McLaren 601A Preamplifier , 501 & 701 Power Amplifiers
McLaren Amplifiers - The 501 Power amp was produced first but (possibly/apparently) had a reliability issue and was replaced with the 701. This 501 amp has not been touched and works well. Replacing the electrolytic capacitors, especially the two upright pair that are joined together at the top, makes all the difference; in my 701 the distorted sound was completely eliminated when they were replaced. From memory they are in the feedback path and had leaked all electrolyte. In the 501 (and 701 I think) they are 100uf at 63 volt and joined in series for some reason? I replaced them with a single 160 volt 100uf. Being in series only the voltage rating is affected, the capacity value remains as 100uf. In the 501 there is around 60 volts across the two of them. This 501 sounds fine and I don't yet know what differences there are between the 501 and 701 (I may have to find or make a schematic) Just a note: I saw reference to the 501 being bipolar transistors (the output pair), they are in fact (or at least in mine!) MOSFET the same as in the 701. McLaren recognized that MOSFETs were at least equal to bipolar in sound and had several advantages in design; McLaren used them in the 702 & 703 power amplifiers although I do believe at least one if not more bipolar transistor amps were designed. I found it very difficult to let these amplifiers go...so I haven't. After replacing the capacitors and having listened in a proper system, well I hate to use cheesy and subjective audio-speak but they sound wonderful, balanced, warm, detailed ...for amplifiers of this age; I have heard many modern amplifiers costing high end prices and these still foot it with them. If you don't like the drab green styling and a lack of flashing lights and lots of buttons and switches well all I can say is that lack is probably a big part of what makes the sound so good and the plain minimal look ...comes in and out of fashion. These are keepers.