Earthing Loudspeaker units worked for me

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C37

Member
2003-03-21 4:46 pm
Brussels
hello to all,

Some time ago i became curious about earthing the loudspeakers units, as Tannoy do. Then recently i stumbled on this site:
http://pageperso.aol.fr/petoindominique/doc_htm/detail.htm
( in french) and i decided to give it a try.
After all it's cheap, and fitting it on my active Genelecs 1031 would be straightforward as there is an earthing connection in the amp at the back of the speakers. I wanted the whole thing to be retrofittable in case i didn't like it so i connected the pole pieces of both tweeter and bass/mid to a copper solid core wire coming out through one of the vents openings in the front and connected it to the earth tag of the amp at the back.
The author of the above mentioned article on the net warned that this would bring subtle changes that need some time to win you over.( he mentions 24 hrs)

Well as soon as my first speaker was done i could' nt resist palying it for a bit before tweking the second one. i could immediately tell something different was going on on the left side ( tweaked speaker) so i hurried to do the second one.

The result is my system is amazing and was immediately felt and heard.To make a visual analogy, the sound seems to come from a much darker background. It is quite a bit cleaner too. Speech and lyrics are now much more understandable. For example, i have some takes of Burhan Ocal, a turkish percussionist/singer that were made at a concert we organised 2 years ago. i surprised myself singing along with him on this intoxicating feed only that this time i was able to repeat clearly all the words- even if I don't speak turkish at all. He is accompanied at the double bass by Volker Biesenbender and it really finally blossomed.

So i started playing with records which i thought agressive or poorely mastered - and the shock went on... Sybilants under control by now, soundstage more focused, less distorsions..., Any drawbacks? Well, on some recordings the pace and rythm of the music seems a tad slower- but this could be due to the fact there is more defined bass (?)

I can only urge you to try it by yourselves, the cost could be zero if you have some solid core copperwire hanging around and if you have ported loudspeakers you could try it without having to drill anything. Just be extremely careful not to mess with the tiny leadouts wires on the tweeters.

Finally a question that puzzles me since: could it be that the copper wires i added around the speaker's front and rear magnet poles could mess with the magnetic field presented to the voice coil somewhat?

Success!

all the best
T
 
hi

we would have to differentiate Tannoy and your Genelecs - Modified ( & not modified ) in two cases

Firstly both are great drive units (we all know it but I guess they deserve a speacial mention )

Tannoy has a shorting ring placed inside the magnetic flux lines thereby reducing third harmonic distortion by reducing the interference created by the magnetic field generated by the charged voice coil & the flux lines of the permanent magnet

we must appreciate that this creates the drive force of the driver -
but as these two forces interact the Inductance of the voice coil changes to - x - on the inward stroke to - z - right at the center of the magnetic gap and to - y - on the outward stroke

the shorting ring stabilises this inductance change - as - by a changing inductance there arises distortion and a cause for frequency responce to shift and be in-accurate to design parameters of the driver

In Tannoy there is a wire connected / soldered to this shorting ring and is brought out through a hole in the back plate and then grounded

Like shown in the diagram , attached

To modify your Genelecs to have this additional Improvement -

Please check a thread recently commenced -
where I have explained the process of opening up the motor structure to insert - shorting rings - and improve the motor structure to SFG etc.

In your case of modification :- did your original drive units have a wire taken out by the driver manufacturer through the bottom plate as shown in the diagram attached below - if yes and you have grounded it - then you need not modify the Genelecs any further

If the above is not fulfilled in the Genelec Drivers :-

As far as my Knowledge goes :-

Firstly - any thing you add like some copper / or wire etc outside the magnetic flux lines center line - unless - very strageteically placed on the pole piece itself inside the voice coil winding - in its travel distance over the pole piece or quite near the extremes of its travel it will not have any effect to the performance of the driver

while on the above the shorting ring :-
a shorting ring placed outside the center of flux lines mentioned above will reduce even order distortions in a similar fachion explained above - by stabilising vc inductance

In your Genelecs I guess the earting of the Top / Bottom plates may have resulted in grounding some stray Eddies that may have been induced on to the magnet plates by the chrged travelling voice coil

Suranjan Das Gupta

Transducer Design Engineer
 

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Hi

to modiify any driver to include the shorting ring used by Tannoy as shown in the diagram please refer to the thread :- Repairing and Modifying your drivers - started by - Hayden , ( where i have mentioned the process to open up a motor structure to carry out modifications )

the shorting ring can be of any non magnetic conductive material like - aluminium or copper

Suranjan
 

C37

Member
2003-03-21 4:46 pm
Brussels
fascinating and puzzling

Thank You Suranjan for taking the trouble answering and enlighting me. I am puzzled because the effect in this system is very noticeable on the whole audio band, and that really puzzels me as to why? Will go and investigate on Eddy curents now... Maybe the fact that there are a couple of wires for the on/off leds on the tweeter front place that run along the audio wires might play a role. I will check your thread. Thanks again

Thomas
 
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