Topic: PMD661 for ambient recording

[dream]

Before you run out and buy a new pre/recorder I'd suggest taking a look at the cable that came with your NT4.

The stock Rode Y cable has a 12dB pad built in which seriously compromises the performance of the NT4. You can either mod the cable or replace it.

That's only true for the 7 pin XLR to stereo mini jack cable. The Y-cable with two XLRs doesn't have this. Although I use a higher quality Y-cable with my NT4 than the
original Rode one, I just opened the connector of the Rode XLR Y-cable to double check this.

[spzkt]

I stand corrected.  I was using a minidisc recorder at the time, so using the y to stereo mini cable.

Even so, unless the PMD661 has faulty preamps the overall self-noise improvement from upgrading to a SD preamp is going to be marginal. The Avisoft self-noise tests include a link to a page titled http://www.avisoft.com/tutorial_mic_recorder.htm, which discusses what I was trying to show with the calcs above. The illustration in particular shows the relationship mic self-noise and sensitivity vs recorder EIN.

Where the recorder EIN really becomes important for ambient recording is when the mics have low output noise. The AT3032 and it's replacement the AT4022 are pretty popular mic for nature recording, and the AT3032 was independently tested as having a self-noise of around 8dB(A) and a sensitivity of 20mv/Pa. This gives an output noise of -117.8dBu(A) which makes it a fairly demanding mic in terms of preamp self-noise, and these mics require a recorder with an EIN -126dBu(A) or better.

cheers
Paul