On Fri, 14 Dec 2012 13:54:30 +0000,
(D.M. Procida) wrote:

RJH wrote:

Well, it won't do that without some force. Something is pushing it
back. Maybe it is not as free as you think. Alternatively, look at
Jim's suggestion that the bias is set wrongly. I don't know how it is
applied on this arm, but if you adjust it off as far as possible, that
will tell you if it is responsible.

d


Sounds like a combination of wildly out tracking weight, bias adjustment
and turntable level. Can't think how/why else that could happen. Has the
TT been moved or adjusted recently?

I had a new cartridge fitted a while ago by a local hifi shop.

On further checking, the tracking weight is too low.

In fact it can't be set higher than 1.6g (for a Goldring Elan cartridge)
because the cartridge has been mounted right at the close end of the
mount, rather than in the middle.

If they'd put it in a more sensible place there'd be a proper range of
adjustment.

I'll try it on 1.6g and see what happens, but I am not very impressed by
the way it was installed.


It seems to me that it may be something wedged around the tone arm
pivot (you mentioned a cartridge change in your later posting). If you
can, take a closer look at the cartridge lead wires where they exit
the tone arm and verify whether or not they are misrouted in such a
fashion as to create the effect of springy 'end stop'.

Regarding cartridge tracking downforce, it's usually best to choose
the upper end of the recommended range, rather than the lower end. A
1.4 gramme downforce equates to a 1 gramme groove wall force which,
with an effective tip mass of 1mg (typical for most quality
cartridges) yields a maximum acceleration of 1,000G. Loud passages on
some heavily modulated pressings can easilly exceed the 1,000G mark.

Insufficient down force will create mistracking distortion (where the
stylus stops following the groove wall modulation (the HiFi equivilent
to the issue of weak valve springs on a high revving souped up car
engine where this produces valve bounce).

In this case, the groove wall modulation falls away from the stylus
tip faster than the downforce can accelerate it, resulting in it
parting company only to smash into the groove wall when the modulation
starts to (or has started to) reverse direction.

A record played sufficiently often on such a setup will eventually
suffer groove wall damage emulating the original tracking distortion
when the condition is either corrected or it is played on a better and
properly setup turntable. IOW, insufficient downforce does more harm
than a modest excess of downforce ever will.

Regarding the issue of sideforce bias compensation, the word
"anti-skating" should never grace any discussion involving record
decks and tone arm setup. The correcting bias can only be an
approximation to counter an effect directly attributable to the
overhang required on a single pivot arm to minimise angular
displacement from the ideal 90 deg wrt the tangent at the point of
contact.

There was a period (mercifully brief, afaicr) where you could buy a
blank grooveless record to calibrate your "anti-skate" compensation.
The (bogus) idea being that you could immediately see the effect of
the adjustments as a veering away from the halfway point either
inwards or outwards. Sadly, the condition that pertained with a blank
grooveless disk was so radically different to 'real life' that any
such adjustments became totally inappropriate when playing an actual
vynil disk recording.

The best way (apart from using the tone arm or cartridge
manufacturer's guidelines) was to use a test record with a range of
fixed frequency tones specially chosen for the task at varying levels
and points along the groove where you could carefully audition for
mis-tracking distortion or (for those more technically dedicated) use
a distortion meter or oscilloscope.

When I was doing this, some 30 odd years ago, I was staggered by how
much of the highest level of 300Hz test tone energy was reaching the
pivot of the SME3009 (detected by the vibration that could be detected
by a finger tip pressed to the junction of the arm's pivot bearing
mounting and the baseboard.

The SME was mounted to the baseboard using rubber vibration damping
gromets - those gromets were quite obviously having a (hopefully)
beneficial effect in reducing the risk of pivot bearing chatter adding
to the mistracking distortion levels.

Some manufacturers (B & O being one that comes readily to mind) did
try to eliminate this issue by using a servo tracked arm hanging off a
slide bar and lead screw assembly running parallel to 90 degrees wrt
the tangent of contact of the stylus tip with the groove. It certainly
solved the sidethrust issue but introduced other issues (which,
afaicr, may have been more significant that those in the traditional
arrangement - quite possibly the idea was simply dropped due to the
relatively high cost and added complexity for a marginal improvement).

--
Regards, J B Good