Mystery!

[Malcolm]

Can anyone explain this strange phenomenon? When I think I have finally arrived at an acceptably restored 78, I listen the whole file a few times and I start to hear heavy ?clicks? and dull ?plops? that were not there before. I highlight the affected zones and replay only to find that the offending sounds are gone. I play again the file and the noises appear elsewhere in the file. I zoom in and find no transients or strange waveforms present ? they are elusive! How can this be, and how can I burn a CD and guarantee that the final product will not contain these phantom defects?
?Perplexed?

[Craig Maier]

Re: Mystery!

I do not know what the problem is, but I have never seen this one. Perhaps your sound card has an intermittently noisey op amp? (Very high incidence of 1/F or 1/F^2 noise). I have seen that occur in my general engineering experience outside of the audio world.

[Malcolm]

Re: Mystery!

Craig, thanks or your input. Does "F" = frequency?. Would you expect the sound card people(Turtle Beach) to have knowledge of, or a fix for this possible cause? One thing, however, I have not found the same problem using the new DC5/Live Forensic software, so hopefully the issue may be moot.
malcolm

[Craig Maier]

Re: Mystery!

F is frequency, and 1/F noise is the type of noise that becomes larger in amplitude as one views band slots lower in the audio spectrum. I would think that Turtle Beach would be familiar with this terminology associated with op amps. However, I can not explain why Millennium did this, but DC 5 did not based on the op amp explaination. Perhaps, Turtle Beach had some sort of problem in dealing with MME drivers? The DC 5 uses direct X instead.

[weskola]

Re: Mystery!

I have also had this happen to me. It happens very rarely but I have heard it. I have noticed it mostly when I use the EZ-Impulse filter but I have also heard it on the standard INF as well.

On the EZ-Impulse I have heard it if the "Crackle" setting is too aggressive. On the standard INF it seems to be the threshold control. Sometimes it seems that some combinations of size and threshold will cause this with some material. Sometimes changing the size will make it go away, sometimes changing the threshold will make it go away.

These "plops" or "thuds" are usually very difficult to see. Sometimes I will select the area where I think it is located only to find that it actually resides a little earlier than the selected area. Even then, there is usually nothing that makes it appear to be obviously different from anything else. Sometimes it is hit or miss, trial and error interpolating until you finally hit the right one.

Now, I have only heard these on previews. I have yet to have them introduced on anything that I have filtered. When I say that they are difficult to see, I am speaking from my experience with 3rd party declickers. One in particular is notorious, from my experience, for introducing these sounds.

[JimP]

Re: Mystery!

I have noticed the plops and thuds on the original recording.

If you were fortunate to have recorded the wave in srereo. You can use either the left or right channel so see if it appears on one or the other.

Try your best to locate it and then copy the other channel and paste over the plop or thud. Sometimes it works and you can go on.

If the plop or thud is on both, or a single, if that be the case. Try a careful cut and be sure to paste interpolate where the wave is now joined.

Jim

[Craig Maier]

Re: Mystery!

Plops or Thuds sometimes exist only in the vertical plane of the recording. The channel blender set to a crossover frequency of about 200 Hz may also get rid of the problem without distorting the stereo image. This action will remove the vertical displacement vector of the recording for all frequencies below 200 Hz.