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Using a 78 adapter on an Edison disc phonograph

Posted: Tue Mar 13, 2018 12:07 pm
by VictorVV-X
Hello all, I recently bought an Edison C-150 that came with a 78 adapter. The set up works, but near the final quarter of the record, the sound becomes distorted. When I try the same record on my Victor VV-X it sounds fine all the way through.
Currently I set the reproducer normally on the record and then engage the Edison's drive for the horn as that is the way I saw it done. This is when the sound distorts near the end. I have tried my rebuilt Victor No.2 reproducer and it does the same thing. Also, I have tried not engaging the horn drive, but this doesn't really work well either.

Am I doing something wrong or is this just the nature of the set up?

Thanks in advance.

VictorVV-X

Re: Using a 78 adapter on an Edison disc phonograph

Posted: Tue Mar 13, 2018 12:57 pm
by PeterF
Sounds like the tracking angle is the issue. The groove pitch (spacing) is different for typical lateral discs than the standard Edison pitch on Diamond Discs. But a Diamond Disc phonograph has a built-in drive that moves the horn (and tonearm throat) across the record face at that same pitch.

If the lateral adaptor and horn are set perfectly aligned to the first groove of the lateral record, by the time everything has moved towards the end of the record as it plays, the horn will not have moved as far inward as the reproducer has.

The lateral adaptor allows horizontal movement, so the needle is still able to remain in the groove, but by the end of the record quite an angle has developed in the horizontal plane. That's the source of the distortion you describe.

The solution is to add a little bit of an angle on the front end, so the angle on the tail end isn't as extreme. This is of course a compromise, because using a lateral adaptor is itself a compromise, but the results are usually acceptable. And if they are not acceptable, you have a great way to rationalize purchase of a nice new additional phonograph for the lateral records!

Re: Using a 78 adapter on an Edison disc phonograph

Posted: Tue Mar 13, 2018 1:02 pm
by alang
I experienced the same thing when I tried a 78 adapter on my Baby Console. It appears that the feed screw transports the horn at the wrong speed for a 78, which means that the grooves are a different width. My adapter swivels both horizontally and vertically, so I watched that it got ahead of the horn towards the end of the record. Then instead of setting it straight at the beginning I set it on the record at a slight angle (the horn a bit ahead already) to compensate for that difference. That allowed it to catch up with the horn while playing and no distortion. Because of this it is obviously not ideal for playing 78s, because the needle is not always at the correct angle to the direction of the record. In the end it works, but I treat it more as a novelty, not for regular playing.

Andreas

P.S. I see PeterF beat me to it :)

Re: Using a 78 adapter on an Edison disc phonograph

Posted: Mon Jul 23, 2018 5:40 am
by Salon
There is a simple solution to this problem, which I adopt on my C-19 Chippendale disc phonograph. Never use the feed-screw mechanism when playing regular 78s -- disengage it completely by leaving the lifting lever in its down position. With the adaptor and soundbox for lateral-cut discs installed, place a 78 on the turntable, set it in motion, wind up the motor, move the arm assembly and re-position the soundbox if necessary until the needle point is a fraction past the centre spindle of the turntable. Holding the arm in that position, so you have as near-perfect a playing arc as possible, swing the lower half of the adaptor to the beginning of the record and play it. I obtain excellent reproduction by using a Goldring Luxus Electro box. Three inches in diameter, it has a mica diaphragm and pivoted stylus bar. All 78s sound just as good as when played on a top quality gramophone.