Coherent Systems - Reviews

HiFi World - August 2008

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American Team

It sometimes seems to me that we here in the UK are sometimes short-changed when it comes to hi-fi equipment that is not designed within our shores. When one considers the fact that large Japanese corporations have a history of not sending us their biggest and poshest products, and the sheer number of unknown names that can be found fairly close to home when one visits the likes of the High End show in Munich, there is defiantly a whole lot of equipment out there that we’re missing out on!

Unsurprisingly, this is true of the U.S. which one would expect to have a large number of manufacturers, simply because of the size if the place. Obviously, we know of the bigger players such as McIntosh, JBL, Martin Logan and Krell, but some of the smaller names are still unknown; I certainly can’t name a UK store that currently sticks Salk Sound, Salagar, Portal Audio or Magico. Fortunately, some more intrepid distributers looking for high end quality equipment have had the sense to venture further afield in this direction...

One of these distributers is Tony Sallis of Coherent Systems, a man with extensive experience within the industry and a keen ear for a good product. It should come as no surprise then, that one of the product lines for which Coherent are responsible un the UK are indeed a small IS manufacturer. Power Modules Inc. Is based in Pittsford, New York and run by David Belles, who has over thirty years experience in high quality amplifier design.

David states that “All Power Modules are state-of-the-art designs, using top quality components. Each unit is hand assembled and tested to ensure it meets our high quality standards for fit, finish and audio performance”. As a result, their range encompasses several preamplifier and power amplifiers, including a hybrid valve/solid state preamp, plus a forthcoming integrated design. The most recent additions to the lineup however, are the Soloist range, currently comprising a preamplifier and power amplifier, with an MM/MC phono stage rumoured to be on the way soon.

The Soloist 3 preamplifier features five line level inputs (although one is labelled ‘phono’ it is still a line level item), plus a single fixed input and output that can act as a bypass in the context of an A/V system. Rear panel socketry is completed but two pairs of preamplifier outputs. Remote control is provided for input switching, volume, balance and muting and I was a little disappointed to see that the remote is the only way to switch inputs and to activate the preamp on power-up (it starts up in a ‘mute’ condition).

The remote is a small item and could easily be lost, where upon you lost your sounds until you obtain a new one – something we know all too well from our pre-production Anatek A50R, which had the same muting operation. Needless to say, in a recent office move, this was the only remote we lost! The Soloist 3 is a compact design, measuring 51x305x216mm (HxWxD) and weighing in at 4kg.

The Soloist 5 power amplifier is equally small, but taller at 90mm high, and tipping the scales at a healthy, but still reasonable 7kg. Under the bonnet is a simple amplifier circuit rated as delivering 65 Watts into 8 Ohms and 110 Watts into 4 Ohms [see MEASURED PERFORMANCE]. The Soloist 5 offers a pair of phono input sockets and two pairs of good quality gold plated binding posts and that’s it, apart from a 12V turn-on trigger input for remote operation.

Sound Quality

After a thorough warm-up the Belles combo set off to a highly promising start. What struck me instantly was the bass provided but the power amplifier – I can safely say that I have not heard any £900 design that grabbed hold of our Spendor S8es with such authority and control. Bass lines were massively deep, confident, swift, highly rhythmical and blessed with superb amounts of detail. The bass guitar on the intro to Simply Red’s ‘Sad Old Red’ was amongst the best I have ever heard it and, through a less than capable loudspeaker and amplifier combo, it can sound like a sluggish, marshmallow blob. Through the Soloists however, it was taut, focused and each string pluck was immaculately defined.

The rest of the performance was equally capable. Sound staging was not the widest I have ever heard but it was impressively deep and well ordered between the loudspeakers, The most impressive facet, however, was the stunning solidity that the units conferred upon the central image. The main action really did step out of the soundstage, smack in the middle of the loudspeakers, which gave a quite uncannily realistic effect at times.

Aiding this was the realism that the combo imparted onto instruments. Individual string plucks were crisp and piano keys hit home with pleasing precision. Thanks to that central image stability, lead vocals stood well clear of the backing track, giving a lovely atmospheric turn to proceedings. Kat St. John’s ‘Paris Skies’ was delightful – the introductory glockenspiel rolling across the soundstage and Kate’s vocals projecting expertly.

The more I played with the Belles combo, the more I was impressed, but I did start to detect a certain hint of hardness across the upper mid with some more strident vocalists or less well recorded classical material. The Soloists’ top end was sweet and insightful, without any harshness, but there was definitely lower down.

Switching equipment round a little, it seems that the power amplifier is the source of this, as swapping the preamp for the Creek OBH-22 did not remove the problem and, in fact, dulled the overall sound, removing the life, atmosphere and ebullient presentation of the Soloist 3.


The Belles Soloist 3 and 5 combo really are a musically coherent and pleasingly dynamic pairing. The preamplifier is a sweet and open performer with a good range of inputs in a compact package that is not excessively priced. The power amplifier is even more impressive in some respects, particularly in its superbly tight, deep and well controlled low end. It does also introduce the only slight issue with the sound, namely a slight hardness across the upper midband at times, but it is in no way a hard and steely sounding device and this aspect of its sound should be easily tuned out by choosing a relatively laid-back pair of loudspeakers.

All in all, I enjoyed my time listening to the Belles Soloist 3 and 5 combo; they work very well together to offer a musically cohesive whole, and offer fine quality at a sensible price – welcome visitors from across the pond!

Measured Performance

The Soloist 5 power amplifier comfortably exceeded its rated power output into 8 Ohms, delivering 85 Watts, rather than the expected 65W. This increased to match the rating of 110W into 4 Ohms, so the power supply is not quite hefty enough to double output into the lower load, but the amplifier does not lack power and should drive most loudspeakers. The Soloist 5 has an unusual negative damping factor, but this is a high value of 138 so it should have tight and well controlled bass.

Distortion was commendably low at 1kHz at both 1W and full output, but increased by a factor of ten or more at 10kHz. This is the effect of classic crossover distortion so is not an uncommon phenomenon. Channel separation and noise were both very good.

The Soloist 3 preamplifier offers a gain of x2.2 across its line level inputs and has a similar frequency bandwidth to that of the power amplifier, being 2Hz-30kHz. Noise was low, channel separation good and distortion low at 0.002% across medium and high frequencies. Output overload occurred at a high 8.5V so the Soloist 3 should be capable of driving an insensitive power amplifier if required.

All in all the Belles combo measures well and should offer a tight and focused performance, but the higher frequency crossover distortion noted in the power amplifier may make them a touch less smooth and refined towards the top end than some of their competitors.

Power 85 Watts
Frequency Responce 2Hz - 27 kHz
Separation 90dB
Noise -95dB
Distortion 0.2%
Sensitivity 1V
Damping Factor -138
Gain x2.2
Frequency Responce 2 Hz - 30kHz
Separation 93dB
Noise -98dB
Output Overload 8.5V
Input Overload >6V

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