and looper@1/2Speed).

Managing CPU is often about compromises - lots to choose from here - managing effectively, one can get a huge amount of capacity from Ax3 but there's trade offs to consider when adding more as with most processor based products.

Keep presets at or below the recommended 80% redline and you wont be "paranoid about crashing / freezing" due to hi CPU - over 80% and shit can start happening - often gradually (i.e. the odd digital pop or click here or there at 81-82%, expression pedals reacting really slowlly at 84-85%, full on freezing at 88-90%). Also be aware that, if, while operating a preset, you change block channels with underlying changes in "Type" within some blocks (ie: at scene change, a pitch block changes from "Dual Detune" to "Dual Diatonic", and/or a drive block changes from "Micro Boost" to "Tone of Kings", and/or a Reverb changes from "Spring" to "Hall" ... there are many examples), then you will get a CPU increase when you make the scene change (could result in CPU issues occurring after the scene change even though the preset was fine wrt cpu at initial load). When CPU testing a preset, all the various channel combinations built into it for real time usage have to be tested to confirm no CPU red lining (I've wondered how many actually do that when testing presets that approach 80% 🤔)
 

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Brewce said:
Also, as I thought a big part of IR processing has its own chip (not the CPU), I'm surprised it does eat so much.
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Wondering where you discovered this - from my experience and Ax3 usage, Cab processing is done using the "Fx Side" CPU (the one we see the status of) vs the "Amp Side" CPU (I put those names in quotes as I don't really know what the official names are)
 
siin82 said:
Is it a dumb question to ask why you need 4 cabs?

DynaCabs take up a lot of memory...especially if you use a preamp.

Reduce to 2 dynaCabs per cab block and I bet you'll be OK.

My 2 cents...
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I find blending IR's to be the best way to use them.

I can count on one hand the number of single IR's that don't sound annoying to me. But once I started blending them, I got better tones than I'd ever been able to achieve before that by a wide margin.

Basically, blending IR's is the way. For me at least. That's why I run 4 per cab block. The other reason is that I like to run 4 of Fractal's IR's, and you can't blend Fractal IR's in cab lab, so I have to stick with blending 4 of them per cab.
 
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GreatGreen said:
I find blending IR's to be the best way to use them.

I can count on one hand the number of single IR's that don't sound annoying to me. But once I started blending them, I got better tones than I'd ever been able to achieve before... by a wide margin.

Basically, blending IR's is the way. For me at least. That's why I run 4 per cab block. The other reason is that I like to run 4 of Fractal's IR's, and you can't blend Fractal IR's in cab lab, so I have to stick with blending 4 of them per cab.
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Blend, yes; 4, too much (for me). Two is enough.

Most of my presets are like the OP's: two amp blocks, two cab blocks. Blending is where it's at! It's a big part of what makes Axe Fx III so great (IMO).
 
sprint said:
Wondering where you discovered this
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Probably in their own promo info and/or shared by Cliff.

Here is another reference...
https://forum.fractalaudio.com/threads/fm3-demo-preset-creation.158923/post-1898926
He seems to suggest it's maybe on the CPU? I was pretty sure it was a separate chip/component.

I'm not saying this is doing ALL the work, but I remember this chip since way back that is especially used for helping with IRs in some way... It may just do one thing.
 
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Greg Ferguson said:
You can IF the Cab packs include the embedded factory Dyna-Cabs, which they don't.
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Not sure that's totally fair since Fractal has released 8 or 9 Cab packs that, from what I can see having purchased them, are indeed extended versions of the equivalent ones that are embedded stock, + they have stated that they are committed to releasing more.

I think you get the point though - folks are perfectly fine to mix them on board with a CPU hit (can't have our cake and eat it too), but if you find yourself mixing 8 cabs in a preset at Max rez and are having CPU constraint issues, then looking into spending a few $ on an equivalent Fractal Cab Pak or other similar 3rd pty IRs to mix externally is a perfectly viable option to get some significant CPU headroom back (though I think there's a lot of other benefits also - all my presets use externally mixed IRs).
 
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Brewce said:
Probably in their own promo info and/or shared by Cliff.

Here is another reference...
https://forum.fractalaudio.com/threads/fm3-demo-preset-creation.158923/post-1898926
He seems to suggest it's maybe on the CPU? I was pretty sure it was a separate chip/component.

I'm not saying this is doing ALL the work, but I remember this chip since way back that is especially used for helping with IRs in some way...
Click to expand...
The thread you referenced is for FM3. It has a special coprocessor for IRs, so does the FM9.

I don't think the Axe Fx III does...
 
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