Noticed this similar report on AK -
Platter RPM measurement app for android - AudioKarma.org Home Audio Stereo Discussion Forums
Building a Plinth for Lenco L75
- Thread starter jls001
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Noticed this similar report on AK -
Platter RPM measurement app for android - AudioKarma.org Home Audio Stereo Discussion Forums
For the intrepid lencophile, here's another not too tough DIY: magnetically levitated bearing.
If you use an acrylic mat (or have it lying somewhere), and a record center weight, try this tweak of using a layer of bubble wrap cut to the size of the mat, placed between the acrylic mat and the platter. Use a record weight (or an universal record stabilser ring) to flatten the bubble wrap. It is important that the mat is rigid. Rubber or felt will not do.
Link: http://www.lencoheaven.net/forum/index.php?topic=18357.0
Pls post your impression.
Link: http://www.lencoheaven.net/forum/index.php?topic=18357.0
Pls post your impression.
I have put off servicing the Lenco motor for too long, partly due to fear on my part that I may mess it up. I have read and re-read the very detailed instructions on how to do it at Lenco Heaven, knowing that I'll do it. Someday.
Just yesterday, I had made a temporary support for the bearing by stacking a couple of concrete blocks and a wood block, with a wood shim. This provides additional support to the bearing which bears the weight of the platter. I had been meaning to do this for even longer, since I use stacked platters and the bearing has to take about double the regular load. While not epiphanous, it certainly helped to focus the sound better. Encouraged, I decided to take apart the motor and clean and relube it.
For those interested, LH's Lencopedia section has detailed instructions. I followed them almost to the T, except for mixing a drop of oil to the grease (which I forgot to do). On opening the two ends of the motor, I was greeted by 40+ years of brown grease. I used tissue paper to scrape off all grease and followed it with a wipe of tissue wet in lighter fluid. All the bearing parts - bronze bushes, chamfered nuts, springs, circlips and adjustment screws were cleaned with lighter fluid (Zippo, about Rs 150 IiRC).
While putting it back together, the tricky part is inserting the circlip lock. Once you get that right, follow the motor tuning steps carefully. Without tightening the lock nut, adjust the adjustment screw for the lowest noise. Place your ears very close to the motor to listen for the changes in the motor noise as you turn the screw slowly. You will come to a point where the motor noise is the least. This is the most significant step in the servicing the motor. In fact this adjustment can be done even without relubing, but it is good to clean and lube the motor as it is a vintage TT.
The result? Is nothing less than an epiphany. It is the single most important thing you can do to improve your Lenco. A quieter motor results in significant upgrade in resolution, and dehomogenisation of the sound resulting in much better separation of voices and instruments. But the best outcome of this exercise is a very significantly improved bass texture, weight and overall slam.
If you own a Lenco and haven't done it, this is a MUST do.
Lenco Heaven instruction page here:
http://www.lencoheaven.net/forum/index.php?topic=2087.0
Just yesterday, I had made a temporary support for the bearing by stacking a couple of concrete blocks and a wood block, with a wood shim. This provides additional support to the bearing which bears the weight of the platter. I had been meaning to do this for even longer, since I use stacked platters and the bearing has to take about double the regular load. While not epiphanous, it certainly helped to focus the sound better. Encouraged, I decided to take apart the motor and clean and relube it.
For those interested, LH's Lencopedia section has detailed instructions. I followed them almost to the T, except for mixing a drop of oil to the grease (which I forgot to do). On opening the two ends of the motor, I was greeted by 40+ years of brown grease. I used tissue paper to scrape off all grease and followed it with a wipe of tissue wet in lighter fluid. All the bearing parts - bronze bushes, chamfered nuts, springs, circlips and adjustment screws were cleaned with lighter fluid (Zippo, about Rs 150 IiRC).
While putting it back together, the tricky part is inserting the circlip lock. Once you get that right, follow the motor tuning steps carefully. Without tightening the lock nut, adjust the adjustment screw for the lowest noise. Place your ears very close to the motor to listen for the changes in the motor noise as you turn the screw slowly. You will come to a point where the motor noise is the least. This is the most significant step in the servicing the motor. In fact this adjustment can be done even without relubing, but it is good to clean and lube the motor as it is a vintage TT.
The result? Is nothing less than an epiphany. It is the single most important thing you can do to improve your Lenco. A quieter motor results in significant upgrade in resolution, and dehomogenisation of the sound resulting in much better separation of voices and instruments. But the best outcome of this exercise is a very significantly improved bass texture, weight and overall slam.
If you own a Lenco and haven't done it, this is a MUST do.
Lenco Heaven instruction page here:
http://www.lencoheaven.net/forum/index.php?topic=2087.0
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Moving on to building a new plinth for the L75, I have stripped it completely with the intention of retaining only the pan of the top plate and cutting away the rest since I don't use the stock arm hole. I sort of developed cold feet and decided to first try reinforcing the top plate.
I'm using MDF sheet for now to check correct cutout size and thickness. Most likely I'll use teak wood for the final filler. Getting the thickness of the filler exactly correct is very important here, as it must form a solid layer that must firmly be wedged between the bottom of the top plate and the top layer of the plinth. I measured 6.5 mm but even 7 mm will do, though that will leave a slight gap between top plate edge and plinth, but I think it's safer to err on the side of caution so that rigid mating is ensured which will hopefully stop the top plate from any more flexing. This is the one well-known Achilles Heel of the Lenco.
I haven't decided on material mix for the plinth. Current thinking is to use a mix of wood layers and may be some form of stone as per availability, but the choices are still flexible. Most likely I'll avoid MDF as the received wisdom is that it tends to deadens the sound a bit too much.
I'm using MDF sheet for now to check correct cutout size and thickness. Most likely I'll use teak wood for the final filler. Getting the thickness of the filler exactly correct is very important here, as it must form a solid layer that must firmly be wedged between the bottom of the top plate and the top layer of the plinth. I measured 6.5 mm but even 7 mm will do, though that will leave a slight gap between top plate edge and plinth, but I think it's safer to err on the side of caution so that rigid mating is ensured which will hopefully stop the top plate from any more flexing. This is the one well-known Achilles Heel of the Lenco.
I haven't decided on material mix for the plinth. Current thinking is to use a mix of wood layers and may be some form of stone as per availability, but the choices are still flexible. Most likely I'll avoid MDF as the received wisdom is that it tends to deadens the sound a bit too much.
Joshua, try damping the underside with Bitumen sheets. you can also do that to the bottom of the circular plate below and then screw them in (yes some cutouts will need to be made)
I bought this foam and plan to use that whenever i get to my Part Deaux
Try using the formula i had copied form the audiogon thread before it got deleted
I bought this foam and plan to use that whenever i get to my Part Deaux
Try using the formula i had copied form the audiogon thread before it got deleted
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@arj, I'm following the current gospel about mating top plate to plinth, namely, direct top plate metal to plinth contact, without any sort of damping layer in between the two.
Regarding damping the hollow portion of the top plate, I thought long and hard. My initial thought was to place a number of wooden biscuit-shaped pieces at strategic locations, but then I thought full coverage would strengthen the top plate much more.
Regarding the bottom of the pan, it is also similarly mated directly to layer 2 of the plinth. And screwed down liberally. I think it's effective. When using your method of feeling the vibration using screw driver bitten with teeth, I can feel a strong vibe when touching the motor chassis, but absolute zero vibe when feeling the pan, even nearest to motor.
Regarding damping the hollow portion of the top plate, I thought long and hard. My initial thought was to place a number of wooden biscuit-shaped pieces at strategic locations, but then I thought full coverage would strengthen the top plate much more.
Regarding the bottom of the pan, it is also similarly mated directly to layer 2 of the plinth. And screwed down liberally. I think it's effective. When using your method of feeling the vibration using screw driver bitten with teeth, I can feel a strong vibe when touching the motor chassis, but absolute zero vibe when feeling the pan, even nearest to motor.
Thats exactly how mine is setup now ie top plate screwed on to the birchply plinth beneath it.
For the circular section I somehow feel the bitumen sheet will only help as it is very thin and one can still bolt it in. But with any thicker foam it might be better to avoid that area. and you are right about the screwdriver experiment..it works the same way for me as well
For the hollow portion better to use a good damping agent than MDF even cork with a good adhesive would be good else just go ahead and Blu tac it
With MDF the bond between the wood and the plate migh just have a big impact than the MDF itself
BTW thanks for reminding on the motor. i need to do that as well !!!
For the circular section I somehow feel the bitumen sheet will only help as it is very thin and one can still bolt it in. But with any thicker foam it might be better to avoid that area. and you are right about the screwdriver experiment..it works the same way for me as well
For the hollow portion better to use a good damping agent than MDF even cork with a good adhesive would be good else just go ahead and Blu tac it
With MDF the bond between the wood and the plate migh just have a big impact than the MDF itself
BTW thanks for reminding on the motor. i need to do that as well !!!
Yes, please do this ASAP. In terms of sonic benefits, it has been the single most important thing I have done.
I have a slightly different take on this, though I don't know how it will eventually pan out in practice, but here's my thought - the top plate being thin, it is prone to micro flexes. If one were to RIGIDLY couple the top plate with a filler that will fill the void below the top plate, especially using a two-part epoxy glue that will harden and become rigid when it sets, it will help to substantially increase the rigidity of the top plate, perhaps taking it closer to the level of a Garrard 401 top plate, which is known to be one of the most rigid top plates around.
To stretch the rigidity thing even further, I am guessing an aluminium sheet would provide greater rigidity than any wood or MDF or acrylic of the same thickness. But I will have to check whether the local laser cutters will be able to cut 6 to 7 mm thick aluminium.
Once we have a flex-free top plate, we can then play around with damping layer somewhere below the filler layer. In fact a thought just occurred to me - a silicone sheet below the filler layer would make the structure a genuine CLD!
Do you think this line of thinking has some merit?
Only one way to find out 
Maybe you are onto something good.
I somehow felt the best way might be to elminate top plate altogether.
the Folks who have completely done away with the top pate have generally been happy.
One design i liked was the base plate cut all along the circular base except for a triangular section keeping the On/Off/Engage Knob such the it overall looks like a tear drop. if the topmost layer of the plinth is cut int eh same shape then this can be mounted flush (leaving space for the speed adjustment mechanism as well.
I still have my PTP5 and am still not sure if i go that way or retaining the current plate !!
Maybe you are onto something good. I somehow felt the best way might be to elminate top plate altogether.
the Folks who have completely done away with the top pate have generally been happy.
One design i liked was the base plate cut all along the circular base except for a triangular section keeping the On/Off/Engage Knob such the it overall looks like a tear drop. if the topmost layer of the plinth is cut int eh same shape then this can be mounted flush (leaving space for the speed adjustment mechanism as well.
I still have my PTP5 and am still not sure if i go that way or retaining the current plate !!
Here's how DIY your own thrust plate for your Lenco's platter bearing using something you can easily buy from any music shop - guitar pick. Most good picks are made of Delrin, a modern plastic commonly used in this application. Here's what I used:
Here's my thrust plate - Stainless Steel bottom without any plastic pad. I thought I'll give plastic a try:
Find a circular coin that's approximately the size of the cutout you want to make. Luckily, a Malaysian 10 cent coin does the trick for me.
Use a marker pen to mark the pick:
Here's my thrust plate - Stainless Steel bottom without any plastic pad. I thought I'll give plastic a try:
Find a circular coin that's approximately the size of the cutout you want to make. Luckily, a Malaysian 10 cent coin does the trick for me.
Use a marker pen to mark the pick:
Lots of small and big changes made to the Lenco L75 over the years of ownership have contributed to improving the sound of the Lenco. Just for info of other owners who may want to go down a similar path of tweaking:
1) the stock box plinth is the biggest enemy of the Lenco. When used with the stock plinth, the L75 rumbles. Throw it away, and make yourself a multilayered plinth. What the powerful motor needs is some mass to drain off the vibration away from the top plate. As far as material choices go, you can't really go wrong with plywood. Use gapless plywood. I have not used it myself but shopkeepers told me that 'Garjan' plywood is the best available (from gapless point of view). Lots of builders have also used a mix of MDF and plywood. One can also use exotic materials like Corian, aluminium, slate stone, hard wood, or panzerholz (provided one can source it without too much effort, and also - more importantly - get it cut to appropriate shape and size). Birch or Beechwood plywood are also very good, though difficult to source locally. Whatever shape and size and material you choose to use for the plinth, make sure the pan of the top plate is supported firmly by the plinth layer below it. The top plate of the Lenco is thin and needs all the support it can get. This is a critical point to adhere to, IMO.
2) the bearing needs thorough clean up and re-oiling and greasing. Soft cloth or tissue paper dipped in naptha (lighter gas) makes for an excellent cleaning agent. Just take care to do this away from naked flame as lighter fluid is highly flammable. My personal formula for lubricating the bearing is to dab some lithium grease at the bottom of the spindle where the bearing ball meets the thrust plate, and to use 5W30 synthetic engine oil for the rest of the bearing. Add some amount of this oil to the grease at the bottom. If using stock bearing, don't use grease anywhere near where it can come in contact with the bronze bushing. If grease enters the pore of the bronze bushing, it can clog the pores and prevent oil from seeping in and out of the pores. It can lead to dryness where lubrication is most needed. The pores in the bronze bushing is meant to be an oil reservoir to facilitate constant lubrication. Further, in my experience, sewing machine oil is too thin for use as bearing oil. The high torque motor works best when it works against friction, so thicker oil like 5W30 is better. If you can source it, single grade compressor oil are supposedly even better.
3) Clean and oil the motor and tune it for quietest operation. This is another critical servicing. A quiet motor lowers overall noise floor, bringing out more detail and nuances from your player.
Other good to do processes:
1) use a better tonearm
2) use the best cartridge you can afford to use
3) use the best phono stage you can afford to use
4) use filler below hollow top plate. Instructions given some posts back on this thread
5) use better thrust plate for the bearing
6) replace bearing ball with new one (5 mm diameter).
1) the stock box plinth is the biggest enemy of the Lenco. When used with the stock plinth, the L75 rumbles. Throw it away, and make yourself a multilayered plinth. What the powerful motor needs is some mass to drain off the vibration away from the top plate. As far as material choices go, you can't really go wrong with plywood. Use gapless plywood. I have not used it myself but shopkeepers told me that 'Garjan' plywood is the best available (from gapless point of view). Lots of builders have also used a mix of MDF and plywood. One can also use exotic materials like Corian, aluminium, slate stone, hard wood, or panzerholz (provided one can source it without too much effort, and also - more importantly - get it cut to appropriate shape and size). Birch or Beechwood plywood are also very good, though difficult to source locally. Whatever shape and size and material you choose to use for the plinth, make sure the pan of the top plate is supported firmly by the plinth layer below it. The top plate of the Lenco is thin and needs all the support it can get. This is a critical point to adhere to, IMO.
2) the bearing needs thorough clean up and re-oiling and greasing. Soft cloth or tissue paper dipped in naptha (lighter gas) makes for an excellent cleaning agent. Just take care to do this away from naked flame as lighter fluid is highly flammable. My personal formula for lubricating the bearing is to dab some lithium grease at the bottom of the spindle where the bearing ball meets the thrust plate, and to use 5W30 synthetic engine oil for the rest of the bearing. Add some amount of this oil to the grease at the bottom. If using stock bearing, don't use grease anywhere near where it can come in contact with the bronze bushing. If grease enters the pore of the bronze bushing, it can clog the pores and prevent oil from seeping in and out of the pores. It can lead to dryness where lubrication is most needed. The pores in the bronze bushing is meant to be an oil reservoir to facilitate constant lubrication. Further, in my experience, sewing machine oil is too thin for use as bearing oil. The high torque motor works best when it works against friction, so thicker oil like 5W30 is better. If you can source it, single grade compressor oil are supposedly even better.
3) Clean and oil the motor and tune it for quietest operation. This is another critical servicing. A quiet motor lowers overall noise floor, bringing out more detail and nuances from your player.
Other good to do processes:
1) use a better tonearm
2) use the best cartridge you can afford to use
3) use the best phono stage you can afford to use
4) use filler below hollow top plate. Instructions given some posts back on this thread
5) use better thrust plate for the bearing
6) replace bearing ball with new one (5 mm diameter).
M
mpw
Guest
JLS
Your dedication is well appreciated , admired and even a bit envied.
Regards
Your dedication is well appreciated , admired and even a bit envied.
Regards
I made multiple changes in one go, namely, reinforcing the underside of the top plate (non pan areas) and also reduced the thickness of the plinth from 6-7 layers to just three. And prior to that I had serviced motor. So honestly I don't hear improvement I can specifically attribute to the bearing support. But in theory it reduces the flex of the pan. The area around the bearing is not directly supported by the plinth layer below, so it is a weak area, whereas it has all the weight of the platter concentrated in the area. An alternative support for the bearing is to use brackets at the bottom of the bearing housing. I will try to implement a bracket in my new plinth build.
Thanks, mpw.
I had gone through lots of experiments. The ones I've listed above are the ones that improved the sonics.
And despite the temporary plinth, the sound of the Lenco is the best I've heard in years of tuning and tweaking. It is very lively, just the way I want it. The Decca London Super Gold cartridge contributes here immensely.
The Lenco has immense drive, with superb attack and decay, and does wild dynamic swings. Servicing the motor has helped to focus the sound and dehomogenises it, making lateral and depth imaging very specific, while also improving the resolution. Using a good thrust pad helped improve those qualities further, while also somehow making the SPL higher. I'm at a loss for explanation of this phenomena. But the downside is that not all records sound good on this player anymore.
Also, a very attacking sound is not to the liking of many listeners. No wonder quite a few visitors favour the TD 124 (paired with another DIY arm and a Denon DL 103) for its mellower and smoother sound. Another contributor to the sound is my wooden DIY unipivot arm. This may sound a bit conceited, but it betters all my factory made arms by some margin. So the DIY arm does regular duty while the factory boys are left with bench warming duties.
Another factor I deliberately left out is the DIY bearing, only because it is not something others would be keen to replicate for their own setups, mainly due to the difficulty in finding a competent machinist to make one with very tight tolerances. Of course those interested can buy very good after market bearings from reputed vendors on eBay and elsewhere. But they cost a lot. I mean a lot.
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From the above nice-to-have list I forgot to add stacked platters. It increases the moving mass and therefore the inertia. A higher moving mass will have less speed variation due to stylus drag. This fact is well known by modern turntable designers who favour high mass platters for belt drives. To implement, one obviously needs a second platter (or DIY one with aluminium, copper acrylic, SS, etc), a means of extending the spindle, and possibly a reinforced spindle bearing. Result is a more forceful drive and greater thrust in the sound. What you lose is may be half a second in start up time for the platter to reach normal speed. But you gain substantially in run down time, circa 30-40% (without the brake engaged).
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