Low Noise Sound card
"Mr.T" MrT@home wrote in message
"Arny Krueger" wrote in message
...
Both the sound card and the amplifier are properly
modeled as a fixed noise source and a variable signal.
Therefore, as you turn the signal down, the SNR of both
the sound card and the amplifier will get worse because
there is less signal but the same amount of noise.
Do tell how a passive analog attenuator will reduce the
signal but leave the noise untouched?
Quite easily if the most significant noise source is
downstream of the attenuator, which is often the case.
Arny I'm really surprised I have to spell it out for you,
a passive analog attenuator reduces both signal AND noise
at *it's output* (amplifier input)
Of course, but read what I wrote: it does nothing to reduce the noise at the
output of the amplifier which is often the weakest link.
The OP *wasn't*
complaining about his amplifiers noise!
In this case he had an amplifier with atypically low noise.
IF that was his problem, asking for a low noise sound
card is even more stupid!
The problem of coming up with an audio interface with dynamic range and SNR
108 dB was solved long ago.
This is one of my favorite "audiophile myths". The
audiophile has a power amplifier with 80 dB SNR,
attached to a CD player (93 dB SNR @ FS) with a digital
attenuator. He's beside himself with anxiety over the
issue we are discussing. He *solves* his alleged
problem by introducing a passive attenuator. In fact,
the best case is that he did not further muck things up.
****, it's a pretty woeful amplifier that only gets 80dB
S/N these days! Hardly "audiophile" quality!!!!
Look at the spec sheets for some modern integrated amps.
I'm here to tell you that many power amps that spec 100 dB are a little
optimistic.
Of course you can't *improve* on the amplifiers s/n, but
a digital attenuator does have a fixed noise floor
greater than a passive analog one, which is only
governed by it's thermal noise floor.
Yes, but the amplifier's noise floor is often the
weakest link, particularly if the amp is tubed.
For a tube amp perhaps, but power amps with over 100dB
S/N are easily obtained these days.
They can be obtained, but 100 dB is not a low mark, especially if you test
them on the bench.
Also consider that most CD players are attached to integrated amps, not
power amps.
Exactly! (well actually no CD player can really do 100dB
wide band since it's above the theoretical maximum for
16bits, but let's ignore the slight difference)
However it can easily be degraded by running the amp gain
flat out and using the soundcard digital attenuator as
the OP said he was doing!
Like I said, the OPs specific problem is in my views resolved days ago.
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