input noise specs for LM3886?

[albireo13]

I've got the Chipamp boards and am building a modest, 30-40w/ch stereo amp. Has anyone characterized the LM3886 for input noise (En, In) ?
I'm looking for noise spectral density (nV/rt-hz, pA/rt-hz).

Thanks,
Rob

[diy_audio_fo]

Originally Posted by albireo13

I've got the Chipamp boards and am building a modest, 30-40w/ch stereo amp. Has anyone characterized the LM3886 for input noise (En, In) ?
I'm looking for noise spectral density (nV/rt-hz, pA/rt-hz).

Thanks,
Rob

AFAIK the only information released by National is from datasheet:

eIN (Note 4) Input Noise IHF—A Weighting Filter
RIN = 600Ω (Input Referred)
2.0 μV Typ 10 μV (max)

SNR Signal-to-Noise Ratio PO = 1W, A-Weighted,
Measured at 1 kHz, RS = 25Ω
92.5 dB Typ

PO = 60W, A-Weighted,
Measured at 1 kHz, RS = 25Ω
110 dB Typ

[albireo13]

yes, I like to see noise vs. freq plots, to see what 1/f behavior looks like.

Might have to just test and measure myself.

Rob

[wahab]

Originally Posted by diy_audio_fo

AFAIK the only information released by National is from datasheet:

eIN (Note 4) Input Noise IHF—A Weighting Filter
RIN = 600Ω (Input Referred)
2.0 μV Typ 10 μV (max)

SNR Signal-to-Noise Ratio PO = 1W, A-Weighted,
Measured at 1 kHz, RS = 25Ω
92.5 dB Typ

PO = 60W, A-Weighted,
Measured at 1 kHz, RS = 25Ω
110 dB Typ

EIN should be between 14nV/sqrt hz (typical) and 70nV /sqrt hz (max)according to these numbers...

The typical figure is quite good , but the max value is somewhat
high for a hifi amplifier..

[tomchr]

Originally Posted by albireo13

yes, I like to see noise vs. freq plots, to see what 1/f behavior looks like.

1/f noise is mostly dependent on the fabrication process and the devices used (MOS typically has higher 1/f noise than BJT). So I'd expect the 1/f noise corner frequency to be about the same as other National LF/audio products of that era. I'd guess a 1/f corner frequency of 1~10 Hz.

Originally Posted by albireo13

Might have to just test and measure myself.

I dunno... That sounds like hard work... Hard work is to be avoided at all cost.

Speaking of hard work to be avoided. I should go mow my lawn. Dammit! Anybody got any Astroturf they want to get rid of?

~Tom