ICONS accurate input calibration

KFF said:
Is that the front Input? Have you tried the rear one?

Actually... I haven't checked the MK I specs. MK II definitely listed as +20dBu on the rear instrument Input.
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That was for the front input. I never tried the back, but I'll give it a whirl (you only live once eh! 🤣) and report back my findings.
 
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KFF said:
No teeth... no bite!!! 🤣

Curious to see the results! 👍
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The front input has the secret sauce so I've always tended to favour it. Also, I find the rear input somewhat awkward to get to given my rig configuration :oops:. Anyway, I fumbled my way through it and surprise surprise, I also get 17.6dB headroom on the rear input - so in my case anyway (Ax3-mk1) it makes no difference - front, rear, it's all the same to me! 🤣
 
sprint said:
The front input has the secret sauce so I've always tended to favour it. Also, I find the rear input somewhat awkward to get to given my rig configuration :oops:. Anyway, I fumbled my way through it and surprise surprise, I also get 17.6dB headroom on the rear input - so in my case anyway (Ax3-mk1) it makes no difference - front, rear, it's all the same to me! 🤣
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Rear instrument input also has the secret sauce.
 
KFF said:
Easy now! 🤣



Inneresting. Going to see if I can locate specs for MK I... just out of curiosity.
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The manual specs sections seems to say +16dBu for both Front and Rear inputs. Input2 tho is +20dbu. I seems to get 1.6dBu more headroom - maybe they just rounded to 16 as a nice standard value.

1771034973275.png
 
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sprint said:
The manual specs sections seems to say +16dBu for both Front and Rear inputs. Input2 tho is +20dbu. I seems to get 1.6dBu more headroom - maybe they just rounded to 16 as a nice standard value.
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Nice.

Thought this might add some clarity, too (from AXE manual)...

Screenshot 2026-02-13 213023.png

As you said...

-Front and back Instrument Inputs: +16dBu. Both have Secret Sauce IV. Front overrides rear and has auto impedance switching.
-Inputs 2 - 4: +20dBu. No Secret Sauce, but can handle guitar... HiZ.

So that clears up the AXE. My question now is about AM4. It specs at +20dBu on the Instrument Input. So...

Is it the equivalent of an Input 2 - 4 on the AXE (no Sauce), or...

Is it an improved headroom (4dBu) Instrument Input from the AXE WITH Secret Sauce IV?

I'm sure the answer is echoing around these hallowed halls somewhere, but I don't recall seeing it. Wiki also doesn't say specifically.

@FractalAudio tnx
 
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I've put 0.707 RMS = 1v Peak through the AxeFx III Instrument Input and that reads -18.2dBFS in DAW when setting SPDIF Output as Input 1.
AxeFx III MKII has 17.4dBu of headroom, which means ICONS expects 17.4dBu of headroom with default Input Gain at 18dB.

Focusrite Scarlett Gen3 and Gen4 interfaces have 12.2dBu at Instrument Input with minimum gain, one has to turn down the Input Level in ICONS plugin to 13dB to have the same response as Fractal hardware.
 
KFF said:
Nice.

Thought this might add some clarity, too (from AXE manual)...

View attachment 166637

As you said...

-Front and back Instrument Inputs: +16dBu. Both have Secret Sauce IV. Front overrides rear.
-Inputs 2 - 4: +20dBu. No Secret Sauce, but can handle guitar.

So that clears up the AXE. My question now is about AM4. It specs at +20dBu on the Instrument Input. So...

Is it the equivalent of an Input 2 - 4 on the AXE (no Sauce), or...

Is it an improved headroom (4dBu) Instrument Input from the AXE WITH Secret Sauce IV?

I'm sure the answer is echoing around these hallowed halls somewhere, but I don't recall seeing it. Wiki also doesn't say specifically.

@FractalAudio tnx
Click to expand...
So front and rear both have secret sauce, but only front has auto impedance switching. That's what i thought, which biases me quite strongly towards using the front input.
 
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James Freeman said:
I've put 0.707 RMS = 1v Peak through the AxeFx III Instrument Input and that reads -18.2dBFS in DAW when setting SPDIF Output as Input 1.
AxeFx III MKII has 17.4dBu of headroom, which means ICONS expects 17.4dBu of headroom with default Input Gain at 18dB.

Focusrite Scarlett Gen3 and Gen4 interfaces have 12.2dBu at Instrument Input with minimum gain, one has to turn down the Input Level in ICONS plugin to 13dB to have the same response as Fractal hardware.
Click to expand...
Does the AD sensitivity adjustment affect this?
 
PhillipsLJ said:
Does the AD sensitivity adjustment affect this?
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A little at extreme values - on my Ax3-mk1 I notice the headroom starts to creep upward from 17.6dB at A/D Sensitivity values higher than 93.5%. At 100% A/D sensitivity, headroom is at 20dB (+2.4 from what it is constantly at 3% thru 93.5% A/D Sens). At the other end, with A/D sensitivity at 3% or below, headroom increased by 0.1 to 17.7dB - so very little impact on headroom at very low A/D sensitivity settings compared to very high A/D sensitivity levels. For most A/D sensitivity settings (3% thru to 93.5%), there is no impact on headroom from what I see.
 
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To keep the measurement party going, here is the values I got for my Axfx2-mk1:
  • Headroom @ Front input = 18dB.
  • Headroom @ Back input = 17.8dB (this one surprised me as the manual says it should be 20dB but I (it's the newest Ax2 manual so maybe thats showing XL+ spec)).
Not sure if the rear input has secret sauce on Ax2-mk1 (I think it has the original SS version but I could not find reference). Front has the auto-impedance switching.
 
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James Freeman said:
AxeFx III MKII in DAW I read 17.4dBu on both front and rear Input 1.
The small error between my and @sprint's measurement is probably due to DVM reading and adjustment of the test voltage.

My DVM measured exactly 0.7746v RMS which is 0dBu but it is indeed form China and not calibrated either.
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I'd say those differences will not be ruining any takes. :)

good info. Thanks to you both.
 
James Freeman said:
AxeFx III MKII in DAW I read 17.4dBu on both front and rear Input 1.
The small error between my and @sprint's measurement is probably due to DVM reading and adjustment of the test voltage.

My DVM measured exactly 0.7746v RMS which is 0dBu but it is indeed form China and not calibrated either.
View attachment 166671
Click to expand...
Cheap meter here also - I say we split the diff and call it 17.5
 
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