For all you idler fans, this a link to an article that you might find interesting. https://korfaudio.com/blog94
It would be interesting to see what VA makes of it as he our idler guru
Idler TT blog
-
NSNO2021
- Posts: 1010
- Joined: Thu Jul 04, 2019 1:06 pm
- Location: Industrial waste lands of the north west
- Has thanked: 559 times
- Been thanked: 488 times
Idler TT blog
Modified Airlink BPS 3110S with LDA DC filter
TTs, Kenwood KD 8030 with AT OC9XSH, Opera Consonance Wax Engine mk2 with modified Apheta 2 MC cart, PT TOO awaiting restoration.
LDA MCJ3 phono,Schiit Freya plus pre amp, NAD M23, Audiolab 9000 CD transport, Denafrips Pontus 2 DAC, Mano Ultra2 streamer, Cisco switch, Audio Technica ATH 70 cans, Serhan Swift Mu2 mk2 speakers & NSNO W48.5 speaker cables
TTs, Kenwood KD 8030 with AT OC9XSH, Opera Consonance Wax Engine mk2 with modified Apheta 2 MC cart, PT TOO awaiting restoration.
LDA MCJ3 phono,Schiit Freya plus pre amp, NAD M23, Audiolab 9000 CD transport, Denafrips Pontus 2 DAC, Mano Ultra2 streamer, Cisco switch, Audio Technica ATH 70 cans, Serhan Swift Mu2 mk2 speakers & NSNO W48.5 speaker cables
-
Geoff.R.G
- Posts: 1569
- Joined: Thu Aug 11, 2016 2:46 pm
- Location: Denham UK
- Has thanked: 133 times
- Been thanked: 483 times
Re: Idler TT blog
Shall we ignore the glaring error in the text? Lenco style drives do put a side load on the main bearing, pushing upwards on one side has exactly the same effect as pushing the platter rim sideways.
-
Vinyl-ant
- Posts: 766
- Joined: Sat Jul 01, 2017 12:51 pm
- Location: South yorkshire
- Has thanked: 1 time
- Been thanked: 364 times
- Contact:
Re: Idler TT blog
Im not going to contradict any of that
I would argue that no bearing is under purely a side load when it is being driven, as the drivetrain introduces a tipping force into it, whatever manner you care to drive it. The side load is in the opposite directions at the top and bottom of the bearing shaft because you are pushing or pulli g at one end of the bearing shaft only. As the lenco upwards force pushes the top of the bearing towards the arm it correspondingly puts sideways pressure on the bottom of the bearing shaft towards the motor. The garrard drive puts a side load into the top and a corresponding opposite load into the bottom. A belt pulls the platter towards it at the top so induces side load at the top and opposite side load at the bottom. It is just the lenco puts the side load at the top of the bearing in adifferent direction to the garrard and belt drive. With any bearing there will be a tipping force if the motive force is applied anywhere but the centre point of the shaft, and that the enture assembly is weight balanced above and below the drive centre. Then it will only be subject to a side load. Even when it is not being driven, the weight distribution of the shaft and platter means that because the platter, which is the heavy bit, is above the bearing sleeve or bushing is always inder a tipping load. The only drivetrain that doesnt induce a side load in the bearing is a direct drive, that is more of a very subtle lobing force as the rotor chases the stator pulse. But it still has its own tipping load because the weight is above the bearing sleeve or bush.
Its the degree of load that is there, not the fact that the load is there that is the important part..
A garrard induces left/right oscillations, a belt does the same, a lenco induces up/down oscillations. Thus it affects the cart in a different manner as vertical compliance is always different to horizontal compliance a dd induces rotary oscillations if you can call it that where you get minute speed variations as the drive passes from one coil to the next. As dd motors run so much slower than clock motors or idler motors the frequency of these oscillations is lower too. An ac motor will have a blend of 100hz and mechanical noise, a dc dd motor will have mechanical and 33 or 45hz.
The crux is how all the noise is dealt with by the entire assembly and plinth structure. Is is far too simplistic to just take the motor drive into account
I would argue that no bearing is under purely a side load when it is being driven, as the drivetrain introduces a tipping force into it, whatever manner you care to drive it. The side load is in the opposite directions at the top and bottom of the bearing shaft because you are pushing or pulli g at one end of the bearing shaft only. As the lenco upwards force pushes the top of the bearing towards the arm it correspondingly puts sideways pressure on the bottom of the bearing shaft towards the motor. The garrard drive puts a side load into the top and a corresponding opposite load into the bottom. A belt pulls the platter towards it at the top so induces side load at the top and opposite side load at the bottom. It is just the lenco puts the side load at the top of the bearing in adifferent direction to the garrard and belt drive. With any bearing there will be a tipping force if the motive force is applied anywhere but the centre point of the shaft, and that the enture assembly is weight balanced above and below the drive centre. Then it will only be subject to a side load. Even when it is not being driven, the weight distribution of the shaft and platter means that because the platter, which is the heavy bit, is above the bearing sleeve or bushing is always inder a tipping load. The only drivetrain that doesnt induce a side load in the bearing is a direct drive, that is more of a very subtle lobing force as the rotor chases the stator pulse. But it still has its own tipping load because the weight is above the bearing sleeve or bush.
Its the degree of load that is there, not the fact that the load is there that is the important part..
A garrard induces left/right oscillations, a belt does the same, a lenco induces up/down oscillations. Thus it affects the cart in a different manner as vertical compliance is always different to horizontal compliance a dd induces rotary oscillations if you can call it that where you get minute speed variations as the drive passes from one coil to the next. As dd motors run so much slower than clock motors or idler motors the frequency of these oscillations is lower too. An ac motor will have a blend of 100hz and mechanical noise, a dc dd motor will have mechanical and 33 or 45hz.
The crux is how all the noise is dealt with by the entire assembly and plinth structure. Is is far too simplistic to just take the motor drive into account
- These users thanked the author Vinyl-ant for the post:
- thebhoyricky (Wed Sep 14, 2022 8:31 pm)
Analogue: oracle delphi sme 309, jbe series 3 cx unipivot dv20x2l, roksan xerxes tabriz vm750, jvc ql-y5f rigb at440, jvc ql-y3f vm750, lenco 75, technics sl150
Phono stages: cole lcr, benedict audio hothead
Digital: cyrus cd7, wiim mini x2, topping e30, jds labs el dac 2+
Amplification: nelson pass b1, nelson pass f5
Speakers: 15" fane aperiodic wardrobes
Cans: myryad z40, hifiman sundara + deva, fostex t50rp, sennheiser momentum on ear +over ear, b&w p5 and p7
Phono stages: cole lcr, benedict audio hothead
Digital: cyrus cd7, wiim mini x2, topping e30, jds labs el dac 2+
Amplification: nelson pass b1, nelson pass f5
Speakers: 15" fane aperiodic wardrobes
Cans: myryad z40, hifiman sundara + deva, fostex t50rp, sennheiser momentum on ear +over ear, b&w p5 and p7
-
Geoff.R.G
- Posts: 1569
- Joined: Thu Aug 11, 2016 2:46 pm
- Location: Denham UK
- Has thanked: 133 times
- Been thanked: 483 times
Re: Idler TT blog
It is worth remembering that the problems with drive stability are shared by all turntables, and indeed tape machines. It is the way the basic problem, there is no motor that doesn’t suffer some degree of irregularity in rotation, is handled that differs. The nearest to a completely smooth drive is the old wind up gramophone.
Belts are simple enough but getting one to perform properly isn’t and the actual belt deteriorates relatively quickly. Idlers are equally simple, the difficulties are just different and, unlike a belt, the idler can be damaged by not disengaging it when switching off.
Direct drive is less simple to design but doesn’t suffer the problems associated with coupling the motor to the platter.
The choice therefore is which set of compromises do you prefer, or put another way, which do you think sounds better? Korf Audio’s comments on bearing wear, excluding the erroneous one relating to Lenco, are relevant only over an extended period, one could equally lament the wear on arm bearings. The loads on bearings in turntables are very light and that is itself a potential problem.
I found the most interesting thing on the site was the arm cartridge matching articles. None the less they didn’t go so far as to consider what effect their conclusions had on the sound.
Belts are simple enough but getting one to perform properly isn’t and the actual belt deteriorates relatively quickly. Idlers are equally simple, the difficulties are just different and, unlike a belt, the idler can be damaged by not disengaging it when switching off.
Direct drive is less simple to design but doesn’t suffer the problems associated with coupling the motor to the platter.
The choice therefore is which set of compromises do you prefer, or put another way, which do you think sounds better? Korf Audio’s comments on bearing wear, excluding the erroneous one relating to Lenco, are relevant only over an extended period, one could equally lament the wear on arm bearings. The loads on bearings in turntables are very light and that is itself a potential problem.
I found the most interesting thing on the site was the arm cartridge matching articles. None the less they didn’t go so far as to consider what effect their conclusions had on the sound.