We remember the classic turntable that arguably launched the vinyl revolution, Thoren’s beautifully built TD 150…
To show that there is nothing new under the sun, here is a belt drive turntable with a weak motor and a heavy platter, an underslung counterweight and a lid that you had to pay extra for, just like the ones still on sale today!
It may seem familiar, but the Thorens TD 150 seen here first went on sale in 1965, that’s nearly fifty years ago. Then, as now, the thing that set in apart from most other turntables was a suspended sub-chassis, a floating platform inside which holds the platter and arm base rigidly together, but which otherwise moves freely in space with the aim of providing prefect isolation from external vibrations. The TD 150 was not first turntable to be built like this, but it was the first to sell in large numbers, thanks to its fine sound quality and remarkably low price.
Many imitators followed in the next decade and I think it’s not too unfair at this point to remark on the physical and engineering similarity to the mighty Linn Sondek LP12, no less. And don’t forget Ariston, STD, Systemdek, Rovolver, et al., either!
Thorens TD 150 seen here first went on sale in 1965
Before the suspended sub-chassis, turntables had been typically constructed on a pressed steel plate to which the various items – arm, bearing, motor, etc. – were all attached. The motor was usually mounted on rubber bushings in an attempt to stop the vibrations it produced reaching the record and stylus but these were largely bypassed by the idler drive mechanisms which were popular at the time.
The complete turntable unit was sometimes mounted on coil springs too, to try to block some the very low frequency vibrations that may otherwise spoil the sound, Thorens offered a machine of this type in the early sixties, the TD 135, which was very much a typical design of this period – you can image how slim, neat and modern the TD 150 must have looked in comparison.
Thorens TD 135
In the TD 150, the platter floats softy just above the top plate, and when it is moved the arm and the black arm board beneath it move with it together. It is essential in the design of any turntable that the relationship between the axis of the arm and the platter is constant and in the TD 150 design this is achieved by two shallow steel channels which are spot welded together into a ‘t’ shape, the cross of the ‘t’ holding the arm board above. This assembly is suspended on three compressed coil springs located radially movement only loosely constrained. The motor is mounted solidly to the plinth and a flat rubber belt too the platter acts as a mechanical low-pass filter which transmits the drive, but blocks the bulk of the vibrations. Belt drive turntables were not new in 1965, but even so it was still an unusual feature.
Because of the high quality main bearing and the absence of any turntable driven automatic function, a very small and light motor, similar to those found in electric clocks, was used. Being a synchronous design its speed was locked to the mains supply frequency, not its exact voltage. The motor required around 115V, so for those examples sold in Europe a resistor was fitted to drop the excess voltage – if your TD 150 smells slightly of burning when first switched on then dust harmlessly burning off this resistor us likely to be the cause. Conversion of a USA-spec example is not easy though different diameter pulley is needed but since this is solidly bonded to the motor shaft a whole new motor would still be required.
TD 150 design this is achieved by two shallow steel channels which are spot welded together into a ‘t’ shape, the cross of the ‘t’ holding the arm board above
The TD 150 was available in four versions, as a motor unit only (no suffix), with a Thorens TP 13 arm but no plinth (suffix A), with a plinth but no arm (suffix B) or complete and ready to run except for a cartridge (suffix AB). In the case of the B version, the blank arm board could be drilled anywhere to suit most arms, but the machine’s small size precluded the use of the popular SME 3009 unless an SME plinth was used as well.
The TP 13 arm was a simple design with a few clever features; the weight for example could be positioned roughly at first and then fine-tuned using a large and heavy screw at the rear. At the other end, the headshell was fully adjustable and could be slid in and out to compensate for stylus overhand and tilted to correct for VTA, refinements that were usually absent from modestly priced turntables of the day. To set the down force, a pressed metal plate was fitted to the top of the arm about a projecting screw just behind the pivot. The screw was aligned with the desired down force marking on the plate and the arm balanced, one the plate was removed the desired down force was then applied to the stylus, a clever method except that it relies on the plate not being lost. If this has happened sometime in the past four decades a conventional stylus balance can be used in its place.
Another smaller ball mounted on a calibrated shaft ahead of the pivot set the down force
A tidied-up Mk II version of the TD150 appeared in 1969. The speed control now had the ‘off’ position between the two speeds instead of being activated by lifting the whole control upwards and the cueing device was now a matching knob fixed rigidly to the plinth rather than being a level attached to the flexibly suspended arm, making accurate operation easier.
Those versions which included an arm now came with the TP 13A, recognizable by its distinctive spherical counterweight. Another smaller ball mounted on a calibrated shaft ahead of the pivot set the down force so there was no need for the separate plate any more. A further small weight on a piece of fine cord allowed anti-skating compensation to be added, this facility had been absent from the original TP 13.
The TD 150 Mk II lasted until 1973 by which time it had been joined in the range by the TD 125, a similar (but larger) machine whose key new feature was an electronically controlled three-speed motor.
A tidied-up Mk II version of the TD150 appeared in 1969
When new, the TD 150 would have been partnered with quality cartridges such as the Shure V 15, the Goldring G800 or the Decca Deram. To take the cartridge out of the equation for my listening tests I used an Ortofon 2M Bronze, which was tricky to fit to the headshell since the mounting is intended for cartridges where the fixing screws can be inserted from underneath.
Once attached, setup was easy since the beveled edge of the 45 RPM center puck is also the reference point for stylus overhand – if only all turntables were so thoughtfully designed! I was surprised how pitch-steady the TD 150 is for a belt-driven design, the wide flat belt and the heavy (3.4kg) platter combining well to give accurate results. Only during sustained piano notes was a slight pitch waver apparent, but to less of an extent than some more modern designs which use belts which are more elastic than that fitted to the TD 150.
In its day, Thorens’ TD 150 performed well beyond its price point, and it still sounds surprisingly good today…
This particular TD 150 was made in 1967 under license by EMT, the famous German producer of heavyweight broadcast decks so I couldn’t resist getting out an early copy of Sgt. Pepeers… (The Beatles) and seeing how it may have sounded way back then. Some turntables give a very neutral sound which is difficult to place and some have a very distinctive ‘vinyl’ sound with bright highlights and a distinctive squawky midrange, particularly noticeable with instruments like trumpets. The TD 150 definitely fits into the latter category which makes it can easy, familiar device to listen to that makes old recordings sound ‘right’.
TD 150 is for a belt-driven design, the wide flat belt and the heavy (3.4kg) platter combining well to give accurate results
My favorite track on the album, She’s Leaving Home, had a light and delicate air about it and plenty of space between the sounds, the sound was perhaps a bit sharp and dry, but consider this against the backdrop of the bland cone tweeters and soggy sounding amplifiers that were the mainstay of the nineteen sixties hi-fi scene and it all makes perfect sense. The sharpness of the treble did make the vocals slightly sibilant, but this again is a common turntable trait and certainly not one unique to the venerable TD 150.
As a more demanding test I also tried a live recording of Beethoven’s Concerto No.2 (Op. 19) and found that will music of this type the tonal character of the TD 150 was less apparent. Speed stability was adequate (it is difficult to really enjoy piano music on a belt drive deck after hearing it played on a direct drive one or from a CD) and the performance fluid. The only real shortcoming I noted was a slight lack of bass precision, perhaps as a result of the rather basic construction of the arm. What did impress me was the way that the music retained its scale and drama; the TD 150 proved equally able to render a softly struck piano solo as it was to convey the power of the whole string section suddenly coming to life. A fuller lower register would have been welcome but this is a minor point.
In its day, Thorens’ TD 150 performed well beyond its price point, and it still sounds surprisingly good today. So don