TT set up question


I was listening to a friends TT yesterday and it sounded really good, but on two LPs there was a crackling sound near the end of the LP. This sound did not occur earlier in the LP, and both of the LPs were new. What did he do wrong?
uppermidfi
Since you're unsure, here are the main possibilities. There are three common causes of "static-like" noises:
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1. Pressing flaws from the factory.

These can occur anywhere on a record, though they tend to occur on the L channel more than the R. There is no cure except to replace the record.

Since you've heard these LP's play without such noises this can probably be ruled out.

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2. Stylus mistracking due to inadequate downforce, record dirt and/or stylus dirt.

This tends to occur in timing with dynamic peaks in the music. That is when a stylus is most likely to mistrack. It is also more likely to occur as the stylus get nearer the center of a record.
This can be cured by addressing the causes. Records must be cleaned before the first play. Styli must be cleaned after every side. Then try increasing VTF until the noise goes away.

IMPORTANT: stylus mistracking must be cured immediately to avoid scenario #3.

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3. Permanent damage to the record from being played under the conditions described in #2.

Since this damage is caused by problem #2, it occurs at the same times.

It is nearly impossible to hear the difference between #2 (active mistracking) and #3 (damage from previous mistrackings). The only way to know is to try the cures for #2. If these don't help then one suspects #3.

There is no cure except replacing the record.

You've got some detective work ahead of you. Good luck!
Doug
I'm not sure when I will be able to get back to his place to listen again, but I will be listening differently when it happens. He has the zero dust stuff and a record cleaner, but that doesn't rule out the possibliity of dirty LPs.

Is there a point when tracking weight is simply too much? I know he has a digital scale, but that doesn't rule out errors. I'm just trying to get some ideas here, I don't have answers.
Is there a point when tracking weight is simply too much?
Yes. Every cartridge has a range of VTF where it tracks and sounds best. Too light and you get the problem described above. Too heavy and high frequencies usually get smothered. Heavier still, above the design range of the cartridge, and you risk accelerated wear of the suspension, stylus and vinyl.

For an excellent primer on how to set VTF (and VTA) by ear, give your friend this link:

http://www.walkeraudio.com/fine_tuning_your_turntable.htm

I know he has a digital scale, but that doesn't rule out errors.
Very true. A scale can't help you find the optimal VTF for a cartridge. That must be done either by listening to music or with test records. All a scale can do is:

a) get you in the ballpark and,

b) identify the optimal VTF after you've found it by listening.

Knowing the exact VTF a particular cartridge likes makes swapping cartridges and other adjustments go faster. Otherwise a scale serves little practical purpose.

Doug