Re: [LAU] nice piece of USB hardware for 7.1 output

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To: <linux-audio-user@...>
Date: Thursday, June 6, 2013 - 8:57 pm

On Thu, Jun 06, 2013 at 01:32:08PM +0200, Jörn Nettingsmeier wrote:

> gigaport hd+ connected to a micstasy line in at normal Z (5.6kOhm

So dynamic range should be 88.4 - 13 or around 75 dB.
No really impressive...

> now if i feed it a white noise signal from JAAA at -1.0dBFS, the

That would be a really invalid measurement. Peak / RMS ratio for
jaaa's noise generator is something like 12dB, so noise at -1 dB
RMS will be clipping as hell. That 12 dB is an implementation
limit, real gaussian noise has (in theory) an infinite peak / RMS
ratio. So better stay at -20 dB RMS or so.

> the -1.0dbFS sine tone at 1kHz shows a first harmonic at -95dB, and

OK.

> however, there is a thumping DC impulse every few seconds which

Very suspect. Should be interesting to record the waveform and
have a look at it (zita-scope would be handy, but not yet ready
for the real world).

> a white noise steady-state spectrum shows a slight raise of 2.5dB

Again suspect, but see above. Could you try with a lower noise
level ?

General remark about the Jaaa screenshots: to measure noise you
should really use the noise, not peak, markers.

Ciao,

--
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

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Messages in current thread:
[LAU] nice piece of USB hardware for 7.1 output, Jörn Nettingsmeier, (Wed Jun 5, 2:26 pm)
Re: [LAU] nice piece of USB hardware for 7.1 output, Harry van Haaren, (Wed Jun 5, 9:18 pm)
Re: [LAU] nice piece of USB hardware for 7.1 output, Jörn Nettingsmeier, (Thu Jun 6, 11:36 am)
Re: [LAU] nice piece of USB hardware for 7.1 output, Fons Adriaensen, (Wed Jun 5, 8:57 pm)
Re: [LAU] nice piece of USB hardware for 7.1 output, Jörn Nettingsmeier, (Thu Jun 6, 11:32 am)
Re: [LAU] nice piece of USB hardware for 7.1 output, Fons Adriaensen, (Thu Jun 6, 8:57 pm)
Re: [LAU] nice piece of USB hardware for 7.1 output, Jörn Nettingsmeier, (Thu Jun 6, 12:13 pm)
Re: [LAU] nice piece of USB hardware for 7.1 output, Jörn Nettingsmeier, (Wed Jun 5, 4:35 pm)