Edison Disc Machine...Lateral Position

[Victrolacollector]

When playing lateral 78's on a Diamond Disc machine and the adaptor in place....Should the feedscrew be engaged?

[De Soto Frank]

I believe it should.

When the set-up is placed properly, the feed mechanism will keep the steel needle vibrating at right-angles to the groove at point of contact. (Or as close as possible.)

Without the feed-screw engaged, the horn neck can "float", and perhaps swing unpredictably.

Also, if the horn / neck are stationary, and we rely on the joint of the lateral adapter to provide the tracking swing, the farther the needle gets from the starting point, the worse the tracking angle becomes, increasing wear on the record.

If we place the horn/neck all the way to the outside of the machine, the tracking angle may start-out okay, but will worsen towards the center of the record. If we center the horn / neck in its range of travel, the tracking angle will be best in the middle of the record, but worst at the beginning and end. If we place the horn / neck at the inside end of its range, tracking will be worst at the beginning of the record, and least-worst at the end.

The above is based on my observations with a couple of lateral adapters: one a Kent with a long arm, the other two with "short" arms...

Unfortunately, I have no instructions for any of them, so I do not know what the original manufacturer's suggestions are for placing the feed and reproducer.

When playing laterals on my DD player, I try to set-up the reproducer so that there is a straight line through axis of the reproducer diaphragm and the horn neck. If this is not possible, I try to start the record so that the axes through the horn neck and the reproducer diaphragm are parallel to each other. In both cases I have the feed is engaged.

This keeps the geometry pretty decent through the record.

Your results may vary.

I save playing laterals on a DD mostly as a demonstration for guests, not as a regular means of listening.

[fran604g]

I agree completely with Frank.

If you play a record with your adapter and don't engage the feed screw, this might possibly throw off the adapter's intended travel geometry (or simply run out of "travel"), dependant on which adapter you use.

Fran

[edisonplayer]

I rarely use my Kent adapter to play laterals on my C-250.When I do,I make sure it's lined up properly.And,I use the feedscrew. as stated on the box which I have.edisonplayer

[fran604g]

Another consideration I will add:

The angle of the needle where it meets the groove of the record should be that as prescribed by the manufacturer of lateral machines (ie Victor, Columbia, etc.), meaning it should be held approximately at 45 degrees. If the DD Phonograph horn is in the "up" position, then the angle of the needle will be larger than 45 degrees, and approaching a right angle. I assume this means there will be a pronounced incidence for wear caused to the record.

By lowering the horn into the "play" position, the angle of the needle should be (more) correct.

Fran

[RAK402]

I had wondered about this too.

Are the number of grooves per inch on a 78 consistent?

Is this the same number as the Edison feed screw?

[fran604g]

I think you're referring to the "pitch" of the thread of the Edison feed mechanism; it is 150 T.P.I., except for the Long Playing models, which is 450 T.P.I. (but that's another story).

The pitch of the groove on the Edison DD records corresponds accurately to the feed mechanism. As for "78" lateral cut records; I don't know, but would assume that there wasn't necessarily a hard and fast rule for the pitch of the groove, simply because there was no need for it to coincide to a drive mechanism.

Fran

[winsleydale]

Lateral grooves were necessarily coarser to make room for the side-to-side undulations, so that loud passages won't form a locked groove. I think the pitch is around 70-90, somewhere in that range. Far coarser than an Edison disc, hence the Edison discs having a higher capacity.

[PeterF]

You have to set the lateral adapter a bit to the right of the horn throat as you start playing the record, and you will find it a bit to the left of the throat at the end of playing the record. The horn moves laterally at a slower rate than the grooves of the typical lateral record want, as described by Comrade Winkleygrail above.

So the tracking angle varies from optimal through the course of playing the record...but is certainly close enough for satisfactory and listenable results.

[VintageTechnologies]

Yes, the feedscrew should definitely be engaged. I have used a Fletcher adapter that way for at least 45 years. The adapters allow the head to swing through a large arc to compensate for the thread pitch of the 78 and the Edison machine being different.