Differences Between +4/-10 Levels.

[streaml1ne]

Found this the other day, excellent article:

http://www.sweetwater.com/support/summits/dB.php

"Over the past few years we've brought you the news and answered hundreds of technical questions about everything from burning CD's to synchronizing MIDI to film, to tracking down ground loop hums, to buying gear on the Internet. During that time we've received hundreds of other questions that we answered privately via e-mail. But there's been one burning question through all of this that we've never really been able to get to... until now.

What is the actual difference between -10 and +4 and what does it mean at a practical and technical level?"

[dex Otaku]

The interesting thing about this is that there are companies out there who follow neither established standard.

I prime example of this would be my M-Audio Revolution 7.1 sound card.

Its line input appears to be calibrated so that 1Vp-p = 0dBFS.

It may seem sensible for a piece of consumer equipment, but it's not.

The vast majority of consumer equipment now put out signals higher than 1Vp-p. Cassette decks, radio tuners, and phono preamps might be the last holdouts, actually.

Basically all CD players will clip this input.

HIFI VCRs clip this input.

Mixing board outputs usually clip this input [unless they have the friendly -10/+4 switch].

The only way I have been able to record from the vast majority of line sources using this card is to put the signal through an attenuator beforehand.

I asked M-Audio about this and they told me that it's simply the way they design things.

Which seems odd for a company that has made some of the most popular multitrack PCI audio cards in existence [i.e. the Delta series]. Especially since, if they design those cards the same way, one would pretty much never get a usable recording with them without using attenuation for every single channel.

Bleagh.

[streaml1ne]

I asked M-Audio about this and they told me that it's simply the way they design things. 

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Good to know. Scratch them off my list of potential capture boards.

[dex Otaku]

Good to know. Scratch them off my list of potential capture boards.

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I wouldn't be so hasty. I only asked them about the revo 7.1. There's more than a good chance that the Delta series cards are all referenced to +4dBu. Otherwise they probably would never have sold as much as they do.