Plinth design with 2 tonearms

[Evdbrink]

I selected the tonearms, I’m going to use.
It’s a 12” carbon tonearm and the original S-arm from the Lenco 76

I place both arms, motor and mat on the drawing. That way I hope to tackle future problems.

I want to minimize the exposure of the cartridge to the magnetic effect from the motor.




What do I need to check?

- Exposure magnetic field
- dimensions plinth (try to visualize the assembled player)
- What is the path from the cartridge tot the start of the record
- What is the path from start to end of the record
- what are options for a dust over

[Evdbrink]

I checked how far the 12” tonearm can move in the base from the Lenco 75.
It’s a bit hard to measure it, but I think it can rotate 60°.




On the first picture I placed the arm more to the left.
On the second picture I placed the arm more to the right.

I want the arm on rest position aligned with the player.

[vkirti]

Hi,

Did your project move forward ? Am planning to do the same in the near future so am fairly interested in how this turned out.

Regards

VKS

[niclaspa]

You need to know the spindle to pivot point distance for the tonearms.  Then you can experiment with the position of the tonearms.  The Lenco motor has a quite strong magnetic field that can induce hum in cartridges.  Some cartridges are more sensitive than others.  The best place for the cartridge move over the platter is where the distance to the motor is greatest.

[vkirti]

Thanks Niclas Am planning a plinth with two 12'' tonearms (Removing the original). To my mind the correct position's should be on the right and left rear edges of the plinth. One tonearm in the same orientation as the original and the other at 90 degrees to it. The same orientation as shown in the images by Evdbrink. Is that a correct assumption ?

[niclaspa]

Thanks Niclas Am planning a plinth with two 12'' tonearms (Removing the original). To my mind the correct position's should be on the right and left rear edges of the plinth. One tonearm in the same orientation as the original and the other at 90 degrees to it. The same orientation as shown in the images by Evdbrink. Is that a correct assumption ?

Yes, that is right.  However, sensitive cartridges may pickup hum from the position that puts it closer to the motor.

[vkirti]

Meaning, the left arm cartridge may be prone to the hum.  What can I do to nullify this effect ? Will rotating the lenco 90 degrees counter clockwise while keeping the arms position unchanged help reduce the hum ?

[analogadikt]

Meaning, the left arm cartridge may be prone to the hum.  What can I do to nullify this effect ? Will rotating the lenco 90 degrees counter clockwise while keeping the arms position unchanged help reduce the hum ?

Rotating the top plate 90° ccw shall bring the motor coils nearer to the RHS cartridge when it is playing the last track
 The ergonomics also will not be good, the on/off at the rear and speed change under the stylus.

Regards,

Anwesh

[vkirti]

Okay, thanks for the prompt response.

Which position will produce the least amount of hum if two (2) 12 inch tonearms are to be used discarding the original Lenco arm. The tonearms are a Thomas Schick 12'' and Jurij's EMT Clone 12'' arm. 

Can anyone point me to an earlier project where someone has used two 12" tonearms discarding the original ? I have searched the forum but was unable to make much progress.

Thanks in advance

[niclaspa]

Check out where the cartridge crosses the platter on an original Lenco.  That is the position that will give least hum.  To find out where to mount the tonearm, use the spindle to pivot distance of the tonearms to find possible locations.

If you put the other tonearm as suggested, you can still use many cartridges without hum.

[tabarddn]

Hi, I is easy to mount two arms on a standard plinth size, even a 12'' Just check out the attached. You can DIY or buy, the choice is yours.
https://www.lencoheaven.net/forum/index.php?topic=42470.0


Cheers Derek

[vkirti]

Thanks Derek, it is a really elegant solution.

Regards

VKS