Sony APM-6

Sony APM-6 Monitor

1 9 8 1 june 1981
1 9 8 6 1986

The APM-6 was launched two years after the original APM-8 monster exercise and in Japan named APM-6 MONITOR because of its simpler 2-way arrangement - better phase response & sound dispersion.

While the APM-8 made it to the State of the Art award, the APM-6 MONITOR was awarded a Stereo Sound Best Product tag right after its official launch, along with a Grand Prix from a roundup of japanese audio critics.

The rounded shape of the laminated wood enclosure was to avoid diffraction at the sides, as tried on several post- APM-8 and APM-4 prototypes.

Like the APM-8, the 3-piece filter was SBMC-encapsulated and made with the finest parts available as well as 99,99% LC-OFC copper ; the two tuned bass-reflex ports are L-shaped inside - a small labyrinth.
The bass driver isn't a scaled-down version of the one used in the APM-8 but an entirely new item made solely for the 6 ; same for the tweeter.

It is arguably sonically the best of the three big ones (APM-8, APM-6 and APM-4 / APM-77) but it is also the most difficult to find (or even see) : despite a production run above that of the APM-8 (possibly 500 pairs) there seems to be very very very few left today (unlike the 8).

Several Sony/Columbia studios used a pair as main monitors and Sony used them very often as demos in audio Fairs and salons. One pair was sold in the UK in late 1982, several have been spotted in Germany, France, the US of A and, of course, Japan but it is a very elusive item. And naturally, it is the one everybody wants !

The "6" also is, alas, the one which careless "restorers" and DIY'ers did ruin without mercy or afterthought, applying senseless "methods" to re-make a square surround, ruining along the way the extremely fragile layers of carbon-fiber damper and aluminium which cover the bass driver's honeycomb structure.

The worst of these tortures was spotted in the US : one north Hollywood shop cut the corners of the the square honeycomb (!) and "adapted" a too large round surround (!!), "closing" the areas thus opened at each (ex-) corner with cloth taped from the inside !

Others seen had had their bass drivers "searched through" with screwdrivers, the surrounds replaced with car rubber, the damping layer glued with something too thick and too abundant, letting some peek through the five front posts, again ruining geometry, weight and freedom of movement... you name it, it's been done. The APM-8 and APM-4 have seen fewer nuthouse mods (in proportion).

Before closing WEGA as an audio brand, Sony SDL made a prototype meant for more visible studio uses :
black with an added base of equivalent height holding dedicated amplifiers and external heatsinks, plus an added cutout next to the APM tweeters, perhaps for level control which the original 6 didn't have.
This prototype was a one-off test which didn't survive the end of WEGA but it still resides in Germany...

Akio Morita was however proud enough of the APM-6 to pose with it for a photograph in 1982 in one of Sony's anechoic rooms. He didn't do that for many products.

The top image comes from a 1982 japanese ad, the one below from a 1982 german catalog, the woofer's closeup from a december 1981 Best Compo japanese magazine. I have many other beautiful images of it - all yet unscanned.

A japanese APM-dedicated website with plenty of images right here.

One badly restored pair here (with a black aluminium surround) and another one here as well (with a very ugly white chamois custom surround).

Sony APM-6, image 1 Sony APM-6, image 2 Sony APM-6, image 3
Sony APM-6 specifications
Title Value
Type : 2-way bass-reflex
Bass/mid driver : 502cm2 APM with four coils/pistons plus centering rod
High driver : 16cm2 APM
Frequency response : 20Hz...20Khz
SPL : 88dB /1W / 1m
Nominal impedance : 8 Ohm
Crossover frequency : 1,2Khz
Nominal power input : 100W
Maximum power input : 300W
Dimensions : 54,5 x 82 x 37,5cm
Weight : 48kg.
List price : 500,000¥
Optional metal stands : WS-6M
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page online since : 2005
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page type : LGT / KNB
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