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Acousticbuoy Scorpio

Valve Pre-Amplifier

Product: Acousticbuoy Scorpio Valve Pre-Amplifier
Manufacturer: Acousticbuoy - Canada
Cost, approx: 4699 US Dollars (YMMV)
Reviewer: Geoff Husband - TNT France
Reviewed: November, 2009

[Scorpio front view]

[Italian version]


How times change. 20 years ago a valve pre-amplifier was a rare beast indeed, now it seems that a new one comes out every few weeks. Why? Perhaps in a more affluent world, the extra costs involved in making such a design properly are now more easily met? The increase in availability of both valves and valve amp manufacturers from the ex-Communist Bloc and China gives us more choice and a lower cost base? Or is it that when it comes to processing our precious small signals only valves will give us that last bit of fidelity? Who, knows, but the phenomenon is a real one.

And to stand out in this wave of designs in an increasingly crowded (and now depressed) marketplace, a design need to have some stand-out feature to survive. Which brings us neatly to the Acousticbuoy Scorpio.


When I first clapped eyes on the Scorpio I was strongly reminded of old Rotel transistor amplifiers from the 80's. Dark grey in colour and with a very understated design dominated by the volume knob, here was an amplifier that seemed to abandon the ever increasing trend to dressing up every valve amp in so much 'bling' that it looks like a Christmas bauble.

[Scorpio volume control]

But getting close and actually touching the thing makes the resemblance superficial at best. The weight is only about 11 kg, nothing exceptional, but that belies a very substantial construction. The whole pre-amp case is made of slabs of aluminium bolted together and 'hermetically' sealed. The controls work with satisfying weight. I was pleased to notice that the volume knob was mounted using annular bearings - something I had suggested to Korato when I reviewed their pre-amp and found that a strip of PTFE tape had been wound round the volume shaft so as to give a smooth 'quality' feel (it didn't).

I liked those old-fashioned toggle switches that give on/off (hooray!), control (slight) of balance and that rare attribute 'mono' (more on this later). The input selector worked with satisfying precision and the use of LED's thankfully restrained.

At the rear three pairs of Phono sockets handle input and one pair output - a standard IEC socket taking mains.

And that dear readers is all you can see.

Gripes? The logos for input are engraved in the alloy faceplate and are pretty much invisible in most lights - it's something you get used to a bit irritating. Thankfully the input selector has three small LED's to indicate input. Beyond that there are only three inputs (enough for me) and no remote (I hate them) - so here you have a real minimalist, even hair-shirt design.

The understated casework obviously takes a fair whack of the component budget, but opening up the amp shows that plenty was left for the internals... Acousticbuoy have an excellent website where you can read all the specs, but rest assured the component level is extremely high and the amp is dual-mono throughout with each channel using a 12AU7 and 6C4 valve.

Remember I said that to succeed a pre-amp needed to do something special. Well if I were to sum up my immediate reaction it would be one of obsessive attention to detail. The volume control and its annular bearing I've mentioned, but the bearing shaft runs right into a classy stepped-attenuator. For most better amps this would be enough, but in the Scorpio it is mounted on a special bracket machined from a solid block of alloy and then compliantly mounted on the chassis - all to control vibration in that essential component. The same technique is used for the valve sockets - each with it's own bracket - something which should bear dividends as vibrations in valves, notoriously microphonic things, is a bad-thing...

[Valve bracket]

Layout, wiring (star-earthing of course), soldering, PCB's etc are immaculately done. Some amplifiers, especially some cheaper Chinese offerings look great but inside have the appearance of a 15 year-old's technology project. The Scorpio could only be described as immaculate - bravo!


Which all amounts to a pile of dingo's kidneys if the sound is no good, so now off to the torture chamber (my living room system)...

It just so happens that the Acousticbuoy arrived just before I sold (poverty...) my Audionote M3 pre-amp, much loved and much missed, but who's memory was still very fresh in my mind - but at a price nearly three times that of the Scorpio. It's replacement for the moment was an Opera Cyber 222 valve preamp, one of the classy breed coming from China and an amp that combined excellent build/components with a frightening price-tag half that of the Acousticbuoy.

So an interesting comparison - just where would the Acousticbuoy fall in the hierarchy?

First the good news, wiring it up passed the first test - it fired up without pops and bangs, and was noticeably quiet once warmed up. And here a vote for a front mounted on/off switch. Saving the planet might not be No1 in most audiophiles list of wants, but valve gear not only draws a fair whack of juice, but sometimes put out a shed-load of heat too. Though the Scorpio ran cooler that I expected (the large case making an excellent heat-sink) I appreciate being trusted by the manufacturer to know when to switch it on or off. My M3 demanded to be left on all the time (along with the power amps) with it's utterly inaccessible power switch, leaving me with a noticeably larger electricity bill, a very warm listening room in summer and the constant hiss of working amps through my 104 dbl speakers - to quote De-La-Soul, I want to be able to 'turn it off-off-off!'


Climbing down from my hobby-horse had me doing the usual thing of playing random music and not listening very critically as the thing broke in. But of course you do listen carefully and the Scorpio sounded pretty good from cold.

Now another bit of praise for the pre-amp, I've already mentioned that there is a switch to make the output of the amp into monaural. Now I'd not even thought of this as a possible plus point but I was very, very wrong. A lot of my record collection is 'Classic' i.e. early Beatles, Dylan, Stones, Who etc. Once you've sat and heard his Bobbyness sing in that awful ping-pong stereo where his guitar is on the left whilst his voice is on the right, or where a drum-kit resolutely squats, sulking, as far away from the rest of the band as it can get, you really appreciate that with the flick of a switch the piece can once again be a musical whole. I have a recent CD of Mile Davis' 'Kind of Blue' and it only made any sort of sense in mono. I know this has nothing to do with sound quality per-se, but it has become a very, big plus for me, and as a rare attribute does give the amp a strong selling point...

Another nice characteristic was that the volume control as well balanced. I've had a few amps here that have had such stepped volume controls and with sensitive speakers they have a habit of going from 'easy-listening' to 'Grateful Dead' in one click. In the case of the Scorpio the change was nicely gauge.

So an impressed and rather pleased reviewer so far - now to proper stereo and serious listening.

The Scorpio did have the misfortune to be in the house along with the Ayon Crossfire, an integrated valve amp that redefined transparency in my home. The Crossfire does allow direct connection which bypasses the Crossfire's own pre-amp section. And there was no doubt that in the case of all three pre-amps mentioned above, wiring the amp in had a detrimental effect in terms of transparency. Now I know I shouldn't be too surprised, but it does illustrate how a really good integrated can benefit be removing the mass of cables, soldered joints, pressure contacts and compatibility issues that adding a separate pre-amp can bring.

But the comparison was interesting in that the character of the three amps became apparent. The M3, surprisingly, showed the most change from the Ayon - being both warmer, bigger and bolder, but at the same time taking a step back from the music. The Scorpio was much closer to the Ayon's own pre-amp section, again there was a slight diminution in very low-level resolution and the feeling of something extra being put between the music and the speakers, but the result was less noticeable than the M3 if you weren't listening too hard.

The Cyber 222 sounded much like the Scorpio, but there was no doubt that another step back from the music had been taken.

So, a pretty neutral pre-amp, transparent, but not totally so.

Then tragedy struck and a burly driver from some two-bit collection service prised the Ayon from my grasp. The M3 parted from me at much the same time...

But nothing daunted I wired in the next amplifier in my series of 'any SE valve amp except a 300b' reviews - the Yamamoto A-08s, a little jewel of an amp pumping our 2.5 of the sweetest Watts you will ever hear - ah! The trials of the poor reviewer...

So back to swapping pre-amps, now the remaining contenders were the Cyber 222 and the Scorpio.

And the hierarchy soon became permanently established. The two both matched the Yamamoto beautifully, both worked quietly and unobtrusively and the end result was superficially extremely similar. Considering that the two used completely different topologies and valves this is all to the credit of their respective designer. But... But... Switching from one to the other showed that the Scorpio was simply the more revealing of the two.

When you have two amplifiers which are voiced in the same way this becomes difficult to describe. But I'll have a go. Imagine that the music is divided into a series of layers, like pages of a book. The first layer contains the lead singer, guitar and drums. The next the rhythm guitar, the bass and so on. As you go on through the layers the trick the pre-amp, and all the other components are trying to pull is to get down to the layers right at the back of the mix. Time and time again the Scorpio just managed to pull more off the recording, it was almost as if you had to listen harder to try and catch things that the 222 was doing, that on the Scorpio came naturally. And of course if you don't have to try so hard the result is that the music becomes more effortless. Long-term, i.e. over the course of an evening's listening, I came to have a strong preference for the Scorpio, a preference that would baffle a listener who'd just walked into the room and found the two pre-amps so closely matched.

One piece of music I use for this sort of thing is Tears For Fears 'Woman in Chains'. This is a complex swirling recording that shows the very best of multi-tracked trickery. It opens with a tiny bell going 'ting-ting' and this continues, unchanged, at the same level throughout the opening of the song.
Of course from the sparse opening, to huge crescendo means that the little bell seems to drift in-and-out of the mix, but it's always there! This is a hideous test of dynamics (picking up low-level sounds when the recording is going bananas) and detail resolution, and here the Scorpio allowed you to hear that little bell more clearly, more of the time. With the same disc, the (fake) ambience was just clearer through the Acousticbuoy...

There's an important caveat here. I described my living-room system as the torture chamber because it is so revealing, and this primarily down to the Loth-x Polaris speakers residing there. Of course the rest of the system is important, but replacing the Polaris with the Acuhorns I had on test at the time made the superiority of the Acousticbuoy vanish. No doubt a more revealing system than mine would have opened up the gap between the two even more, but the fact remains that the extra money spent on the Acousticbuoy over the Cyber 222 is wasted unless the rest of the system is both very transparent, and I suspect - expensive.

Beyond this it's hard to pick the character of the Scorpio because it adds so little character, and that is I suppose how it should be. It never put a foot wrong and excelled in fine treble detail as much as pounding bass.


Given the right standard of ancillaries the Scorpio is a fine pre-amp. That it held it's own with the far more expensive M3 is tribute enough. If push comes to shove I'd still take the M3 for its sheer power and macrodynamics, but in all the essential elements the Scorpio was a match. It's advantage over the 222, a superb amp considering it's price is significant enough to more than justify the price differential, but be warned that you'll need a fine system to make that worth while.

In the end the Scorpio gets my vote for being a component that has obviously been built with much thought and great care. For someone looking for a simple, but high quality pre-amp that doesn't look like a Christmas tree it makes a lot of sense.

The manufacturer wanted to add the following points on the details of the design.

Manufacturer's comment

In the design stage, we tried:

  1. Using relay as volume control with remote function... but it caused a noise during volume up and down, the cost is only USD30.
  2. Using IC as volume control with remote function... but it will loss lot of small signal and make a lot of un-measurable distortion, the cost is only USD10.

Finally, we wanted the very best so we decided to use this attenuator as the volume control!!! But the cost of this volume control is USD120!!!

***For the manufacturing perspective... it is very expensive things!!!

In the initial stage, we make all circuit is using the socket as PCB to PCB connection (easy for production), but the sound bad, finally, we change all the "type of connection" as direct soldering to maintain the lowest signal loss, called "Socket-less production".

systems used

Copyright 2009 Geoff Husband - www.tnt-audio.com

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