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Belles 150 a Reference power amplifier


Mr Coherent

[align=center]The Belles Reference 150 Amplifier.[/align]



[/align] [align=center][/align] ‘Oh No!’ I hear you groan, not another amplifier review (I know the market is awash with them!!) and from a dealer as tooL. Well then you might as well stop reading now.

Shame because if you did, you would miss something that’s not just different, but rather special when it comes to solid state amplification.

“But don’t all amps sound the same!!!†I hear the cry echoing through the forums & listening rooms of the land nowJ.

Most definitely not!

So why should this neatly constructed, small footprint (for a large power amp) burnished alloy font plated box sound any different form all the others?

After all it’s certainly not visibly light years different, so why should it sound any different? A very valid point……………………….one which I will try and answer.

I will start with the specs. Retail cost is £2795 with a 5 year non transferable warranty. It weighs 22kg’s heavy enough to show purpose, yet not a back bending or hernia inducing 50Kg plus.

Amplifier size is a very modest 431mm wide by 330mm and a height of 127mm.

Will fit quite happily on standard sized UK racks.

The unit has integral heat-sinks fitted along the horizontal axis of the casework (satin black) and rather simple yet elegant burnished alloy font panel, which carries just the on/off switch and the obligatory blue LED.

The rear panel sports a pair of singled ended (RCA) inputs. A single XLR balanced for monoblocing purposes and the fuse-hold/inlet IEC.

The Reference 150 does use a rather nice pair of quality speaker binding posts too.

Power ratings are 125w (Rms) into 8 ohms 250w (Rms) into 4ohms.

Monobloc configuration rises the power to a genuine 500w (Rms) @ 8 ohms.

Again, not much different to a lot of other units on the market I’ll grant you.

The topology of the 150 reference is a true dual mono design; each amplifier module is totally separate from the other giving better isolation between the two channels from the other.

Benefits from this include, clearer and more open sound-staging, increased depth of field, greatly improved texture and layering coupled with better instrument and vocal separation.

The Belles 150a differs here form the vast majority of dual mono designs, in that it uses only one (1Kva) transformer (usually 2 smaller units are used, one for each channel).

David Belles (the designer) feels that a single larger transformer produces better defined, stronger and textured bass. Once you hear one of these, I think you’ll find you will agree with him!

The 150a actually uses three stages of amplification in producing its sound.

An input stage with matched dual J-FETS/Bi-polars, in a cascaded differential pair.

A voltage gain stage using bi-polar transistors.

A final stage using a source follower with 8 power mosfets, class B biased.

Negative feedback is used to stabilize the gain and reduce distortion, noise and output impedance. DC stability and speaker offset voltage is properly regulated by using an accurately trimmed DC servo amplifier. This method introduces less coloration than using coupling capacitors.

Now we realise that the use of negative feedback is frowned upon by a few and loved by others, also the use of DC servo amps instead of coupling caps as well.

The interest for us was the use of the matched dual J-FETS/Bi-polars in a cascaded differential pair and a voltage gain stage using bi-polar transistors.

This implementation looked interesting, and after a 6 week evaluation period we can honestly say Oh yes!

Enough of the technical stuff, how does the Belles 150a perform?

Well I’m going to be a little different here, this time I am going to give a complete kit partnering list, warm up issues, and synergy quotient (a new scale for giving you an idea of how it fits in with a wide variety of systems and configurations).

Musical preferences that may be evident (IE does the kit like to rock, but makes classical a touch unbearable, is Jazz smooth and cool for you cats, or horribly forward etc), possible room problems if manifested.

So in essence, I will be as open and as real world as possible.

Straight out of the box it’s pretty obvious the Belles needs some serious running in time, its sharp, forward, bass is pretty well uneventful at best.

The manufacturer recommends at least 200-300 hours before performance is at its peek.

I can wholly concur with this statementJ. The 150a went through a gamut of changes over the 2.5 to 3 weeks of constant use, before I felt it was ‘up to temperature’ so to speak.

Equipment used:-

Sources’ Belcanto CD-1 player/Ayre CX5e/Wadia 301/Wadia 861/Art V2/Esoteric X-03se/X-01Le/Naim cds3/Heavily modified Arcam FMJ cd23.

Pre-amplification:- Belcanto pre 2/pre3/Spectral dc15/Belles 28a/Hovland Hp200/ Coherent systems Pre2 signature.

Speakers:- Neat Acoustic Motive 3/2’s/MFS/Meadowlark Kestrels/Blue heron II’s (both stock and Coherent versions)/JM lab Chorus 806/826’s/1007be’s/1027be’s Electra’s/Utopia be Micro’s/Diva’s and Alto’s.

Cabling was all Coherent Systems Connoisseur

Isolation was Townshend VSS equipment and speaker stands plus still-points under the cdp’s and amps.

Musical selections as follows

Dr John......... .................Creole Moon

Harry Conick Jr.................Forever for now

Katie Melua......................Piece by Piece

Fleetwood Mac..................Rumours

Jeff Beck..........................Blow by Blow (SACD)

Porcupine Tree..................Up the downstair

Stravinsky........................Rite of spring Telarc digital master (SACD)

Bartok.............................Dance suite

Elgar................................Cello Concerto in E minor

Led Zeppelin.....................Physical Graffiti

G3...................................Live in Tokyo.



The Amplifier was used through-out this review in stereo mode using single ended interconnects.

The first system the 150a was placed in (after the long running period) was.

Esoteric X-03se/Belcanto pre2/JM Labs Utopia Be Micros and matching stands.

System had been running for 3 hours prior to the 150a being placed into the mix (the 150 a itself had been left on for a good 2 hours before listening)

What greets you is a large very well defined soundstage, with great depth and purpose; vocal ranges are strong and well detailed and delineated.

The first track ‘Food for thought’ is a lively number, with great rhythmic qualities, yet also has some really challenging drum dynamics that can upset a lot of quality amplifiers.

The Ref 105a has a bounce and flow that is addictively enjoyable, yet its never portrayed in a forced or forward manner, the vocal textures and realism it renders are just delicious and so believable. Do remember Dr John isn’t the easiest of voices to re-crate!

The articulation of the amplifier is quite something too, nothing seems to ruffle it, whether the sheering heights of Stravinsky’s dances of the adolescents, where the crescendo’s are captured perfectly, with weight and substance, yet never overblown or ‘thick’ sounding. With the delicacy of the aftermath preserved with subtly and lightness that is the moment of the start of the next passage (Game of abduction)

Switching to Katie Melua (something I tend to avoid usually, though for the purposes of this review I had already taken my shotsJ)

Her semi mystic/Asian romp ‘Half way up the Hindu Kush’ is really brought to life, her vocals just fill the room with that warmth and texture coupled with a slightly more upbeat presentation, the sitar’s in the back ground just adding the ambience and air to the song which were kept a just the right levels in the mix, never straying form the performance.

The tonal balance of this amplifier is a nice mix of realism and that full analogue style of sound with just a touch of fruit. It sure makes for an enjoyable and involving performance which really does captivate.

It was time now to let the amp stretch its legs and show its mettle, out went KM at a rapid rate of knots (my CD players always seems to do that with female vocalists for some reasonJ)

The new G3 offering is Live in Tokyo, this time with Joe Petrucci guesting with Satriani & Vai. ‘Glasgow Kiss’ pumping out rather nicely, great sense of presence and real power to the sound, the crashing dynamics are handled with aplomb.

What strikes you with this amp, is its way with the groove factor, (unlike some equipment which majors on this aspects at the expense of all others) the Belles handles the PRaT superbly, yet never forsakes the texture, presence, depth and upper frequencies while grooving baby!

I’ve left out mentioning the treble until last, because I feel its one of its best features, simply put there are No nasties. Its clean, very open and detailed, (transparency on the Belles Reference 150a is amongst the best available) while giving you the feel of the music being played but never over emphasizing the upper frequencies or producing that ‘forward and strident’ sound that afflicts a lot of large solid state devices.

Next up, a change of equipment.

Source Arcam FMJ CD23 (modified) Belcanto Pre 3/Neat Motive 3’s

I know it looks an odd combination, but like a lot of things in life, don’t judge a book by its cover!

The Little Neat Motive 3’s really do make some fantastic sounds for the outlay, No they aren’t going to fill a large room or give you concert levels of volume.

However, they make tight coherent, integrated flowing groovy music, not much mucking around with placement, these babies are great, though I would say they do like a bit of muscle to make them sing.

Right, now for some Zep, ‘Custard Pie’ from the Physical Graffiti re-master, man this rocks, all the rhythmic interplay ‘inside the music’ is so evident here, as is the almost seamless’ integration the system is showing, punchy and fast, yet not overpowering or forced, the bass weight is superb for such small speaker, yet the amplifier is letting the Motive 3 have the time of the lives, the sound is totally out of the boxes, wide open, clean, fast yet full of texture and presence, oh did I mention the staging this amp generates.

Of all the changes in the various systems, one or 2 things really do stick out, the fluidic and groovy nature couple with the huge staging and texture the Belles 150a generates, it’s a extremely addictive combination and one that guarantee’s long term satisfaction.

From the chaos to the sublime, Harry Connick Jr “stardustâ€, his Sinatra like presence and unashamed sound-alike is beautifully rendered in its glory, the vocal tones and textures are pieced together with consummate ease, flowing out of the speakers with such grace and poise. If you put a blanket covering the system up, and I asked you to guess the components, you never would in a month of SundaysJ

Last review system

Source:- Esoteric X-01Le/Coherent word clock/Coherent Pre2/JM Lab Alto Utopia Be’s

The Alto’s do require some driving, so it was time to see if the Belles was up to the task.

Jeff Becks ‘freeway jam’ on SACD remaster, whooo now we are cooking!, the Alto’s really do give the full picture on this, a huge wide open sound with Gravitas and rhythmic poise, the guitar chords, the fretwork all brought to life in such an invigorating way. The correct sense of scale and weight is always maintained with this amplifier, what ever you throw at it, big or small, fast or gentle, delicate or brash.

The headroom is just superb; the way the music ascends and declines though-out presentation, its delineation and texture are just so ‘right’

Last up Fleetwood Mac ‘go your own way’ perennial love/hate song I know, but it’s also a good test for any amplifier, the gathering speed/the obvious rhythmic drive, the dynamic guitar and Mick Fleetwood’s drumming, plus the most important issue keeping it integrated and coherent.

Wow this amp does all these things and more, the marco dynamics going inside the music are really brought to life, the drive of the music really gets your foot going, the top end, never hard or fragile, just open and sweet, bass weight and speed first class, involvement factor off the scale.

Yes this have been a long piece for a review, however I felt it was warranted.

We do like this amp a lot (not that you would have guessed!) and we are quite picky about equipment we sell/recommend, so its takes a lot to impress us.

To summarise then, the Belles 150a reference, is a reasonably big, neat looking solid state class ‘B’ power amplifier of 125w (RMS)@ 8ohms (it feels like an awful more in real life!).

It does get reasonably hot if you drive it hard for long periods (as do just about all class ‘a/b’ designs) but not overly so.

It matches/pairs well with a lot of equipment ranging from £650+ therefore giving it a HIGH synergy quotient.

I was trying to think of comparison with other models to give you an idea of the sound, I’ll try!

The Belles has the mid range sweetness and fluidly of the old Alecto monoblox, only a lot more so, greater rhythmic drive and timing than naim/densen, yet it doesn’t loose all its other strengths to achieve this.

It has the grip and power of a Bryston, without the dryness and matter of factness. Coupled with the openness and staging of the Gamut D200, but with greater dynamics both micro and macro.

If you’re in the market for a music making power amplifier with poise/power/PRaT/total coherence and major bass response/speed and top notch transparency and dynamics, then the Belles 150a reference is serious candidate for audition.

I can't believe how good these amps are, and that no one here in the UK has twigged yet, that is all about to change!

Not forgetting you can always add another one and monobloc, that is really something else!

Check out the soundstage review as well........




Wammer Plus
Sep 20, 2005
HiFi Trade?
  1. Yes
Very good review Mr. C.

As a theoretical question using the 150A's in mono with the Impressions what pre would you recommend to get the best out of CD and Vinyl (assuming a seperate phono stage).

I like the intimation of bass control and power.

After havin gthe Impressions for some time I find the bass, full range not merely upper bass, is on lots of music where I had never previously suspected.

This does not detract from the vocals and delicate cymbol work/ string tone that simply fills the room and is clearly different from track to track on the same album.

These speakers are simply astounding in their range of abilities AS THEY OUGHT TO BE !

What gets your vote the Belles or the Bel Canto Refs as the more absolute amps, irrespective of price, with which pre to give the best chance to the power amps for this particular pair of speakers in a room just over 4m X 4.2m that is only used for music so domestic considerations do not apply.

Give Mr. PB a blast with both on his Emotions as I know my speakers are better than his


Mr Coherent


What pre would I use with the impressions? (knowing how the sound with my own personal equipment).

Though I found they weren't too fusy on placement and bass boom wasn't an issue, I did feel I was missing a good few hz at the bottom compared to the Heron's

I would suggest the Belles 28a ( A review will follow in a week, a listen and you will know), a Spectral DMC30L, possibly the Hovland 200 pre.

" I like the intimation of bass control and power."

We here at Coherent have a mission statement 'Totally cohesive music' when this happens the musical picture becomes whole.

Having quality bass responce is paramount to completing that picture *However* it must not take control of proceedings and impinge on the rest of the audio spectrum.

For me personally for the musical presenation I wish to have, I build me own amps.

Of the two you cited, its difficult both have a damping factor of 1000+, both do superb control, and both groove like naim would love too. Yet both have a differnet slant on the sound, imo equaly as good but in different areas.

The Belcanto's having the edge on dynamic transients and depth, and size. The Belles, having that all emcompassing analogue feeling that just gets out of the way of the music. You have to listen to both in all fairness Mike, its not an easy decision.

Due to your room constraints, getting the units under control may take more than just quality electronics sir, consider speaker isolation and having the room measured professionally and as you have no domestic worries, some treatment acoustically will bring a lot to the party.

I'll be honest here and say the Heron replacements too a long time to find and it did require some extra room treatment too Mike.

Hope that helps sir


earl of sodbury

Blimey Tony, thought you'd been quiet lately!

Great review actually, put it this way I've started buying the Lottery scratchcards again...


Mr Coherent

Well Earl we've been piecing together some quite exemplary systems at a range of price points, plus an awful lot of upgrade work.

We are very pleased with the Belles, both in terms in sound quality and build it genuienly offers a great alterative to the mainstream products.

Mind you, you can always opt for the Reference 350 version

OH and pre well thats just......................................



Wammer Plus
Sep 20, 2005
HiFi Trade?
  1. Yes
Thanks Tony,

I may have missed the Heron replacements. What are they as I have seen mention of the JMlabs but I've not heard them sound extra special in any system.


Mr Coherent

yoda900 wrote:

Thanks Tony,I may have missed the Heron replacements. What are they as I have seen mention of the JMlabs but I've not heard them sound extra special in any system.
Mike,You will have to wait a little while longer for that announcement sir.

I will agree on the The JM labs not always sounding 'special', its purely down to finding how/why they (JM labs or any other piece of equipment works).

And as always personal tastes do come into the fore more so with speakers I feel that any other equipment unless its a real stand out piece.

I can genuinely say, you will not have heard any of the JM labs transducers produce a sound to their fullest potential until you listen @ Coherent (same appiles to Art and Neat plus Audio Physics too) Bold statement yes. However we'll stand by it.


Mr Coherent

Just a picture of the Belles pair together.............





Wammer Plus
Sep 20, 2005
HiFi Trade?
  1. Yes

Is that what you are going to play for PB as I would like to read his views.

What speakers will you put it with.

Obviosly the Emotions first then your own preference.

Could be very interesting.



Mr Coherent


The chap who 'used to own the 555' listened to this very set up and went well er....a funny colour after while.

Total price of the system played to him including the speakers was £600 more than just his player alone.

I'll proberly start with this system Mike and progress form there.

We have a few choices of speakers to pair them up with, will choose on the day with PB help I suspect.


Mr Coherent

Do bear in mind, PB may not have his crank turned so to speak he may yet like it!, so I'm sure he will let you know in his own inimitable way



Jul 20, 2006
Brittany , France
Farmer Rich
I had one of those! I used it with an Audible Illusions 3A preamp to great effect...bet the system sounds very nice.

Nice review...although you wouldnt say it was bad now would you!


Mr Coherent

no harm in drooling sir, all part of human evolution Lee especially when drooling women are concerned:D




Seriously happy with the Sugden at the minute. I just like the plain looks.Nothing fancy just money spent where it should be.

I will have to get down for a listen to some of your gear soon.



Mr Coherent

This afternoon PB and myself had a good session with these, they are seriously analogue sounding amplifiers, if you love that style of sound, you really do owe it to yourself for a listen, you'll kick yourself if you don't


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