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How to calibrate levels on the Focusrite ISA 2

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Re: How to calibrate levels on the Focusrite ISA 2

Postby Hugh Robjohns » Wed Jan 22, 2020 7:13 pm

armans wrote:Ok thank you for clarifying but I still have to say that there is something not quite right about this.

I don't know how to make it any clearer.

No two different meters on different devices will ever show exactly the same readings on programme audio (anything other than steady test tones). They might get pretty close if they are the same types of meters, but even then the chances are some different material will still reveal differences.

If you want identical readings you have to have identical meters. That's why every studio across the BBC uses exactly the same type of PPM built to exactly the same specifications.

In your case, you have a virtual software meter and a hardware meter, and we don't actually know the specifications for either of them. However, your tests have already revealed that they are different types of meter with very different characteristics.

...as it stands, the meter is of no use to me at all!

As I said, all you have to do is familiarise yourself with the kind of acceptable readings displayed on each type of meter for normal recordings.

I used to work with tape recorders having VU meters on them, and mixing consoles with PPMs. Very different displays with different material, but I learned to interpret them perfectly well and make reliably consistent recordings using either. I'm sure you can learn to do the same -- and you have the added advantage of being able to tweak the calibration of the ISA meter to make it display something better suited to your own specific requirements...

Focusrite they assured me that peak RMS values have nothing to do with it. They confirmed that what the meter shows on the ISA is what should be in my DAW.

Very clearly, that statement is a nonsense and either you or they didn't fully understand the situation being discussed.

...for now I stand firm that the ISA meter does not work correctly.

You could, of course, be right... but I very much doubt it. I believe it's simply that you have two different meters but expect them to behave identically to music programme... which simply can't and won't ever happen.

If there is such a difference in level between the sine tone and white noise / pad instrument then it would be more accurate to calibrate to those levels than to the sine tone...

You can't because, as I have explained several times, different material has different Crest Factors and so different material -- different instruments, different keyboard presets -- will always give different -- and unpredictable results.

Instead of getting bogged down and fixating on trying to obtain identical readings, can I suggest you simply figure out what would an acceptable recording level as displayed on each kind of meter. When tracking, the absolutely peak levels really aren't critical as long as you're working with a decent headroom margin. They could be anywhere between -20dBFS and -6dBFS without any problem whatsoever. You can then tweak the recorded tracks to suit the mix as necessary without any issues at all.

Moreover, if you keep your monitoring levels consistent, you'll soon learn to set recording levels entirely by ear without ever looking at a meter, and probably do so with an accuracy of decibel or two quite easily.
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Re: How to calibrate levels on the Focusrite ISA 2

Postby ef37a » Wed Jan 22, 2020 8:29 pm

Armans, I can give you two examples of the problems I faced with 'meters'.

Many years ago I made peak reading LED device to fit inside my quite decent Yamaha cassette machine. I was not happy with the mechanical VU meters. I set the LED to just start to glow at 3dB over Dolby level*.

Over the next few weeks I was recording a variety of things, mainly R3 and some vinyl for the car. I noticed that very often, although music was not that loud, the LED blinked even though the VU meters were hardly moving (BBC bogs called then "Virtually Useless"!) I checked the calibration several times over a month or so but it was always spot on. The fact was a short crack on a snare would light the LED but not move the needles. That is about as extreme an example of two different meters not agreeing as you can get but as Hugh has pointed out several times (sigh) only identical meters will track on programme or noise.

A similar situation arose only a few years ago when my son was trying to even out the loudness of some 4 hours of music, mainly punk, for his sister's 40th birthday party.
He tried to do this in Samplitude, Sonar, Cubase and Audacity but no meter system was consistent from song to song. In the end he had to rely on the Mk 1 lugs!

Just thank your stars you are 'digital' and have that MOOOhassive dynamic range to play with!

*YOU! Will have to Google that if you want to know but it is water gone well under the pont now.

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Re: How to calibrate levels on the Focusrite ISA 2

Postby armans » Wed Jan 22, 2020 9:15 pm

thanks for all the help and for sharing your experiences. I will report back if I have any breakthrough :)
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Re: How to calibrate levels on the Focusrite ISA 2

Postby Hugh Robjohns » Wed Jan 22, 2020 10:26 pm

:thumbup:
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Re: How to calibrate levels on the Focusrite ISA 2

Postby armans » Sat Jan 25, 2020 11:39 am

Hugh Robjohns wrote:
You CANNOT use any type of noise to 'calibrate' an audio meter, or to check levels.

From the Sweetwater website.

https://www.sweetwater.com/insync/pink- ... medium=CPC

Pink noise is the right type of noise to use to calibrate audio equipment (at least if you are using it for equalization calibration). Here’s where everyone gets confused:

Is calibrating meters so different?
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Re: How to calibrate levels on the Focusrite ISA 2

Postby Hugh Robjohns » Sat Jan 25, 2020 12:15 pm

armans wrote: Is calibrating meters so different?

Yes... for all the reasons I've already explained.

Pink noise (not white noise) can and usually is used for setting levels from monitoring speakers -- which is what that article is fundamentally referring to (room/speaker equalisation). It's also a handy reference sound when setting initial mix levels, and it's even quite good for masking background noises when you're trying to get to sleep...

But pink noise cannot be used as a reference level for accurate meter alignment.

And actually, that article is rather confused and inaccurate anyway, BTW... ;)
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