This pickup was produced by Japanese manufacturer Maxon in the early 1970s - possibly earlier. Maxon started applying date codes to the undersides of their pickups in the early-mid 1970s, which is quite helpful in dating the guitars which have them. It is not clear how widely this specific pickup was used (i.e. with the same construction, magnet, number of turns etc), but was fitted to the Aria 5522, Univox Rhythm and Blues U1982, Jedson 4444), and Shaftesbury 3400.
Although the broad construction of this pickup did not change, there was a significant update in late 1972 or early 1973. The baseplate, formers (bobbins), magnet all appear to be unchanged (at least in dimensions), but the cover is 2mm taller, and the polepieces 3mm longer. They are also slightly more widely spaced, increasing from around 9.4mm to just over 10.0mm (see image below).
The DC resistance of early seventies pickups vary between 11.8kΩ and 12.0kΩ - the 1973 version is lower varying between 7.8kΩ and 8.0kΩ, and appears to have a greater depth of winding on the bobbin. Without dismantling it is hard to make accurate assertions on wire type/coating etc, but it would seem that the new coils are wound with thicker wire (for increased highs?) which would naturally decrease resistance.
Like other Matsumoku parts, this pickup is reasonably complicated in construction, and consists of numerous parts.
List of Matsumoku pickups
A pair of Maxon humbuckers fitted to a 1971 Shaftesbury 3400. The pickups are height and rake adjustable with three 25mm mounting bolts, two at the top (roughly 20mm apart) and one at the bottom.
Underside view. Maxon started applying date stamps to the underside of their pickups in (perhaps) early 1973 - these pickups from the aforementioned 1971 Shaftesbury 3400 have no markings.
With the mounting rings removed. These pickups are largely held together with dark brown glue.
The pickups and their routes
A Maxon humbucker from a 1973 Shaftesbury 3400. The date stamp (13106) can be decoded as follows: 1 = production line #1; 3 = year, 1973; 1 = month, February (Jan = 0, Feb = 1 etc, X = Dec); 06 = day of the month. So this pickup dates to February 6th 1973. Maxon didn't stamp their pickups much before 1973, and the bridge pickup that was fitted to this guitar has no markings.
Beneath the date stamp, (and somewhat hard to see) is the stamped Maxon logo. Again, the bridge pickup matched to this one has no markings.
The gold-plating of this pickup has largely worn away, although it is most visible on the pickup sides, generally the areas protected by the plastic mounting rings.
The gold-plating of the cover is still very strong on the underside of the cover. With this removed, the structure of the pickup is apparent: two side-by-side coils, with adjustable polepieces passing through one coil (on the left), and a non-adjustable 'crenellated' polepiece strip through the other.
These pickups share several features in terms of construction with the trapezoid single coil pickups fitted to Matsumoku guitars from 1966. For example both pickups have a vinyl fabric strip over the polepieces. Another similarity between the two pickups is the shape (but not dimensions) of the polepieces.
An end on view shows two metal bars beneath the coils: the one on the left (with rounded ends) is threaded to hold the polepieces, the piece on the right, centred below both coils, is the bar magnet itself.
The other end shows the connections between the two coils, and where the output wires attach to the underside of the baseplate.
From above, the actual coils are visible through the semi-translucent formers. Note also the threaded polepiece holes inside the bottom coil.
With the coils lifted off, the magnet, 'polepiece holder' and baseplate are clearly seen.
Whilst one coil surrounds the adjustable polepieces, the other coil surrounds this non-adjustable metal 'crenellated' strip. Actually, the strip is two similar strips glued together. The strip has dimensions 55.5mm x 4.6mm wide x 12.5mm tall, but it is not particularly uniform. The 'gaps' are roughly 4.9mm-5mm across x 5.4mm deep; the crenellations 5.1mm-5.4mm wide v 5.4mm tall.
The vinyl fabric strip has approximate dimensions of 60mm x 16mm, though it isn't perfectly rectangular or uniformly cut. The purpose of this strip is not entirely clear! Any ideas? Please comment
Vinyl fabric strip underside view.
The gold plated polepieces have dimensions 16.3mm long, approx 7.7mm of which is threaded. Major diameter 5.5mm. The thread is pre-1967 Japanese standard M4 (i.e. pitch of 0.75mm).
Matsumoku Maxon humbucker mounting rings, bolts, screws and springs. Three height adjustment bolts / pickup: 25mm oval cross head with pre-1967 Japanese standard M3 thread (pitch of 0.6mm). The plastic surrounds have approximate dimensions 94mm x 50mm with a cutout of 71mm x 40mm. Their heights vary somewhat, as the bottom edge is curved to match the arched top of the guitars body, but the neck pickup surround has a maximum height of 4.3mm, the bridge 9.3mm. The surrounds are held in place with four oval cross head screws sometimes 20mm, sometimes 15mm at the bridge; and 10mm at the neck.
As explained above in late 1972 or early 1973, the polepiece spacing was increased whilst a larger diameter wire was used for the windings.
1971 Maxon humbucker (left) and 1973 Matsumoku Maxon humbucker (right) with covers removed. Both pickups have the same size former (bobbin), roughly 67mm x 16mm x somewhere between 8.5 an 9mm - but note the increased volume of windings on the '73; the decreased DC resistance suggests this is due to thicker gauge wire as opposed to more windings (which would increase resistance). pre-73 pickups typically measure 11.8-12kΩ, '73 onwards pickups typically measure 7.8-8kΩ.
1971 Maxon humbucker (left) and 1973 Matsumoku Maxon humbucker (right) with covers removed. Both pickups have the same size magnet, centred beneath the coils: 58.0mm x 10.7mm x 3.3mm.
1971 (top) and 1973 (bottom) Maxon humbucker covers. Note the differing pole piece spacing: 9.4mm for the 1971, and a shade over 10mm for the 1973.
1971 (left) and 1973 (right) Maxon humbucker covers. Note the differing heights: 14mm for the 1971, and 16mm for the 1973. Both covers are 70mm long x 39mm wide.
1973 (left) and 1971 (right) Maxon humbuckers.
1971 (left) and 1973 (right) pole pieces. Both share a 5.5mm diameter and a pre-1967 Japanese standard M4 thread (0.75mm pitch) but the 1973 is longer: 19.0mm vs 16.3mm. Note also the slightly curved top of the 1971.
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