I bought this long ago, I think it was 375 or something around that.
Building a Plinth for Lenco L75
- Thread starter jls001
- Start date
I bought this long ago, I think it was 375 or something around that.
Yes, I have put the correct value of the capacitor recommended in the user manual. It is in parallel to the incoming power supply. But there is no change. I still get pops when switching the speed selector. Also, when switching on/off power points in the room, it gets picked up by the 124.
Even after making arm board for the Origin Live Silver arm and fitting it in the 124, the problem has been persisting. The new tonearm has a cable that emerges out of the base of the tonearm and is plugged in directly to phono pre-amp. It is very well shielded with absolutely no exposed wiring except at the headshell.
Even with this, the pop remains so I have ruled out noise pick up happening from tonearm cabling. There is something else wrong. I will get to the bottom of it.
One good thing that has emerged out of all this exercise of peering into the underbelly of the 124 and poking, screwing/unscrewing things - I have fixed the inconsistency of the speed selector to engage 33 rpm. Now it engages every time after making a small adjustment in the lever.
Some small progresses:
1. For fixing the turntable to the new plinth, I needed threaded rods measuring 5 to 6 inch. Since I could not find it in this length, I decided to DIY it. So off I went looking for stainless steel rod of 5 mm diameter but I could not get it so I ended up with 5 mm brass rod. Here's a picture of the prototype rod. Please excuse the rather poor shot.
By jls001 at 2012-03-30
2. Here's a close up of the completed rod side by side with the raw rod.
By jls001 at 2012-03-30
3. Another closeup: with the 4mm die. The die is high speed steel and the handle is normal steel.
By jls001 at 2012-03-30
Next step is to re-drill the 4 holes in the plinth as the ones I have drilled are misaligned. I anticipate that this is going to be a tedious and painful process since all layers have been drilled. So it is going to be more of correcting the mistake.
I will first try with my drilling machine. If it works well, good. The alternative will be to try manual wood drill (corkscrew type).
1. For fixing the turntable to the new plinth, I needed threaded rods measuring 5 to 6 inch. Since I could not find it in this length, I decided to DIY it. So off I went looking for stainless steel rod of 5 mm diameter but I could not get it so I ended up with 5 mm brass rod. Here's a picture of the prototype rod. Please excuse the rather poor shot.
By jls001 at 2012-03-30
2. Here's a close up of the completed rod side by side with the raw rod.
By jls001 at 2012-03-30
3. Another closeup: with the 4mm die. The die is high speed steel and the handle is normal steel.
By jls001 at 2012-03-30
Next step is to re-drill the 4 holes in the plinth as the ones I have drilled are misaligned. I anticipate that this is going to be a tedious and painful process since all layers have been drilled. So it is going to be more of correcting the mistake.
I will first try with my drilling machine. If it works well, good. The alternative will be to try manual wood drill (corkscrew type).
After a long hiatus, I got back last night to the task at hand. I made a cut out for the second arm (SME 3012). What had held me back for a long time was my uncertainty with the pivot-spindle distance for the 3012 II. This distance is variously given as 294 mm or 296.5 mm. I decided to take the plunge and go with the more commonly quoted figure of 294 mm. Anyway, the difference of 2 mm, and if my cutout is wrong, distance can be compensated since the SME arm can move back and forth.
I used 1 inch wood drill bit to cut out the rounded ends of the arm pivot slot (the two large black holes in the picture). The recommended bit size is a wee bit larger than 1 inch. On my other SME armboard, I find the recommended size to be larger than necessary, leaving little room for the 4 wood screws. So I decided to keep the slot size to a tight-ish fit.
Uploaded with ImageShack.us
After cutting both 1 inch holes, the next step was to cut off the shaded portions in the picture. As reported earlier, the blade of my jig saw keeps flipping to one side making it almost impossible to make a straight cut. Since I bought this new, I was not ready to consign it to the dustbin as something defective and unusable. I had even gone to a tools shop to see if I could get something similarly cheap and cheerful. All were above my mental budget so I decided I had nothing to lose and opened up the jig saw. I have opened up my drilling machine in the past but what greeted me on opening the jigsaw was a much more complicated mechanism. And while opening it, some springs and other bits and pieces fell off.
So I spent at least 15 minutes trying to understand the general mechanism and where to fit back the fallen parts. The parts inside were surprisingly good, though there definitely were some cheap looking parts. Goes to prove the maxim "what you pay is what you get".
In the end, I managed to fit everything back and close the saw. I was glad that I found out the culprit and fixed it by stuffing two pieces of plastic to strengthen the action of a spring which wasn't doing its job well.
Then something made a clanking sound and a part fell to the floor. Another round of unscrewing and searching where to fit the newly fallen part ensued.
After some searching, managed to fix the part. And now the damned jigsaw cuts straight as an arrow
I wound up around midnight after filing the edges of the tonearm slot for the top layer of the plinth. Subsequent layers will be cut based on this template. Hope to complete making the slots over the next few nights.
Also to make: hole to route tonearm cable to rear of plinth where two female RCA points and grounding pin will be mounted on a custom cut aluminium plate.
Also need to make a largish hole on rear of plinth to route tonearm cable of main arm (which has an integral tonearm cable).
Lots of work to do before I can glue it all together.
I used 1 inch wood drill bit to cut out the rounded ends of the arm pivot slot (the two large black holes in the picture). The recommended bit size is a wee bit larger than 1 inch. On my other SME armboard, I find the recommended size to be larger than necessary, leaving little room for the 4 wood screws. So I decided to keep the slot size to a tight-ish fit.
Uploaded with ImageShack.us
After cutting both 1 inch holes, the next step was to cut off the shaded portions in the picture. As reported earlier, the blade of my jig saw keeps flipping to one side making it almost impossible to make a straight cut. Since I bought this new, I was not ready to consign it to the dustbin as something defective and unusable. I had even gone to a tools shop to see if I could get something similarly cheap and cheerful. All were above my mental budget so I decided I had nothing to lose and opened up the jig saw. I have opened up my drilling machine in the past but what greeted me on opening the jigsaw was a much more complicated mechanism. And while opening it, some springs and other bits and pieces fell off.
So I spent at least 15 minutes trying to understand the general mechanism and where to fit back the fallen parts. The parts inside were surprisingly good, though there definitely were some cheap looking parts. Goes to prove the maxim "what you pay is what you get".
In the end, I managed to fit everything back and close the saw. I was glad that I found out the culprit and fixed it by stuffing two pieces of plastic to strengthen the action of a spring which wasn't doing its job well.
Then something made a clanking sound and a part fell to the floor. Another round of unscrewing and searching where to fit the newly fallen part ensued.
After some searching, managed to fix the part. And now the damned jigsaw cuts straight as an arrow
I wound up around midnight after filing the edges of the tonearm slot for the top layer of the plinth. Subsequent layers will be cut based on this template. Hope to complete making the slots over the next few nights.
Also to make: hole to route tonearm cable to rear of plinth where two female RCA points and grounding pin will be mounted on a custom cut aluminium plate.
Also need to make a largish hole on rear of plinth to route tonearm cable of main arm (which has an integral tonearm cable).
Lots of work to do before I can glue it all together.
Cutting out the tonearm slot on the plinth layers is a lot more hard work than I anticipated. Last night I managed to complete the second layer of the plinth (18 mm marine grade plywood).
I think I will need to do it to two more layers and it will be deep enough for the tonearm to sit without scraping something below.
The next layer is 17 mm MDF so I anticipate that things will be easier on the saw blade and wood drill bits. The jig saw and drill get real hot. Smoke curls up from the hole as the drill bit goes deeper. And lots of saw dust.
The layer below that is acrylic and I am already cringing at the thought of cutting and drilling acrylic. It is much tougher than ply or MDF.
I think I will need to do it to two more layers and it will be deep enough for the tonearm to sit without scraping something below.
The next layer is 17 mm MDF so I anticipate that things will be easier on the saw blade and wood drill bits. The jig saw and drill get real hot. Smoke curls up from the hole as the drill bit goes deeper. And lots of saw dust.
The layer below that is acrylic and I am already cringing at the thought of cutting and drilling acrylic. It is much tougher than ply or MDF.
To continue from Post # 25 here, and to revive a long dormant thread, the pictures below show the stock tonearm hole of the L75 being widened in one direction to increase the mounting distance (distance from tonearm pivot to turntable's spindle) by about 7 mm.
Required mounting distance = 223 mm.
Mounting distance of stock L75 arm hole = 210 mm.
Extra length needed = 13 mm.
Extra length obtained by extending the arm hole = 7 mm
13 mm - 7 mm = 6 mm is being compensated by positioning the cartridge in the headshell.
1) Making the marking for extending the tonearm hole by 7 mm:
Once you're happy with your marking, file away to glory. You will need D shaped files. It is better to have a snug fit so keep trying out the fitting when you think you are nearly done.
2) Ensuring the extension is in the correct axis along the arm tube:
Notice the rubber band that replaced the idler wheel spring.
3) Here's how the cutout finally looks like:
I am not clear why imageshack rotates pictures 2 and 3 by 180 deg:lol: but I hope you can still make out the cutouts.
Caveat: this process is irreversible. If you would like to retain stock top plate, don't do this. Also, since the arm is pushed to one side, it leaves a fairly large gaping hole on one side. This may not be cosmetically acceptable for some. I can live with it as the sonic gains are substantial.
Effect of having correct mounting distance: I had thought all along that I have fantastic sound from my L75. How untrue
I knew even before others helpfully pointed out that it is sub-optimal to not have correct mounting distance.
There were two constraints that were holding me back - first, I absolutely didn't intend to buy one more tonearm as I already had way too many. Secondly, I was quite reluctant to go through another round of cutting through all six layers of the plinth to make a better arm hole. Besides, it is a pain lugging the heavy plinth to the (not very far) woodworking workshops in my neighbourhood. But I guess I will have to eventually do this. Or better still, build a new plinth from the ground up.
The effect of adhering to correct arm mounting distance is dollops of new-found airiness, increased details, and better separation of voices and instruments. I guess these are due to improvement in the mids, upper mids and highs. The difference is substantial. It is akin to installing a more resolving cartridge, or introducing a better phono stage in the chain.
Required mounting distance = 223 mm.
Mounting distance of stock L75 arm hole = 210 mm.
Extra length needed = 13 mm.
Extra length obtained by extending the arm hole = 7 mm
13 mm - 7 mm = 6 mm is being compensated by positioning the cartridge in the headshell.
1) Making the marking for extending the tonearm hole by 7 mm:
Once you're happy with your marking, file away to glory. You will need D shaped files. It is better to have a snug fit so keep trying out the fitting when you think you are nearly done.
2) Ensuring the extension is in the correct axis along the arm tube:
Notice the rubber band that replaced the idler wheel spring.
3) Here's how the cutout finally looks like:
I am not clear why imageshack rotates pictures 2 and 3 by 180 deg:lol: but I hope you can still make out the cutouts.
Caveat: this process is irreversible. If you would like to retain stock top plate, don't do this. Also, since the arm is pushed to one side, it leaves a fairly large gaping hole on one side. This may not be cosmetically acceptable for some. I can live with it as the sonic gains are substantial.
Effect of having correct mounting distance: I had thought all along that I have fantastic sound from my L75. How untrue
I knew even before others helpfully pointed out that it is sub-optimal to not have correct mounting distance.
There were two constraints that were holding me back - first, I absolutely didn't intend to buy one more tonearm as I already had way too many. Secondly, I was quite reluctant to go through another round of cutting through all six layers of the plinth to make a better arm hole. Besides, it is a pain lugging the heavy plinth to the (not very far) woodworking workshops in my neighbourhood. But I guess I will have to eventually do this. Or better still, build a new plinth from the ground up.
The effect of adhering to correct arm mounting distance is dollops of new-found airiness, increased details, and better separation of voices and instruments. I guess these are due to improvement in the mids, upper mids and highs. The difference is substantial. It is akin to installing a more resolving cartridge, or introducing a better phono stage in the chain.
I wanted to share my home-made protractor - this is for making a new arm hole, and also to obtain correct overhang:
The picture is drawn to scale, but it is not clear in the attachment. If you want to see a clearer picture, I can send you a .pdf or a png.
Since your tonearm measurements may be different, here's how to make your own:
1) get yourself a blank A4 sheet of paper. If you want to make it for a 12 incher, glue two A4s.
2) Draw a long straight line across the middle of the longer length of the paper
3) one end of the line is the center point of the mounting hole = the pivot.
4) from the pivot, measure the correct mounting distance, e.g. 223 mm for my tonearm.
5) Draw a square slightly larger than 7 mm (actually 7.2644 mm = 0.286") centered at 223 mm. This is your spindle hole. Don't bother with a round hole. The square one works equally well and is much easier to cut out. Stick a transparent tape over the hole, and cut out the tape over the hole. This strengthens the hole.
6) from the center of the spindle, measure the overhang. Draw an arc with a radius of effective length (= mounting distance + overhang). e.g. 223 mm pivot to spindle distance + 17 mm overhang = 240 mm. You have correct overhang when the tip of your stylus coincides with this arc.
How to use it:
1) if you are planning to drill an arm hole, use the end of the line marked "Pivot" in the diagram to mark the center hole of the mounting hole. With "Pivot" as center, draw hole with a diameter appropriate to your tonearm.
2) if you are just mounting a new cartridge and want to get the overhang right, place your spanking new protractor on the 'table with the spindle inserted on the square spindle hole. But prior to this, use the Stupid Protractor to align your cartridge to the inner and outer null points. Choose the correct geometry (Baerwald or Loefgren). Once you are happy with the null points alignment, align your new protractor in such a way that the long straight line lies exactly parallel and below the arm tube. Carefully lower the cartridge over it. Check if the tip of the stylus coincides with the arc. If not, adjust as required. Recheck nulls. Do be careful with the stylus. Don't break it.
The picture is drawn to scale, but it is not clear in the attachment. If you want to see a clearer picture, I can send you a .pdf or a png.
Since your tonearm measurements may be different, here's how to make your own:
1) get yourself a blank A4 sheet of paper. If you want to make it for a 12 incher, glue two A4s.
2) Draw a long straight line across the middle of the longer length of the paper
3) one end of the line is the center point of the mounting hole = the pivot.
4) from the pivot, measure the correct mounting distance, e.g. 223 mm for my tonearm.
5) Draw a square slightly larger than 7 mm (actually 7.2644 mm = 0.286") centered at 223 mm. This is your spindle hole. Don't bother with a round hole. The square one works equally well and is much easier to cut out. Stick a transparent tape over the hole, and cut out the tape over the hole. This strengthens the hole.
6) from the center of the spindle, measure the overhang. Draw an arc with a radius of effective length (= mounting distance + overhang). e.g. 223 mm pivot to spindle distance + 17 mm overhang = 240 mm. You have correct overhang when the tip of your stylus coincides with this arc.
How to use it:
1) if you are planning to drill an arm hole, use the end of the line marked "Pivot" in the diagram to mark the center hole of the mounting hole. With "Pivot" as center, draw hole with a diameter appropriate to your tonearm.
2) if you are just mounting a new cartridge and want to get the overhang right, place your spanking new protractor on the 'table with the spindle inserted on the square spindle hole. But prior to this, use the Stupid Protractor to align your cartridge to the inner and outer null points. Choose the correct geometry (Baerwald or Loefgren). Once you are happy with the null points alignment, align your new protractor in such a way that the long straight line lies exactly parallel and below the arm tube. Carefully lower the cartridge over it. Check if the tip of the stylus coincides with the arc. If not, adjust as required. Recheck nulls. Do be careful with the stylus. Don't break it.
reubensm
Well-Known Member
what a lovely effort, have a question for you - i have a few granite slabs lying around and was wondering if I could use them for the top layer of a multi-layered plinth which I can get fabricated if I decide to go the idler way. I've seen numerous granite, marble, concrete and stone designs, any comments on these vs the usual ply wood or MDF versions?
sachu888
Well-Known Member
Its not a good material for plinth.Few members at Lencoheaven tried Granite with not so good result.You can try slate,its available cheap in India.
Regards,
Sachin
In a multi-layered design using various materials, I feel granite should work too. But if one were to use it standalone, it won't be desirable as granite is known to ring.
Adding on. what works best is a CLD design (Constrained layer).ie if you use Granite on the top layer , use a combination of MDF/hardwood below and you should be ok.
there are a couple of designs with Granite combos at Lencoheaven.
the key to a lenco is in Increasing the Mass and Damping the vibration (as against suspending).
there are a couple of designs with Granite combos at Lencoheaven.
the key to a lenco is in Increasing the Mass and Damping the vibration (as against suspending).
Jean Nantais seems to think so (I mean more mass). Look at the dimensions of his offerings:
1) Classic Mark II: 23? x 19? x 6?, 75 pounds (34 kg)
2) the version above that is 24 1/2? x 20 1/2? x 7 1/4?, 100 pounds (45 kg)
3) Reference: no mention of dimensions, but seems to be same or similar to S/N 2.
For a comparison, the dimensions of my plinth are 23" x 17" x 3.5". I have not weighed it, but I am assuming it will be between 15 to 20 kg.
Right..he builds mammoth plinths..the one he made for Salvatore is apparently 100lbs !
The first this he recommends ..something i can confirm is throwing away the original plinth and resting it on bricks.. its plinth is its biggest enemy !!
then you try to make the Biggest/Meanest plinth that will not break your back and your wife will allow.
The first this he recommends ..something i can confirm is throwing away the original plinth and resting it on bricks.. its plinth is its biggest enemy !!
then you try to make the Biggest/Meanest plinth that will not break your back and your wife will allow.
Hi Guys,
I am using the L78 in stock plinth and the chassis is suspended on hydraulically damped springs, I dont hear any rumble on zero track at full volume. I have read everywhere that a heavy CLD plinth is a must for Lenco, and I am planning to make one, however I would like to know what are the drawbacks of the suspended chassis, and how the damping is better than suspending the vibration?
Regards,
sann'
I am using the L78 in stock plinth and the chassis is suspended on hydraulically damped springs, I dont hear any rumble on zero track at full volume. I have read everywhere that a heavy CLD plinth is a must for Lenco, and I am planning to make one, however I would like to know what are the drawbacks of the suspended chassis, and how the damping is better than suspending the vibration?
Regards,
sann'
Last edited:
The idea behind high-mass plinths is they drain off the vibration from the high-torque motor. And the coupling is most effective when it is direct - without intervening spring or rubber dampers. The vibration that the plinth receives from the motor is drained off as harmless heat.
I think you can go ahead with the high-mass CLD, sans springs or rubber mushrooms.
kuruvilajacob
Well-Known Member
Right now I have a Lenco L 75 which is on it's original plinth. My brother is using it and he is quite happy the way it sounds with stock arm and Pickering V 15 cart and it is being played through Quad 33 & 303 combination. Though I have a spare marine ply plinth ready to accept the Lenco L 75, my brother is not willing to part with the Lenco for the plinth operation. Of course, multi layered will certainly absorb some motor noise and resonance but I am just wondering how noisy is the Lenco motor? I am sure it is quite a smooth operator when compared to a Garrard 301 motor
its NOT about rumble..please do yourself a favour and remove those springs..you are only hearing 30% of the Lenco if you have them...and the very reason they fell out of favour untill Jean nantais rediscovered what they could do.
Ideally lose the plinth altogether and put them on Bricks to hear what they can do
please read this
its not worth the effort of buying a Lenco if you are keeping them in their own plinth !
sorry if i am sounding too excited/repetitive..but its criminal to keep a Lenco on its original plinth unless you have massloaded the insides of the plinth with cement and lost the springs... you will be better of with a rega or a project otherwise
I am equally exited arj, and after hearing the Lenco, it has multiplied. I had been reading about it for months, before I got one (actually two, the other one is on its way, its a 78SE version with a S shaped Jelco arm, how I got two is a different story)
What ever you said about the plinth, has put me in a dreaming mode thinking about the 70% I am missing.
Thanks again! - sann
What ever you said about the plinth, has put me in a dreaming mode thinking about the 70% I am missing.
Thanks again! - sann
Some updates:
I had been thinking hard whether to re-build a plinth from the ground up so that an arm hole can be drilled at the right distance. Since I had left some space on the rear of the plinth to accommodate the SME 3012 arm, and since the 3012 is not gonna enter active service anytime soon, I measured 223 mm mounting distance for my arm near where the 3012 arm hole is already drilled. See the area marked in red rectangle. The diagonal hole to the right is the unused 3012 arm hole.
Below is a close-up. The top layer has a larger cutout (80 mm x 80 mm). That's where the arm board will fit in. The second layer (counting from top) had to be enlarged after this photo was taken to accommodate the large nut that holds the tonearm from below. The third layer and below have 50 mm x 50 mm cutouts to accommodate the tonearm base and allow the tonearm wires to pass through. It opens to the bottom. So this plinth needs footer to raise it and not squash the cables.
The arm board (about 80 mm x 80 mm, 13 mm thick teak wood), drilled with 26 mm hole to accommodate the 23 mm base of the tonearm. 3 mm slack is useful to make fine adjustments to mounting distance. As usual my measurements weren't the most accurate, and I ended up utilising the 3 mm slack to get the right mounting distance. Of course there's always the headshell slot - one can get a useful 5-6 mm of adjustment by adjusting the position of the cartridge in the headshell slot.
Arm mounted, screwed down at the four corners with 3/4" wood screws. The arm base had to be raised by 5 to 6 mm for correct VTA. I still use the headshell spacer (slightly more than 5 grams and about 2 mm thick) as that contributes to giving the arm much needed effective mass (default effective mass is 12 grams, and climbs to about 18 grams as per the Image Hifi Test Record after addition of the spacer - with 10 Hz resonant frequency). The second mat which was earlier necessary to get correct VTA is now dispensed with.
Top view:
Ahead:
1) top layer of plinth to be changed to 10 mm thick MDF or HDF. Current top layer is 12 mm and it wrong. I end up using ad hoc fillers below the top plate and second layer to mate the top plate to the plinth. So whoever is going to build a plinth in the near future for your beloved Lenco L75, take note -- use 10 mm top layer. I went to many plywood shops but none had 10 mm thick plywood or MDF. Some shops claimed there is no 10 mm plywood or MDF. They offered 6 or 12 mm. Is it true that standard thickness is 6, 12, 18, etc mm?
2) need to decide whether to keep this plinth and complete it properly, or build something else that has caught my fancy
I had been thinking hard whether to re-build a plinth from the ground up so that an arm hole can be drilled at the right distance. Since I had left some space on the rear of the plinth to accommodate the SME 3012 arm, and since the 3012 is not gonna enter active service anytime soon, I measured 223 mm mounting distance for my arm near where the 3012 arm hole is already drilled. See the area marked in red rectangle. The diagonal hole to the right is the unused 3012 arm hole.
Below is a close-up. The top layer has a larger cutout (80 mm x 80 mm). That's where the arm board will fit in. The second layer (counting from top) had to be enlarged after this photo was taken to accommodate the large nut that holds the tonearm from below. The third layer and below have 50 mm x 50 mm cutouts to accommodate the tonearm base and allow the tonearm wires to pass through. It opens to the bottom. So this plinth needs footer to raise it and not squash the cables.
The arm board (about 80 mm x 80 mm, 13 mm thick teak wood), drilled with 26 mm hole to accommodate the 23 mm base of the tonearm. 3 mm slack is useful to make fine adjustments to mounting distance. As usual my measurements weren't the most accurate, and I ended up utilising the 3 mm slack to get the right mounting distance. Of course there's always the headshell slot - one can get a useful 5-6 mm of adjustment by adjusting the position of the cartridge in the headshell slot.
Arm mounted, screwed down at the four corners with 3/4" wood screws. The arm base had to be raised by 5 to 6 mm for correct VTA. I still use the headshell spacer (slightly more than 5 grams and about 2 mm thick) as that contributes to giving the arm much needed effective mass (default effective mass is 12 grams, and climbs to about 18 grams as per the Image Hifi Test Record after addition of the spacer - with 10 Hz resonant frequency). The second mat which was earlier necessary to get correct VTA is now dispensed with.
Top view:
Ahead:
1) top layer of plinth to be changed to 10 mm thick MDF or HDF. Current top layer is 12 mm and it wrong. I end up using ad hoc fillers below the top plate and second layer to mate the top plate to the plinth. So whoever is going to build a plinth in the near future for your beloved Lenco L75, take note -- use 10 mm top layer. I went to many plywood shops but none had 10 mm thick plywood or MDF. Some shops claimed there is no 10 mm plywood or MDF. They offered 6 or 12 mm. Is it true that standard thickness is 6, 12, 18, etc mm?
2) need to decide whether to keep this plinth and complete it properly, or build something else that has caught my fancy
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