The add-a-tone and other such "features" that funnel the outside of the reproducer diaphragm in some purposeful way was all just marketing bilge. Several variations of this were tried, culminating in the Kalamazoo Duplex and other twin-horn designs. Yes, the wavefronts are largely out of phase and interfere with each other, even including those designs that have a fairly long horn loading one side of the diaphragm which does add a little time delay to that path. Depending on where the listener is positioned relative to the two sound outputs, the interference will cause comb-filtering of the audio spectrum which makes the sound quite different from place to place. It was merely a sales gimmick.
Greg Bogantz ----- Original Message ----- From: "Robert Wright" <[email protected]> To: "Antique Phonograph List" <[email protected]> Sent: Monday, February 11, 2008 1:16 AM Subject: [Phono-L] Portables > Here's another Carryola on eBay: > > http://cgi.ebay.com/VINTAGE-1920S-ORNATE-VIOLIN-CRANK-PHONOGRAPH-COOL_W0QQitemZ300197975631QQihZ020QQcategoryZ1442QQssPageNameZWDVWQQrdZ1QQcmdZViewItem > > My question is about the add-a-tone patent of 1925 referenced on the > reproducer. It looks like a combination recorder/reproducer design from > the late 1870's (figuratively, of course)! Surely this wasn't intended > for home recordings. More likely, I assume, just another sound source for > more volume. This typically wouldn't be conducive to pleasant playback > (and certainly not accurate playback), as waves coming from the front side > of the diaphragm (the side not facing the tonearm tube/horn) would be out > of phase and time-misaligned with the waves coming from the horn, but > maybe they thought the extended length of that overly-curvy tonearm would > make the distance traveled by the waves coming out of the horn long enough > that phase issues would no longer have a detrimental effect -- thus by > amplifying the waves coming from the non-tonearm side of the diaphragm, > they were "add"ing more "tone". > > Or was it just another way to establish a BS patent/avoid a Victor patent > infringement? > > Thoughts? > > Best, > Robert > > > _______________________________________________ > Phono-L mailing list > http://phono-l.oldcrank.org
