My new 'summer' amplifiers
Recently acquired, a pair of Quad 510 monoblock amplifiers. These were bought as an alternative/back-up to my Mark Levinson ML-2 monoblock amplifiers.
The Quad 510 is essentially one half of the Quad 520 stereo amplifier (the circuits are identical in both the 510 and 520) but with one very important difference. Whereas in the 520 the output is connected directly to the output terminals, with the 510 the output is connected to the primary winding of a transformer with multiple secondary windings. In this respect the 510 is similar to the Quad 50D and 50E monoblock amps.
Interior of the Quad 510, showing the output transformer
The presence of the output transformer means that the various secondary windings can be combined in series/parallel combinations so as to cover a range of load impedances (or a range of maximum output voltages). This latter facility, selected by the insertion of the appropriate PCB, is very important as it permits the safe use with Quad 57 speakers, which must not be subjected to a signal of more than 20V rms, otherwise damage due to arcing might occur.
The Quad 510s also have a balanced input. Again this is important, as it means I can locate the amplifiers directly behind each speaker with very short speaker leads, and feed the amplifiers using long balanced-line leads from the preamp (either a Mark Levinson ML-28, or an ML-25/26 combination, both of which have balanced outputs).
So why do I refer to the 510s as my ‘summer’ amplifiers? Well for the last year or so I have been using a pair of Levinson ML-2 25W amplifiers. These amplifiers operate in pure class A mode (which means the power doubles for each halving of the speaker load). They sound superb and when used with Quad 57s are a “match made in heaven”. Being class A however the dissipation is very high: in fact it is 400W per amplifier, so they run hot. Fine during autumn and winter – they supplement the central heating, but are a bit too much in the summer months. Hence, therefore my search for something more efficient - yet have a similarly high quality.
Mark Levinson ML-2 amplifier
Will they sound as good? Well I have yet to find out. I already use a Quad 520 in my second system (using a Mark Levinson ML-10A preamp and feeding Bowers & Wilkins DM2a speakers) and am delighted with its performance. Both the 510 and 520 were designed for professional use. Often professional power amplifiers are viewed by audio enthusiasts as being ‘all brute force but with no finesse’. Well in my experience with the 520, this is not true. These amps have subtlety, finesse and are revealing, yet have a sense of authority and ease. So I’m expecting similarly good results with the Quad 57s. I will report my findings in due course.
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