Please explain dBu, dB & how much headroom is required for

[jess123]

Hi guys,

I read an article which says "If you record at a 24-bit rate (Chapter 4 has more about bit rates), you want your levels peaking at about -10 to -12dB. This approximate level gives you the necessary headroom (room for transient peaks) so that your signal doesn't overdrive your converters and software and produce distortion. If you record at a 16-bit rate, you need to raise this level a bit (peaks no higher than -6dB)"

Man, is this for real? Cos, My Cubase is setup as 24-bit 44.100 kHz and when I bounce out the mix with the same settings. I've no conscious to average around that kinda dB in my mix. Sorry for being repetitive, but am I doing within the norm?

[Compyfox]

Wait... I'm a bit off the hook with the book atm. Does Katz mean Peak or RMS level? Cause personally I say it's a bit less with these levels if we talk about "peak".

Personally I say "whatever suits you best", then again if I record or render down I try not to go higher than -2dB to -3dB peak to have enough headroom for final tweaks, and I'm save from spikes of synths. Putting the stuff into the right loudness level is really for the mastering step only.

[P.T.]

I have heard from a few sources that you should be peaking around -10 or -15 when recording.

With analog, (tape) you would want to be around 0db. Digital is different. You have a much greater signal to noise ratio. Also, digital clipping is very ugly.

For a final, before mastering, mix down the peaks on the 2 channel wave should be no more than -6db.

[jess123]

Wait... I'm a bit off the hook with the book atm. Does Katz mean Peak or RMS level? Cause personally I say it's a bit less with these levels if we talk about "peak".

Personally I say "whatever suits you best", then again if I record or render down I try not to go higher than -2dB to -3dB peak to have enough headroom for final tweaks, and I'm save from spikes of synths. Putting the stuff into the right loudness level is really for the mastering step only.

This is by "PC Recording for Dummies - Jeff Strong" (Don't laugh). Not sure he meant peak or not.

" I record or render down I try not to go higher than -2dB to -3dB peak " OK, sounds like it's a good idea. That means, using the PSP Meter and setting at K-14, it's alright to peak around -2 Db?

[Compyfox]

THAT is RMS once again. Use the the meters in Cubase (which are wrongly labeled VU, they're peak meters!) and don't let it peak louder than -2dB. RMS should be automatically around K-20 then.


BTW:
Recording at -10dB to -15dB "peak" is a fairly low volume level. Digital recording devices are good these days, but IMO I think this is just too low. Because if you record it at -15dB peak, then normalize it up to -3dB peak for mixing or something like that, you also raise the noise floor that you have to remove once again, etc.

Sure there're guidelines and recommendations. But we're not in the analogue world anymore, so it should be fairly save to record no louder than -3dB peak. That's still enough headroom for all kinds of spikes.

[jess123]

Heh guys, Thanks for your patience.

I went to the Roger nicholas site and downloaded a free inspector just to have visibility of both the Peak adn RMS. I even downloaded the 20dBFS pinknoise from here http://www.digido.com/User/Assets/Activ ... st_441.WAV

Oh well, seems to be a discrepancy ranging from 0-2db difference. RMS is hovering around -21 till -22 and the PSP meter says hovers around -1 till 0 db. But, I think it doesn't matter. As long as I mix softer then before I should be in theory better off.

[Compyfox]

There's the problem, the RMS of Inspector Free doesn't correspond to the K-System. It's meter reacts too fast, therefore it's 3dB off. If you could set it up to 600ms integration time, the RMS meter would be standing still at -20dB RMS.

The PSP vintage meter should be hovering "close" around 0dB if setup to 600ms. Then it's correctly setup.


If you'd get a proper metering tool for your speakers now, and level them in to 89dBU (if I'm not mistaken), then your system at home is setup correctly for the K-System, but that's all written in the book by Bob Katz.


REMEMBER:
Peak is the volume level, while RMS/VU is the loudness level. So if you use Cubase, the meters there shouldn't go louder than -1dB peak (if you use K-20), while the RMS/VU needle of the Vintage Meter shouldn't go higher than the "zero point" (0dB VU) up to +2dB.

A bit troublesome at the beginning, but as soon as you get it, it's fairly simple.

[Lee702]

compyfox can you explain how i would set up the vintage meter? Ok i have vintage meter and pink noise from bob katz website. Also a sound level meter. So how do i get all this set up right? Sorry its a bit confusing.

[Compyfox]

Setting up is simple (as written on Page 1).

Set the integration time (backside of PSP Vintage Meter, click on the logo) to 600ms
Set the 0VU reference level to the corresponding K-System (-20dB for K-20, -14dB for K-14 and -12dB for K-12)

Now if you'd run the pink noise on the meter setup to K-20, then it should hover around 0dB on the meter (front page, click on the dials to have either a 0dB to +3dB or 0dB to +6dB response) if in VU mode (dip-switch directs upwards).


Now how to setup your speakers... get an SPL meter, heavy needle (or something like that, please look on Katz' page). Then loop the K-20 pink noise in your audiotool and turn up the volume of your speakers up till you reach 89dBu on the SPL meter. Then your system and Vintage Meter is correctly setup to K-20.

It's fairly simple, only a bit confusing written on Mr Katz page. But if you know how, you can even use freeware tools like the PSP Vintage Meter (like I did for almost 2 years before I switched to iXL).