Sussex Hornman
Member
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amends accordingly to the buyer and that other pairs of Lowthers he's selling on Ebay Marketplace in Germany will be withdrawn so that others do not buy thinking that units like this are in any way representative of Lowther.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
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