Topic: fr-2le preamp too noisy?

[merrycinemax]

So many good mics! Please tell me which one you are testing and I will look up the spec for you.

i can do that, but i have no idea what the self-noise of my mics are. feel free to look that up for me. see signature below.

[sygdwm]

see my edit. whats the point of testing if you can hear cnn, 2 pets, and my AC running?

[merrycinemax]

I can't find the spec of the mic. By the way, do you have a moment when those unwanted sound disapear?I appreciate it if I can have a reference to see if my system is in trouble.
  My FR-2LE+NT-1A, maxium gains --> -30 dBFS noise in the LCD meter. The environment has some hum but is so quite you will not notice it.
Thanks a lot.

see my edit. whats the point of testing if you can hear cnn, 2 pets, and my AC running?

[sygdwm]

sure i can cut off the tv and put my dogs outside, but my friend, there is now way (even for you) that i will turn off my AC to conduct this test. lets assume your box is just fine unless you are recording birds from 6 miles away.

[Jammin72]

I think you're getting waaaaay to concerned about numbers.


Are you using it for it's intended purpose?

Is it too noisy for you for that intended purpose? (Determine this by listening to your recording on your preferred playback system, not the unit.)

Answer those questions and you'll save yourself much grief.

[merrycinemax]

  I am using it to record vocals. It is supposed that where the voice is 30 cm away from the MIC, of course set to low gian (12-oclock), I should not hear any background noise in silent period even I turn the headphone volume to maximum. This is what I find in some professional postcasts.
  In theory, if the preamp has EIN=125 dBu and the Rode NT-1A has EIN=118 dBu, the cascaded noise would be less than 116 dBu. This noise is less than the noise floor of the fr-2le's ADC (95 dB SNR at -12 dBFS reference, so about -95-12-2=-109 dBu). But I surely hear uncommon noise palying the file in silent devices (headphone max). I bought this from japan for a lower price and it is not easy to return it if mine is defective.
  Therefore to test if the machine is defective, setting gain to max with a microphone plugged and watching the level meter for noise would be the easiest way for A-B comparison. If mine is really defective, I will soon return it back for a good one.

Thanks a lot for the help.

Kim

[sygdwm]

i doubt yours is defective.

[it-goes-to-eleven]

Not many people on this site are concerned with pre-amp performance at max gain.  Most folks interested in high gain are recording nature sounds. Vocals from the 12" distance you specifcy won't require much gain (you're not recording mouse whispers from 6'). You might find more people with an interest in high gain on the naturerecordists mailing list.

From reading the thread it sounds like both your fr2le and dre's have -52dB of noise when the gain is at max.  How much gain does the fr2le add at max gain?  I think I saw a reference to 40dB earlier.  -52db does seem a bit high but it could be due to the measurement method.

Are you still using the recorder's built in headphone amp?  As someone else already pointed out, it isn't a good way to evaluate noise because it is noisy.

You could make a series of recordings with increasing amounts of gain. Then review them with an audio tool to see whether the noise floor is non-linear as gain is added.

[merrycinemax]

You are right:
Let me check again:

MIC sensitivity :-32 dBu/94dBSPL
Leave 20 dB headroom for 94dBSPL
We want gain to be around 10 dB :  -32dBu + 20 dB headroom +10 dB gain =-2dBu < 0dBFS.

However, I just suspect the noise should not be so high in this setting (10 dB gain relative to minimum gian, 12-oclock in the trim, I've tested it) when listening to the slient period recorded (of course I use a quiter device to play it back. How silent is the device? I play a pure silent file in the device with maximum volumn to headphone, almost no noise can be heard.) You know I don't want the combination of NT-1A+FR-2LE to have the same noise perfomrnace with Zoom H2 via internal MIC or some cheapers.
  To test it in maximum gain is just a quick A-B comparison to see if my unit is defective. (such that you can see the noise level in the meter and you don't have to make off-line FFT analysis).

Thanks a lot.

Kim

Not many people on this site are concerned with pre-amp performance at max gain.  Most folks interested in high gain are recording nature sounds. Vocals from the 12" distance you specifcy won't require much gain (you're not recording mouse whispers from 6'). You might find more people with an interest in high gain on the naturerecordists mailing list.

From reading the thread it sounds like both your fr2le and dre's have -52dB of noise when the gain is at max.  How much gain does the fr2le add at max gain?  I think I saw a reference to 40dB earlier.  -52db does seem a bit high but it could be due to the measurement method.

Are you still using the recorder's built in headphone amp?  As someone else already pointed out, it isn't a good way to evaluate noise because it is noisy.

You could make a series of recordings with increasing amounts of gain. Then review them with an audio tool to see whether the noise floor is non-linear as gain is added.