Again,let me bring up the Deutsce Gramophon microgroove 78s rom 1950,'51 or so. Anybody care to discuss these ? Roger --- On Wed, 10/14/09, George Brock-Nannestad <[log in to unmask]> wrote: From: George Brock-Nannestad <[log in to unmask]> Subject: Re: [ARSCLIST] late date 78 To: [log in to unmask] Date: Wednesday, October 14, 2009, 6:37 PM From: Patent Tactics, George Brock-Nannestad Hello, Milan Milovanovic asked: > > Speaking of micro versus wider grooves, would wider grooved cut record be > more resistant to micro scratches and easier to get clean from dust etc. > than "microgrooved" LP record? > > Also, would 78 rpm speed be more suitable for recording/reproducing > especially at the last 1/5 of disc with no groove distortion added in this > area (often connected to ordinary 33 rpm records)? > > > Hello, > > > > Mike Biel wrote: > > > >> Theoretically the best sound at 78 would be with a microgroove size > >> groove since it would be capable of higher frequency response than a > >> wide groove, or a microgroove at slower speeds. > > > > > > ----- now, I am speculating why this should be so. I do not understand why > > a > > microgroove should give a higher frequency response than a NORMAL groove. > > It > > has to do with the maximum acceleration of the tip and the ability of the > > tip > > to trace precisely the groove shape. If the smaller radius of an > > elliptical > > stylus (or the radius of the edge in a line contact stylus) is able to > > trace > > without error a curve in one flank of the groove, it does not matter > where > > the other flank of the groove is. > > > > If microgroove is associated with a higher groove pitch (which would > mean > > well above 200 grooves per inch), then the maximum amplitude would be > > reduced > > compared to the ca. 100 grooves per inch in a traditional 78 rpm record. > > If > > we maintain the 100 grooves per inch but reduce the groove width and > > depth, > > we would have more land to use, and the modulation could be higher, > which > > would give a low frequency advantage. That is the rationale behind disco > > singles (albeit at 45 rpm). And all of this without variable groove pitch. > > If > > that is used, then we are even better of, bass-wise. > > > > Kind regards, > > > > > > George