It’s been a while since I owned a suspended belt drive turntable. I did have an Lp12 some years back which if memory serves was an early ‘80s mostly stock configuration in a state of disrepair. At the time I didn’t consider it anything special and did nothing with it, later giving it away. Personally I thought it quite poorly made, and having learned in the intervening years of the story of how the LP12 came to be, I am glad to have avoided jumping on that particular audiophile bandwagon.
Putting the questionable ethics involved aside, in my personal opinion it, and the Ariston RD11 on which it is based are a poor copy of a pretty competent design, and subsequent attempts to ‘improve’ upon the design have done more to cover up its engineering shortfalls rather than fixing the underlying deficiencies in the design. To me, the LP12 is proof that clever marketing is more important to the popularity of a product than the quality of the product itself. Though it should be noted that despite selling well (over 100,000 units to date), sales of the lP12 still pale in comparison to the Technics 1200 and its more than three million sales of the original lineup over its shorter lifespan.
The design of the original LP12 borrows (is identical to) the Ariston RD-11, which in turn borrowed from the Thorens TD-150, it in turn based on the Acoustic Research XA turntable. Edgar Villchur designed the XA for AR, the basic principle of which was that all aberrations in turntable performance are caused by unwanted relative motion between the pickup cartridge and the record. He therefore mounted the tonearm and bearing as rigidly as possible relative to one another on a T-shaped steel sub-chassis and suspended it from the top plate. This isolated the working components of the turntable from acoustic feedback and also from the motor, which was mounted to the top plate. This same basic design principle has been used since through the decades by Thorens, Ariston and Linn, though with many of the earlier designs especially being so similar that their parts are quite literally interchangeable.
Which brings us nicely to the project featured herein. I wanted to build a suspended turntable, but have no wish to own a Linn. The TD-150 is a great alternative as the design and dimensions are very similar, and used models are plentiful and still relatively cheap to acquire; especially if condition isn’t a concern. I acquired two of them, both MK2 models. One came in the original plinth with the wood-framed dust cover and looked to be in mostly original condition, supplied with an original Thorens arm board cut for an SME arm.
The other had been transplanted into what looked like a poorly engineered custom plinth. It had clearly once been equipped with the factory Thorens tonearm as the lift knob and a couple of remnants of the lift assembly were lurking within. It had however been fitted with a Linn arm board, also cut for an SME arm. The plinth on this one was a bit of a mess and the deck was falling to bits, but I only wanted the inner workings so this was of no real concern.
I decided to build two decks. One would be based around a Maple plinth and would be a TD-150 MK2 in stock configuration, besides having a slightly wider arm board. The other, based in a Cherry plinth, would use the inner workings of the TD-150 (sub-chassis, bearing, platter and motor) but with a new top plate and extensive modification. Both would be cut for Rega 3-point mount arms, and both would be made to LP12 dimensions which are very similar to those of the TD-150. The only difference is that the top plate is 0.6 mm deeper (305.5 as opposed to 304.9) and the arm board is 22 mm wider (102 mm as opposed to 80 mm). A TD-150 will therefore fit perfectly into an LP12 plinth, and the TD-150 sub-chassis is interchangeable with that of an LP12.
This project coincided with the introduction of the new TD-150 LP12 conversion kit from Vinyl Passion. The kit consists of a thick steel top plate (33% thicker than that of an LP12), carbon acrylic arm board and the required fixings to fit an LP12 plinth. A massive thanks to VP for not only letting me get my hands on one of the very first batch of parts, but also for offering help and advice along the way. VP are experts in all things LP12 and TD-150 and market a range of cleverly designed and well engineered upgrades for both.
Other parts were from SRm/Tech. These include platter, bearing and motor damping, a motor thrust bearing and isolating feet. I’ve reviewed SRM products here before and have found them to be well engineered, keenly priced and extremely effective.
The Next Instalment will cover the build of the stock TD-150 MK2. In Part Three we’ll build the modded TD-150 which will hereafter be named the AAP12. And finally in Part Four, we’ll sum up the series with some listening impressions and general notes.