Problem With Continuous Noise Filter Display

[vikingfrank]

After taking a noise sample, I am unable to view frequency spectrum of the sampled noise in red. It is well below the the viewing area. How do I adjust it so that it comes into view?

[Craig Maier]

Since the bottom of the scale is -100 dB, it sounds like you recorded the wavefile too low or the noise floor on the material is simply in the mud. Double check the recording level that was used.

[vikingfrank]

"Double check the recording level that was used"

Could you please elaborate. I am in the begining stages of mastering this program.

Thanks for your patience.

[Dan McDonald]

Craig's saying that the recording level is probably too low. That is, when you recorded the material, the recording level is not high enough. If you re-record the material, check to make sure the levels are 'bouncing' around (but not going into the red), like in the old days with tape recorders. That will give you a good level.

If you've got a good level (so that when you play it back, it sounds like there's plenty of sound there - music or speech or whatever you recorded), but when you sample, there's no noise, it could be that what you recorded doesn't have much noise. For example, if you recorded a CD audio through a stereo, you won't get much noise because there isn't much noise to find.

If the source is noisy, then increasing the levels when you record should make it so that you will get something to work with.


You can also check the level of the file you recorded by sampling a portion with music or speech. The CNF sample should have plenty of material in red because it's sampling all of the sound that is there. If it doesn't, then that means the recorded file was just recorded at too low a level.


Dan

[vikingfrank]

I have the recording level set so hits in between -1 & -2 dB. After using the sample noise button, I view the frequency spectrum window and notice that every thing to the right of the 1000Hz mark is still below the bottom of the viewing area. What do I do now?

[Dan McDonald]

OK - there's probably not much noise above that frequency then. By any chance is this from an mp3 file? If not, what sort of material is it and how was it recorded?

Dan

[vikingfrank]

The source is an old Somerset Stereo LP recording from the 50s intitled Video All Stars Play TV Jazz Themes by Skip Martin.

[Craig Maier]

It sounds like your reproduction / record transfer system has no "high" end. What type of turntable and phono cartridge do you have? What type of preamplifier are you running it through? Are you running it through any filters before the signals arrives at your sound card input?

[vikingfrank]

I have a Stanton STR 8-80 turntable hook into an Onkyo TX-8211 Stereo Receiver, which is connected to the sound card. My sound card is a M-Audio Delta Audiophile 192. I have no preamp. The turntable can also be hooked directly into the sound card using the S/PDIF input. The catriage is the one that came with the turntable.

[Craig Maier]

That should be fine. What CNF Mode are you using? Normal CNF Mode or one of the other modes like spectral subtraction or Auto Spectrum CNF?

Are you sampling noise between the cuts of the record? That is the best way to do it. Never sample on the noise that exists when the record is not playing.

As a test, what happens to the CNF graph if you sample on the music rather than on the noise? Does it produce a red line?

[Craig Maier]

Maybe the best thing to do is to send me a 10 second snippet of the wavefile, including some intergroove noise so that I can evaluate it here.

My email address is:

dctools@aol.com

Thanks,

Craig

[Craig Maier]

Hi Vikingfrank,

I sent you an email regarding your wavefile, so if you received that, just ignore this posting.

I received your wavefile and looked it over. The average recording level seems to be about -20 dB and the peak seems to be around -17 dB. That is kind of low and probably explains the problem with the CNF graphic. It would be much better if you can get it up around -3 dB on the peaks. I also noted that the top end (5 to 20 KHz) is rolling off a bit faster than I would normally expect.

But -

There is another problem. The peaks at -17 dB on that file were totally distorted. That implies that you have some kind of hardware problem in your system. It looks and sounds like analog distortion to me - - - not digital clipping. It is hard for me to diagnose your system remotely, but you need to check out your signal pathway and find out why the signal is so low and distorted.

[mightymic]

hi your using a digital sound card, after recording a lp file the first thing you must do is to "normalize the gain" and the delta card does record at -15 to -20 db. i generaly boost the file up to about -5 or so. then start working on your recording.

the gain boost is found in the CD prep area. i use the delta audiophile sound card too.

[vikingfrank]

Hi Crag

I talked to one of the techs at Tracer and we found that the problem is with the phono preamp inside the Onkyo Receiver. Thanks for all your help.

Thanks for the imput mightymic, I tried your suggestion and it brings more of the red line into view. I am still having trouble seeing the red line to the right of th 10000Hz mark. Should'nt I be able to see this part of the red line?

[Craig Maier]

I am a little confused about it. Did you fix the Onkyo preamplifier or replace it? If not, then you will still probably be having problems with the CNF. Keep in mind that I not only saw a weak signal on the wavefile that you sent, but it was very distorted and having a weak top end as well.

Please let us know what you did after you and Tracer diagnosed the problem to be the Onkyo preamplifer.

Thanks