ICONS accurate input calibration

sumitagarwal

sumitagarwal

Inspired
Love the fact that ICONS looks like they've moved the goalpost on input calibration with repeatable reference tones, etc. But from what I'm looking at, seems like there's another approach we could use with ICONS too.

One thing I hate about plugins is there's no firm target on what the "correct" input level is, because they're designed to be interface agnostic. That's not the case with ICONS, since there is a particular input level methodology for specific hardware (FAS hardware modelers). Given that there's a real target there, I think we might be able to get it accurate across any interface with a published or measured maximum input level.

NAM embeds this concept with calibrated NAM profiles. The plugin let's you enter the interface's maximum input level in dBu.

Anyone more technical than me know how we'd do this in the ICONS world?
 
sumitagarwal said:
One thing I hate about plugins is there's no firm target on what the "correct" input level is, because they're designed to be interface agnostic
Click to expand...
+1 - without some sort of publication of the "input" standard, there just doesn't seem to be any way to know if you're hitting the input of most plugins as the author intended or not, even if you know the precise headroom of your own interface.

sumitagarwal said:
Anyone more technical than me know how we'd do this in the ICONS world?
Click to expand...
The Icons Plugin Manual outlines pretty well here how to do the calibration using the embedded tool.

I'm no expert, but for other plugins where the, for lack of a better word: "native" input level is published (ie Jason Sadites publishes an "Input Gain Reference" value for his Tonex Captures - ie: "0dBu = -11 dBFS"), I adjust to that value for the interface I'm using to feed that plugin. FWIW, here's the detail of what I did in this case as an example:
  1. I get a value for my audio interface headroom by sending a measured 0dBu signal (0.775V) to it's instrument input (gain@0) from an external source (I use an HXStomp oscillator for this set to 400Hz (common freq for guitar) with volume set to measure 0.775V at the output cable's end using a DMM) and seeing what level pops out in my DAW with no intermediate processing. So for example, using my Axefx3 (input1-front) as my interface I read -17.6dB Peak / -20.4 dB RMS. (I think we use the Peak value (not RMS) for the math below but I'm never quite sure - maybe someone here can advise). The other option is just to get the headroom value from the back of the interface's manual but those haven't been all that accurate ime. (When measuring other interfaces, the headroom value would need to be lowered by the amount of added gain one likes to set on the interface input channel - with axfx as the interface, this is not needed since it's always 0 (compensated)).
  2. So now that I have my own interface headroom (ie 17.6dB from above for Ax3 Front Input1), I compare that to what the plugin author publishes (hopefully) - in this case 11dB. So using my Axfx3 to feed this plugin, I'll need to add 6.6dB of gain onto the front of the plugin since, given the same input, my Axfx will feed my Daw 6.6dB quieter compared to the plugin author's interface during creating of the plugin. On most plugins there's a global input gain knob that can be used to hold this calibration value - I like to use that but this compensating value but it can be done in other places as long as it's before the plugin's gain stages.
  3. For plugins where there's no "native" input level published I tend to assume 12dB since that seems to be a popular interface headroom value but I could be out to lunch on that + who knows what odd interface an author used if they have not published it.
Anyway - that's what I do - seems to work well in that my tones makes sense compared to the demos I hear when I'm using plugins / Tonex captures at least where some info is available on "native" input level to calibrate from.
 
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sprint said:
+1 - without some sort of publication of the "input" standard, there just doesn't seem to be any way to know if you're hitting the input of most plugins as the author intended or not, even if you know the precise headroom of your own interface.
Click to expand...
I asked about this in the main thread as I know Neural DSP uses a sine wave at 1vp for calibration, and sets the interface input gain up until it hits -13dbfs.

Not sure if it can be answered or not due to the "secret sauce" that Fractal has and how this would effect the results, but it would be awesome to know.

That said, I love the idea of calibrating with existing guitar tracks like ICONS does.
If other amp sims had this it would make things so much easier!
 
sprint said:
(ie Jason Sadites publishes an "Input Gain Reference" value for his Tonex Captures - ie: "0dBu = -11 dBFS"), I adjust to that value for the interface I'm using to feed that plugin.
Click to expand...
We thought that the eyes of the average bear would just glaze over. Also, some interfaces modify levels in a ways that aren't always obvious. Our approach works to get the majority of people spot on or quite close. And of course, we could possibly supplement it with additional information for those who can handle a bit of engineering.

PS: Also, while accuracy is absolutely critical to some, input levels can also be taken with a (small?) grain of salt. I was really surprised to watch some people -- serious players and producers -- basically say, "I don't care" and just bring up a clean preset, give a quick listen to a clip, adjust input gain as clean as they wanted it to be, and then move on. "I'll tweak it if I have to. That's why it's there".
 
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It's no different than having an optional pedal attached to the input of an amp that cleanly boosts or attenuates.
Adjust to taste and then save it as a preset. Easy peasy lemon squeezy.
Done.
 
sumitagarwal said:
I think we might be able to get it accurate across any interface with a published or measured maximum input level
Click to expand...
That's exactly why I specifically built a link into ICONS Input Calibration page which is 301'd to point to whatever additional information emerges as people grow into the system. For example, here are the some instructions for the RME Fireface:

RME Fireface UFX
1. Use a Mic/Line Instrument Input. I used Input 10.
2. In Totalmix, click "Instr." to set the channel to Instrument Input.
3. Set Gain to 20.0.
4. Make sure that EQ and Dynamics are OFF.
5. Turn the fader that would send your DI to the speakers all the way down. (I use Analog 1/2, shown below.)
6. Leave ICONS Input Level at the default setting of +18.00 dB.

1770819478901.png
 
vangrieg said:
For what kind of guitar/pickup? Input gain settings won't work universally for everybody, unfortunally.
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That setting is fine for a wide range of guitars. As stated in the generic instructions -- If you're clipping your interface, trim it down... But with the RME at 20.0 ICONS Input Level setting will be all the way up.

We also can't take into consideration what might happen if someone were to use a real drive pedal or preamp between their guitar and their interface (or, for example, a guitar with an onboard preamp at, say +18 db). At some point, one needs to speak to the majority and leave experimenters to themselves. The same is true for our hardware: our input pads have reasonable limits based on majority use cases.
 
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vangrieg said:
For what kind of guitar/pickup? Input gain settings won't work universally for everybody, unfortunally.
Click to expand...
FAS hardware handles it great, where any changes in actual hardware input gain is compensated on the digital side so that both low output and high output guitars behave authentically with the amp model.

I've never really bought the common plugin mindset that we should be manually normalizing all our guitars so that an edge-of-breakup amp setting is equally edge-of-breakup whether you're using a vintage Melody Maker or Dimarzio X2N. Seems like FAS is trying to bring their hardware mindset to the plugin too, which will improve with time and documentation.

FWIW, with modern audio interface noise levels and high bit depth dynamic range I think its generally reasonable to leave the hardware input gain low enough to accommodate the highest possible output pickups and have a known fixed gain level that stays the same across all instruments.
 
Admin M@ said:
That setting is fine for a wide range of guitars.
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Checked out specs for this interface, interestingly they say:
  • Maximum input level, Gain 8 dB: +21 dBu
  • Maximum input level, Gain 50 dB: -21 dBu
That looks like a ton of headroom, kudos to RME for a proper input (also with 116 dB SNR).

This interface will truly work for anything.
 
Admin M@ said:
We thought that the eyes of the average bear would just glaze over. Also, some interfaces modify levels in a ways that aren't always obvious. Our approach works to get the majority of people spot on or quite close. And of course, we could possibly supplement it with additional information for those who can handle a bit of engineering.

PS: Also, while accuracy is absolutely critical to some, input levels can also be taken with a (small?) grain of salt. I was really surprised to watch some people -- serious players and producers -- basically say, "I don't care" and just bring up a clean preset, give a quick listen to a clip, adjust input gain as clean as they wanted it to be, and then move on. "I'll tweak it if I have to. That's why it's there".
Click to expand...
I'd just include the number anyway, there is no good reason to hide the information. I had to manually measure my AxeFX input, and then work out the level for my DI based on that. A straight number would have saved me the effort. FWIW it seems to be 1Vp=0.707V RMS=0dBFS. I dont think it should be up to users to work this out.


Dom Mcsweeney said:
It's no different than having an optional pedal attached to the input of an amp that cleanly boosts or attenuates.
Adjust to taste and then save it as a preset. Easy peasy lemon squeezy.
Done.
Click to expand...
ICONS has no input control available on the main view, you can only adjust it in the calibration page. IMO for the intended results (as in, to sound and behave like the AxeFX hardware across all effect blocks) I think it's important to at least be close to the intended level. If you want to optionally boost, you can do so within the blocks, like on the AxeFX.
 
vangrieg said:
That's like -1 dBu, can it be correct?
Click to expand...
Yeah, 1Vp=0dBFS is the default reference level for SPICE. It's not unheard of for plugins to run with this although it's not the most intuitive IMO.

A lot of plugins add a certain amount of gain as a kind of buffer which is why (say) NDSP have 1Vp=-13dBFS. Most manufacturers do this because otherwise you'd need to set your input level where it looks like your signal is clipping and to most users this isn't intuitive. Thats why you can have a signal thats almost clipping your A/D and the ICONS input level still needs to add 10+ dB more level.

Some Softube amp models use 1Vp=0dBFS, and most people are unintentionally under-gaining things (especially because they dont really give the user a process to calibrate correctly).
 
vangrieg said:
So how in the world can -1 dBu at the physical input be 0 dBFS, it's way too low
Click to expand...
1Vp=0.707V RMS=-0.79dBu=0dBFS

This is the reference level used by ICONS, if the input knob in the plugin is at 0. It's absolutely far too little headroom to actually record with - the default AxeFX setting is +18dB, which is essentially giving you 18dB more headroom to work with. The need to boost by 18dB is to reach the internal operating level of the plugin. If you record with less headroom than the AxeFX (say 12dBu or so), then you don't need to boost your level as much to reach that calibration.

You basically have to get your guitar signal in at a decent level without clipping, and then add the remaining gain at the plugin input to reach this calibration.
 
sumitagarwal said:
since there is a particular input level methodology for specific hardware (FAS hardware modelers).
Click to expand...

I'm really really happy with that. I've always been wary of integrating audio interfaces because of the level/gain issue.
Now I can just use any of the FAS devices with ICONS, with Input Level at 18 dB.
 
MirrorProfiles said:
1Vp=0.707V RMS=-0.79dBu=0dBFS

This is the reference level used by ICONS, if the input knob in the plugin is at 0. It's absolutely far too little headroom to actually record with - the default AxeFX setting is +18dB, which is essentially giving you 18dB more headroom to work with. The need to boost by 18dB is to reach the internal operating level of the plugin. If you record with less headroom than the AxeFX (say 12dBu or so), then you don't need to boost your level as much to reach that calibration.

You basically have to get your guitar signal in at a decent level without clipping, and then add the remaining gain at the plugin input to reach this calibration.
Click to expand...
Ah, so the actual 0 dBFS is more like +17 dBu with Axe-FX without these shenanigans.
 
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