[PStamler]

On Monday, March 18, 2019 at 6:50:44 PM UTC-5, Tobiah wrote:
I ordered a Jethead Phantom to see whether it would improve
the S/N used with my NT1-A's, and an M-Audio Fast Track
Ultra audio interface. I also have a 'dummy mic' as we
recently discussed, using the 150 Ohm resister soldered into
a male XLR connecter trick.

Given the dummy mic, the microphones, the interface, and
the Jethead which will arrive on Wednesday, how would you
go about deciding whether the Jethead is going to be able
to deliver clean enough gain that it surpasses and improves
my existing preamps. I know I could just listen, but it's
tough to pick out the noise in my residential bedroom from
machine noise.

How would we do this in science class?

You'll probably also need an audio oscillator. It can be a cheap one -- even the Shure Oscillator in a plug will work (do they still make that?)

Here's one way. Set the oscillator to some mid-frequency, like 400 or 1,000Hz. Is your current interface still set from your last recording session? If not, set it to the gain setting you used (you did keep notes on that, right?) Set the oscillator to a low level and connect it to the interface input. Make sure it isn't clipping your DAW -- if it is, turn *its* level down; don't touch the interface's controls -- and note what level it's producing on the DAW. Let's say it's -15dBFS.

Don't touch the oscillator's controls. Also don't touch the interface's controls. Now plug your dummy plug into the interface's input and record a 30-second file. Entitle is "OLD". Connect up the new interface, and your doohickey if you're planning to use it, and plug the oscillator into it. Adjust the interface (not the oscillator) to produce the same -15dBFS level on the DAW. Good, now the new setup has the same gain as the old setup; plug the dummy plug into it and record another 30-second file. Entitle it "NEW". Compare the noise levels of the two files using an audio VTVM. If you don't have one of those, select a 10-sec segment of each file and increase its level 60dB. Do destructive edits here; save your files.

Loop the boosted segment of the OLD file; do likewise on the NEW file. Listen to each on headphones. One will probably be noisier than the other; the quiet one is the one to use for future recordings. Also look at the boosted segments with a spectrum analyzer, which many DAWs have. See what the two spectra look like; look for hum or any other discrete frequencies.

If you can't hear any difference, boost each of the segments a further 20dB, for a total of 80dB of boost. Save the results. If you still can't hear any difference, then there probably isn't enough noise difference between the two setups to justify spending money on the new one.

That's a relatively simple, though crude, way to compare the noise levels of the two interface setups when they are set for comparable gains. Save the dummy plug; it's your friend.

Peace,
Paul Stamler