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Bow Technologies Wazoo

It does the "Waz", but is not so good with "oo"

[Italian version]
[Bow Technology Wazoo]

Product: Bow Tech. Wazoo integrated amp
Manufacturer: Bow Technologies - Denmark
Approx. price: US$-Euro 2,300
Reviewer: Dejan Veselinovic

This model is something of an unsung legend - eberybody knows about it, you see its pictures regularly in magazines, but to the best of my knowledge, very few hands-on tests are available on it (but see "Stereophile", February 1999, p. 119-131). Well, TNT-Audio is about to change that - power to the people!

A bit of background history may not be amiss. Bow Technologies is the brainchild of Mr Bo Christensen, a Dane and an architect by training. Way back in mid-eighties, he started out by co-creating a company under the name of Primare, itself something of a legend, if for no other reason, then by its striking design, subsequently copied by other well known industry names.
However, Mr Christensen had a falling out with the other 50% of Primare's owners, sold his share and established a new company, Bow Technologies. From the outset, their goal was threefold - to produce valve-like sounding solid state electronics, to produce strikingly designed products and to offer very high quality. Prices are collateral damage.

I could now describe how it looks, but I won't - look at the photos and make up your own mind. Aesthetics are a personal thing. Maybe next time they'll get somebody like Giugiaro or Bertone to do the design.


As seen on the picture, the insides are exquisitely neat and demonstrate clearly that much thought has gone on the outlay. Circuit board quality is top class, and the red blocks you see are Wima polyester capacitors, well known quality parts.
Around them, you'll find two large value capacitors, rated at 10,000uF/40V, flanking each channel, with additionally mounted four caps rated at 470uF/160V per channel. It would seem as if each large value capacitor is fed by its very own four high power diodes serving as discrete rectifiers, while the high voltage section has its own, also discretely executed rectifier using what seem to be fast recovery Schottky diodes.

Actual amplifier stages seem very simple in component terms, using just four small signal transistors by Philips, one Hitachi transistor for the simulated Zener diode bias circuit, and a pair of Toshiba 2SK1530/2SJ201 power MOSFETs (all per channel). Without proper circuit diagrams, I can only guess how all this is connected. I'm tempted, so very temped, to draw a parallel with the Hiraga amp ...

Towards the back of the unit, one will find the ubiquios NE5532 IC, flanked by two transistors per side, and that's about all of the "preamp" you'll find here (quotation marks because I am not at all sure what this circuit does - it could well be a DC servo or some such). On the front side of the board, you'll find the necessary electronics for controlling the motor-powered volume control by Alps. This section is powered by its own small, encapsulated transformer, as it needs to be alive all the time, so you can use the stand-by mode.

And in the middle, you'll find a hefty power transformer, with separate windings for each channel. This unit by Wiesser is rated at 4x25V/5A, which gives it a capacity of some 500VA - generous for an amp of this power rating. It's heavy as hell, let me tell you. Why is it not a toroidal unit, I cannot imagine.

On the back, you'll find the mains power switch, an IEC power socket with a fuse on it, a remote sensor socket, heavy duty gold plated binding posts for speakers by WBT, 5 Line in RCA Cinch gold plated sockets, one RCA Cinch output socket and two Canon XLR Line 1 input sockets, obviously doubling the Cinch Line 1 inputs. Not much, but quite sufficient for most. The "Monitor" function is not marked as such, but to use it you need to use Line 2.

On the front, you'll get massive milled volume and selector knobs, with two smaller push buttons, one for tape monitor, and the other for the stand-by mode.

The sides of the all-aluminium cabinet are massive heat sinks, nicely rounded so as to remove any possibility of accidental injury (or so they think!). Their sizing is most generous and always very welcome. At a rough guess, their radiating area is over 7,000 square centimeters, but since they are affixed to the front plate and the back, the entire case acts as one big heatsink, at well over one square meter.

And they're very well machined, rounded and all - but, Mr Christensen, I still managed to cut my fingers. How? Simple, I was lifting it above my head so as to put it on a high shelf and got my fingers between the fins, and ... well, we could call it "First blood" and hope I eventually make out as well as Sly Stallone.

The quality of wormanship is very good, even excellent, but not quite up to the best; I've seen better at this price level. Also, there's a surprising amount of internal wiring, something one is not happy to see, and at this price even less so. True, the wiring is tidy, but others, like Thule Audio (also from Denmark), have managed to do much better. Still, despite these complaints, the Wazoo looks and feels like a high quality item that it is.

The Heat Is On

At first, I thought the enormous heatsinks were really overdoing it, you know, just for show, to dazzle the simple of mind - rough calculation shows a radiating area of over 7,000 sq. centimeters, enough to keep a 150W/8 ohms amp in check. However, after about an hour of operation, this modestly powered 50/90W into 8/4 ohms amp managed to get them warm - not hot, just warm, you can keep your hand on the sinks as long as you like, no danger of burning yourself.

That was on a day when my room temperature was around 21 centigrade. However, the next day was warmer, and the room was at 24-25 centigrade; now, the Wazoo was getting very warm - note, still warm, not yet hot, but well on the way. Two things to note: one, it will get hot whether on stand-by or working since in strand-by only its output is muted, while everything else is as if it was on, and two, like most class A units, the best way to cool it down is to make it work, since current is dissipitaed by the load rather than the output stage. While this isn't a true, full, pure class A unit, it is nevertheless highly biased towards class A (Otalla rulez!(1)).

Still, if you live in a hot climate, make sure this unit has plenty of cooling during hot summer days.


The Wazoo is a strange one - it needs a good hour to warm up properly upon first turn on, after which it's always ready to go. Upon turning it on, it will display some, but not all, of its character. It will provide a sweet sound, but one lacking some focus; however, after about an hour's use at moderate levels, once it reaches its normal operating temperature, its sound will come into full focus. Then, you will hear plenty of details, and then some - it will very likely make you drop what you are doing and make you sit down, close your eyes and let yourself go.

Actually, the amp doesn't sound like much - it doesn't sound at all, it just seems to disappear, vanish into thin air and let you live it up. If it's details you want, you'll get a-plenty with Wazoo; if it's a warm, almost corporeal sound you want, the Wazoo will oblige you, and then some. What it will not do is provide you with false sheen, that particular brightness, sometimes edge, many transistor units tend to project, some more, some less. There's no transistor sharpness, but the music is not falsely rounded off in the higher range as in many tube units.

I guarantee you'll be surprised by what your speakers, even if only modest ones, are capable of. I've had some good ones over, but this one is the best so far. And it doesn't choose speakers - it'll squeeze the very best from cheap units like my small system's JBL CM62, mid priced units like my JBL Ti600, let alone relatively costly speakers (in their day), like my recently revamped AR94.


With such a gutsy interior, it should come as no surprise that this amp can play loud. When asked to do so, it will do one of the most difficult tricks of all for any amplifier, at any price - it will play exactly the same as when playing quitely, but just more loudly. Generally, amps change in character, even if only a little, but try as hard as I may, I could detect no overall sonic difference other than the volume (of course, taking into account the natural loudness curve of the human ear).

And the sound is still very generous, big hearted, with no anomalies I could put a name on. Still no sheen, still no harsh notes, just music, and then more music. All this was on JBL Ti600 speakers, well behaved and fairly efficient (91dB/1W/1m).

I changed to AR94s, which are a more difficult load to drive and are some 3 dB less efficient, which means that for the same loudness they require twice the power. Well, the Wazoo drove them to ear shattering levels all right, and still remained the same in sonic terms. But it's been a very long time since I've heard the ARs deliver THAT kind of performance, and the last time was at about twice the money.

Overall sound

The overall sound stage created by this amp is in many ways very impressive and even seductive. Probably the most impressive part of it is the three dimensional aspect - the soundstage has an excellent sonic perspective both left to right and front to back. I have to hand it to the designers, they really know how to do it. For better, you'll have to pay more - much more, like Audio Research or Mark Levinson more.

For example, I played Hevia's track one "Busindre reel" over and over again, marvelling at the spread of instruments and performers. And an almost forgotten track by a Dutch (?) group called Golden Earring, "Radar Love", came to new life. I never thought that track was well recorded, but the Wazoo made me wonder. And Enigma's capital CD, "MCMXC a. D.", assumed a completely new ambience - it wasn't overblown, or accented, or changed, it simply offered more, much more than I usually get. Kitaro just shines with this unit.

This goes to such extent that even by connecting very cheap speakers, like JBL's CM62, with the obvious gross price mismatch, the Wazoo made them sound a good class up better. It's an uncanny effect.

Since nothing is perfect, the Wazoo also has its faults. It was designed to emulate tube audio, and it comes closer to its goal than any other solid state device I have ever heard, and I've heard quite a few of them over the last 30 years or so. I could argue with that logic, but ultimately, it's a matter of taste. The Wazoo uses MOSFETs, and it cannot escape some of the classic MOSFET output stage characteristics, more or less present every time (however, see also TNT's review of AM Audio's 100W integrated amp).

It simply lacks the sheer energy, the almost animal drive sometimes required for certain wild pieces of music. I am referring to its bass drive here - in all honesty, I couldn't say it doesn't have bass lines, it does, but they are so polished that on occasion they sound unreal. Hey, I beat the hell out of some drums in my time, and I know what that sounds like. The Wazoo just doesn't make it quite to the top in that department. It has bass, but that bass is somewhat mellow, rounded and very gentlemanly, so much so that it's more like a fairy tale than reality. Hell, even 007 kills somebody in the first half hour of the movie, tuxedo, pretty girl and nice car notwithstanding.

Enigma is a good case in point. While gaining much ambience and clarity elsewhere, the disc looses some of the vibrant bass energy it has, resulting in a somehow calmer than intended sound. Still very enjoyable, of course, but calmed down. Similar things happened with Hevia, and even with Zucchero ("If Not Tonight") - the guitars came across really well, but the drum section just lost some of its weight and gusto. Play some "original" heavy rock, like Led Zeppelin, and you can't but notice that the lower part of the spectrum, while there, is lighter than in reality.

Now, I always complain about MOSFETs being deficient in the bass region, so I checked myself out. I rewired my JBL Sub10 active subwoofer with its own 100W amp inside to my JBL Ti600, something I never before felt the need to do. As transplanted, with the volume control on the sub at 10 o'clock, nothing much happened. But when slowly cranked up, things began to cook. I ended up with the control at between 11 and 12 o'clock for just the right sound to my ears.

Next, I replayed the repertoire with first the much less expensive H/K 6550, also at 50W/8 ohms, and got a very overblown bass, albeit with the necessary drive, rhythm and power. H/K went out and Yamaha AX592, my reference for consumer audio, came in - bass still overblown, and that amp is known to have performance fall-offs at both extremes.


Ultimately, I always have to ask myself - would I dish out that kind of money for this unit?

Actually, I don't know. It depends.

It has many virtues, too many to even short list them here. Lovers of tube audio will probably like this unit very much, as it has a similar sound, but with the added control of solid state and minus the output transformers (electrically, any and every transformer is just so much problems and compromises, even if it was made with 11 kilos of pure silver and came from Japan, since each and every one of them is a set of compromises by default). Opera and classic music fans will just love this unit, and with good reason - not many can create such a vast and well defined 3D sound stage. Even fewer will have such refined sound, and those that do will almost surely cost a lot more.

But in case of modern music, all that refinement sometimes gets in the way. Heavy metal is not supposed to be polished, it's supposed to be wild. Drums are supposed to be unruly, heavy and bone-crunching sometimes. And that the Wazoo does not do so well.

The other problem I have with this amp is that it reminds me very, that's VERY very strongly, of Electrocompaniet's EC-2 integrated amp, also with 50W/8 ohms, but at just over one half the price. That model had some problems with absolute speed, but lacked nothing in the way of bass lines.

Ultimately, I feel the Wazoo is overpriced, partly as a result of what I think is overengineering. I refer to the case - I realize it's good to have big heat sinks, and a nice facia, but I also believe too much money went into the case and its looks. While the components used are no doubt quality parts, flipping through several catalogues of part suppliers convinced me they didn't cost too much, and certainly not enough to justify this price tag (and those were retail prices, too). On the other scale of the balance, there's the development work, the marketing, and so forth.

So, if you are into classical music, or any music with strong ambience content, this could be the one for you - it fully justifies its "High Resolution" name. But be sure to also check out Electrocompaniet's EC-2, you might feel like I do and possibly save some serious money. The EC-2 isn't quite what the Wazoo is, but the difference is awful small.

If you're into more modern types of music, especially those with a strong bass content, I don't think this one is for you. Try the EC-2, it has a more realistic bass and almost as much 3D imagery, but at almost half the price. If you want blood, sweat and tears, buy an active subwoofer along the way, and you'll still save money.

My hearty thanks to the boys from Radix of Belgrade for the loan of this unit.

* * *

(1) In the early seventies, Prof Dr Matti Otala (with Jan Lohstroh, then both of Philips) published a paper in IEEE, in which he identified Transient Intermodulation Distortion as such and its mechanisms, and proposed a solid state, zero TIM, low feedback (20dB, or 10:1, at a time when 60dB, or 1,000:1, was the norm), wide bandwidth (>1 MHz), high slew rate (>100V/uS), 25/50W into 8/4 ohms, power amplifier. He also had that unit biased to 2,9/5,8W into 4/8 ohms (600mA), producing a lot of heat, but also some wonderful sounds. That design was later marketed by the Norwegian company Electrocompaniet, which to this day uses circuit topology derived from that original circuit.

Trust me, I hand made a unit according to his schematics, and was idiot enough to sell it off later on. Fortunately, I still have a pair of printed ciruit boards, so one of these days, ....

In my next flashback, I'll cover the creation of the universe - yep, I'm THAT old, all of 47, and I worked with germanium transitors.

© 2000 Copyright Dejan V. Veselinovic - http://www.tnt-audio.com

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