tonearm weight?

[contessa]

I am wondering of how much would gramophone tonearms weight, without their soundbox.

The lesser the weight, it would be preferred, as stress put on record walls shall be smaller.

I am curious how manufacturers have dealt with this problem.

I would appreciate if any information could be shared.

[Daithi]

A lot would depend on how the tonearm weight is distributed. Since the pivot end is usually larger in diameter than the soundbox, and is normally heavier, some of the weight is supported by the pivot bearing. Many tonearms break in the middle so that only the part of the tonearm attached to the soundbox, outward of the break, is bearing on the record.
The effect of inertia is a factor regarding the overall mass of the tonearm. Sticktion is also an issue however the vibration generated by the sound itself tends to minimize that.

[contessa]

A lot would depend on how the tonearm weight is distributed. Since the pivot end is usually larger in diameter than the soundbox, and is normally heavier, some of the weight is supported by the pivot bearing. Many tonearms break in the middle so that only the part of the tonearm attached to the soundbox, outward of the break, is bearing on the record.
The effect of inertia is a factor regarding the overall mass of the tonearm. Sticktion is also an issue however the vibration generated by the sound itself tends to minimize that.

To make my statements more clear..

As there is no feedscrew mechanism on disc shaped records, the entire tonearm and soundbox will be guided by the record wall.

As the needle tracks the record, it is the mass of the entire sounbox-tonearm mechanism, even encluding the slightest friction caused by the bearing in its base, the record wall should solely bear. Therefore, it is not a matter of distribution.

Please correct me if I am wrong...

[marcapra]

How did phonograph engineers deal with this in the past? By the early 30s, Victor was making the back end of the tonearm a heavy counterweight. If you take the pickup off of the tonearm, the tonearm will lift up and the heavy counter weight will go down. I've also seen a spring put on the back of a 1929 Radiola tonearm to make it take pressure off of the pickup. In the case of an Edison disc phonograph, the tonearm is fully supported by the horn and neck. Only the bottom weight of the reproducer is putting weight on the record groove.

[contessa]

How did phonograph engineers deal with this in the past? By the early 30s, Victor was making the back end of the tonearm a heavy counterweight. If you take the pickup off of the tonearm, the tonearm will lift up and the heavy counter weight will go down. I've also seen a spring put on the back of a 1929 Radiola tonearm to make it take pressure off of the pickup. In the case of an Edison disc phonograph, the tonearm is fully supported by the horn and neck. Only the bottom weight of the reproducer is putting weight on the record groove.

Thanks for your reply.

However, as I have mentioned, I am concered about the force put on record 'walls' instead of record 'grooves'.

The added counter weight would decrease the latter, but increase the former even more.

[epigramophone]

The finest acoustic gramophones, made in the UK by EMG and Expert, had their tonearms mounted on top quality bearings.
With the soundbox on my Expert in the raised position, I can blow on it and make the tonearm move.

As for weight adjusters, my Micro-Perophone Chromogram has this simple and elegant arrangement :

[emgcr]

The Brunswick Ultona reproducer with double head capable of playing lateral-cut, Edison and Pathé vertical-cut records complete with in-built counterweight was one of the cleverest designs I have come across :

https://www.nipperhead.com/old/brult.htm

[CarlosV]

Thanks for your reply.

However, as I have mentioned, I am concered about the force put on record 'walls' instead of record 'grooves'.

The added counter weight would decrease the latter, but increase the former even more.

You are correct, Contessa. A gramophone head should not be too light, as it will reduce the quality of reproduction and increase wear. The definition of the optimum weigth is always specific to the type of record being played, the type of needle (steel or thorn) and the mechanical properties of the soundbox and tonearm. It is a trial-and-error process for each gramophone.

[Daithi]

The effect of inertia is a factor regarding the overall mass of the tonearm.

To make my statements more clear..

As the needle tracks the record, it is the mass of the entire sounbox-tonearm mechanism, even encluding the slightest friction caused by the bearing in its base, the record wall should solely bear. Therefore, it is not a matter of distribution.

Please correct me if I am wrong...

I addressed your concern with the following sentence which you appear to have missed. "The effect of inertia is a factor regarding the overall mass of the tonearm."

[contessa]

Nice counterweight mechanism guys. And also thanks for confirming my thesis.

Now I have concluded that the mass of the tonearm module should be minimised in order to reduce record wall wear, while retaining adequate mass for controlling vibration and other factors... (Tracking weight should also be considered of course.)

By collecting data on various weights of tonearms, I assume that it would be possible to get closer to the sweetspot of tonearm mass their designers would have settled with!