Harbeth 40.1

Beschrijving / Description

Harbeth M40.1 Domestic loudspeakers are three-way, bass reflex monitors. Their dimension ratio surely isn't very modern. Some similarity might be found in Audio Note speakers (see AN-E). Front panel is very wide even wider than the size of bass unit would require. And that woofer is a really big one - 300mm in diameter with polypropylene diaphragm. For its predecessor the M40, Harbeth used a Vifa driver that, according to some, was a bit boomy. Once Vifa stopped making it Alan Shaw decided to have a better one, and what's better than a thing you do yourself. So now Harbeth manufactures its own improved (comparing to Vifa) woofer with a large cast basket and double magnet. Midrange woofer is also pretty big diameter 200 mm, also manufactured in-house, and it's placed in a separate chamber inside the cabinet. Its diaphragm is made of some kind of polypropylene called Radial 2. Its development was possible thanks to a grant from the British government. Here we already have its version no. 2. Both woofers are fixed to the front panel from behind. The only outsourced driver is a 25 mm fabric dome tweeter manufactured by Norwegian SEAS from Excel line, with a small Harbeth's modification called HexGrille. This tweeter looks like T25C003 double magnet, a chamber for eliminating unwanted resonances, but without ferrofluid. The tweeter is fixed to the front panel from the front side. There are two BR ports just above the bass unit.

The cabinet is made of relatively thin MDF boards. That's a trade mark of all Harbeth loudspeakers. There is not much bracing inside it's built more like an instrument. All walls are covered with bituminous mats, and inside some places are filled with some kind of quite stiff foam, and some tight rolls of a natural wool.
The PCB with crossover circuit is bolted to the back panel. Some elements are bought from external manufacturers and hand-picked and others are made in-house. There are single speaker posts (the M40 sported triple posts as in studios they often use multi-amping). These are solid but surely not fancy I know them from many budget products well, Harbeth surely chose them for a reason. Front and back panels are not glued but fixed with 16 screws (each). There is a grill based on metal frame that may be fixed to the front of each speaker but if you do that the whole charm of these beautiful speakers is gone so I would suggest leaving the grills in boxes. Each driver has its serial number including information whether it's for the left or right channel. All measurements for each of them are kept in Harbeth's database in case any of them ever needs replacement.

These loudspeakers have a very level impedance of 6 ohm which makes them good partners for tube amplifiers. Their real sensitivity is very low though John Atkinson's measurements for the above mentioned Stereophile review (Art Dudley's review from October 2008) proved that it was as low as 84,5 dB/2,83 V/m. I tried driving the Harbeths with my modified Leben CS-300 [Custom Version] that offers 2 x 7 W output power and it was clear that more power was necessary to drive those speakers properly. Manufacturer suggests minimum 50 W which surely is a good idea but in smaller rooms 20-25 W might be enough.

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Harbeth 40.1

Beschrijving / Description

Specificaties / Specifications