I've been maintaining Lowther units for many years and today was sent a pair for service.
They had been bought within the month from German ebay classifieds. Said to have been professionally reconed and refoamed the units didn't seem quite right.
Upon opening the parcel I found that the cones were sitting right at the bottom of the frames and not moving in the magnet gap. Taking them to pieces . . .
PM6C units have to have the top of the voice coil flush with the back of the frame . . . Um . . .
and when refoaming old foam and the glue if possible has to be removed properly before new foams are attached . . . and it's rather a good idea to make sure that the cone is centred . . . and the foam is properly and evenly glued . . .
A very professional refurbishment indeed.
I reported accordingly:
I advised: whilst I could bodge, introducing packing between frame and magnet, applying more glue where missing, possibly replace the spiders or more, the units are still likely to end up a mess and potentially troublesome with potential issues with the voice coils and unknown glues which may not be able to be removed successfully. For this reason and bearing in mind they were sold as having been competently rebuilt, they should not be returned to the seller for him to re-bodge and re-sell as Lowther units and instead should be forwarded to Lowther for service replacement at his expense.
I hope that the seller will make amends accordingly to the buyer and that other pairs of Lowthers he's selling on Ebay Marketplace in Germany will be withdrawn so that others do not buy thinking that units like this are in any way representative of Lowther.
Best wishes
David P
They had been bought within the month from German ebay classifieds. Said to have been professionally reconed and refoamed the units didn't seem quite right.
Upon opening the parcel I found that the cones were sitting right at the bottom of the frames and not moving in the magnet gap. Taking them to pieces . . .
PM6C units have to have the top of the voice coil flush with the back of the frame . . . Um . . .
and when refoaming old foam and the glue if possible has to be removed properly before new foams are attached . . . and it's rather a good idea to make sure that the cone is centred . . . and the foam is properly and evenly glued . . .
A very professional refurbishment indeed.
I reported accordingly:
- the voice coils should be near flush with the back of the baskets / front of the magnets on the C series Lowthers and upon re-foaming they have not been set up properly. This may be part to do with mis-mounting, and may also be a result of using non-original foams
- the old foam had not been removed and cleaned properly from the cones
- the old glue had not been removed from the cones. This causes difficulty in properly locating new foam in position
- the new spiders had been installed on one skew, which would cause problems with centring and skewed from perpendicular motion, and on the other, off centre and not properly glued.
- on one a voice coil repair has been carried out with new lead-in wires down the cone. Without disassembly I'm unable to see the join but (a) such joins are very difficult to achieve, (b) unreliable and (c) if a voice coil has failed in one place it is likely to fail in another place for the same reason as the first failure. Such units should be returned to Lowther for their service replacement service.
- on one voice coil there is a noticeable vertical line across all turns, probably caused through abrasion past something in the magnet gap. The wire is visibly kinked. This is soft aluminium wire and if thinned or fatigued by such a kink increases probability of failure.
- by eye the voice coil of at least one of the units does not appear to be perfectly circular. Circularity has to be achieved using a special tool if necessary and possibly steam if particularly bad, and this is clearly beyond the scope of whoever was responsible for the repairs. It is critical as at best there is only 1/4mm tolerance within the magnet gap and poor circularity can reduce that beyond the wisker leeway.
I advised: whilst I could bodge, introducing packing between frame and magnet, applying more glue where missing, possibly replace the spiders or more, the units are still likely to end up a mess and potentially troublesome with potential issues with the voice coils and unknown glues which may not be able to be removed successfully. For this reason and bearing in mind they were sold as having been competently rebuilt, they should not be returned to the seller for him to re-bodge and re-sell as Lowther units and instead should be forwarded to Lowther for service replacement at his expense.
I hope that the seller will make amends accordingly to the buyer and that other pairs of Lowthers he's selling on Ebay Marketplace in Germany will be withdrawn so that others do not buy thinking that units like this are in any way representative of Lowther.
Best wishes
David P
Actually looking at the photos, so distracted by the workmanship I've missed the obvious! DX or A series cones in the C series frames . . . OUCH!
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that is well beyond a bodge, it’s downright fraudulent misrepresentation!
I have always been intrigued by the Lowther brand, so I got myself one of the little cute A55 units, currently still in it’s box but hopefully will find itself in a nice 2-way mono project before the end of 2021.
I have always been intrigued by the Lowther brand, so I got myself one of the little cute A55 units, currently still in it’s box but hopefully will find itself in a nice 2-way mono project before the end of 2021.
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In the light of day I looked again at the cones - they are C series cones but not mounted properly.
The ebay seller has responded:
TEX REMOVED
The photos below show the mounting of the front foam with the cone.
They are simply not fitted properly.
Best wishes
David P
The ebay seller has responded:
TEX REMOVED
The photos below show the mounting of the front foam with the cone.
They are simply not fitted properly.
Best wishes
David P
The seller has responded to the buyer:
TEXT REMOVED
To make it very clear I do not sell Lowther speakers.
A link to one of this seller's pages is:
Lowther PM 6c, 2 Stuck, reconed, einwandfreier Zustand in Baden-Wurttemberg - Pfinztal | Lautsprecher & Kopfhorer gebraucht kaufen | eBay Kleinanzeigen
showing location 76327 Baden-Württemberg - Pfinztal
Best wishes,
David P
TEXT REMOVED
To make it very clear I do not sell Lowther speakers.
A link to one of this seller's pages is:
Lowther PM 6c, 2 Stuck, reconed, einwandfreier Zustand in Baden-Wurttemberg - Pfinztal | Lautsprecher & Kopfhorer gebraucht kaufen | eBay Kleinanzeigen
showing location 76327 Baden-Württemberg - Pfinztal
Best wishes,
David P
On ebay at the moment is a pair of Stamm drivers in LothX cabinets which I have rebuilt with very lightweight especially produced cloth surrounds. The back spiders used by Stamm were cloth also so these units will last a lifetime, especially as the voice coil isn't aluminium. I tested the frequency response and they are better in the 14-20kHz region. Loth-X Troubadour speakers | eBay Potentially well worth going to hear and in my opinion a bargain at the price. The owner is a recording producer and he has needed to standardise his home speakers in line with his recording engineers.
Best wishes
David P
Best wishes
David P
Please read the forum The German seller is now advertising a pair of Fostex units
and he specifically states now on the advert:
Suffice to say the buyer of the Lowther units hasn't had much joy from him . . .
Best wishes
David P
and he specifically states now on the advert:
Suffice to say the buyer of the Lowther units hasn't had much joy from him . . .
Best wishes
David P
Hello David,
"the voice coils should be near flush with the back of the baskets / front of the magnets on the C series Lowthers " - how should they be located at the A series?
Regards, Volker
"the voice coils should be near flush with the back of the baskets / front of the magnets on the C series Lowthers " - how should they be located at the A series?
Regards, Volker
Likewise. The top turn of the voice coil should be flush with the top of the magnet pole face. This is why Lowthers should be horn loaded so that they don't move more than 1 or 2 mm out of the magnet gap.
Whilst not liked by some, the hi-ferric treatment helps to keep the voice coil centred on the maximum magnetic field.
Best wishes
David P
Whilst not liked by some, the hi-ferric treatment helps to keep the voice coil centred on the maximum magnetic field.
Best wishes
David P
Chiming in, not for this particular speaker but a general purpose answer:
rather than aligning with frame, itself not a part of the magnetic circuit which might or might not always rest in the same position relative to it, the "golden rule" is aligning voice coil winding length symmetrically within or around front plate/gap thickness.
* If VC has same length, align its front/first turn with gap/top plate edge, as mentioned above. By definition other winding end will align with the internal (magnet side) gap end.
* If longer (which usually happens although I don´t know this Lowther speaker details) then front ends must NOT be aligned, as it will be very unsymmetrical and among other things cause unneeded low frequency distortion.
In that case, extra length must be evenly split front and back.
Example: if top plate is 8mm thick and voice coil winding is 12 mm long, you must sit it so 2 mm show on top, you can safely assume symmetric 2 mm would be visible from the bottom.
Of course, use actual measurements from that particular speaker.
EDIT: just read your answer, so these speakers have plate thickness winding length?
Nice to know.
Just curious, would you share its winding length?
Even better, any VC closeup picture? 🙂
Designing and making speakers for over 40 or 45 years by now, but still learning every inch of the way, plus Full Range Hi Fi units are outside my daily experience.
Thanks in advance.
rather than aligning with frame, itself not a part of the magnetic circuit which might or might not always rest in the same position relative to it, the "golden rule" is aligning voice coil winding length symmetrically within or around front plate/gap thickness.
* If VC has same length, align its front/first turn with gap/top plate edge, as mentioned above. By definition other winding end will align with the internal (magnet side) gap end.
* If longer (which usually happens although I don´t know this Lowther speaker details) then front ends must NOT be aligned, as it will be very unsymmetrical and among other things cause unneeded low frequency distortion.
In that case, extra length must be evenly split front and back.
Example: if top plate is 8mm thick and voice coil winding is 12 mm long, you must sit it so 2 mm show on top, you can safely assume symmetric 2 mm would be visible from the bottom.
Of course, use actual measurements from that particular speaker.
EDIT: just read your answer, so these speakers have plate thickness winding length?
Nice to know.
Just curious, would you share its winding length?
Even better, any VC closeup picture? 🙂
Designing and making speakers for over 40 or 45 years by now, but still learning every inch of the way, plus Full Range Hi Fi units are outside my daily experience.
Thanks in advance.
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