I wanted to share a trick / modification that can reduce distortion of any (audiophile) speaker chassis that has a (ferrite) magnet.
Speakers have two pole pieces attached to a permanent (ferrite) magnet. One is located around the voice coil (usually attached to the speaker frame) and the other is located inside the voice coil (attached to the rear side of the magnet)
These two pole pieces are usually not electrically connected (multimeter shows a few Mega Ohms resistance) and this seems to be the cause for increased (dynamic) distortion. Ferrite magnets are electrical insulators so when a speaker has one of these installed the pole pieces are not electrically connected.
The modification consists of electrically connecting both pole-pieces together using a piece of wire, clamp or foil.
One pole piece is usually connected to the metal speaker frame and to the rivet that holds the speaker connection terminals.
The other pole piece is at the rear of the speaker (round disc).
One can easily solder a wire to the rivet and clean the metal disc on the rear of the speaker (file / sandpaper) and solder the other end of the wire to the edge of this disc using suitable soldering iron / soldering tip.
In multi-way speakers one has to repeat this mod for every speaker chassis (tweeter, midrange, woofer).
The effect of this mod can be tested during listening by placing a switch in series with the wire so one can connect / disconnect both pole pieces during listening.
Speakers have two pole pieces attached to a permanent (ferrite) magnet. One is located around the voice coil (usually attached to the speaker frame) and the other is located inside the voice coil (attached to the rear side of the magnet)
These two pole pieces are usually not electrically connected (multimeter shows a few Mega Ohms resistance) and this seems to be the cause for increased (dynamic) distortion. Ferrite magnets are electrical insulators so when a speaker has one of these installed the pole pieces are not electrically connected.
The modification consists of electrically connecting both pole-pieces together using a piece of wire, clamp or foil.
One pole piece is usually connected to the metal speaker frame and to the rivet that holds the speaker connection terminals.
The other pole piece is at the rear of the speaker (round disc).
One can easily solder a wire to the rivet and clean the metal disc on the rear of the speaker (file / sandpaper) and solder the other end of the wire to the edge of this disc using suitable soldering iron / soldering tip.
In multi-way speakers one has to repeat this mod for every speaker chassis (tweeter, midrange, woofer).
The effect of this mod can be tested during listening by placing a switch in series with the wire so one can connect / disconnect both pole pieces during listening.
Has you done actual measurements? I have to think this is associated with eddy currents, something that are basically very bad and why copper shorting rings are added to better drivers.
Wonder why I have not seen this on $200 drivers?
Wonder why I have not seen this on $200 drivers?
As my drivers have to come out again this week, I'll give it a try along with the 'Electron Loop' used by BudP.
Though Eminence Beta 12Lta's aint 'audiophile' it might do some thing......
I shall report back with subjective impression.
Though Eminence Beta 12Lta's aint 'audiophile' it might do some thing......
I shall report back with subjective impression.
The LTA is a wonderful driver. Not pretty to look at, but used right it's a real sleeper.
I'd be interested to see before and after (or shorted and non-shorted) measurements of this trick.
I'd be interested to see before and after (or shorted and non-shorted) measurements of this trick.
If you look at this picture:
http://www.hhelectronics.com/images/technology/HH-loudspeaker-parts.jpg
are you talking about a jumper between the front plate and the yoke?
Thanx
http://www.hhelectronics.com/images/technology/HH-loudspeaker-parts.jpg
are you talking about a jumper between the front plate and the yoke?
Thanx
This user whole heatedly agrees - and it's cheap / strong enough to mess about with.
balerit:
I would guess so, having just plumbers caulked this area as part of basket damping, I'm going to have to go digging to get there......*sigh
An alternative would be to laminate the pole piece, but apparently no one found an easy and cheap way to do it.
I think I'll try this asap with some cheaper bass drivers I have around, it's quickly done and who knows...
a) Measure the voltage, if any, between the yokes with a very sensitive diff-amp.
b) Redundantly, connect the yokes with the lowest possible resistance and measure current, if any, with a precision current clamp.
I don't expect to see anything (the professional driver designers would certainly know this trick after some 100years of experience, me thinks), but who knows...
Then if there is something, multitone distortion testing of the driver's impedance would certainly show a difference (IME much clearer and more reliable than acoustical measurments).
a) Measure the voltage, if any, between the yokes with a very sensitive diff-amp.
b) Redundantly, connect the yokes with the lowest possible resistance and measure current, if any, with a precision current clamp.
I don't expect to see anything (the professional driver designers would certainly know this trick after some 100years of experience, me thinks), but who knows...
Then if there is something, multitone distortion testing of the driver's impedance would certainly show a difference (IME much clearer and more reliable than acoustical measurments).
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