Quote:
Originally Posted by Jimbo  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. |
Yes the lower the load the lower the noise, not all mic pres react the same when comparing numbers, say going from a 150 to a 300 ohm load, I mean that one pre might have a 2db difference and another only one db difference, noticed this the other day comparing 2 pres for noise.
The way the specs are stated can make them look better than they really are.
The above specs on the DAV is a good example, it's not EIN spec. So you have to do a little math to get the EIN spec. The filter used also has a huge influence, a 20 to 20khz is common.
I came up with EIN -122db for the DAV.
A condenser mic has a far hotter level than a ribbon mic, so the same source/distance will produce a perceived LOWER noise.
The gain has to be the exact same when comparing noise, both at 60db for example.