Pathé Postcard

[epigramophone]

Email on it's way Graham.

Roger.

[emgcr]

Many thanks Roger.

I paid a visit to Ian Maxted in London yesterday who was his usual extremely helpful and generous self. We managed to find three suitable new governor springs in his amazing stock of such things and then proceeded to borrow the back bracket and "onion" horn connector with tonearm/soundbox from his fine machine. This is the result :

https://www.youtube.com/watch?v=xU0gv_bylT8

This was an initial "workshop" try-out and obviously the whole mechanism needs to be restored but it was good to see everything vaguely in working order and instructive to hear what sort of sound this rusty horn makes. The latter should look rather attractive I hope when painted---the rim has impressed peacock feathers.

The motor, in spite of very worn bearings and sharp pinion teeth, ran pretty quietly and fairly constantly on pitch---except at the end of this 50cm (slightly under 20 inch) centre-start record. Why on earth Pathé decided upon centre-start I shall never know---French I suppose ! The digital strobe showed an easy and consistent 120 rpm. One interesting comparison with Ian's machine was in relation to one of the intermediate driving gear diameters. My motor has been drilled for two alternative positions so that a smaller or larger wheel could be used. His only has a drilling for the larger wheel. This is all rather strange as, in both cases, the speed quadrant is identical with similar calibration---90 to 135 rpm. The number of my machine is 854---much earlier than Ian's at 2284 so it would seem that some development was taking place when mine was built---possibly around 1907 ? The only good reason for the option I can think of at present is that, by varying the diameters, torque is changed which, in turn, may have an effect on playing time. Certainly the torque on mine was good although I was unable to test Ian's as his mainspring has broken. I seemed to have to wind the spring on mine regularly and this may be the "trade-off".

Unfortunately, the back bracket I had intended buying from Ian turned out to be from a smaller model thus the job is now to cast a new one in iron and make a copy "onion". I have the tonearm and soundbox. I am currently investigating the possibilities of 3D printing which might be too expensive at present (especially in metal) but we shall see. If anyone is also in need of these parts please do get in touch as economies of scale would assist greatly.

[epigramophone]

Various reasons have been put forward to explain Pathé's use of centre start for their early disc records.

Centrifugal force tends to throw the soundbox outwards, so centre start offers less resistance to the stylus. Because Pathé grooves are shallow, the stylus is in danger of being thrown out of the groove at peak volume. Peak volume usually occurs towards the end of the record, which on a centre start is nearing the edge where the grooves are less crowded.

Whatever the merits of centre start, Pathé abandoned it in about 1915 when etched labelling gave way to paper. Having said that, I have a few "crossover" discs which are centre start but with paper labels. That's Pathé for you!

[CarlosV]

Whatever the merits of centre start, Pathé abandoned it in about 1915 when etched labelling gave way to paper. Having said that, I have a few "crossover" discs which are centre start but with paper labels. That's Pathé for you!

The Pathé 50-cm discs made for German market had black paper labels, and started from the center, I have a couple of them. As to center start, some radio transcription records produced in the 40's also started at the center - these were 16 inch vinyl records. The centrifugal acceleration explanation certainly does not apply for these, they were 33 rpm records.

As to Pathé's reasons for designing such center start technique, my guess is that it was for patent infringement protection, and not for any purportedly technical reason, since when the design changed to outer start the discs and machines followed exactly the same techniques, with no detriment to the tracking.There is no documentation to support or contradict any theory about this, anyway.

[emgcr]

Here is a rather attractive and informative Italian contemporary advertisement.

Click on image to enlarge.

[Orchorsol]

As to center start, some radio transcription records produced in the 40's also started at the center - these were 16 inch vinyl records. The centrifugal acceleration explanation certainly does not apply for these, they were 33 rpm records.

At least some 16" transcription records, where a sequence of sides comprised a programme, alternated between centre start and outside start from one side to the next - so that the listener wouldn't notice the difference in treble response between the inside and outside of the disc (due to the wide difference in linear speed).

Centrifugal force (which physicists will tell you doesn't exist per se) wouldn't apply to the tonearm, only to objects actually travelling on the record. On the contrary, forces on the needle act towards the centre of the turtable, hence e.g. the need for bias or anti-skate force with later turntables, and unfortunately the dreaded needle run damage on some of our favourite 78s!

Good luck with the restoration Graham - great stuff! I'm sure you'll keep us posted.