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.

 

[volkan]

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.

do you know about

RME Fireface UCX first version is it still relevant for today?
what is the diffrerence between ucx ıı and ı?​

 

[2dor]

do you know about

RME Fireface UCX first version is it still relevant for today?
what is the diffrerence between ucx ıı and ı?​

I don't recall specifics to be completely honest. I do know I did very thorough research before settling on the UCX II.

The UCX II has a 1Mohm instrument input impedance which is similar to a lot of real guitar amplifiers; it does not load your pickups down & you get a good signal representation across the frequency spectrum.
The UCX only has a 470kOhm input impedance on the instrument input so that alone disqualified it from my list.

 

[FrankyFire]

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.

That's a very different animal. I assumed you're using the Focusrite that you're referencing in the Video. Having used multiple Interfaces in that price range I can assure you that they need added gain or will add lots of hiss.

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.

OK, I'm lost in translation here, I assumed that "A/D Wandler" translates to "A/D Transformer", but converter was the correct term (Counter-intuitive: "Wandel" translates to "Transformation" or "Change").
Still, increasing the gain as high as possible without clipping results in best SNR and lowest noise floor. Look at Julian Krause's video explaining it including measurements from a range of audio interfaces (great channel by the way). The SNR changes DRASTICALLY with increased gain and stagnates a a certain threshold (usually above 40dB gain).

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.

Sure, that does make sense. Again, I only worked with entry level Interfaces and none of them worked this way. At 0 they just added no gain resulting in worse SNR and they usually have no Pad or negative Input. Still my point stands: More gain results in better SNR.

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.

That is a very good approach.
Still I haven't understood how I know the level of the Sine wave? Or am I trusting the manufacturers values for the input in that case as as 2dor mentions in his video and just input a sine wave of any level?

 

[MirrorProfiles]

Still, increasing the gain as high as possible without clipping results in best SNR and lowest noise floor. Look at Julian Krause's video explaining it including measurements from a range of audio interfaces (great channel by the way). The SNR changes DRASTICALLY with increased gain and stagnates a a certain threshold (usually above 40dB gain).

No. This is only the case if you are recording something of lower noise than the converters themselves. In a real world use, you will have louder noise in the signal chain when recording the instrument. Your SNR can only be as high as the loudest source of noise in your signal chain. Making measurements of converters is not the sort of real world situation you’ll come across, you need to factor in the noise from your instrument and cable etc.

Still my point stands: More gain results in better SNR.

No. SNR is constrained by the loudest source of noise in your signal chain. If your interface noise is already below your loudest source of noise, raising the gain increases the noise by the same amount and your SNR is the same. Moreover, on many interfaces you don’t have much room to increase the gain by any meaningful amount. Many have spec’d their designs to have JUST enough headroom rather than too little.

Still I haven't understood how I know the level of the Sine wave? Or am I trusting the manufacturers values for the input in that case as as 2dor mentions in his video and just input a sine wave of any level?

You only need to know the level analog level of the sine wave if you are calculating your headroom. If you just need to know how much level you are adding, the sine wave can be any level and you just add “X amount” to that. You can also work it out if you have gear where you know the headroom from the specs (for instance comparing 2 pieces of gear against each other if you know the specs for one).

 

[FrankyFire]

No. This is only the case if you are recording something of lower noise than the converters themselves. In a real world use, you will have louder noise in the signal chain when recording the instrument. Your SNR can only be as high as the loudest source of noise in your signal chain. Making measurements of converters is not the sort of real world situation you’ll come across, you need to factor in the noise from your instrument and cable etc.

Well, I understand that and it does make sense. But coming back to my initial statement: I tried what you did in your first video and had different results. There was a very noticeable difference when recording my guitar DI and running into any sort of Amp plugin. 0 Gain and digital Gain (Reaper set to 32 bit internal processing) into the Amp plugin was noisier than High gain on the interface input and less digital gain. Seems like my Interface (when gain is at 0) is the loudest source of noise in my case.
The video I posted contains my interface in the graphs and it is on par with other brands (in the price range).

Many have spec’d their designs to have JUST enough headroom rather than too little.

Stupid question: How do I know how much headroom I need?

You only need to know the level analog level of the sine wave if you are calculating your headroom. If you just need to know how much level you are adding, the sine wave can be any level and you just add “X amount” to that. You can also work it out if you have gear where you know the headroom from the specs (for instance comparing 2 pieces of gear against each other if you know the specs for one).

Thanks a lot for the explanation and videos! Was searching for exactly that. Stupid YouTube/Google search is only returning "most relevant" results nowadays, feels like I can't find what I'm searching for anymore there.

 

[MirrorProfiles]

Well, I understand that and it does make sense. But coming back to my initial statement: I tried what you did in your first video and had different results. There was a very noticeable difference when recording my guitar DI and running into any sort of Amp plugin. 0 Gain and digital Gain (Reaper set to 32 bit internal processing) into the Amp plugin was noisier than High gain on the interface input and less digital gain. Seems like my Interface (when gain is at 0) is the loudest source of noise in my case.
The video I posted contains my interface in the graphs and it is on par with other brands (in the price range).

It's hard to diagnose things remotely, especially as I can't seem to find a manual for the MK2 Komplete Audio 6. I suspect it's ultimately just quite a noisy interface, especially compared to similarly priced alternatives. Krause's information is great, but for it to be relevant here it needs more context. He's essentially just verifying the information listed in the specs is correct (which it isn't always), or showing the caveats on how they achieved their results. For recording guitar DI's, we have slightly different priorities to focus on. Noise absolutely matters, but it's usually a fundamental part of the design of the manufacturer and they make their design accordingly. It doesn't always hold true but most seem to know what they're doing.

Stupid question: How do I know how much headroom I need?

The amount of headroom you need depends on what the loudest source you are trying to record is. Are you recording vintage single coils, or are you recording EMG's? or are you recording a maxed out TC Integrated Preamp/DIrty Tree? Manufacturers tend to hover around 12-13dBu=0dBFS because it's JUST enough to be able to record most passive humbuckers at their maximum, while also offering a decent (relative) level for single coils. If you have 20dBu of headroom, loud humbuckers might be peaking at -6 or -7dBFS (which is fine really), but quieter single coils might be a little quiet. There are very few built in instrument inputs with that much headroom, although there are some out there.

 

[FrankyFire]

It's hard to diagnose things remotely, especially as I can't seem to find a manual for the MK2 Komplete Audio 6. I suspect it's ultimately just quite a noisy interface, especially compared to similarly priced alternatives. Krause's information is great, but for it to be relevant here it needs more context. He's essentially just verifying the information listed in the specs is correct (which it isn't always), or showing the caveats on how they achieved their results. For recording guitar DI's, we have slightly different priorities to focus on. Noise absolutely matters, but it's usually a fundamental part of the design of the manufacturer and they make their design accordingly. It doesn't always hold true but most seem to know what they're doing.

Well, he made a video on that interface too (he has one on almost any interface right now):

The amount of headroom you need depends on what the loudest source you are trying to record is. Are you recording vintage single coils, or are you recording EMG's? or are you recording a maxed out TC Integrated Preamp/DIrty Tree? Manufacturers tend to hover around 12-13dBu=0dBFS because it's JUST enough to be able to record most passive humbuckers at their maximum, while also offering a decent (relative) level for single coils. If you have 20dBu of headroom, loud humbuckers might be peaking at -6 or -7dBFS (which is fine really), but quieter single coils might be a little quiet. There are very few built in instrument inputs with that much headroom, although there are some out there.

According to the Video he measured 109dB(A-rated) headroom. I have no clue what that means and cannot find resources on that. Though I can assure you that I have never had issues with Signals being to loud and clip.
I've had pickups though that I was unable to record properly. The signal looked hard clipped but the Input was not. I was able to replicate this on other interfaces as well (Seymour Duncan Pegasus & Sentient I think). This is probably what you are referring to. So how does headroom differentiate from the "ceiling" (where the input is clipping)?

 

[MirrorProfiles]

According to the Video he measured 109dB(A-rated) headroom. I have no clue what that means and cannot find resources on that. Though I can assure you that I have never had issues with Signals being to loud and clip.
I've had pickups though that I was unable to record properly. The signal looked hard clipped but the Input was not. I was able to replicate this on other interfaces as well (Seymour Duncan Pegasus & Sentient I think). This is probably what you are referring to. So how does headroom differentiate from the "ceiling" (where the input is clipping)?

You'd need to know the specs for the instrument input as they often have different circuitry and levels. Im presuming his measurements are made through the mic input or line inputs.

You'd also need to know the headroom levels too really to make sense of the SNR value. Imagine your guitar outputs a constant level sine wave signal no matter what you play from it. On some interfaces, this sine wave could be very close to clipping at 0 gain. On others, this could be very quiet and close to the noise floor. The noise level on its own isn't really helpful, because we need to know how it represents the level of your signal. So 109dB may be fine if your signal is loud enough, and maybe not if your signal is too low. You really need the context on the loudest signal it's able to handle, as well as its noise floor, as that is the range you are operating in.

Regardless, if you are experiencing noise and a low signal level, then turning it up will help. This does not mean everyone else will have the same problems, or improvements. Its worth understanding why it may work for you but not be applicable as a rule.

I've had pickups though that I was unable to record properly. The signal looked hard clipped but the Input was not. I was able to replicate this on other interfaces as well (Seymour Duncan Pegasus & Sentient I think). This is probably what you are referring to. So how does headroom differentiate from the "ceiling" (where the input is clipping)?

This is different. Were you using any pedals or buffers or active circuitry? They'll often clip at a certain point which will produce a squared off waveform. It's why EMG waveforms can look totally sausaged.

 

[FrankyFire]

This is different. Were you using any pedals or buffers or active circuitry? They'll often clip at a certain point which will produce a squared off waveform. It's why EMG waveforms can look totally sausaged.

No I wasn't, my band mate has the same issue with some high output Seymour Duncan Pickups (Nazgûl I think) and a Steinberg entry level Interface. Also I remember watching a video from Kohlekeller where he shares the same experience with some Pickups and MOST (even very expensive - excluding RME) audio Interfaces.

 

[MirrorProfiles]

No I wasn't, my band mate has the same issue with some high output Seymour Duncan Pickups (Nazgûl I think) and a Steinberg entry level Interface. Also I remember watching a video from Kohlekeller where he shares the same experience with some Pickups and MOST (even very expensive - excluding RME) audio Interfaces.

I have no idea. I have high output seymour duncan’s in most of my guitars. They can clip UA interface inputs somewhat easily which have 12.2dBu of headroom before clipping. RME have a fraction more headroom, and so are a little harder to clip (but it’s still possible). It could be that you’re clipping the input, and then the circuitry is padding it down before the preamp gain stage. Without knowing the specific gear and gear how it behaves I can’t really say remotely.