Mounting of a tonearm.


I have an Oracle turntable with a rare Micro Seiki TA-1 tonearm. I don't have any dimensions or instructions for the installation of the tonearm.
How critical is the measurement from the spindle to the tonearm.?
How would i be able to determine the correct measurement ?

The tonearm sounds great the way it is installed but on some recordings i hear a little distortion on the last track and i am wondering if this dimension would have anything to do with it.
Thanks
Todd
tshulba
That's good news.

IGD is a function of tracking angle error and the shorter modulations of inner grooves, but that's not your problem or you'd have it on many records. IGD has nothing to do with the age or condition of any particular record, so the term doesn't apply here.

Out of curiosity, which LP is this and what does the distortion sound like? It might be interestng to figure out what's actually happening.
Thanks Doug for providing a good insight to IGD. IMO, IGD is most likely caused by a worn stylus.
Tshulba,

welcome to the whacky, insane world of vinyl! Sounds like you've discovered my number 1 rule of thumb. First assume the simplest (dumbest in my case) scenario and work your way up.
Sorry guys for not replying sooner , have been away.
I have 2 new Clear Audio records that do it. One is Friends of Carlotta on the track Time
After Time , at the very beginning the piano has some smearing type distortion. The second record is Bella- tracks of the heart. The electric guitar has the same type of distortion .Both of the instruments have large amounts of echo mixed in so it could be in the recording. The funny thing is the voices are crystal clear with no distortion ,it is only these 2 instruments on 2 tracks.
I don't know how to describe the distortion i am hearing i don't know the correct terminology for all the distortions.

I have been using Doug's cleaning method with the Magic eraser after every play and the stylus is very clean now. I am now using Audio Intelligent #6 cleaning solution and things are sounding great except for the distortion. I am beginning to suspect the tonearm but the interesting thing is it only distorts on specific tracks on certain records at different locations on the records too.
I have learned alot in the last month and the sound has improved an incredible amount thanks to Doug and everyone else that has helped out.
Todd
Tshulba,

Thanks for the further description.

"Smearing" is an excellent description of what can result from tracking angle error distortion.

When the cantilever is non-tangent to the groove (as it is on an LP's inner- and outer-most grooves) the stylus contact edges play the two groove walls with a slight time shift. The only way to prevent this is to use a linear tracking arm. All pivoted arms produce tracking angle errors. The only way to reduce them is to fiddle with your cartridge alignment. Eliminating them will not be possible. Tracking angle errors are a mathematical certainty with a pivoting arm, one of the irreducible weaknesses of vinyl playback.

BTW, it's unsurprising that one of your problem passages is on the very first grooves. Tracking angle error is highest on the first grooves of an LP (assuming a two-point cartridge alignment).

Now if an LP were artificially mixed with 100% unique information on each channel (ping-pong stereo) this slight time shift wouldn't matter. But most LP's have information from any given instrument on both channels. That is what gives us imaging, lateral soundstaging and image placement. Certainly all live, acoustic recordings do this (most classical and jazz). With the same information on both channels, any time shift between channels puts sounds that should be congruent slightly out of phase.

Echoes and reverb add to the challenge, since they're another example of time-shifted sounds.

If a system maintains these slight phase shifts perfectly all the way through the speakers, it doesn't sound smeared. Images shift L or R from where they should be, but that's about the only effect. The trick is getting the system NOT to smear similar or identical but phase-shifted sounds into mush.

This depends on every component in the chain. Any time you put two similar waveforms with a slight time shift through a component you are testing its temporal linearity, transparency and ability to resolve and maintain very fine differences. My toughest test LP's for this phenomenon contain strong, pure tones from two very similar sources (alto recorder, alto vocalist) playing identical or harmonically related notes at the same time. The recording was made in a stone-walled church, so in addition to the doubled voices the echoes are quick, powerful and closely overlapping. This LP brings most systems to their knees. I've been working on ours for five years and it's "almost" right, but it's been a long struggle.

The phono stage probably has the toughest job, since it has to amplify the lowest level signals without mushing them together. I've only heard two or three phono stages that can cope with my toughest LP's in this respect. I've heard many more that blend similar waveforms into a distorted smear.

Line stages and amps can do the same thing of course. So can tonearms, interconnects, speaker cables and speakers. Every component in the signal path is an opportunity for phase shifting and distortion. The best components minimize this and that's a major part of what we've strived to achieve with our system.

One thing I can say from experience is that your Airy 3 is not a major contributor to the problem. It doesn't have the unearthly transparency of the UNIverse, but even entry level ZYX's like the Bloom present difficult signals to the phono stage with exceptional clarity. Maintaining that clarity is difficult however. In that respect a ZYX may challenge a system in ways that some less resolving cartridges simply gloss over.