LP12 Bounce Measurement

[Spannko]

An important aspect of LP12 setup is the quality of the bounce and it’s only just occurred to me that it may be possible to create a 3D picture of the motion of the suspended elements using the accelerometer built into modern smartphones. Some apps allow a record to be kept, allowing comparisons of before and after adjustment.

I’ve got a suspicion that an accelerometer could reveal problems not visible to the human eye, such as a loss of pistonic motion at the very end of the bounce. How about not measuring the bounce, and just measuring the turntables response to shock? Eg building a jig to allow a weight to be dropped a fixed height and measuring the response. A similar jig could be made to generate a lateral shock. The accelerometer would show the micro movements and I’m sure that any natural resonance which deviates from perfect vertical motion would generate a suboptimal output from the cartridge.

Anyone prepared to get an accelerometer app and feed back your findings?

[John]

I would think the weight of the iPhone on the platter would throw off the level of the platter much different from the weight of a record and have an adverse effect on the bounce.

Here’s something to strive for.

https://youtu.be/43_lQvVI13k

[Spannko]

Maybe, maybe not! Only by trying will we really know 😉

The video you link to certainly looks impressive, but in all honesty, I’ve never seen an LP12 bounce like that when playing a record. The spring movement when transducing vibrations into heat is imperceptible, so how do we know for sure that the suspension mechanism isn’t subject to stiction?

The iPhone suggestion was for a quick test of the idea. If it works, 20g sensors are available for £€$30-35 which work with a smartphone.

[sktn77a]

I think that would be a great idea to get accelerometer measurements to help diagnose "bounce" problems.
I'm not sure stiction would come into the equation with springs (unless the springs were sticking to the grommets).

[pdcman]

I would think the weight of the iPhone on the platter would throw off the level of the platter much different from the weight of a record and have an adverse effect on the bounce.

Here’s something to strive for.

https://youtu.be/43_lQvVI13k

Theres a video that follows yours by Linn Kasa, trying to tune a MLP12. She has no idea what she's doing. :)

[John]

I would think the weight of the iPhone on the platter would throw off the level of the platter much different from the weight of a record and have an adverse effect on the bounce.

Here’s something to strive for.

https://youtu.be/43_lQvVI13k

Theres a video that follows yours by Linn Kasa, trying to tune a MLP12. She has no idea what she's doing. :)

I took me some time to get mine dialed in. Something I really don’t look forward to doing. It’s nice to pick up ideas from others who do it more often. It was hard to tell in that video what she was doing with the springs. She didn’t mention anything about turning the top grommet and spring together. It was at least nice to see her releasing tension on the spring.