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Gear / Technical Help => Recording Gear => Topic started by: merrycinemax on March 17, 2008, 06:26:56 AM
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I set the MIC trim and signal level to maximum with phantom power off and
no load in the MIC input. The 24-bit 44.1kHz recording is done to record the
noise floor. About -50 dB relative to full scale of noise is shown in the
voltage meter in the LCD, And I can hear loud noise via the headphone while
playing the recorded file.
If the full scale corresponds to 1 dBu, the esimated EIN would be :
EIN=-50dBu-gain=-50 dBu-40 dB=-90 dBu. However, the fr-2le is tested to have
-125dBu noise floor for the preamp with 150 ohm load. What a huge
difference?
Is there something wrong with my fr-2le? For those fr-2le owners, what do
you see from the voltage meter when you set MIC trim and signal level to
maximum?
Thank you so much.
Kim
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Im not too savvy with the numbers, but I do know the headphone output is quite noisy. Im sure this has something to do with the
readings you are gettingnoise you are hearing..
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I set the MIC trim and signal level to maximum with phantom power off and
no load in the MIC input. The 24-bit 44.1kHz recording is done to record the
noise floor. About -50 dB relative to full scale of noise is shown in the
voltage meter in the LCD, And I can hear loud noise via the headphone while
playing the recorded file.
If the full scale corresponds to 1 dBu, the esimated EIN would be :
EIN=-50dBu-gain=-50 dBu-40 dB=-90 dBu. However, the fr-2le is tested to have
-125dBu noise floor for the preamp with 150 ohm load. What a huge
difference?
Is there something wrong with my fr-2le? For those fr-2le owners, what do
you see from the voltage meter when you set MIC trim and signal level to
maximum?
Thank you so much.
Kim
Generally you should put a load resistor on the input. Take a male XLR connector, solder a 1k resistor between pins 2 and 1, and a second one betwee pins 3 and 1. That should do it. Also, as another poster mentioned, the headphone amp is noisy (and also distorts at high sound levels too), so record something, transfer to your computer, and measure there.
Actually, the FR-2LE is one of the quietest (inexpensive) recorders out there! People on the nature recording boards use it.
Finally, noise requirements depend on both your application, ie., what is your ambient noise level? how sensitive are your mics?
Richard
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Thanks a lot for the inputs. ::)
I will try to put two resisters to see if there is any difference. However, there is no help for the noise when I short-circuit pin 2, pin3, and pin1. I hope my new one is not a broken one.
As for microphone, the noise performance seems worse. I use Rode NT-1A, with as little as 5 dBA self noise. Of corse, the phantom power is on. Making trims and level knots to the maximum, -36 dB of noise(hum) is shown in the volt-meter. Listening to the headphone jack, a huge amount of hum can be heard, much louder than the noise I heard without a MIC load.
The headphone is noisy I know, but when recording with trims turned to the minimum, the noise heard from headphone is much quieter than the case when the trims turned to the maximum. So I guess, in the latter case, the headpone noise should not dominate and the loud noise is due to recording noise not to headphone noise. I will use a quiter device to play the recording file and tell the difference.
I measured it in the midnight, when the environment is supposed to very quiet. However, listening carefully, I can hear some hum from the background, but as quiet as unnoticable. Using pillows to keep away the hum, makes no difference!
Kim
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Richard,
Would you please do me a favor? Since you own a fr-2le, would you please make a record without MIC connected, setting MIC trims and level knot to the maximum, and see the level of recorded noise in the LCD volt-meter?Mine is around -50 dB in the volt-meter. If yours is the same, I think mine should be problem-free.
One thing I notice from the MIC trims is that the trims are not so linear. Turing the trims to maximum, the gain is about 40 dB, three-oclock 20 dB, telve-clock 10 dB and minium 0 dB. When the trim is set to three-clock, there less than -60 dB noise level in the vot-meter in my fr-2le.
Thanks a lot.
I set the MIC trim and signal level to maximum with phantom power off and
no load in the MIC input. The 24-bit 44.1kHz recording is done to record the
noise floor. About -50 dB relative to full scale of noise is shown in the
voltage meter in the LCD, And I can hear loud noise via the headphone while
playing the recorded file.
If the full scale corresponds to 1 dBu, the esimated EIN would be :
EIN=-50dBu-gain=-50 dBu-40 dB=-90 dBu. However, the fr-2le is tested to have
-125dBu noise floor for the preamp with 150 ohm load. What a huge
difference?
Is there something wrong with my fr-2le? For those fr-2le owners, what do
you see from the voltage meter when you set MIC trim and signal level to
maximum?
Thank you so much.
Kim
Generally you should put a load resistor on the input. Take a male XLR connector, solder a 1k resistor between pins 2 and 1, and a second one betwee pins 3 and 1. That should do it. Also, as another poster mentioned, the headphone amp is noisy (and also distorts at high sound levels too), so record something, transfer to your computer, and measure there.
Actually, the FR-2LE is one of the quietest (inexpensive) recorders out there! People on the nature recording boards use it.
Finally, noise requirements depend on both your application, ie., what is your ambient noise level? how sensitive are your mics?
Richard
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i'll try and make a recording for ya
let me see if i have this right
you want a recording with the internal mics
and the mic trim set wide open (to the right)
and the gain set to max (the right)
???
then report back as to how high the LCD meter reads?
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Please choose external MIC setting without connecting MIC in the XLR.
Yes the mic trim and gian are set to the most right. By the way, are you using the mod fr-2le?
If this is the case, you may have higher maximum gain and the noise will be higher.
Thanks a lot. :D
Kim
i'll try and make a recording for ya
let me see if i have this right
you want a recording with the internal mics
and the mic trim set wide open (to the right)
and the gain set to max (the right)
???
then report back as to how high the LCD meter reads?
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Please choose external MIC setting without connecting MIC in the XLR.
Yes the mic trim and gian are set to the most right. By the way, are you using the mod fr-2le?
If this is the case, you may have higher maximum gain and the noise will be higher.
Thanks a lot. :D
Kim
i'll try and make a recording for ya
let me see if i have this right
you want a recording with the internal mics
and the mic trim set wide open (to the right)
and the gain set to max (the right)
???
then report back as to how high the LCD meter reads?
i'm stock
i'll try and do it tonight
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i just tested my busman vintage mod fr2le. using your parameters, it was at about -52db.
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Thanks a lot for the input.
So do you think the noise of -52 dB is normal?
If the gain is 40 dB (do you have higher gain in the vintage mod fr-2le compared to original one? how much gain) the EIN would be -92 dBV wihout MIC load? Did I calculate it right?
i just tested my busman vintage mod fr2le. using your parameters, it was at about -52db.
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i dont know the answer to your questions. maybe busman could pop his head in here and clarify.
that said, i dont run the trims past noon and i have never heard any "noise" in my recordings(loud pa rock). i also have never used the headphone amp.
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Could I have more information or link about the busman mod? As I tested the gian when the trim set to noon is about 10 dB relative to the minimum trim. :)
Thanks a lot.
i dont know the answer to your questions. maybe busman could pop his head in here and clarify.
that said, i dont run the trims past noon and i have never heard any "noise" in my recordings(loud pa rock). i also have never used the headphone amp.
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his web page isnt really up to date. there may be some info in the retail section of this board for busman audio.
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Richard and dre,
Would you please also test the same condition with MIC plugged? What are the self-noise of the test MICs?
Thanks a lot.
Kim
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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.
edit: upon thinking this over whilst setting up peluso p2 stereo mic>fr2le, i cant exactly turn down the self-noise of my house to properly test what you want me to do.
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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.
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see my edit. whats the point of testing if you can hear cnn, 2 pets, and my AC running?
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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?
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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. :)
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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.
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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
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i doubt yours is defective.
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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.
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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.