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.
Tough one. If it is more prominent in one channel than the other, then anti-skate needs to be adjusted. You did not say if you have a JMW-9 or Signature, but this is certainly the place to start. If all is well in anti-skate world, and I don't think that it is, you may need to increase tracking force to the top of the suggested range. Most MM cartridges put out between 3.5mv and 5.0mv, so with 2.5mv output from the Blacbird, you are certainly not overloading the phono stage.
I have been tracking at 2.0 gr, which is what is recommended.
It is a JMW 9, and the buzz is only on some records and is not just in one channel, so I doubt its anti skate.

I'll try a little more tracking force.

Could it be bad pressings?
First, it is probably a fairly serious problem, when the stylus loses contact with the groove wear is accelerated on both the cartridge and record. You say that it is not anti-skate, but have you put a twist in the wire from the tonearm to achieve anti-skate, and if so, how have you measured that the amount is correct? This is the trickiest arm to get anti-skate correct on, as it is so Mickey Mouse. I recently set-up a Dynavector XX-2 on a Super Scoutmaster and really had to monkey around until I got the anti-skate just right. Remember, if it is not correct, there is more force exerted on one wall of the groove than the other and side with less force will experience compromised tracking. My only other thought is are you measuring the tracking force in the plane of the record? Most scales require this, the exception is the, rather crude Shure balance, which is designed to work on top of the playing surface. And it could be bad pressings, but usually these make noise, but not buzzing, which would seem to indicate that the stylus is loseing groove contact. Are these the highly-modulated high-frequency passages that are problems?
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.
I'll disconnect one channel at a time to see for sure if it is one channel only.

Yes, it is the highly modulated passages, very loud and high frequency..like human voice (soprano), violin, or upper piano range.

What is the best way to do the "twist" on the wire? Please explain how you can see whether you have it the right way. You know VPI really hasn't embraced anti-skating, although their signature arm does have a mechanism. Maybe I need to upgrade.
Sounds like mistracking to me and has nothing to do with anti-skating. Increase the VTF (with AS dissabled)and note if distortion reduces. Upgrading the arm isn't going to solve mistracking problems.
Bob P.
OK, I can verify that it is only the right channel that distorts. I checked and did not have a twist in the wire. I increased my VTF to 2.2g, using a digital guage placed on top of the platter. Still the buzz was there. I then put a single counterclockwise twist in the tonearm wire and no help. I then tried screwing with the azimuth, rechecking the VTF after each adjustment. Then I undid the twist and tried different azimuth settings. I tried two twists and it was really bad! It got worse, then better, but never fully gone. Could I have a bad stylus? Was I right in checking and trying different azimuth adjustments? I have checked the routine alignment and overhang with the jig given by VPI. As far as my 51 year old eyes can see, its OK.

Is it possible the cantilever is tilted. It always seemed tilted toward the spindle just a little when I looked at it, so I had originally adjusted the azimuth to try to get the stylus/cantilever perpendicular to the groove, again by eye. I am new to analog so I don't have the experience to know what to listen for. But the channels seemed balanced and frankly I love the sound on most discs. Its just the distortion on some things that is killing it. HELP.

Should I get and try a new cart? I need my analog, cause it beats the hell out of CDs.
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.
Dolifant, when you say:
" I checked and did not have a twist in the wire. I increased my VTF to 2.2g, using a digital guage placed on top of the platter"
- do you mean you placed the cartridge directly onto the digital scale?

If so, the indication on the digital scale may be reading 'high' by a significant amount due to magnetic attraction to the scale parts. My own pocket digital scale would read about 0.3-0.4g higher than the actual VTF if the cartridge was placed directly on the weighing tray. Those MC magnets are quite powerful.

The best option is to build a small ladder adapter (Wally Malewicz's idea) that distances the cartridge from the scale and also allows measurement adjustment to record height.
You post is very interesting. I too have a VPI Scoutmaster with Dynavector 20xL feeding into a Musical Fidelity A308. It's a great phonostage for being inboard, don't you think?

I had the same problem, a light crackling echoing high soprano voice and some high staccato piano passages. I tapped in the counterweight about a millimeter, (my audio guy set my TT up and I don't kwow where he set the tracking force, I hope it's not too much now, I'm waiting for him to call back), and it removed the problem, except for a very few passages of which I have since tested on multiple pressings. Same problem, whether London/Decca/SXL.

One of the worst offenders was Solti's Strauss Der Rosenkavalier in the final Rose trio; luckily it's not a problem on the Karajan EMI. I find it interesting that the VPI tracks 99% of other, sometimes insanely demanding high vocal and/or piano passages without any problem at all, why is that? Some pressing simply may be incompatible with some turntable combos. Luckily for us, as you seem to like Classical, we get to choose from many performances and pressing of the same thing.
I want to thank everyone who responded to my question. The problem is solved. It was the anti-skate, or rather the lack of.

I assumed I needed a counterclockwise rotation of the wire to provide the anti skate. WRONG! When I read the manual it said to balance the tonearm with the counterweight and move the tonearm toward the spindle. It should stop and back up away from the spindle. If not, then untwist the wire one rotation. It turns out that was CLOCKWISE, not counterclockwise, as I had suspected. When I twisted clockwise it applied force in the centrifugal direction, as needed. BINGO. One clockwise rotation and gone was the buzzing at high frequencies. I am again in analog heaven.

I promise to read the manuals carefully from now on.

Thanks again