Musical Fidelity A1 Electrolytics
By ARS, Mar 29 2012 04:05PM
Along with the Cyrus 1 and 2 amplifiers the compact Musical Fidelity A1 is another very good value excellent sounding amplifier as long as you partner it with reasonably sensitive speakers.
Biased mostly into class A it runs very hot though with the top of the amplifier forming the heatsink which reaches temperatures of up to 60 deg C. Incredibly the earlier examples were a sealed box with no ventilation whatsoever! The end result of this is everything is slowly cooked with the electrolytic capacitors suffering the most.
The picture below shows all the electrolytics removed from a 1987 example . Some are well known respected brands such as Dubilier and Rubycon and others, Sunking, Liyeh and Bennic not so.
Out of the small signal electrolytics pictured below 30% of these were out of spec with low (if any!) capacitance and high ESR. These included all of the orange Sunking ones, the 3 grey Liyeh and a couple of the brown Bennic ones. All of the Rubycon PSU smoothing capacitors were still within Spec but after 25 years they were probably on borrowed time. In fact with the slow deteriotation of capacitors over the years it it probably isn't easy to notice the gradual fall off in performance until they are replaced in one hit as done here.
All small signal capacitors were replaced with 105 deg C Rubycon's (all originals were only 85C rated which does not bode well for a long life in such a hot environment). The PSU caps were replaced with
some nice compact 32mm high axial Epcos 35V ones as the original 25V rating is pushing the boundary a little. More expensive brands are available but at 3 to 4 times the price I doubt the lifetime would scale accordingly.
Once replaced along with a new ALPS blue 50K pot the A1 was returned to it's original smooth sweet sounding personality and for such a basic design and only 20W sounds fabulous once again! The only other drawback with these amplifiers and similar MF equipment of that era is the consistently poor internal build quality more resembling something built from a kit on a kitchen table by a keen amateur! However this is no different to several other UK products from the 1980's so perhaps it was considered acceptable at the time and simply looks rough compared to todays standards.