Bose 1800 Dual Slave Amp
The construction is very solid, making the total weight approx. 80lbs. Both the sides of the case and a large proportion of the back panel are finned heat sinks for efficient cooling. An enormous mains transformer and two very large electrolytics fill the centre of the case and there are printed circuit boards on each side of the electrolytic.
The construction of each amplifier board is quite complicated because all the amplifier components, including the output transistors, are mounted on the board. An intermediate heat sink transfers the heat from the output transistor to the main heat sink and all the electrical connections go to the boards via plugs and sockets. The result is that a complete amplifier can be removed and replaced in less than five minutes.
The quality of components and workmanship is good and the wiring tidy and well secured.
The mains cable is of the retained type and has the wrong colour coding for use in Europe. It also has a moulded-on American mains plug which is also unsuitable for use in this country.
The amplifier comes complete with input leads, L.S. connectors and an instruction book.
|Power O.P. (one chan only)||595 W.r.M.S.||Into 4 ohms at onset of clipping||Very good - spec.|
|365 W.r.M.S.||into 8 ohms @ 1 KHz||400w into 4 ohms and 250w into 8 ohms|
|Distortion (total harmonic)||0.07%||@ 400w into 4 ohms @ 1 KHz||Very good|
|0.635%||@ 100w into 4 ohms @ 1 KHz|
|0.06%||@ 4w into 4 ohms @ 1 KHz|
|Output Short circuit test||OK||2 minutes short circuit |
Thermal cut out operated after 1 min. 40 sec.
|Open circuit output test||OK|
|Capacitive load test||10% overshort of square wave||4 ohms and 2uF load||OK|
|Sensitivity||1.49 V.r.M.S.||for 250 watts into 8 ohms||Not sensitive enough for some European pre amps.|
|1.33 V.r.M.S.||for 400 watts into 4 ohms||This level is + 4dBm|
|Output level indication||Worked at correct levels||Very good, imaginative and useful.|
|Frequency response||-1dB||at 16KHz||Good - No detectable bass roll off at 10Hz|
|Noise||—98dB||Below clipping (400w into 4 ohms) |
broad band measurement
|Thermal cut out||Ok||Good - Self-resetting|
A very good quality product with an excellent performance that well exceeds the manufacturers claims. With a total power output capability of 800 watts with both channels operating, a price of £550 excluding V.A.T. is not expensive, viewed on the old pound per watt basis.
We contacted the manufacturers about the American colour coded mains lead supplied (common to most imported American equipment) and we were advised that this is going to be changed to the European standard in the future.
Review by Bruce Gibbs
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