GrooveMaster 1 tone arm for Lenco and Thorens

We at Audio Creative have always been charmed by the Lenco L75 turntables. Introduced in 1967 and manufactured in Switzerland. Starting in 1970, Lenco turntables were also built in Italy. They are rock solid devices. Only later on, however, it became clear how good these turntables are and quite easy to transform into a top turntable....

The Thorens TD160 is a generational counterpart of the L75 and also highly regarded to this day. Unlike the intermediate-wheel driven Lenco, the Thorens is a belt-driven transport with a loose sprung subchassis. At first glance, both famous turntables have the only similarity in that both make for very pleasant vinyl listening.
 
But what the players also have as a feature, the Lenco more obviously than the Thorens, is that the tone arm clearly has room for improvement. It will not be for nothing that the Thorens TD160 at the time could also be purchased without a tone arm.
In retrospect, the Lenco L75 has always suffered from a tone arm acting at a significantly lower level than the turn transport. That may be why it took so long to realize how good the rest of the L75 actually is.

And then suddenly there was the plan to once develop special GrooveMaster tonearms for both the Lenco L75 and the Thorens TD160. A year after the first sketches, the moment has now arrived....

Old but by no means out of date

On the first generation, the Thorens TD160 had a significantly better tonearm than the Lenco L75. The TP16 with the familiar tart shovel headshell. This TP16 closely scraped against the top class tonearms in the early 1970s.

By the way, Thorens went terribly wrong with the TP16 mk.2 version. What a disaster device that was. In this, the tonearm connector had been moved from the headshell to close to the arm bearing. To give the tonearm a lower mass and make it interchangeable.

But the new connector is of such a lousy quality that contact problems arose after a while. I had a TD160 mk.2 myself, with a few loose arm parts. At a certain point I just pulled the arm wiring all the way through and glued the arm connector in place.

The Lenco L75

This turntable has tremendous qualities. A large motor that is easy to service and a beautifully turned balanced turntable of 4 kg. If the half-century old L75 is built into a nice heavy pedestal, the drive is given a good overhaul, a better tone arm is fitted, this turntable has the potential to play in the top class.

This inspired us to start developing the new parts for the Lenco. With this special Lenco kit, the L75 can even be restored to like-new condition. I dare say even better than new...and ready for the next half century of musical enjoyment. These conversion kits are now going around the globe.

I even enjoyed playing with an L75 for years, in a heavy-duty casing, with an early version of the GrooveMaster tonearm on it.

And then there's the eureka moment...

While in Munich in 2024 for the München High End show, the idea was suddenly there to create a drop-in tonearm for the classic Lenco and Thorens turntables. The same evening, the first ideas were sketched and written on a couple of beer felts while waiting for our ordered schnitzels at our favorite restaurant. What 'it should be able to do, how it should be, etc.

In the following weeks Marco and I continued working on it together with our constructor/drawer. Marco made a first draft for a fitting headshell in his well-equipped workshop. Then, when the shape was to your liking, everything was drawn up and prototype parts were manufactured.

And how did it end up?

It has become a straight tone arm with ( needless to say) the same geometry as the original Thorens and Lenco arms.

This allows the existing tone arm elevators and clamps to keep their function. This saves tremendously in manufacturing costs and it also makes the tone arm a lot easier to construct, not to mention much simpler to install.

Mounting hole

The GrooveMaster 1 should be mounted simply in the original mounting hole in the chassis. Sawing, drilling and filing is not needed.
'Drop-in' should really be drop-in. Old tone arm is taken off, new one is put on. Only the wiring needs to be re-soldered.

A fixed headshell

An interchangeable headshell will increase the cost immediately because of the high-cost connectors required. The GrooveMaster 3 and 4 use connectors developed in-house, with every part being custom made. If we were to use this construction with the GM1, the arm would become a lot more expensive again.

However, the headshell should be of a rock-solid quality and the stylus can be placed exactly in line with the arm. Of course, the headshell can also be tilted to align the stylus perfectly in the record groove.

The wiring

The above solution with a fixed headshell makes it possible at the same time to run the wiring in its entirety from headshell to solder connector in the turntable itself. This saves yet another expensive DIN connector in the arm base. Also, in the GM3 and 4, these are of uncompromising custom-made quality and therefore expensive.

For the GM 1, arm wiring from the well-known Cardas brand was chosen. We fiddled with other, cheaper, wiring, but that was quickly consigned to the trash bin as “not good enough. Wiring offered for sale on the internet through the usual channels turned out to be of such poor quality that it brought down the arm quality.

The bearing house

What also quickly becomes clear is that the bearing housing must have the same uncompromising maintenance-free ceramic bearing that we also use in our GM3 and 4. To compromise on the budget there would seriously undercut the GM 1.

The antiskating: we could do it inexpensively with the familiar string/weight method, but we really don't think that's appropriate anymore. And certainly not appropriate for a quality arm that the GM 1 should be anyway. So once again the qualities of frictionless magnetic antiskating are chosen.

Titanium

The arm tube: in this case, quality takes priority. The GM 1 also gets a titanium tone arm tube. The material that has more than proven itself in the GM3 and GM4.

Once all the components have been drawn up, the first prototypes can be made. A few weeks later, the first 2 arms from the zero range can be built. That looks promising! But even better: the tone arm sounds above expectations when built into a Lenco L75 chassis.

Some more fine-tuning is done, the drawings are adjusted and the 'courageous decision' is taken to have the (still quite a lot of) components of the first series of the Lenco and Thorens version GM1 tone arms produced.

Counterweight

We could use a simple screw or slide weight. Or run the counterweight over an ugly coarse thread. That would certainly be cost effective.

But this was quickly dropped. It is, after all, a GrooveMaster! Besides often not looking very nice and chunky, it also works against accurate needle pressure adjustment. The counterweight is too an important and tone-defining part of the tone arm to cut costs there.

The counterweight is constructed of stainless steel and nickel-plated brass. The combination of these two metals effectively extinguishes any resonances. The super-smooth nickel coating allows for smooth operation.

The 20-fold thread, with silicone oil damping, thus ensures a very pleasant operation. Thanks to the multi-thread, the weight can be moved swiftly and at the same time the needle pressure can be set to one hundredth of a gram.

Tone arm exchange

When the parts are delivered a month later, the real work can begin. The assembly of the GrooveMaster 1 progresses as desired. All precision parts, often with fits of a few thousandths of a millimeter, make assembly a party. As a result, a beautiful tone arm stands on the workbench at the end. It is subsequently moved to the ready-to-use Lenco and Thorens turntables.

Assembly

Conversion of the Lenco L75 with old arm to new GM1 went off without a problem. The job can be done within an hour. After that it is only a matter of assembling an cartridge and adjusting it. With the protractors made for the GM1 that is not a difficult job either. It just requires common sense and no rushing. The Goldring element may take its place in the GM1 as the first candidate.

Put a record on the turntable, put the needle in the groove and ... silence ... and then music, just music! Surely this is very different from the old tonearm that was on the turntable. Really not comparable at all. Not in comfort of use and not in the qualities the GrooveMaster 1 manages to distill out of the groove compared to the original tonearms. You may know that we are very proud of this result.

Not long after

A couple of days later, it is clear that the mission was well accomplished with the GrooveMaster 1.
 
A tonearm that may be called a real GrooveMaster in all aspects and has many characteristics and qualities of its more expensive GM3 and GM4 brothers.

The compromise we had to make in order to make a more affordable GrooveMaster is easily lived with. The GM1 is a full-fledged member of the now quite extensive GrooveMaster stable.

Any more ideas?

Are there any more ideas? Well, we certainly have. The first is a GrooveMaster 1 specifically for use with a Technics SL-1200 turntable and family members. Another turntable with great qualities.

And not entirely coincidental also equipped with a tone arm that is perfect for DJ use, but for the more demanding audio enthusiast, who uses the player at home, is also not of the caliber of the very wonderful Technics Direct Drive principle in terms of quality.

Unfortunately, with the Technics it is a bit less drop-in than with the Lenco and Thorens turntables discussed above, but certainly not very difficult to do. It requires a bit more screwdriving, but also no drilling, sawing and filing in the chassis. With still minimal soldering of the five wires coming out of the GM1's bearing housing. We have a lot of confidence in it!

De GrooveMaster 1 for Lenco in the webshop
De GrooveMaster 1 for Thorens in the  webshop

We have already done several stories on restoring Lenco turntables.

And here you can find stories about Thorens players.

Specifications