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Any Lenco experts / tonearm earthing gurus?

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Dan K

pfm Member
Last week I collected a new to me Lenco GL75 with an Audio mods 4 arm from another pfmer (thanks Jason). Deck sounds lovely, but I decided to check it over with the multimeter and found that the signal and arm earths were joined together. My question is:

Is it always without question better to seperate the 2 signal returns from the arm earth and have them join only inside the phonostage?

I ask this as I would, up to now, have said that it was. Turns out that seperating them made it sound slightly less involving and seemed to reduce the soudstage. I think what is happening is that the combined returns in both my (silver) phono cables provide a far lower impedance than the slightly flimsy copper earthing lead between the deck and my pre.

So, is it really always better to keep signal and arm tube earth seperate, or did the builder of this TT know something (perhaps unique to Lenco/ idler decks) that I don't?

I should also add that the motor and platter side of the deck is totally isolated from the arm and cart.

Thanks
 
Not sure about the advice on that thread, but thanks. The 'B' connection in the diagram will form a loop inside the pre, unless an earth lift resistor is used.

Up to now I would have said that the Naim Armageddon method was the only way to go. The 5th wire is the tonearm tube/ shield wire and is isolated from the chassis. The chassis earth is connected to the mains safety earth. This routing has sounded best to me on an LP12, a PT Too and an Alphason Sonata. The Lenco (perhaps only initially) appears to be different. I'm suspectg that it's due to the impedance of the (cheap) dedicated arm earth cable vs my phono leads.
 
Looking at that diagram again, perhaps it is better to connect the 2 signal earth's together as they exit the TT and then ground them immediately to a radiator or similar, along with the tonearm - keeping any noise out of the phonostage/ pre. Not straightforward
 
Dan K said:
Not sure about the advice on that thread, but thanks.
Click to expand...
Ignore the advice, and indeed the rest of the thread. I posted the link because of the diagram, which is original Thorens. It's from the olden days where you might be powering the turntable, and possibly a tuner and/or tape recorder, from a two-pin auxiliary power outlet on the amplifier, which provides the earth for the whole system (via the signal leads). There should be no loop as only the left (originally mono) channel is connected to chassis and arm, to provide a ground, and the right (additional when stereo records arrived) channel is not connected to anything else (except whatever happens at the preamp). There should be no other earth, everything goes via the (pre-)amplifier which will provide a common earth point (CEP) and thence through the mains lead to Earth/Ground (the real one). It's just to show that Lenco were not the only ones doing "other" arrangements.
 
Is the Lenco using 3 core mains lead, earthed to the top plate? Or still the original 2 core mains lead with no earth?

Go with what sounds best at end of day, but I‘d recommend 3 core mains lead earthed to top plate, and then arm earth connected to top plate and separate from signal return arm leads.
 
3 core mains lead is used which grounds the platter/ plinth and motor. Arm is isolated.

Thanks Dowser. What you've suggested above is Linn's std wiring, which in the past I found to be bettered by breaking the link between the arm and plinth and taking the arm earth to the pre amp (Naim Armageddon wiring)
 
Am I right in thinking the Audiomods arm is based on a Rega? If so there is a chance the arm earth is taken to one of the signal returns as that is just the way Rega do it. I’d contact Audiomods and get their explanation.

PS At a more general level my recommendation is to consider the deck and arm as entirely different entities, e.g. my TD-124 has a proper chassis mains earth which means it is entirely safe and also that the centre spindle is grounded which helps hugely with static. The arm is on a wooden armboard, so electrically isolated from the turntable chassis and the arm is grounded as normal to the preamp via its earth wire. This is my preferred method in any scenario, even if it means actually taking a earth wire to the main bearing as I had to with my old Spacedeck (which killed static pops etc).
 
Thanks Tony, what you've said aligns with my previous thinking. Deck and arm totally separate. Arm is indeed based on a Rega, but is wired straight through to the rca connectors at the back of the TT. I think it's just the case that my phono leads have a lower impedance to earth than the dedicated earth lead.

Here's the build thread:
https://www.lencoheaven.net/forum/index.php?topic=9854.0
 
I run up to seven Lenco's (not at the same time!) and have the top plate earthed via a mains cable, and the signal earth from the arm to the preamp as well. I've only noticed hum when a motor is incorrectly wired. Arms include Rega's, which, in earlier models, had the earth and signal earth combined. At least mine do, and no hum or noise.

Top plate needs a separate earth in case of disaster! Ensure leads to motor are thin 2 ply, so that the motor can hang freely.

Enjoy your Lenco.:cool:
 
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