Mistracking and VTA

[Varun]

What a sound knowledge of medicines-Bisoprilol- a B blocker would probably stop the heart from beating and Frusemide rupture the bladder!!!

[Barry]

Hello Varun

You say that mistracking and VTA are neither exclusive nor inseparable. I would agree in principle, however I believe the tracking force, temperature and arm bearing quality have a far greater effect on the ability of a cartridge to trace heavily modulated, high frequency, grooves than VTA alone. I have done a little research and it would seem that the cutter VTA is continually altered as the record is being cut, to allow for both the amplitude and frequency of the modulation as well as allowing for vinyl 'spring back'. To complicate matters, in the ‘60s the typical cutter VTA was ~15º, later changing to ~20º, with 22º being typical. Cartridge manufacturers followed suit, however the IEC tolerance on this parameter is ±5º !

In general a lower VTA favours the bass response, whereas a higher VTA leads to better high frequency tracking.

A guide to the whole problem of VTA has been written by Roy Gandy (of Rega Research, whose arms do not have a convenient method of making this adjustment)
http://www.n.mackie.btinternet.co.uk...regaonvta.html

This is a clear ‘no nonsense’ article and explains why in Gandy’s opinion the provision to adjust VTA is to send the user off on a ‘fools errand’. His arguments are persuasive, however I would question his claim that a change in tracking weight of 0.1g results in a change in VTA of 1.5º (my ‘back of an envelope’ calculation taking a Linn Asak cartridge, having a compliance of 8cu and a cantilever length of 3mm, suggests a figure of 0.15º, equivalent to an arm height change of 0.6mm for 9" arms and 0.8mm for 12" arms.)

The Gandy’s thesis is further explored in:
http://www.tnt-audio.com/sorgenti/vta_e.html

wherein the author, Geoff Husband, is clearly sceptical about the whole VTA ‘fuss’. This article makes a clear (if pedantic) distinction between stylus rake angle (SRA) and VTA. The author also suggests that the type of arm used is important, that is, if the centre of gravity of the arm/cartridge combination lies above or below the record surface, and this could explain why some listeners can hear minute changes in VTA.

A guide to the correct setting of VTA can be found at:
http://www.enjoythemusic.com/magazin...rtridgevta.htm

For those who believe that it is necessary to adjust the VTA each and every time a record is played, might be interested in:
http://www.audioasylum.com/audio/vin...ges/27755.html

In the above posting, reference is made to the audible effect observed by making a change of 1 minute of arc in the VTA. That corresponds to a change of 66um (or 2.5 thousandths of an inch) at the rear of the arm!

Finally, the following is part of an item written by or for (?) Eminent Technology (a manufacture of tone arms) on VTA adjustment. They suggest that if the VTA of the cartridge used lays between 18 and 20º then the arm should be set up so that the arm is parallel to the record surface. If the angle is > 22º then the rear of the arm should be lowered, so that the angle is reduced by 3º. The problem is they don’t say how the angle is measured.
http://www.eminent-tech.com/Manuals/et2manualpart2.pdf

So after all this what is my position? Well I’m really an agnostic here; I believe that once you have set up the cartridge overhang, using an alignment protractor (and here we could go into minute and pointless discussion as to whether it should be according to the theories of Stephenson, or of Baerwald and Lofgren) and the tracking force using a test record with the arm parallel to the record surface, then small adjustments to the rear of the arm can be beneficial. Once the best position has been found, by ear using a variety of records (of various thickness or weight) lock the arm in this position and leave well alone. If my hearing was sufficiently sensitive that I could hear the effect of different record thickness, then I would use two or three decks individually set up for those records, rather than fiddle with the VTA each time.

I would disagree with you over the effects of correct azimuth. I believe that the major effect of correctly setting azimuth is to symmetrically minimise the inter-channel crosstalk. Whilst this has an effect on the effective dynamic range: being defined by the difference between the crosstalk and the maximum amplitude modulation that can be tracked by the cartridge, I believe the increase in second harmonic distortion caused by cartridge mistracing heavily modulated grooves due to misadjusted VTA, is subjectively more noticeable and has a greater affect on perceived dynamic range.

No doubt to be continued………

Regards

[DSJR]

Excellent post Barry.

[Varun]

I have nothing more to add Barry. Ever since I had my first LP12 in 1980, every cartridge installation has always been carried out meticulously and I have never had any problems. The arm has always been parallel to the record surface and that I would see as a 'neutral mid position' assuming that all records are the same thickness and pressing.

This then results in half way compromise between thick vinyls and thin vinyls.

Those who do not listen to classical music need not worry as majority of LPs since the 70s have been 'thin' including classical music.

The point was that the sound does change and it is not a question of extreme of frequencies either. There must be a reason why the designers of two highly regarded TTs - SME and VPI have provided these facilities.

I do not think I can add any more-but please see another thread starting soon and would value your comments hugely Barry.

[Varun]

Final Comment from me-

The lowering of the arm by degrees so that you can see the arm being either parallel or not is TOO HUGE for the magnitude of changes I am talking about-the dials change the VTA by fractions. Consequently the arm looks parallel all the time, if it does not then the change made has been big.

I saw that happen last evening. I was listening to Steely Dan-Greatest Hits. This is a two record album of very thin records-and it sounded awful. So the VTA was adjusted-but the arm was still parallel.

Varun

[DSJR]

Apparently, playing a record will slightly deform the vinyl for a few minutes, so if you play it again before the vinyl "springs-back," you'll get a slightly different sound the second time. Also, the "mold-release-agent" can be pushed out of the way on one playing and then creep back over a few months in storage.

Lastly, the more sophisticated the tip profile, the more fussy it'll be, especially on older pressings. I think this is where I came in

[NRG]

Apparently, playing a record will slightly deform the vinyl for a few minutes, so if you play it again before the vinyl "springs-back," you'll get a slightly different sound the second time. Also, the "mold-release-agent" can be pushed out of the way on one playing and then creep back over a few months in storage........

Really!? I find that rather hard to believe.....the release agent thing I went through in the eighties, there was a cleaning kit you could buy to clean the stuff out....no matter how many times I used it the sound didn't change or actually got worse! There where little stickers you could apply to the outside of the album cover labeled 0-9 to indicate how many times you had cleaned a particular record...what a load of b.....s

[Varun]

Thanks Dave,

I should clarify, I had listened to 2 tracks on side one-not sure-so listened to three tracks on side 2-and it was the second tract-East St Louis Toddle-oo which was unaccetable-the lot and specially the Piano. Also the opening of 'Ricky don't lose the number' soft and fluffy. Not quite what you are talking about Dave.

Sound changes from day to day- and depends on one's own state of mind. It takes time to analyse that the sound may not be right. It never is a question of first few grooves and switch.

Somwhow- we are talking at cross purposes as with a parallel arm-no matter which TT- differences in thin and 180 records is unacceptable to a critical listener. It never is a question of 'bloated bass' or 'pops and crackels' far more. As here the Piano which sounded awful in tract 2 is midrange.

The point being that I will leave that setting as 'reference' now and see-mind you I have changed the cables as well and biwired.

Varun

[Varun]

Mike was right-the thread keeps going and going. I was going to ask him whether it should be closed as we have sharply divided opinions-all very acceptable to me-but we keep on repeating the same points over and over.

Varun

[StanleyB]

-but we keep on repeating the same points over and over.

Try the arm lift.