dB and gain

[Peter Groom]

I looked online and the software appeared to Use VU meters. Obviously not an analogue version of it, but an emulated digital form at least inits weighting and on screen representation. very odd i thought.
Peter

Peter

[Ty Ford]

Freddy,

What they look like on a computer screen has absolutely no bearing on how they display transient peaks, which is what matters.

Regards,

Ty Ford

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[Dave Haynie]

You have to keep in mind that “dB” itself is a dimensionless ratio between two different logarithmic quantities. You only get something akin to an actual unit (eg, like volts), which the basis for your ratio is a known quantity.

For example, in my day job I do digital radio design. We usually work in dBm, the “m” being shorthand for milliwatt. That means my “zero” is at one milliwatt… 10dBm is thus 10mW, 20dBm is thus 100mW, 30dBm 1000mW = 1W, etc. (if you didn’t understand logarithmic scales, hope that makes it a little clearer).

For digital VU meters, you set the 0 point at full scale, whether that’s going to be a numeric reading of 65,535 or 16,777,215 or whatever depends on your bit resolution. But these numbers get large and meaningless, the log scale is a far more useful scale, and lets you concentrate on relative signal strength, regardless of the resolutions involved.

For sound level meters, you probably measure in dB(spl), spl = sound pressure level. If you do recording, you’ll find ratings on your microphones in db(spl)… you probably want something in the 120-140dB(spl) range on that kick drum. Technically, on this scale, the zero is set at 0.0002 microbar of sound pressure, which is more or less the threshold of human hearing.

The reason we use log measurements for hearing is simple: the human ear has about a trillion to one dynamic range. Rather than dealing in large numbers of crazy and meaningless precision, we can do the same thing in dB(spl) from 0 (threshold of hearing) to 120 (“The Raconteurs” in concert, also, where permanent hearing damage can occur).

-Dave

[Ty Ford]

Dave,

On behalf of The Cow, thanks for stopping by and offering such an articulate explanation.

BTW, what guitar is that in you shot?

Regards,

Ty Ford

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[Dave Haynie]

Hi-
I’ve been hanging out in other areas of the Cow for years, but doing more audio these days, I decided to poke around here. Hope that explanation was useful.

The guitar is the Martin “Backpacker”, designed by my friend Bob McNally for Martin. I keep this one in my computer room for quick access, and do actually take it backpacking on occasion.

-Dave

[Ty Ford]

I know the backpacker.

Nice little piece for exactly the reasons you say.

Regards,

Ty Ford

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