Blue Angel wrote:Twinhit wrote:Now that's a cool cart. That AT23a eminds me of a precision micrometer head.
Do you have any documentation for that?
Someone ought to start a tone arm gallery.
My dream tone arm is a balanced 3-4 foot long tone arm. The needle's arch radius reduces with greater length and as a consequence the stylus diamond's inner groove angle deviation from the outer groove is substantially reduced and
mimicry of the vinyl lathe's tangential (linear) path is more accurately realized with a much flatter arch than with shorter arms. At least, that's my
current theory.
Of course there would needs be much more research and attention to details than
that.
Yes, I do. I bought it new.
I have a customer who favours extra-long arms - way beyond 12".
ba
Way beyond 12"? Interesting!
I made some quick calculations and drew up a rough sketch of the various arcs and radius'.
(Using round numbers) for example:
An 64" arm that has (64" radius from arm fulcrum to stylus) will have an arc width of approximately .065" at the center point of a straight line (lathe line) distance between the outer rim of the record to the center spindle hole.
Approximately 3.5" width from vinyl rim's edge is allowed for program grooves.
When the needle is aligned with at the outer edge grooves, it will steer to the right toward the spindle as the needle advances towards the inner grooves.
The greater the needle-arc-line deviates away from that lathe line, the more that stylus' groove alignment is altered. The shorter the tone arm's (stylus to fulcrum) length, the greater the deviation.
IMHO, opposed to a typical 9" class tonearm, a 64" arm, dramatically reduces the stylus arc's "lathe line" deviation and as a result, the needle's angular orientation stability remains more consistant throughout the record's program section. though not a perfect straight line as a tangential arm would be, longer arms when well engineered to address other issues, could be a worthy investment costing thousands less than many high end Radial arms, let alone Tangential arms..
Try to imagine a 1" diameter arm that is 5.33' (feet) long! ie 5.3' from the stylus to the fulcrum.
Mind you, this is a traditional Radial type arm.
By doubling the length to 10.66", the arc is reduced to .0325", the stylus' angular rotation is reduced by half, yet again.
Of course no matter how long the arm gets, it will never be as true as a tangential arm. The only way it can hope to compete would be the incorporation
of technology such as used in old school drafting machines. B&J did this decades ago. I honestly would love to see that design in action.
Well, anyway, I just fell waaay off topic.
sorry.
