NAM calibration: find audio interface unity gain level

[2dor]

I saw your video and got confused. You turned your Interface Input as low as possible and never turned it up again. No wonder there's tons of hiss. I was hoping to get a guide on how to set it up so that I can still add gain on the Interface input to have a better SNR.
Still I do appreciate your effort in trying to shed light on this topic!

Well, you can turn up your interface's gain knob say by 7 dB and watch for clipping; if there's none, the just subtract 7 dB in the DAW (first thing in the signal chain) and you're good.
Start that way and see on what value (7, 5, 10 dB) you land - first & foremost, avoid clipping the converters.

FWIW you wouldn't get less hiss by the way with the real amps if you ran that amount of gain.

I wasn't explaining this for the studio-savy folks or audio-engineers and I made that very clear in the opening of the vid - I'm trying to get most folks up & running so that they can make the most of these profiles.

 

[FrankyFire]

Make a sine wave, measure the voltage in the analog domain with a multimeter. Then feed this sine wave into your input, note down the level in dBFS. You can calculate your headroom with that.

That does make sense.

Turning to 0 doesn't mean extra hiss, unless your signal is extremely quiet and the noise floor of the interface is loud enough to be heard over the other noise in the signal chain. For most interfaces in 2026, you will not have an issue with hiss, nor will you benefit in SNR by turning your interface up by a few dB (as they'll already be hot).

Tried that with my NI Komplete Audio 6, it is a completely different experience between 0 Gain and as much as possible without clipping. Transformers work way better if they're driven hard. It is a bad idea to leave gain at 0.
Audio source was a Guitar with loud Pickups (Fishman Fluence) into High-Z Input.

If you have issues with low signal/high noise, then you'll need to measure your levels and set the gain accordingly. All the info you need is in this forum and on YouTube.

That's basically what I meant with my post. And my complaint was mainly that I'm missing an easy guide to achieve this.

Well, you can turn up your interface's gain knob say by 7 dB and watch for clipping; if there's none, the just subtract 7 dB in the DAW (first thing in the signal chain) and you're good.
Start that way and see on what value (7, 5, 10 dB) you land - first & foremost, avoid clipping the converters.

On many Interfaces there's no reference on how much gain I'm adding. Our digital mixing desk my band is using tells me, the Komplete Audio 6 and the Focusrite you used doesn't.
I assume it is possible by approximating that using your technique. Set to 0, check gain in DAW when strumming the guitar, add gain until shortly before clipping, note down increase and use the same amount to decrease on plugin Input.

FWIW you wouldn't get less hiss by the way with the real amps if you ran that amount of gain.

Only talking from my experience: I had more noise than with real amps on low Input gain settings. Which makes sense, as someone recorded the Amp which adds the gain it always has and afterwards I added noise from low Input gain with bad SNR. There was no perceivable difference when driving the Interface loud.

I wasn't explaining this for the studio-savy folks or audio-engineers and I made that very clear in the opening of the vid - I'm trying to get most folks up & running so that they can make the most of these profiles.

Totally understand that. Still I'm missing a video for tech savvy folks.
Also - again - the best SNR is achieved with high Input gain on the Interface. Try yourself, it will make a huge difference with the Focusrite too.

 

[2dor]

Also - again - the best SNR is achieved with high Input gain on the Interface. Try yourself, it will make a huge difference with the Focusrite too.

I'm using a RME Fireface UCX II which is pretty solid in terms of SNR and performance so I'm not missing anything with the level at unity gain.

 

[MirrorProfiles]

Transformers work way better if they're driven hard

No. I don’t think your interface has any transformers, and transformers in any gear are there to perform a task. Whether driving them or not sounds good is subjective, and not usually something you’d want to do destructively on a guitar DI. Regardless, you’d need transformers on the inputs to have something to drive (if you wanted to alter the tone for some reason, so this is moot.

It is a bad idea to leave gain at 0

No. It depends on what calibration your A/D uses. For many interfaces you can’t boost any level without clipping anyway. So whether or not is a bad idea depends on a lot of factors.

I assume it is possible by approximating that using your technique. Set to 0, check gain in DAW when strumming the guitar, add gain until shortly before clipping, note down increase and use the same amount to decrease on plugin Input.

You can use a sine wave into your input, note the level in dBFS. Then turn the gain up and keep adding until the sine wave is the desired amount louder. Very accurate way to add gain on interfaces without stepped controls.