TOPIC: Adjusting interface input gain for different gtrs

Adjusting interface input gain for different gtrs 6 months 1 week ago #15252

Hi! I'm having trouble adjusting the interface input gain for different guitars / pickups. I have an Alesis io14 with hi-z input, and still gain control on the channel. Jamsden suggested in another topic to keep the VUs beating between -12 and -16 dB, but I should do this for all pickups or should I use this reference for guitars with higher output pickups and when plugging my strat, for example, let The output difference as a characteristic, more or less as with an actual amp.

Thanks!
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Adjusting interface input gain for different gtrs 6 months 1 week ago #15254

I normally strum the guitar plugged in and add gain until the interface shows clipping: open G or even palm muted power chords, then roll the input gain a bit to minimize clippling, it works for me.
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Adjusting interface input gain for different gtrs 6 months 1 week ago #15256

BrunoMariano wrote:
Hi! I'm having trouble adjusting the interface input gain for different guitars / pickups. I have an Alesis io14 with hi-z input, and still gain control on the channel. Jamsden suggested in another topic to keep the VUs beating between -12 and -16 dB, but I should do this for all pickups or should I use this reference for guitars with higher output pickups and when plugging my strat, for example, let The output difference as a characteristic, more or less as with an actual amp.

Thanks!
You could do either one depending on what you want to accomplish. If you're trying to reproduce the tone, feel and behavior of a guitar amp, then set the gain to between -6 and -12 dB to avoid clipping on your audio device's input, then adjust S-Gear's input gain to drive the amp the way it feels right to you on your highest output guitar with the loudest pickup. Use this for all other pickup and guitar combinations. This will reproduce what a guitar amp would do using the same instruments.

But you're not limited to what a guitar amp would do, that's the advantage of amps in the digital domain. You can now push the input of S-Gear just as hard with a single coil pickup as you would a double coil active pickup. Time to experiment with different options, perhaps starting from what you are familiar with and thinking about what you would do if you weren't quite so constrained.
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Adjusting interface input gain for different gtrs 6 months 1 week ago #15260

mohi wrote:
I normally strum the guitar plugged in and add gain until the interface shows clipping: open G or even palm muted power chords, then roll the input gain a bit to minimize clippling, it works for me.

I do something similar. I hit some chords a little harder than I would during normal playing, adjusting the audio interface input gain until the signal just hits the red. That gives me a nice input range in normal playing. Works for my style of playing but might not work if you always hit your guitar hard.

I have two input gains marked up, one for higher output guitars and one for my lower output guitars.

HTH,
Mike
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Last Edit: 6 months 1 week ago by mike.
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Adjusting interface input gain for different gtrs 1 week 3 days ago #16434

mike wrote:
mohi wrote:
I normally strum the guitar plugged in and add gain until the interface shows clipping: open G or even palm muted power chords, then roll the input gain a bit to minimize clippling, it works for me.

I do something similar. I hit some chords a little harder than I would during normal playing, adjusting the audio interface input gain until the signal just hits the red. That gives me a nice input range in normal playing. Works for my style of playing but might not work if you always hit your guitar hard.

I have two input gains marked up, one for higher output guitars and one for my lower output guitars.

HTH,
Mike

Hi Mike,
This is an issue I have struggled with for years perhaps you might be able to shed some light. I know most people will say “use your ears” when it comes to modelers/digital (or anything…), but given that modelers are generally setting about to recreate real-world devices that we interact with in ways we would now consider “traditional”, input gain staging has always been a problem for me.

I had an ElevenRack and then an Axe FX2. One thing I liked about both units is they take the guesswork out of gain staging at the input. For the elevenrack, there was no gain setting, it was already optimized for guitar-level signals. In the case of the Axe FX 2, any gain applied at input to optimize signal to noise ratios is adjusted for before the signal the rest of the chain, meaning the input gain does not affect the level seen by the modeler. Thus, plugging in guitars to the ElevenRack and the Axe FX 2 are just like plugging into a real amp.

The issue I have with adjusting the input gain to “tickle the red” is that amp sim software will see humbuckers and single coils having similar amplitude (albeit with the expected tonal differences). With amps that have bright caps, this has a dramatic impact on the gain the amp is set at, which in turn, due to the bright switch, would have a huge impact on the tone.

One could always “use their ears” and cut a few dB before the signal hits the amp sim, essentially a manual “unity gain” trick that the Axe FX 2 does. But even doing that would require a reference point so that one could calibrate levels. For example, perhaps there could be ranges indicated on the input level monitor for humbucker vs single coil guitars. I know this can be challenging as there is no standardized way to measure output (in mV or impedence? If it’s mv, how was this measured), but perhaps ballpark ranges for single coils and humbuckers could be a good start.

Would you happen to have an indication of what levels in the input monitor would correspond to an “average” real-life humbucker/single coil? This feels to me like the last piece of the puzzle for VSTs, as the quality of modelling as the ability to load IRs has pretty much put them on par with their hardware counterparts.
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Last Edit: 1 week 3 days ago by adamqlw.
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Adjusting interface input gain for different gtrs 1 week 3 days ago #16435

For the sake of the discussion, I'm pasting over some comments from Digital Igloo (Line 6 rep) on a separate forum regarding this.

"With modern audio interfaces and 24-bit recording, the noise and headroom issues no longer require one to maximize input levels. Maximizing signal-to-noise typically introduces more problems than it solves. That said:

Helix Native's input meter has been scaled such that you'll know when you're too hot. The input slider is key here, and your level can always be compensated with the output slider
Unless you expect a sparse mix, many normalized or loud tracks can sometimes overload send/return plugins (and in DAWs that don't have 32-bit floating point headroom, busses)
Basically, just record your guitar at unity and don't worry about maximizing level. Unfortunately, this involves un-learning things we were told over decades."
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Adjusting interface input gain for different gtrs 1 week 3 days ago #16436

Slightly modified approach here:

First, I use my highest output guitar & pickup to set the audio interface input gain - make sure I have sufficient headroom, as outlined above (hit chord hard, leave about 6 dB headroom).

Then, to adapt to different guitar output volumes, I put an EQ/compressor plugin chain before S-Gear's input (I use Cantabile as my live VST environment). Now I can adjust the "raw" guitar input to taste before it hits the amp.

I do this pretty much individually for every song - sometimes I want my strat to be more beefy, so tame the highs, boost the mids and give it a bit more level. Some other time, my LP may be a bit too fat for a clean sound, so some judicious EQ cutting does the trick before hitting the amp. The compressor is not only helpful for volume, but of course you can also do all kinds of dynamics tricks - boost the attack part or, conversely, create incredible sustain - all before hitting the amp.

Makes a world of difference when working with a number of guitars (or in my case a number of different guitar models - Variax user here).

Cheers,

Torsten
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Adjusting interface input gain for different gtrs 1 week 3 days ago #16437

mike wrote:
I I hit some chords a little harder than I would during normal playing, adjusting the audio interface input gain until the signal just hits the red

I set the input level just like you do using the very same method, with the difference that I play quite a bit harder than I'll ever play.

I like having that little extra headroom, you know? B)

HTH,
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Adjusting interface input gain for different gtrs 1 week 2 days ago #16439

As we've discussed here in the past, the electric guitar is an incredibly dynamic instrument. Input gain adjustment depending on the guitar and playing style is the necessary approach. It's impossible to configure an input channel that will work optimally for any guitar/playing style - the Audio Interface doesn't know what (or who!) is plugged in and what to expect. I'm not convinced that you can satisfactorily generalise on Humbuckers vs Single Coils, there is still a lot of variation in output with each type.

I've considered one solution based on using a real tube input stage and placing the A/D conversion on the output of that stage. This way the dynamic range would be reduced (in a nice way) by the tube stage. Higher output guitars could be allowed to clip the stage more than you would be happy clipping an Audio Interface input. Apogee are probably treading down the correct path with their soft-clipping inputs.

If you set up the audio interface for a high output guitar and then plug in a standard Strat, you will want to push the input gain a bit harder to get some half decent signal level into the interface. Of course you could then back off the input trim (in the floating point digital domain) to emulate the lower output guitar hitting the amp. Personally I quite like the effect of the Strat being a bit hotter into the amp.

Mike
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Adjusting interface input gain for different gtrs 1 week 2 days ago #16441

Not every interface react the same way. I used to crank a little bit the input on my interfaces. Once I started to use APOGEE products I realized I did not have to do it. However it took me a lot of time to realize it LOL!

I learned that you have to use your ears .... Yesterday I decided to try more than 15 minutes the apogee Element with no increase at the output. After 30 minutes I was convince. My guitar was more alive and S Gear was even sounding better.

You have to find the sweet spot where your guitar sound is just enough to drive the input of the amp. Sometime I was increasing the input too much and the blend between the guitar sound at the input and the sound of the amp at the output was not optimal. I think the new generation of interface are better for guitars.

Sorry if I am not clear. English is not my main language :-)
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Adjusting interface input gain for different gtrs 1 week 2 days ago #16444

“It's impossible to configure an input channel that will work optimally for any guitar/playing style - the Audio Interface doesn't know what (or who!) is plugged in and what to expect.”

I see what you’re saying here, but in the real world, isn’t that how amps function? I don’t mean to generalize that single coils have output of 100 mv and humbuckers have output of 300 mv, but rather something less specific. For example, according to the DiMarzio
  • DiMarzio’s “standard strat” single coils have an output range of 130 to 200 mV.
  • Hum-cancelling Dimarzio strat pickups have an output range of 90 mV to 325 mV (the 90 mV being the unusual low-output Malmsteen pickups).
  • DiMarzio vintage output humbuckers range 178 mV to 285 mV
  • DiMarzio medium power humbuckers range 250 mV to 352 mV
  • DiMarzio high power humbuckers range 325 mV to 510 mV

If we take 90 mV to 510 mV to but the lower/upper bound of what the input should be receiving, and convert that into zones on the input meter, then we could reliably adjust input gain by aiming for those zones on the input metering (which can be done independent of setting input gain to optimize signal to noise ratio on the hardware), and not by ear, to match up accordingly with the pickup being used. This would take a large part of the guesswork/”use your ears” out of the equation, and brings the modeler closer to a real-world plug-and-play solution. As I understand it, there is no standardized way to measure pickup output. How hard one hits, the type of pick, etc, all confound the process of measuring output. But even without that precision, the broad buckets could be effective in making modelers more accessible to the average guitarist.

As you say, backing off the input trim can emulate the lower output guitar hitting an amp, but the question that has stumped me is just how much to back off. While I can use my ears, part of what I like about using different guitars is how simply changing guitar has a generally predictable impact on tone, which is a function of both the overall response of the pickup as well as the output level. Maintaining as much of that framework in the virtual world seems like a net benefit.

Basically, it feels to me like modelling is pretty accurate but the question mark is how to calibrate input to mimic “real world” application. This seems to have been solved in hardware on the ElevenRack and Axe FX, because the input sensitivity is known and can be compensated for. Hopefully there can be a way to come close to mimicking this by indicating certain known values (i.e. pickup type) to calibrate the input to.
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Adjusting interface input gain for different gtrs 1 week 2 days ago #16446

The one big difference between a "real life" amp input and an audio interface that you must take into account is that an audio interface is simply your entry point into the digital world, after which you can do all sorts of things to your now digital signal before routing it to your virtual amp. You don't want your audio interface to contribute to shaping your sound - you want it to deliver a clean and un-processed input signal for your digital processing chain.

The key point to watch for around an audio interface is to get your signal into the digital domain without clipping but sufficiently hot that you are not losing bit resolution, since your audio interface works with an integer format. With 24 bit converters pretty much the standard today, you're not losing a lot of resolution even when switching from a Les Paul to a Strat without changing the input gain, so I wouldn't worry overmuch about adapting input levels when changing guitars.

So essentially: set up your input gain so it doesn't distort your signal with your loudest guitar / pickup / playing style - but don't leave it too quiet, otherwise you're losing resolution and getting too much noise.

Once your signal is within the digital domain, it will be processed in floating point format between your plugins, so the issue of losing resolution or clipping will essentially disappear - you only need to worry about individual plugins clipping within their algorithms (when you drive a virtual compressor with a signal of 10 times unity, it may behave in a funny way).

Consequently, instead of fiddling with your input gain when changing guitars, it is easier to simply use a gain plugin before S-Gear to raise the level of your strat when you need or want to. Or, if you want to keep it all within S-Gear, simply use the "input" knob (bottom right) to raise the signal coming into your "amp" - but then you'll need to have separate patches for your Strat and your Paula.

The advantage of the "software only" approach to managing your input levels is its flexibility - you simply select a different patch in S-Gear or a different preset in your VST host, and your levels are where you want them to be - depending on the sound you want to achieve. At this point, there isn't really an alternative to using your ears and experience to set the right level that achieves your tonal goals...

Cheers,

Torsten
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Last Edit: 6 days 23 hours ago by ToH2002.
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Adjusting interface input gain for different gtrs 1 week 1 day ago #16453

adamqlw wrote:
...I see what you’re saying here, but in the real world, isn’t that how amps function?

To echo the point the ToH2002 made, there is a key difference between A/D input channels and a typical tube amp input stage. A tube amp input stage can be pushed into clipping and the result is desirable. It will reduce the dynamic range of the signal with grid current limiting and soft clipping. Hence why one might consider an approach where the A/D conversion is made after a first tube input stage.

Cheers,
Mike
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Adjusting interface input gain for different gtrs 5 days 23 hours ago #16463

mike wrote:
adamqlw wrote:
...I see what you’re saying here, but in the real world, isn’t that how amps function?

Hence why one might consider an approach where the A/D conversion is made after a first tube input stage.

Cheers,
Mike

I'm smelling a Scuffham interface (or S-gear hardware)!
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Adjusting interface input gain for different gtrs 5 days 2 hours ago #16468

I would actually advise against this, op.

You really just want to leave yourself with a lot of headroom at the interface input, so you can strum as hard as you can and not even dip into yellow, and to adjust input gain you just use the gain-staging somewhere in the plugin chain (which for me is the output gain of the compressor plug-in I run all my guitars through).

That way if you want, you can even make presets for each guitar within the plug-in you choose to use to set the "input" for everything after it, even if it's a simple trim type plugin to raise or lower the level.

IMO this will make it easier to be consistent and involves less fiddling with knobs.

Sound too quiet? Turn up the monitors :rock out:
Last Edit: 5 days 2 hours ago by LorenzoGamble.
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Adjusting interface input gain for different gtrs 4 days 19 hours ago #16472

I agree with you.

I used to set my input Level just before it reach the Yeallow bar. I had a nice sound.

On day I made a mistake and did not increase it. The input of my guitar was not driving the amp as much as it used to do but I realized I had more room to play with my volume pot. Even when I put a hardware pedal in front of the interface it sounds better. I feel it when I play with or without a pedal in front.

As long as your signal is strong enough and you do not loose definition you are OK.

:rock out:
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Adjusting interface input gain for different gtrs 4 days 18 hours ago #16477

@ToH2002 provides some great advice. I'd only add that you need to be sure that you're using a High-Z input into your audio interface, at least 1M Ohm. That's usually labeled High-Z or Instrument. But check your interface to see exactly what its impedance is. If its too low, it will load your guitar's pickups and suck tone. If your interface doesn't have a High-Z input, you can try using a pedal like Tumnus or something similar that has a buffered input and isn't "true bypass".

Given all this advice, it might still be difficult to know how to exactly setup your interface into S-Gear. Here's an approach I use that should provide a good starting point.

Set your audio interface gain control so that the input meter reads around -12 dB - or about mid-scale. This will give you plenty of headroom for either single or double coil pickups without having to change the gain knob.I also set the PA inputs for live gigs in this same range. With 24 bit inputs, you don't need to worry about noise or clipping at -12 dB.

If you don't have a meter on your interface, turn up the gain until you see some clipping with your loudest instrument/pickup, then turn it down a consistent amount so that the clip light never comes on. Note where the gain knob is set so you can reproduce it.

Then add a gain plugin before S-Gear and adjust it so that the S-Gear Input meter just reaches into the middle of the yellow with that's input knob set to 0 dB. This will ensure your hitting S-Gear with a signal designed for its :"sweet spot". Every plugin has a sweet spot for its input and output, where it isn't noisy, isn't clipping, and works best for what it was intended. The S-Gear Input meter can tell you where that sweet spot is.

Now you don't need to worry about digital clipping as long as the output level from S-Gear doesn't clip the mix buss or hardware output.
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Adjusting interface input gain for different gtrs 1 day 3 hours ago #16520

All the theories didn't work, except one to set audio interface gain to avoid ADC input clipping (in my case it's set to minimum for my hot humbuckers), until I learned how my guitar is working with a real amp - after that I had to turn S-Gear input gain to max and I feel it's not enough. In a DAW I still need to find a most appropriate plugin to make input gain higher and keep S-Gear to its default.

So numbers, such as pickup voltage, audio interface maximum input level, etc. will not help to set S-Gear (or any other amp sim) input gain properly, until compared to a real thing or experience is accumulated.
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Adjusting interface input gain for different gtrs 1 day 1 hour ago #16522

Free Blue Cat's gain (mono) plugin works great for me. www.bluecataudio.com/Products/Bundle_FreewarePack/

On the audio interface I set gain to minimum to avoid any clipping or saturation of Analog-Digital converter, then I restore gain by adding +8 or +12 db using Blue Cat's gain plugin before S-Gear in my DAW and it sounds great.
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