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What is distortion due to?

Every so often I hear distortion (like a buzz) while playing some records. Usually its when a pianist plays the upper registers really loud, like banging on the piano, but also with female voices in the upper register, loudly singing, also woth violin. Mind you, some records do not do this. But even a brand new 45 rpm pressing has one passage where I hear it (female voice).

System: VPI Scoutmaster/Sumiko Blackbird/ Musical Fidelity A308 with MM and MC phono input.

I rechecked azimuth, tracking weight, and cart alignment. Is it the recordings, or is my phono stage maxing out? I am using the MM stage because the blackbird is a high output MC and that is what is recommended.

My cart is relatively new, withless that 100 hrs on it.
dolifant

Showing 2 responses by dougdeacon

dougdeacon
3,338 posts
 
If the noise occurs on both channels then antiskating and bad pressings are unlikely to be involved. Those problems tend to create one-channel noises.

Distorted musical peaks could indicate an overload, but this should never happen with a Blackbird feeding an A308's MM inputs unless the MF has gone bad somehow (pretty unlikely).

A buzz or static-like burst in synch with a musical peak usually indicates stylus mistracking. The solution includes keeping your records clean, keeping your stylus clean and increasing downforce.

Sumiko's recommended VTF for the Blackbird is not 2.0g. It's a range from 1.8 to 2.2. There is no reason to believe that "exactly" 2.0g is optimal for any particular Blackbird, especially one that's new. New cartridges often require more downforce until the suspension breaks in. Every cartridge is unique and many perform best in the top half of their recommended VTF range even after break-in.

VTF cannot be optimized by using a scale. It must be fine tuned by listening. Eliminating obvious mistracking is the first and most important step, since this kind of behavior will permanently damage every record on which it occurs.
dougdeacon
3,338 posts
 
Trying different azimuths was worth doing. I've never had a cartridge so badly off-azimuth that it mistracked, but I suppose there's a first time for everything.

1. Are your records cleaned?

2. Is your stylus properly cleaned after every side?

If the answer to both is "yes", try reversing the cartridge clips and playing a few suspect passages.

If the noise switches to the L channel then the fault lies with your cartridge or its setup. The JMW's hokey antiskate "adjustment" would be a prime suspect, as would the stiffness of a new cartridge not yet broken in.

If the noise stays in the R channel then it's something later than the cartridge.
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