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From: murphy@voder.UUCP (Neil Murphy)
Newsgroups: net.audio
Subject: VTA adjustments of Cartridges
Message-ID: <705@voder.UUCP>
Date: Fri, 8-Mar-85 17:28:45 EST
Article-I.D.: voder.705
Posted: Fri Mar  8 17:28:45 1985
Date-Received: Sun, 17-Mar-85 13:24:51 EST
Distribution: na
Organization: National Semiconductor, Santa Clara
Lines: 54

I could use some help setting my cartridge VTA.
(For those who don't know what I'm talking about,
Verticle Tracking Angle, also called stylus rake angle, I
believe, is the angle at which the cantilever/diamond
tip mechanism of a cartridge meets the plane of the record
surface. The idea is to match the angle used by the cutting
lathe when the record was produced).

I realize that all I can aim for is a good compromise.
The Journal of the Audio Engineering Society ran (several
months back) and excellent article on the subject. Because
of vinyl deformations the actual angle has been quite
difficult to measure with any real accuracy, and it can
vary from cutter to cutter, disk to disk by a surprisingly
large margin.  Idealy, one would be able to adjust VTA for
each disk, much like one would tweek azimuth for tapes
played on different playback systems.  That's obviously
a hassel and probably quite unnecessary.  My set up is
forgiving of mis-tracked VTA, and I don't hear much difference
as I change the angle through a surprisingly large arc...I'd
guess +/- 3 or 4 degrees.  I'm using a modified AR, Premiere MMT 
arm, and an Audioquest 404.  

I spoke directly to the cartridge's designer, and he said
to lower the rear of the cartridge several degrees from the
horizontal.  The actual amount to be determined by ear.  He
said he uses a Joni Mitchel album as a reference, and when
she starts to sound "nasal", he's gone to far.  That's
nice, but I'd like to know a more precise method.  I bought
the arm at Garland Audio in Santa Clara, and they will set
it up for me, but not while I'm around.  Seem to want to
keep the method a dark secret.

I purchased several CBS test records that were advertised
to test cartridge tracking.  One, a square wave test record,
is cut at 15 degrees.  They claim this is now the industry 
standard.  On a scope, I don't notice much difference in
waveform shape as I change VTA.  (There were no hints included
about setting any of the pertinent parameters, by the way.
Assumption seems to be that I knew it all.)  I don't have
a distortion analyzer, so I can't look at this, perhapse,
most obvious parameter.  The records seem to be most useful
for setting anti-skating and tracking force.

So how have you folks out there handled this problem.  Do
I need to have a cartridge that's more sensitive to VTA to hear
the differences I read about?  (If so, I'll stick to what I've
got!)  By the way, my system sounds just fine.  I just like
to make it sound "finer".

Thanks in advance for your ideas-  Neil Murphy
				   National Semiconductor
				   Speech Lab,
				   Santa Clara, Ca.