Calibrating Input Level for Plugins

I measured the max input level for my Xsonic Xtone Stomp and it‘s at 1,5 dBu. This is a guitar interface…really bad design. Even worse than Behringers UMC range instrument input (4 dBu if I remember correctly).
So only low output single coils with this one if you want full dynamic range. Thanks for all the infos in this thread. Really helpful!
 
For electric guitar you want at least +12dBu of headroom.

Why?
Let's take a 9v BOSS pedal as our reference, these pedals have been around for 45+ years and are industry standard.
A buffered 9v pedal gives you 4.5v Peak headroom at best when bypassed, but more like 4.4v or lower.
12v pedal will give you 6v Peak, etc.

4.5v Peak = 3.18v RMS = +12.3dBu
6v Peak = 4.24v RMS = +14.8dBu

It makes sense to have an interface or a modeler that has slightly more headroom than your standard 9v BOSS pedal or buffer.
Helix for example has a headroom of +11.5dBu which is slightly below an ideal 9v pedal, but with the PAD enabled you have extra 5.5dB of headroom thus +17dBu which can take 12v pedals without clipping.

Edit:
EMG 81 is not hot btw, it clips at around 2.5v Peak, it's compressed and mid-rangey but far less hot that an overwound PAF pickup like a Seymour Duncan JB SH-4 for example.
 
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the units modeled were hillariously chosen, pretty sure the "1176" was a very specific Purple Audio MC76 rental unit for instance
that sounds like absolute horseshit, or possibly confused with another company. The link below is from the Mark 1 era and its pretty clear they are comparing their plugin to UA and Urei built 1176's (and you can see non-purple units in the background). The Mark 2 versions that have been out for over 15 years are Rev A, Rev D, and Anniversary Edition, nothing in common with a Purple MC76. Not saying it isn't true, but without any kind of proof it seems like a rumour. Would be very odd for Universal Audio to rent something that they build and own all the rights for, makes no sense at all.


I'm not aware of any developer who says this

There are countless examples of very respected developers saying this, let alone the number of companies totally using their product lineup to do their own take on. URS Plugins, Slate Digital, Arturia, Black Rooster, Plugin Alliance etc. The influence far extends from just the product lineup or UI's, UA are basically the benchmark when it comes to modelling analogue behaviours such as decramped phase responses, program dependent, band interactions, attack and release, saturation etc. Some companies get close to their level of modelling accuracy, but no one has surpassed it. Not saying other comapanies don't have better tech (izotope/fabfilter/etc have awesome R&D and products), but as far as analog modelling they are the benchmark, even now. They're probably most responsible for all other analog modelling studio plugins having to raise their game on modelling non-linearities and complex interactions. The early Bomb Factory and Waves stuff was miles off by comparison.
their nonsense claims about their card vs native cpu use which was utterly and ultimately decimated when it could finally be shown with a plugin that ran on both that not only did the card dongles NOT save you CPU, but it cost you more cpu to run the same number of instances on the card than just straight native.
this has always been bullshit on their part, its been something for them to avoid piracy and charge more for their products. Its up to the user to decide if its worth jumping through those hoops. Tougher sell these days because the competition has caught up a lot and there are good alternatives for many of their plugins (largely because so many have based their product line on offering the exact same things). They have to code and model their plugins on computers and they get ported to DSP when its complete.
And of course, most famously, when almost universally seen as one of the best if not the best coders in the business offered to fix UAD's horrible and unusable drivers for free and they instead said their customers could just suck it and buy the next version of the dongle card that came out
UAD absolutely have a ton of BS, windows support, LUNA (absolute rubbish), expensive prices. They're one of those companies that acts as if they are Apple, but they aren't. But those negatives don't mean their analog modelling and products are any worse. Their stuff is generally very well beta tested and stable.

Anything audible? Can you name it?
totally depends how you use it. Lots of stuff is very much measurable, and its easy to see where other companies fall short (even if their products are still good). Genuinely curious who you think the benchmark for analog modelling studio gear is if it isn't UAD.
 
Universal wasn't making 1176s or really anything else at the time of the UAD-1, it was an acquisition of the name of a former revered pro audio company. It would be a while before they had the staff and techs to know how to create new hardware based on the older units that had previously made the company famous. I'll see if I can dig up some of the history about the models used for the first LA2a and 1176 plugins they made, but they certainly weren't making their own hardware at the time to model.
 
Universal wasn't making 1176s or really anything else at the time of the UAD-1, it was an acquisition of the name of a former revered pro audio company. It would be a while before they had the staff and techs to know how to create new hardware based on the older units that had previously made the company famous. I'll see if I can dig up some of the history about the models used for the first LA2a and 1176 plugins they made, but they certainly weren't making their own hardware at the time to model.
either way, I’m not going to judge their entire impact on the digital recording world based off their first products, especially when SO MUCH has changed since then. In the same way that I wouldn’t judge Fractal or Line 6 off their first offerings.

I actually think UA’s most exciting period probably ended a few years ago and they’re trying to find their place in the world again. Their stuff is still the benchmark IMO, but for a good while there was no comparison if you were looking for decent tape emulations, reverbs etc in plugin form.
 
I checked the input levels of my HX Stomp and FM3 because I wanted to see for myself. I saw the same 6dB nominal difference that previous posts reported.

I tried to get as close to the ideal RMS voltages as I could. My Fluke 289 measures to 4 decimal places.

HX Stomp
0.7070V RMS: -12.1dBFS
0.5002V RMS: -15.1dBFS

FM3
0.7070V RMS: -18.2dBFS
0.5002V RMS: -21.2dBFS

I had always thought the Helix and Fractal inputs were closer in level.
 
FM3
0.7070V RMS: -18.2dBFS
0.5002V RMS: -21.2dBFS
Thanks.
Same reading as on the FM9, about +17.5dBu.
We also measured that the AxeFx3 has 5dB less headroom than the FM3/9, probably internally compensated so the models sound the same.
In any case, there is no Native version of AxeFx so the dBFS/dBu readings are useful if you are using a Fractal with DAW plugins.


Edit:
DAW plugins that we know their calibration dBu value that is.
Most manufacturers will not provide this number or even have a clue what we are talking about, as if nobody engineered/programmed these plugins and they just appeared out of thin air.
 
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Thanks.
Same reading as on the FM9, about +17.5dBu.
We also measured that the AxeFx3 has 5dB less headroom than the FM3/9, probably internally compensated so the models sound the same.
In any case, there is no Native version of AxeFx so the dBFS/dBu readings are useful if you are using a Fractal with DAW plugins.


Edit:
DAW plugins that we know their calibration dBu value that is.
Most manufacturers will not provide this number or even have a clue what we are talking about, as if nobody engineered/programmed these plugins and they just appeared out of thin air.
I tend to record my dry DI tracks with my HX Stomp, and later process with Helix Native, FM3, real amps, or other plugins. It appears that I’ve been hitting the Fractal models with a little more gain that I thought.

It’s always been kind of visually unsettling to have to crank input gain controls on some plugins plugins like S-Gear and Amplitube to get the gain feeling right. It looks like it’s a necessary step with some of the plug-in calibration info compiled in this thread.

Many plugins have have instructions on setting levels, but are so vague and useless. It wouldn’t hurt to offer both simple and detailed calibration steps.
 
as if nobody engineered/programmed these plugins and they just appeared out of thin air.
probably says a lot about how many plugins are outsourced to freelance devs. So much room for miscommunication/misunderstanding, especially if there is language barriers and a lack of technical knowledge from the company selling the software.

It kinda defeats the purpose of having different pickups in the first place.
Yep, and defeats the purpose of having an accurate emulation. It’s so so so important
 
I have official confirmation from Neural DSP that their plugins are made with this reference:

1 Vp = 0.707 VRMS = -0.79 dBu equals -13 dBFS in the digital domain

Which means on my 11.4dBu input, I have to lower the level by 0.8dB. If I use my 12.2dBu UAD Apollo input with gain at 0, its perfect (almost like they did it on purpose :rollsafe).

It took a few goes for me to reach the right person at Neural DSP, but I essentially got a perfectly written response within a few hours of reaching out.

Our plugins are made with the following audio interface gain:
  • Analog domain sine waveform 1 Vp = 0.707 VRMS = -0.79 dBu equals -13 dBFS in the digital domain.
  • In other words, when feeding the audio interface input a sine 1 Vp from a signal generator, it results in -13 dBFS in the digital domain.
If you want to calibrate your interface in order to mimic the input gain our engineers use when creating and testing the plugins, I would advise you to feed a sine waveform 1 Vp = 0.707 VRMS = -0.79 dBu to the interface and set the interface gain to such level that the DAW peak meter shows -13 dBFS. Feeding a sine waveform on different interfaces will result in different values (again, this is the reason why we cannot provide a concrete value). Check these examples of feeding a sine waveform 1 Vp:
  • UAD Apollo x6: -13 dBFS
  • UAD Apollo Twin: -12.9 dBFS
  • Quad Cortex: -15.1 dBFS (1M impedance) Input level at 0 on QC.
  • Focusrite Scarlett: -13.1 dBFS
  • Focusrite Clarett: -14.6 dBFS
  • Apogee Duet: -14.5 dBFS
However, I have to tell you that can be achieved by connecting your guitar to the Hi-Z input of a UAD interface with the gain at minimum (to ease the pain of doing that with all your interfaces and electric guitar combinations). If your interface features a Hi-Z input, leaving the gain input by default (minimum) is more than enough. Add input gain if one of your guitars lacks output level (as our support team suggested, increase it as much as you can without clipping).

What if you use Quad Cortex as an audio interface?
If you use Quad Cortex as an audio interface and you want to get its input close to a UAD interface (-13dBFS), just connect your instrument with the QC's instrument input at 0.0 dB. If you wanna match them exactly, you have to boost Quad Cortex USB output by approx +2.3 dB before reaching the plugin's input.
 
Out of all people, Neural didn't play dumb with you, that's great.
Yep, that's the perfect answer, kudos to them.
Also, choosing UAD Apollo and Focusrite Scarlett as their reference interfaces was a very good move.

PS.
I think they might be reading our forum. :LOL:
 
I have official confirmation from Neural DSP that their plugins are made with this reference:

1 Vp = 0.707 VRMS = -0.79 dBu equals -13 dBFS in the digital domain

Which means on my 11.4dBu input, I have to lower the level by 0.8dB. If I use my 12.2dBu UAD Apollo input with gain at 0, its perfect (almost like they did it on purpose :rollsafe).

It took a few goes for me to reach the right person at Neural DSP, but I essentially got a perfectly written response within a few hours of reaching out.
For once, kudos to Neural DSP for this very detailed information.
 
I just went through this with my Motu M4.
  • Using Output 3, the sine wave generator was set to -14.4dB to hit 500mVRMS
  • The Hard Gate on my Helix Rack opened at -20.5dB
  • The Native Hard Gate, set at -20.5dB, opened at 0dB; at -0.1dB, the Gate closed
So either I did something very wrong, or this setup is very well-matched.
 
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