Recording Level Meters ???

All about the tools and techniques involved in capturing sound, in the studio or on location.

Moderator: Moderators

Re: Recording Level Meters ???

Post by ConcertinaChap »

merlyn wrote:To add to what has been said above I understand dB from a maths angle. Using dB allows multiplication to be replaced with addition.

I've noticed 0dB can be a sticking point. 0dB means multiply by 1.

This is because dB are to do with powers of a number and any number to the power of 0 is 1. Kind of counterintuitive maybe, but mathematically correct :

x^0 = 1

Positive powers of a number make the number bigger :

2^2 = 4

and negative powers of a number make the number smaller :

2^-1 = 0.5

so positive dB mean the signal is getting bigger (has a higher amplitude) and negative dB mean the signal is getting smaller (has a lower amplitude).

You will also see -infdB which means -infinity dB and this corresponds to an amplitude of 0.

For me this works as a good explanation and a useful reminder that dB's are logarhythmic.

CC
User avatar
ConcertinaChap
Jedi Poster
Posts: 11658 Joined: Wed Jul 20, 2005 12:00 am Location: Bradford on Avon
Making music: Eagle Alley
Recording music: Mr Punch's Studio
Strangely strange but oddly normal ...

Re: Recording Level Meters ???

Post by DigitalMusicProduction »

Thanks to everyone for your support on this topic.
User avatar
DigitalMusicProduction
Regular
Posts: 218 Joined: Thu Oct 22, 2020 7:00 pm

Music is a universal language that speaks to every person, a euphoria of moods that inspires, convicts and heals 

Re: Recording Level Meters ???

Post by Gilly1 »

CS70 wrote:The reason for levels going from 0 to negative values is because a fader is just another form of a volume knob, and volume knobs are attenuators. They can't increase a voltage level, but can decrease it. This in opposition to gain devices - amplifiers - that can increase a signal amplitude.

I think this is not correct. Cadets aren't just attenuated, they can both increase the signal voltage level (if adjusted upwards from 0db position) or decrease/attenuate the signal voltage level (if adjusted downwards from 0db position)
Gilly1
Posts: 2 Joined: Thu Sep 29, 2022 4:50 am

Re: Recording Level Meters ???

Post by Sam Spoons »

On most mixers the fader scale goes from -infinity to +10 dB (or something similar) with, as Merlin says, 0dB equalling 'no change in level'. That makes sense but historically the first faders were passive attenuators which can't increase gain, when faders with some gain became available they just adjusted the scale accordingly?

Welcome to the forum BTW :thumbup:
User avatar
Sam Spoons
Jedi Poster
Posts: 17866 Joined: Thu Jan 23, 2003 12:00 am Location: Manchester UK
Your karma has run over my dogma

Re: Recording Level Meters ???

Post by Wonks »

It all depends on the circuit and application. Faders themselves, as Sam says, are attenuators, and if used purely an an in-line device can only maintain or reduce reduce the signal level.

But they can also say form part of an active boost circuit, where the signal is first boosted by say +10 dB before the fader and then passed to the fader (which will have markings up to +10dB on it). At the fader's 0dB point, it will be attenuating the signal by -10dB.
User avatar
Wonks
Jedi Poster
Posts: 13925 Joined: Thu May 29, 2003 12:00 am Location: Reading, UK
Reliably fallible.

Re: Recording Level Meters ???

Post by ef37a »

Wonks wrote: Thu Sep 29, 2022 11:51 am It all depends on the circuit and application. Faders themselves, as Sam says, are attenuators, and if used purely an an in-line device can only maintain or reduce reduce the signal level.

But they can also say form part of an active boost circuit, where the signal is first boosted by say +10 dB before the fader and then passed to the fader (which will have markings up to +10dB on it). At the fader's 0dB point, it will be attenuating the signal by -10dB.

This^ is all true and I know many 'musical people' don't want to get into the electrical facts of sound but it can help. Douglas Self's book Small Signal Audio Design is virtually devoid of mathematics but gives an very good introduction to the world of audio electronics and the ever present challenge between noise at one extreme and distortion at the other.
He also debunks a great many audio myths which can trap and confuse the newb.

IMHO the OP would also benefit from purchasing a small mixer and playing with its faders and gain controls. Many charity and Cash Genny shops have small Behringers and Mackies for little money. A mixer is in any case a very handy box to have around.

Dave.
ef37a
Jedi Poster
Posts: 14909 Joined: Mon May 29, 2006 12:00 am Location: northampton uk

Re: Recording Level Meters ???

Post by Hugh Robjohns »

I think this issue was put to bed 18 months ago... probably no need to rake through it all again.
User avatar
Hugh Robjohns
Moderator
Posts: 35436 Joined: Fri Jul 25, 2003 12:00 am Location: Worcestershire, UK
Technical Editor, Sound On Sound...
(But generally posting my own personal views and not necessarily those of SOS, the company or the magazine!)
In my world, things get less strange when I read the manual... 

Re: Recording Level Meters ???

Post by ef37a »

Hugh Robjohns wrote: Thu Sep 29, 2022 12:18 pm I think this issue was put to bed 18 months ago... probably no need to rake through it all again.

Wonks did not think so?

Dave.
ef37a
Jedi Poster
Posts: 14909 Joined: Mon May 29, 2006 12:00 am Location: northampton uk

Re: Recording Level Meters ???

Post by Hugh Robjohns »

nnnnnnnnnnnnnnnnnnggggggghhhhhhh
User avatar
Hugh Robjohns
Moderator
Posts: 35436 Joined: Fri Jul 25, 2003 12:00 am Location: Worcestershire, UK
Technical Editor, Sound On Sound...
(But generally posting my own personal views and not necessarily those of SOS, the company or the magazine!)
In my world, things get less strange when I read the manual... 
Locked