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Old 2nd January 2010, 10:12 PM   #1
AuroraB is offline AuroraB  Norway
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Question DIY turntable - design principles and ideas

There have been several nice and some really outstanding builds presented here over the last years, and some of the pro's and con's of various designs have been discussed, but the info is scattered over quite alot of threads. Somehow it would be nice to sum up som of these ideas, from variuos people. Hopefully you will respond.

I'm about to start building a plinth and platter for a Teres type bearing, but several bearings are available on the net for reasonable sums of money, so this thread should be useful for a number of people.

There seems to be a few main directions among DIYers- solid wood plinths, and some based on constrained layered damping ( CLD) princicples. MDF are used by several of the commercial mid to high level manufacturers, but somehow MDF has a bad rep....I'm not quite sure if this is fair or not, given the extent of lead damping some people apply.
For myself, I have some limitations in getting hold of some of the more fancy stuff, but hardwoods, aluminium, acrylic,PVC etc are easily obtained.

Now for the platter - Teres used some really gorgeous acrylic platters in the early days of the project, but now it seems mostly hardwoods. Galibier and Redpoint sprung out of the original Teres project, and alu and teflon seems to be their way....
Some years ago, I had a magnesium platter lined up for me, but I lost that for several obscure reasons...

Any takers here who want to chip in????
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Old 3rd January 2010, 03:23 PM   #2
jlsem is offline jlsem  United States
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Quote:
Some years ago, I had a magnesium platter lined up for me, but I lost that for several obscure reasons...
I designed a platter of magnesium for my SP-10MkII that matches the original's moment of inertia and I have the material. The only problem is finding a machine shop that will machine magnesium. If they don't have insurance that specifically covers fire from from burning magnesium, they won't touch it.

John
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Old 25th February 2010, 09:20 PM   #3
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I'm collecting ideas and information now for my table project and would love to see all the info in one place!

Barring that, can some members suggest some "required reading" threads for me?

I understand the basics, and have an interesting bearing design already, but have only "scratched the record surface" so to speak (sorry for the skip!)

I am far more mechanical than electrical, so this appeals to me. I have worked with a LOT of different materials over the years too, so I know what I can, and can't do.

I am willing to buy the things I know I can't make better, but hate to throw money away on basic materials made into beautiful objects (because I can do that myself!)

Ears open!
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Old 25th February 2010, 09:28 PM   #4
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My Rega has a corian platter, and when i pursue my Linn bearing TT project Corian will be the material of choice for the outer platter.

dave
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Old 27th February 2010, 06:03 AM   #5
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Talking My new concept turntable is also in the design stage...

Hey Jim,

I'm also near Long Island, about 1 mile into Queens. So I may be within traveling distance from you, and I know quite a few audio people on LI. Mainly, I'm into building rather sophisticated low power SET Tube Amps, but for the past several weeks my friend and I have been discussing a DIY TT of a novel design ( mostly what we can pull from junk box parts).

Two weeks back, I delivered a motor to him, which we will test to see if it looks feasible. The motor is a 4 pole ~1/20th H/P servo-controlled, pulled from an early 1980's Akai Reel to Reel direct drive Capstan system with a rear bearing, which runs full speed on 80 VAC. The servo-control slows it down considerably, so it may be suitable for this concept design direct drive TT for all three record speeds. I can probably design a more modern, compact, and simplified servo-system than the one done back in the later 1970's which the Reel to Reel used.

The platter will likely be acrylic, which my friend can machine on his lathe and milling machine. It may be supported by an axial magnetic bearing of two opposing ring magnets to reduce friction on the motor lower bearing. That's about as far as we have thought it through, so far. I actually have four working turntables, so I really don't need to build one, but, just as a concept work, with a budget of under $100. I figured it might be fun to do.

If it works well; we could compare it's performance to some others, like the Technics SP-15 direct drive (which my friend owns) and a modified AR-XA belt drive (which I own). What arm we put on this budget unit remains to be seen, I have one from a Dual 1218, or was it a 1209? which with a suitable mounting piece might provide good performance and allow interchange of cartridges, and also fits within the "Hmm. What's in the junk bin of parts that I can use today" concept of this novel design.

-Steven


Quote:
Originally Posted by Jim Leach View Post
I'm collecting ideas and information now for my table project and would love to see all the info in one place!

I am far more mechanical than electrical, so this appeals to me. I have worked with a LOT of different materials over the years too, so I know what I can, and can't do.

I am willing to buy the things I know I can't make better, but hate to throw money away on basic materials made into beautiful objects (because I can do that myself!)

Ears open!
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Old 27th February 2010, 07:52 AM   #6
jloveys is offline jloveys  Belgium
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Hello , my name is Jean and this is my first post here. I jump from my usual forum lencoheaven.net to summarize the evolution of the DIY turntables with Lenco's and the actual trends. Of course there are many different types of constructions and this is very individual, so I will present you my own opinion of what I and other LH members use to use to make a simple, cheap and already good sounding turntable ( Lenco L75 or similar) into a stellar performer .

First the PLINTH. In the beginning we used massive giant plinths made with ply with the stock top plate for damping the motor vibrations and it gave very good results. Then we tried all kind of materials and one of the best we found is slate, first because it has high density and we achieve high mass with minimal volume and also we find it better sounding than wood, metal or acrylic . I personally made it cut by specialist robot cutting machines and the price is fair ( about 200$ ). We make other experiments with synthetic concrete and limestone, also good...

The TOP PLATE. Two schools here: the traditionalist who keep the stock top plate to preserve the "original" look and the PTP , a replacement stainless steel top plate invented by Peter Reynders from Holland ( Peter Top Plate ) witch gives a rigid non resonant structure to fix the motor, bearing and idler system.
The PTP is a real sound upgrade over the stock top plate but the look is not "original" and changing speeds not so easy...and it is possible the rigidify the stock plate with dynamat, steel frames, concrete,...

The PLATTER. The stock platter is quite heavy (4Kg) and good but we found that the heavier the better, so we experimented with STACKED platters, with different materials , with other brands platters and also with slate platters. The results are absolutely astonishing and with 15 Kg platters the sound is more precise, an extended soundstage, bass tighter and more "foundations" to the music.

We use the stock bearing but we will soon upgrade with "superbearings" machined by some of our members.

So those are some ingredients of how to make a cheap vintage turntable into a wonderful sounding one as good as the best out there...
For more tweaks you should have a look at Lenco Heaven - Forum about Goldring Lenco Turntables.

Here some pics of 2 Lenco's with PTP and slate plinth, one with VPI superplatter, the other with DIY slate platters...
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Old 1st March 2010, 12:26 PM   #7
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Quote:
Originally Posted by slbender View Post
Hey Jim,

I'm also near Long Island, about 1 mile into Queens. So I may be within traveling distance from you, and I know quite a few audio people on LI...

-Steven
Very cool! I work in Westbury, so not far at all.

I live out in Huntington, and am currently re-building my house, so the stereo rig is mostly boxed up waiting patiently...

My direct e-mail is jim[dot]leach[at]sulzer[dot]com if you want to chat directly on ideas. I also have a semi-typical bearing design with novel materials and dimensions- basically a silicon nitride ball riding on sapphire. I have studied the 'inverted' bearing designs, and understand the concept; however I am not convinced it in fact reduces the friction of the system. The reason for this thought is that rather than spreading the 'load' over the side of the bearing on a film of oil, now you place a side load at the ball, forcing it into its cup on one side, which increases friction in that small point, and could induce a sound if the pressure is sufficient to drive out the oil. And, on the subject of oil, with the ball on top, it is far easier to run low enough on oil for it to run dry, which is another situation I do not favor...

So, my bearing is 'traditional' in that the ball is on the bottom, well soaked in oil. The dimensions are still up in the air, but this will not be 'your father's turntable bearing' for sure!

I have other plans in mind to ensure the run-out of the platen is kept to near zero as well...
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