[78-L] Approximating 78s age by physical characteristics

[Mark Bardenwerper]

On 3/3/2013 8:50 PM, Mark Bardenwerper wrote:
> On 3/3/2013 5:28 PM, David London wrote:
>> On 03/03/13 23:10, Mark Bardenwerper wrote:
>>> I can't add much to this, but it should be noted that many of the
>>> groove additions came with the invention of automatic changers. The
>>> change in labels had to do with the manufacturing process. The
>>> beginning of the electrical era had something to do with some of these
>>> changes. Before electrical recording, there were electrically driven
>>> platters. Someone more in the know might tell us if there was a
>>> workable changer in the acoustic era. It would have been a challenge
>>> due to the heftiness of the arm, but people could be pretty imaginative.
>> I was wondering also, if changers existed before lead-in grooves. It
>> seems a key addition to a record, else you risk the needle just sitting
>> floating on the leading edge of the record (or did they bias the arm to
>> always swing inward when there was no groove?).
>>
> There was a lead in groove, which then took the needle to be captured by
> a concentric or elliptical groove. The changers worked best with
> elliptical because the adjustment for kicking in the arm lift was less
> fussy (that was adjusted normally by setting the starting point on the
> outer rim).
>
Pardon me, I should have said, "Lead out groove"

-- 
Mark L. Bardenwerper, Sr.

Technology...thoughtfully, responsibly.

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