[78-L] 78-L a shuddering stylus

[Malcolm Rockwell]

Thanks for your replies, folks.
I never have had any problem playing records like these and can adapt to 
just about any condition a record might be in to get al least one clean 
play from them, so that's not a problem. I had never considered a 
tonearm resonance, though. I use a Technics SP-15 table with an Audio 
Technica arm and a combination of Shure and Stanton carts in headshells 
of differing weight. A good, solid set up.
Mal

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On 5/14/2010 11:16 AM, JD wrote:
>> Date: Fri, 14 May 2010 07:10:46 -1000
>> From: Malcolm Rockwell<malcolm at 78data.com>
>> Subject: [78-L] a shuddering stylus
>> To: 78-L Mail List<78-l at klickitat.78online.com>
>> Message-ID:<4BED8416.60806 at 78data.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Has anyone else besides me noticed a little shudder of their tone arm
>> once a revolution on some pressings? It's especially prevalent at the
>> outside edge of indy 1950s issues, but not limited to them and can cause
>> the stylus to jump out of the groove in some instances. In fact I
>> recently received an RCA-Victor record with this problem. It seems to
>> disappear the closer to the center of the disc the groove is.
>> I believe it's due to an unbalanced (or badly lubricated) lead screw, or
>> possibly a bad bearing at the outer end of the lead screw on the disc
>> cutter.
>> Any other ideas?
>> Mal
>>
>>      
> If your tone arm iadjustments and tracking force are properly set and this
> symptom persists you may have a resonance problem between the arm and disc.
> The Dual 608 turntable (single play, three speed, long out of print) was
> able to address this problem via a separate adjustment of the arm
> counterweight. The Shure "ERA IV" test Lp (TTR115) had several tracks to
> test for resonance. Unlike some of the non-existent or imaginary problems
> and tweaks that latter era Voodoo hi-fi loonies have focused upon this could
> be a real problem and the Shure disc could demonstrate it vividly. The
> resonance damping adjustment on the Dual 608 worked perfectly. On some of
> the Shure tracks the arm would vibrate violently. Adjusting the damper would
> cause the vibrations to disasappear. Some months ago I mentioned having
> tried a so-called "DJ" turntable ( a cheesy copy of the excellent and proven
> Technics) of a well known brand. Luckily, one of the first LPs I played on
> it (a classical Mercury Living Presence) began with a clarinet solo. I
> immediately heard what sounded like flutter. I knew darn well that there was
> no flutter on the Lp and verified that by playing it on my Technics SLQX 300
> and my old Empire. I concluded that what I was hearing was an artifact of a
> poorly designed arm exhibiting a resonance effect. That turntable did not
> exhibit real flutter on other recordings but did have
>   other major problems that I soon discovered (unusually high rumble for a
> direct drive and an off-kilter platter). Needless to say it went right back
> to the dealer and I decided to avoid similar TTs in the future.
> So, I suspect from your description (assuming correct adjustments) that
> resonance is the likely culprit. The first thing you should try after
> verfying that arm&  cartridge adjustments are properly set is to play the
> "problem" discs on another turntable of known quality.  Good luck!!!
> JD
>
>