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Jimbo · 15th May 2008, 03:20 PM

Isn't the noise floor of a preamp often dependent on the input load?

I've notice that some manufacturers will state the noise spec of a mic preamp in the context of the input load.

For example:
DAV BG-1 noise: 25 microvolts [-110dB ref +20 dBu. Bandwidth 10Hz-18KHz input loaded 150 ohms, 32dB gain]

I've found that when comparing my ATI preamps with my Hamptone using a ribbon mic the ATI has some noise at max gain while the Hamptone doesn't. However, when I put a condenser mic on both, neither has noise at max gain. Surely this difference is due to the very different input loads generated by the microphones.

This might explain why DAV users are getting varying results.

15th May 2008, 03:20 PM	#22
Jimbo Lives for gear Join Date: Oct 2005 Location: Scrappleland Posts: 890	Isn't the noise floor of a preamp often dependent on the input load? I've notice that some manufacturers will state the noise spec of a mic preamp in the context of the input load. For example: DAV BG-1 noise: 25 microvolts [-110dB ref +20 dBu. Bandwidth 10Hz-18KHz input loaded 150 ohms, 32dB gain] I've found that when comparing my ATI preamps with my Hamptone using a ribbon mic the ATI has some noise at max gain while the Hamptone doesn't. However, when I put a condenser mic on both, neither has noise at max gain. Surely this difference is due to the very different input loads generated by the microphones. This might explain why DAV users are getting varying results. __________________ Jim P. Allen [disclaimer: Audio is my occupation, not my vocation]