tinny-scratchy sound

[kent]

I am using DC-Art 32 version 4.01 and am trying to restore a very scratchy 45rpm record. After running the impulse filter a few times to remove a lot of the clicks, I then use the continuous noise filter to try and get rid of the scratchy surface noise, but keep getting a tinny-scratchy sound. It is most noticeable at the beginning of the recording before the music starts, but since this is a recording of a slow song by a female vocalist with a soft voice and soft orchestra in the background, I can also hear the tinny-scratchy sound throughout the recording. If I move the attenuation up while running the continuous noise filter, it does get rid of most of the tinny-scratchy sound, but it also makes the recording sound hollow and unnatural. I have tried using other filters such as the low pass filter and the dynamic noise filter without any success. Any suggestions on what I can do, or am I trying to do the impossible?

[Beautman]

Re: tinny-scratchy sound

I've had a lot of trouble with that problem, depending upon the source material. Craig probably has better advice, but I suspect it has to do with limited portions of the noise spectrum poking through the filter in the upper-mid/high region where one is inclined to keep the filter lower because that is where it has the most noticeable effect on the program content.

Here are solutions I've found:

1. Use a "flatter" filter. Instead of doing the noise sampling procedure, start out with a flatline and then back it down to where the filter is just starting to work. You can hear that point by listening to the "keep residue." Then raise dots a little bit by ear, but keeping the filter relatively flat above 1khz or so.

2. Run the average filter on a low setting before using the CNF. I don't know why this works, but it seems that you get much more flexibility with the CNF after doing so, even if you don't eliminate much noise with the average filter itself.

3. Sometime I have to just use the CNF on a very low attentuation setting, 3-6. Given the choice, I'd rather leave in more of the source noise than create the scratchy noise, which is unnatural and abrasive.

[Craig Maier]

Re: tinny-scratchy sound

First, try running the Median filter on the recording with a setting of either 3 or 5 samples. That should reduce the crackle somewhat. Next, when running the continuous noise filter, try raising the "Attack" time up to somewhere between 100 to 150 mSec. Also, try reducing the overall threshold line. It sounds like you are trying to be a little too agressive with the Noise Reduction thereby producing digital artifacts. Lastly, try running the dynamic noise filter to clean up any residual hiss left behind.

[kent]

Re: tinny-scratchy sound

Thanks to Craig and Beautman for advice on how to get rid of the tinny-scratchy sound I was experiencing. I still have a small amount of hiss which I am experimenting with various filters to remove. I've been using the DC Art32 for several months now and didn't know this discussion area existed until a few days ago, so I was glad to see that help was available on-line. In my restorations of 45rpm records I have found that the continuous noise filter does most of the work. I used to sample the noise and then run the filter using that noise sample, but then discovered I had better results, in most cases, using the preset "typical 45rpm fingerprint" and then setting the attack time at 14, the release time at 40 and the attenuation at 10. Since the continuous noise filter is the one that seems to do most of the work and yet is the trickiest to use, is there any place I can get more detailed information on exactly how it works and what settings are best for different types of defects in a recording? I have read what information was in the owners manual about the filter. I've come a long way since first using DC Art32 and with each use get better at it. Thanks for the great product.
Kent