LP12

[Geoff.R.G]

Stu, I am not sure how having the motor isolated from the bearing and arm board is affecting the speed unless there is considerable movement between the two. With your stiffer suspension that shouldn't be the case, Linn didn't invent the suspended chassis and belt drive arrangement, the TD150 was using it in 1965, 8 years before the LP12, without any apparent speed problems (none reported that I recall). Speed fluctuations are more likely to be motor induced than as a result of the suspension, as you have it. Obviously if the chassis twists there will be speed fluctuations.

I am also fascinated by Richard's comment that "Belts are for trousers". This completely ignores the fact that for years belt drives were perfectly acceptable in tape machines where one might expect exactly the same problems as are, apparently, encountered with turntables, except that they would be magnified as they affect recording and playback differently.

I have already summarised the pros and cons of the different turntable drive systems, none is perfect.

Good points Geoff. Not having springs anymore means I will not have to suffer with the motor and belt making the subchassis move sideways.

People say that noisy ac motors can produce vibrations which can if you are not careful make their way to the stylus. That would be one good reason to isolate the motor if it really is that bad.

Speed fluctuations due to the power supply is also a concern. My lingo1 probably would benefit from the electrolytic caps being replaced, it is after all 35 years old. The Avondale Audio Taps2 psu (which I haven't tried yet) works on a very different principle- more like the Naim Armaggedon and Norton psu's.

Belts are for trousers Direct drive is seen as better for speed but it probably isn't as good with regards to isolating motor noise.

Geoff, what do you think to my idea with the sand ? Batshit crazy?

My point on belt drive was that speed stability is more important for tape than vinyl because if there is a point on the tape where the speed was low on recording there is no guarantee that the same fluctuation will occur on play back. Belt drive is the norm for tape machines and speed stability is rarely an issue with a good belt. If its OK for tape it is almost certainly OK for vinyl if, big if, the belt length is kept to a minimum. Essentially, the motor shaft is close to the sub platter, move the motor further away and there is more opportunity for the belt's characteristics to show. If there is a serious speed fluctuation with a belt drive the reason isn't the principle of belt drive but inappropriate choice/specification of belt.

Direct drive, without a heavy platter with a large radius of gyration, can suffer from cogging. I also wonder how many people let their turntable speed stabilise before playing a record, starting a heavy platter rotating is always going to result in slowing the motor and it will take a finite time for the a platter to reach a stable speed. This is true for all drive types but particularly so for a belt drive.

I can't see where you expect to put the sand. If you were going to load the sub chassis with sand to make it more inert and lower the centre of mass I can see there might be some advantage. There might also be some benefit to filling the plinth with sand but I would then question whether a solid plinth might be better.

[karatestu]

I can't see where you expect to put the sand. If you were going to load the sub chassis with sand to make it more inert and lower the centre of mass I can see there might be some advantage. There might also be some benefit to filling the plinth with sand but I would then question whether a solid plinth might be better.

It would involve the making of a box without a lid. Fill with sand nearly to the top. Make a new top plate which is just slightly smaller than the open top of the sand filled box. Attach motor, bearing and arm to top plate. There will be things sticking out under the top plate ie bottom of the motor, bearing and arm base. Push this top plate into the sand from above and level. Everything will be in contact with the sand - motor, bearing, arm base, top plate, enclosure.

[Geoff.R.G]

I can't see where you expect to put the sand. If you were going to load the sub chassis with sand to make it more inert and lower the centre of mass I can see there might be some advantage. There might also be some benefit to filling the plinth with sand but I would then question whether a solid plinth might be better.

It would involve the making of a box without a lid. Fill with sand nearly to the top. Make a new top plate which is just slightly smaller than the open top of the sand filled box. Attach motor, bearing and arm to top plate. There will be things sticking out under the top plate ie bottom of the motor, bearing and arm base. Push this top plate into the sand from above and level. Everything will be in contact with the sand - motor, bearing, arm base, top plate, enclosure.

Sand and bearings don’t mix! If you bury the motor in sand you reduce the cooling and a hot running motor can be noisy, which you don’t want.

You are also talking about a level of precision engineering that apprentices achieve by working at it every day for weeks on end. Not suggesting that you can’t do it, simply that it will be time consuming. I also reckon that a good solid top plate will very effectively transmit 100% of the motor vibration to the bearing and the arm. Idler drive turntables have the motor mounted on isolating grommets to reduce said transmission.

Personally I’d keep sand a long way from a turntable bearing, motor bearings and tone arms. If you want to experiment, get a cheap TD160 or similar from eBay and either keep the LP12 as a reference or sell it for a small fortune. If you wreck the LP12 you won’t be happy.

[Vinyl-ant]

Heres wot i did with my lp12. This was about 20 years ago. The top image is an lp12 lenco hybrid, look towards the bottom for the solid lp12 done in bbp and acrylic. There was another solid one before the bbp perspex one but i have no images of that anywhere. So that lp12 went through 4 iterations including its original form

https://bte-designs.weebly.com/turntable-projects.html

[karatestu]

I can't see where you expect to put the sand. If you were going to load the sub chassis with sand to make it more inert and lower the centre of mass I can see there might be some advantage. There might also be some benefit to filling the plinth with sand but I would then question whether a solid plinth might be better.

It would involve the making of a box without a lid. Fill with sand nearly to the top. Make a new top plate which is just slightly smaller than the open top of the sand filled box. Attach motor, bearing and arm to top plate. There will be things sticking out under the top plate ie bottom of the motor, bearing and arm base. Push this top plate into the sand from above and level. Everything will be in contact with the sand - motor, bearing, arm base, top plate, enclosure.

Sand and bearings don’t mix! If you bury the motor in sand you reduce the cooling and a hot running motor can be noisy, which you don’t want.

You are also talking about a level of precision engineering that apprentices achieve by working at it every day for weeks on end. Not suggesting that you can’t do it, simply that it will be time consuming. I also reckon that a good solid top plate will very effectively transmit 100% of the motor vibration to the bearing and the arm. Idler drive turntables have the motor mounted on isolating grommets to reduce said transmission.

Personally I’d keep sand a long way from a turntable bearing, motor bearings and tone arms. If you want to experiment, get a cheap TD160 or similar from eBay and either keep the LP12 as a reference or sell it for a small fortune. If you wreck the LP12 you won’t be happy.

Thanks for that Geoff. Motor cooling wasn't something I had thought about. Same with sand getting in bearings. Doh

[karatestu]

Heres wot i did with my lp12. This was about 20 years ago. The top image is an lp12 lenco hybrid, look towards the bottom for the solid lp12 done in bbp and acrylic. There was another solid one before the bbp perspex one but i have no images of that anywhere. So that lp12 went through 4 iterations including its original form

https://bte-designs.weebly.com/turntable-projects.html

Thanks Ant. Interesting.

[savvypaul]

Stu, I am not sure how having the motor isolated from the bearing and arm board is affecting the speed unless there is considerable movement between the two. With your stiffer suspension that shouldn't be the case, Linn didn't invent the suspended chassis and belt drive arrangement, the TD150 was using it in 1965, 8 years before the LP12, without any apparent speed problems (none reported that I recall). Speed fluctuations are more likely to be motor induced than as a result of the suspension, as you have it. Obviously if the chassis twists there will be speed fluctuations.

I am also fascinated by Richard's comment that "Belts are for trousers". This completely ignores the fact that for years belt drives were perfectly acceptable in tape machines where one might expect exactly the same problems as are, apparently, encountered with turntables, except that they would be magnified as they affect recording and playback differently.

I have already summarised the pros and cons of the different turntable drive systems, none is perfect.

Good points Geoff. Not having springs anymore means I will not have to suffer with the motor and belt making the subchassis move sideways.

People say that noisy ac motors can produce vibrations which can if you are not careful make their way to the stylus. That would be one good reason to isolate the motor if it really is that bad.

Speed fluctuations due to the power supply is also a concern. My lingo1 probably would benefit from the electrolytic caps being replaced, it is after all 35 years old. The Avondale Audio Taps2 psu (which I haven't tried yet) works on a very different principle- more like the Naim Armaggedon and Norton psu's.

Belts are for trousers Direct drive is seen as better for speed but it probably isn't as good with regards to isolating motor noise.

Geoff, what do you think to my idea with the sand ? Batshit crazy?

My point on belt drive was that speed stability is more important for tape than vinyl because if there is a point on the tape where the speed was low on recording there is no guarantee that the same fluctuation will occur on play back. Belt drive is the norm for tape machines and speed stability is rarely an issue with a good belt. If its OK for tape it is almost certainly OK for vinyl if, big if, the belt length is kept to a minimum. Essentially, the motor shaft is close to the sub platter, move the motor further away and there is more opportunity for the belt's characteristics to show. If there is a serious speed fluctuation with a belt drive the reason isn't the principle of belt drive but inappropriate choice/specification of belt.

Direct drive, without a heavy platter with a large radius of gyration, can suffer from cogging. I also wonder how many people let their turntable speed stabilise before playing a record, starting a heavy platter rotating is always going to result in slowing the motor and it will take a finite time for the a platter to reach a stable speed. This is true for all drive types but particularly so for a belt drive.

I can't see where you expect to put the sand. If you were going to load the sub chassis with sand to make it more inert and lower the centre of mass I can see there might be some advantage. There might also be some benefit to filling the plinth with sand but I would then question whether a solid plinth might be better.

My Garrard speeds up after around 20 minutes, then is stable, which I'm told is normal. Apparently mine is very good at 20 minutes - over 30 minutes is common. I now use the Longdog Audio quartz speed controller for my 401, but the above characteristic remains.

[Lindsayt]

Operation Rubikon was a scam whereby nobbled crypto machines were sold worldwide under the pretence that they provided state of the art message encryption. The reality was that the machines gave the impression that they were working fine, but any communication sent by them could be cracked easily enough with primitive computers. With the CIA being in on this fiddle.

https://en.wikipedia.org/wiki/Operation_Rubicon
https://www.youtube.com/watch?v=IxPp604NFwU

Are we supposed to think that Audioflat naming their assembly of flat metal plates the Rubikon is just a coincidence?

[Geoff.R.G]

Turntables, need to stabilise before playing a record in the same way that an oven needs to stabilise before cooking, I believe three cycles are the recommended warm-up. The stabilisation time for a turntable will obviously depend on the mass and radius of gyration of the platter.

[Lindsayt]

Turntables, need to stabilise before playing a record in the same way that an oven needs to stabilise before cooking, I believe three cycles are the recommended warm-up. The stabilisation time for a turntable will obviously depend on the mass and radius of gyration of the platter.

The stabilisation time for my EMT 950 is 0.2 seconds. Thanks to the Hall Effect direct drive motor and feedback system. It has a relatively low mass platter, because that's what EMT found sounded best.