Coherent Systems - Reviews

Henry Tang - Coherent Modification

These solid state monoblox power amplifiers designed and implemented entirely by Coherent Audio Systems are as far as I know unique and one of a kind, or should that be two of kind? The heart of each power amp is based around a Tripath switching amp module (variously also known as PWM, digital or Class-T technology). The amp modules (albeit with one or two component substitutions) are the only off the shelf components in these amps, the rest has of the supporting cast been custom designed and built in order to get the most out of these amp modules. Particular attention has been paid in the areas of power supply regulation and minimising RF interference, two areas that Coherent Audio Systems felt to date no manufacturer implementing amps using this type of technology had bothered to optimise anywhere near enough in order to realise the full potential of this technology. Attention has also been paid to microphony as is evidenced by the amount of case and component damping applied internally. The list of custom components inside includes custom hand wound transformers, hard wiring with specialist cable (the same wire as that used in Coherentís range of cables), and some very unique power regulation circuits. All in all, this is a hand built project implemented from the ground up with many hours of fine tuning and listening performed in order to select the right components which to go make up the final product.

So how do they sound? A straight wire with gain comes to mind as the most succinct description I can think of. This is, in my opinion is how solid state should be. The sound here isnít euphonic, nor is it stark and analytical in the way that a component designed to solely to analyse whatís wrong rather than whatís right with the incoming signal; it gives you whatever the source is presenting to you but also allows you select whether to bask in the music making as a whole or to follow each individual musicianís contribution. There is a noticeable lack of hash and grain to the sound which you suddenly become aware of only when you realise how much louder youíre able to play a lot of recording you previously held the volume back on due to them being a brash, sibilant or just generally nasty at high volumes. The headroom available on these amps seems just about limitless, but then with almost three-quarters of a kilowatt of available power from each amp feeding into the 88dB/w efficient speakers that I own, one might not find that conclusion all that surprising. One of the upshots of all this dynamic headroom is you start to notice the dynamic limitations in the recordings you feed the amps, such as when too much compression or limiting be applied in the recording process albeit this not in an out and distracting manner, or on the flip side with the right recording how much more impact and snap you can get from the drum kit on a favourite album youíve been playing for years. All this power without ever breaking into a sweat too, yes these amps donít ever get any more than lukewarm regardless of whatever levels youíre playing them at due to the technology used in the amp modules being inherently over 90% efficient with their power input.

You might think that with all this power on tap that these amps are not able to handle the grace, delicacy and subtlety required for less visceral music making, but surprising they do just as well here too. Ambient clues, recording venue acoustics and image placement are revealed very well by this amp, yet the sound also remains palpably rock solid and cohesive. There was also more insight into bass lines and in general what was going in the bottom octaves compared to a pair of well known Tripath based monobloc amps I was using before, which by comparison was less well resolved both in the tune as well as the rhythm departments. Further up the audio range, vocals whether they be solo or ensemble have just the right amount of presence, clarity and diction; whilst the top-end brings out texture, shimmer and extended decay without being overtly silky in the one extreme or stridently searing in the other.

In summary, these amps are great all-rounders in everyway whatever your musical preferences, are compatible with a very wide range of speakers and appear to be quite unique in the attributes they are able to offer compared to what else Iíve heard available with a 4 figure price tag. In fact, I really think these amps share attributes Iíve heard from one or two well respected solid-state and non-colourful valve amps that I once aspired to own should I ever win the lottery!


  • Wadia 860x CD player
  • Michell Orbe / SME V / Van Den Hul Frog turntable
  • Bel Canto Pre1P phono stage
  • Meadowlark Audio Osprey speakers (modified by Coherent Audio Systems)
  • Audio Magic Eclipse mains conditioner
  • Coherent Audio Systems Connoisseur mains, speaker and interconnect cables

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