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Hitachi SR-904

Stereo Receiver (1978-80)

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Hitachi SR-904


Tuning range: FM, MW

Power output: 75 watts per channel into 8Ω (stereo)

Frequency response: 8Hz to 40kHz

Total harmonic distortion: 0.09%

Damping factor: 45

Input sensitivity: 2.5mV (MM), 500mV (DIN), 200mV (line)

Signal to noise ratio: 75dB (MM), 87dB (DIN), 87dB (line)

Output: 200mV (line), 50mV (DIN)

Semiconductors: 4 x IC, 1 x FET, 69 x transistors, 90 x diodes, 1 x thyristor

Dimensions: 490 x 144 x 400mm

Weight: 13.5kg

Year: 1978


service manual   English - danickd

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Reviewed Sep 26th, 2016 by pishta

Fascinating Class-G receiver. Packs a wallop at 150WPC in a non-clipping 2nd power rail activated automatic mode when the music gets hot. Its a mundane 75WPC in standard form but can handle spikes in output power that would cause a normal Class-AB amp to clip. The tuner portion is very nice, draws in stations very well and has a very cool feature when you take your hand off the dial: it zeroes in on the station and centers the tuning meter. even if your a little off the station, when it detects a change in capacitance (your fingers lifting off) on the dial itself, it fine tunes automatically! It has a very nice build quality and most all internal components are Hitachi sourced so it is a very good performer with matched components inside. Exterior is not as flashy as a Marantz but has a brushed AL face with a subtle gold tone and a warm glow from 4 meters and a lit tuner table. The multi colored round LED's (5) seem a little small in comparison to the large meters. Chassis is well constructed with a real cabinet grade wood top, no verneer or wood grain print over metal here! Back has usual RCA jacks with a few unique ones, ie. adapter in/out is for a graphic EQ and is loopable by a push button on the front panel. There are 2 tape monitors, AUX and phono inputs as well as 4 speaker connections in A/B format. Now the only reason I didn't give it a 10 was because the same year (or just after this was introduced in Aug 1978) they came out with the awesome SR-2004 which eclipsed this model by a few steps in power and in stature. If you find an unrestored SR-904, I would recommend buying it as the price of these classic receivers is going up. If it has already been restored and they are asking serious money, I may hold out for another more mainstream model, but these are a bargain IF you can find one.

Reviewed Apr 06th, 2015 by Chris Lupson

Have had one of these for a couple of years now and just love it! Sweet sounding with tons of headroom for any speakers I have used with it. These Dynaharmony amps are way under the radar and deserve consideration.



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