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150w Mono power amplifier
Meridian is perhaps better known for their digital electronics, but they first built their reputation on amplification a long time ago, when they introduced the 100 series. Since then, it has been mostly the company's CD players that caught the hifi-world's eyes, though there had been exceptions; the 605s pictured above being a strong case in point.

Designed as part of Meridian's excellent flagship 600 series, the 605s naturally share the same attractive brushed aluminum twin-box housing, but also makes good use of space by showing off the deeply-finned heatsinks as their facia. A Mosfet output design, 6 in all per channel, the 605s claim 150W per channel, and are able to supply 250W continuous into 4 ohms, sustaining peak currents of over 12 amperes. Although not the most powerful power amplifiers around, they are definitely tolerant of difficult loads - my Dynaudio Craffts, whose impedence dips to 3.3 ohms, were driven cleanly even at high SPLs.

Designed by Bob Stuart, the internal topology of the 605s was considered an experimental departure for Meridian, returning to the kind of circuit he designed for Lecson. The standing current is in the region of 200 mA, meaning at lower listening levels that predominate musical performances, the 605s operate substantially into Class A. Feedback levels are also much lower than usual.

The 605s design also subscribed to the 'fast recovery' school of thought for the power supply, using well oversized 400 VA torroidal transformers for each channel to feed the relatively small 4700 microFarad high current selected Elna Cerafine reservoir capacitors, via a low impedence bridge. This design enables the supply to recover more quickly to stable conditions after musical transients.

The mechanical layout takes advantage of the twin-box construction per unit, with the left box housing the electronics and the right the transformer and capacitors. This layout confers some degree and electrical and mechanical isolation to the electronics.

The 605s reproduce soundstages generously with realistically-sized images - a first sign of good sufficient power output of amplifiers towing the Craffts. High SPLs can be achieved with no signs of compression. The sound on the whole is clean and detailed, but somehow not coming across as overtly forward. Treble is well-extended, but bass sounds a little lean, though the latter is only noticeable in the company of power amplifiers like the Michell Alectos. The 605s also have excellent timing, reminding one of the rhythmic qualities of Naim amplifiers, while also sounding fast, fresh and and very vivid.

On the back panel there are balanced and unbalanced analogue inputs. Balanced interconnection is recommended by the manufacturer for a clearer sound.
Documents
605 User Manual (2,030.1kb)
605 Addendum; Connections (116.9kb)
605 Protection Circuit (191.6kb)
605; Packing Instructions (144.0kb)
 
Photos (view all)
605 Front (54.5kb)
605 Pair (59.6kb)
605 Rear (35.6kb)
605 Rear pair (97.2kb)
605 Top (83.8kb)
605; Internal View (381.2kb)
 
Reviews
605 Review; Audiophile March 1992 (1,627.6kb)
 
Internet Links
 

meridian-audio[.info] 2009 by Duncan Rolfe
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