New LP12 top plate production

[johnandchris]

Hi Folks. This may be in the wrong area so Mods please feel free to move it.

I own an LP12 Sondek which i think is a wonderful piece of equipment. When developed by linn (or Ariston) it brought high qualitly turntables to the masses.

It was not without its problems however. The subchassis was pressed steel and the curved top plate (linn say pre bent to provide good anchorage but i suspect it has the curve as it came off a roll) was stainless steel and flexible. Both of these are design flaws and cause inconsistencies in set up.

I wont go into the subchassis here as there are already alternatives on the market including a new machined one from Linn, The KEEL.

The LP12, as a suspended turntable, relies on accurate setup to allow the suspension to work. With the curved top plate, it is nearly impossible to get the springs to hang perpendicular to the top plate. Indeed LINN developed a special tool for bending the springs, although how accurate this is in real life i have my doubts. Anyway, bending the bolts is a fix not a cure and can cause the top plate to bend slightly.

I have an engineering background and as i am also curious, i have looked into the top plate engineering. There is a company called Tiger Paw who make the KHAN top plate, a lovely looking piece of engineering with an eye watering introductory price of £800!!. It is a CNC machined piece of aluminium with some lovely "resonance reducing rings" on top.

It is supposed to be a great improvement on the standard subchassis as it is absolutely flat and the mounting holes for the bolts are machined in so they stand at a perfect 90 degree angle. Its engineering in this department is sound and makes sense, however i believe (my personal opinion) that although it is well made, it is over engineered. I dont subscribe to the resonance reduction claims etc, and i think a more simple option would offer all the benefits at a considerable cost reduction.

I have spoken at length with a CNC machining company and i am currently in the development process for a simple top plate using tried and tested manufacturing processes to ensure a stable, flat and simply constructed high quality top plate. Preliminary investigations indicate that the cost of one of my top plates, machined and anodised would come in, to the consumer, at about £375 to £400, so less than half the price of the KHAN.

I am having a prototype made up and will report back on the finished product, however what i am looking for is an initial indication (rough) of who may be interested. I am not looking for a definite yes or no, but opinions would be gratefully received to give me a ball park figure that i can discuss with the CNC company.

I have been making low cost, high quality interconnects and tonearm cables for many years and have sold hundred all over the world. I have also been a member of this forum for years and have contributed to discussions and had a lot of help with hi-fi matters from various knowledgeable people here so feel this is the correct place to seek opinions etc.

Feel free to leave any constructive comments (negative or positive) regarding what i am planning to do. If you wish to PM me also feel free.

Thanks in advance for your time.

John

 

[johnandchris]

Any comments?

 

[RobHolt]

Hi John,

I recently bought a very old LP12 as you might have seen from the restoration thread.

Certainly one of the weak points is the design of the top plate. Linn made much noise about why the design was chosen initially but it has some clear issues.
Mine was far from sitting perfectly flat on the supports, and from reading reports of those seasoned in LP12 set-up this isn't uncommon.

I tend to agree with you regarding 'resonance reducing rings' on another alternative and agree that a high quality replacement for the original at reasonable cost is desirable.

I don't know what the current policy is over at Linn but you might want to float the idea on the official Linn forum. Certainly Ribikon and Tiger Paw have been given airtime over there so I don't see why Linn should object.

I suspect we don't have a high number of LP12 users here.

Good luck with the project and do keep us updated.

 

[felix]

Good luck with the venture.

Agree with the 'rings'n'things', although that particular example looks beautifully made; at the price I'd like to see some before/after data. Even a contact mic blutac'd to the plate would do. But then surely at some point someone is going to just fabricate a 5-sided fruitbox - from aluminium perhaps, or maybe carbon pre-preg - and make the whole issue go away...

Then again I think at least half the charm of the Linn/Ariston/whatever it is, is that the whole gels meaningfully, when essentially it is only a motley collection of bits assembled - not always that well - to do a job. Put another way: if you started with a clean sheet and perhaps a scant knowledge of kinematics you would not likely end up there...

 

[johnandchris]

hi folks.

Thanks for your input.

I tend to agree, if you were starting from scratch the LP12 would be a very different design. the top plate would not entirely stop the twaking of the suspension (you would still have to turn the springs to get the perfect setup) but it would allow accurate setup rather than what is effectively guesswork and trusting to luck that the mounting is perpendicular.

Thanks
John