Question on Columbia AT Cylinder Phonographs

[rhammond]

I have two Columbia AT cylinder phonographs. These are both early machines with the small floating reproducer, marked "Reproducer." One has the standard Columbia triuniion (sp) but the other has a high triunion (again, I apologize for the spelling). The difference between the two is that the high one has the reproducer playing the top of the record. My question is why did they have the high triunion? Is one supposed to be better than the other. The two machines appear to be identical otherwise.

[phonogfp]

Toward the end of 1902, American Graphophone discovered that if the reproducer was as nearly horizontal as possible while in playing position, the reproducer's weight was maximized and reproduction was louder. From that point, new models using a floating reproducers (such as the AO) were designed with a "drop frame," which meant the mandrel was placed low in the upper works. This allowed the reproducer to play in a near-horizontal position with a relatively short trunnion.

For some reason, the company did not redesign the AT's top casting into a "drop frame" (as was done with the Type C), but simply made the trunnion taller.

George P.

[Lucius1958]

For some reason, the company did not redesign the AT's top casting into a "drop frame" (as was done with the Type C), but simply made the trunnion taller.

George P.

Most likely it was far cheaper to change the trunnion on a cheaper model like the AT, than to redesign the whole casting.

Bill

[rhammond]

When I bought the one with the high tri, I had my choice of the smaller reproducer and the one that appears to be a little bigger, much like the reproductions. I choose the smaller one as I bought this machine to be able to play brown wax. Did I make the wrong choice in terms of the reproducer? If it plays louder, is it harder on the records? I have a collection of exceptionally nice brown wax so I want to be kind to them.

[phonogfp]

The high-trunnion AT was originally sold with a D type reproducer (the larger one). You are correct in surmising that increased weight = more wear, even though the differences are probably pretty minimal in the case of the high vs. low trunnion AT. There's something of a trade-off between higher volume (usually produced by increasing weight or using spring tension) and increased wear. The smaller floating reproducer set at an angle as in earlier Graphophones is probably the gentlest period arrangement.

The early gutta-percha reproducers are quite light, but they don't play as well as the aluminum versions.

George P.

[startgroove]

I'm a little confused. Given that the diaphragm diameter and all else is the same, I can't understand how a heavier reproducer would increase the volume. I have long believed the amount of groove swing (amplitude) was responsible for how much the diaphragm is moved back and forth, and therefore how much volume was produced.

I can see where a heavier reproducer can cause better tracking. Some of my early wax cylinders appear to have been recorded with wider groove swings, and I've experienced a sort of "skipping off the hilltops" with those. My temporary cure was to tape a dime onto the back of the reproducer, which solved that problem while playing that recording.

[phonogfp]

I'm a little confused. Given that the diaphragm diameter and all else is the same, I can't understand how a heavier reproducer would increase the volume.

The diaphragm diameter of a D is larger than that of an Eagle-type reproducer.

George P.

[startgroove]

What confused me are your statements above: "...the reproducer's weight was maximized and reproduction was louder" and "There's something of a trade-off between higher volume (usually produced by increasing weight or using spring tension)…”.

To my training and experience, larger diaphragms usually mean better compliance, making it easier for the stylus to "read" the data on a groove, or to reproduce the data more accurately. (An added benefit being that the stylus is gentler on the groove.) More weight can force compliance by preventing the stylus from skipping off the tops of the "hills", resulting in better clarity. A larger diaphragm could also increase the volume, mostly in the lower frequencies (if they are there to begin with), resulting in an apparent increase in volume. Yet, increasing the stylus pressure alone probably won't noticeably affect the volume output.

[phonogfp]

What confused me are your statements above: "...the reproducer's weight was maximized and reproduction was louder" and "There's something of a trade-off between higher volume (usually produced by increasing weight or using spring tension)…”.

To my training and experience, larger diaphragms usually mean better compliance, making it easier for the stylus to "read" the data on a groove, or to reproduce the data more accurately. (An added benefit being that the stylus is gentler on the groove.) More weight can force compliance by preventing the stylus from skipping off the tops of the "hills", resulting in better clarity. A larger diaphragm could also increase the volume, mostly in the lower frequencies (if they are there to begin with), resulting in an apparent increase in volume. Yet, increasing the stylus pressure alone probably won't noticeably affect the volume output.

There were various steps taken by the cylinder machine manufacturers to increase stylus pressure with the aim to increase volume. These steps included supplementary weights on Edison Automatic, Model B and Model C reproducers (even the early Model H reproducers had holes in their tailweights for supplementary weights to be added); supplementary weights on Graphophone floating reproducers, modifications to Edison Automatic reproducers by Mobley, Fletcher, Blackman, etc. which added weight (even Model C reproducers were modified by Mobley to increase stylus pressure); spring-tension Graphophone reproducers which were designed to increase stylus pressure without additional weights; gradually heavier weights designed for Edison Disc reproducers over the years (as well as spring tension devices) culminating in the "Dance" and "Edisonic" reproducers.

I'm not here to defend the principle or wisdom of the decisions made by the various companies; I can only cite them.

George P.

[Lucius1958]

What confused me are your statements above: "...the reproducer's weight was maximized and reproduction was louder" and "There's something of a trade-off between higher volume (usually produced by increasing weight or using spring tension)…”.

To my training and experience, larger diaphragms usually mean better compliance, making it easier for the stylus to "read" the data on a groove, or to reproduce the data more accurately. (An added benefit being that the stylus is gentler on the groove.) More weight can force compliance by preventing the stylus from skipping off the tops of the "hills", resulting in better clarity. A larger diaphragm could also increase the volume, mostly in the lower frequencies (if they are there to begin with), resulting in an apparent increase in volume. Yet, increasing the stylus pressure alone probably won't noticeably affect the volume output.

There were various steps taken by the cylinder machine manufacturers to increase stylus pressure with the aim to increase volume. These steps included supplementary weights on Edison Automatic, Model B and Model C reproducers (even the early Model H reproducers had holes in their tailweights for supplementary weights to be added); supplementary weights on Graphophone floating reproducers, modifications to Edison Automatic reproducers by Mobley, Fletcher, Blackman, etc. which added weight (even Model C reproducers were modified by Mobley to increase stylus pressure); spring-tension Graphophone reproducers which were designed to increase stylus pressure without additional weights; gradually heavier weights designed for Edison Disc reproducers over the years (as well as spring tension devices) culminating in the "Dance" and "Edisonic" reproducers.

I'm not here to defend the principle or wisdom of the decisions made by the various companies; I can only cite them.

George P.

Not to mention the last Edison cylinder reproducer, the Diamond D...

Bill