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Audio Space Mini-2 Tube Integrated Amplifier
Houston Mini-2 Tube Integrated Amplifier


sixmoons.com / Paul Candy, Sep 2003
http://www.6moons.com/audioreviews/houston/mini2.html

Ah, tooooobs! Tubes fascinate me. They look cool. They glow. You can tweak them. You can watch flies immolate themselves when they crash into one. They can even keep you warm in the winter if your furnace up and dies. For those of you who live in a saner climate and may not know, a furnace is a big metal box that burns oil or natural gas to generate heat and then blows it through the house. It prevents us from freezing to death in this bizarre Ontario climate. In the summer, it's usually drier than a fart in a desert. In the winter, we are subjected to -30C temperatures - and a foot of snow every two days. What kind of climate is this? Why do I live in this infernal country? Well, there's hockey, the beer, the lax pot laws (sorry Mr. Ashcroft). The women are hot and our political leaders make me laugh so hard that I wet myself. On further reflection, so do the political leaders south of the border. But I'll leave that for our Southern neighbors to comment on. I do not wish to be subjected to a cavity search next time I cross the border.

As stated in my bio, I have little experience with the alleged pleasures of thermonic glass bottles. I have heard them in stores, shows and have never really been that interested, partly because the music chosen to demo the gear sucked. It was usually one of those audiophile recordings where a third-rate Jazz ensemble plays like they belong at the local Holiday Inn. I had yet to hear AC/DC or Wagner demoed on tube gear. Many reviewers also complain about limited power, flabby bass and no highs. Thus I got the impression that tubes were fine for small scale 'tinkly' music, i.e. chamber music, Diana Krall, Frank, Dino etc.

The other issue that kept me away from tube gear was its cost. When I was shopping around for a new integrated amp some 6 years ago, all I could find was Jadis, Cary, VTL and Audio Research. They were way too expensive for me. There was Jolida, however. Unfortunately, the build quality left much to be desired - and rumors abounded about poor quality control and reliability. So solid state it was. Fast forward to 2003. Everywhere you look, there are affordable tube amps, mostly from Asia. This no doubt is a result of an expanding global economy. As Srajan discussed in Auroville 17, the sleeping dragon that is China is starting to stir. When it fully awakes, many Western HiFi manufacturers are going to be in for a shock. The build quality I've seen thus far is easily comparable to Western standards, and in some cases surpasses it. Best of all is the cost. Asian imports are generally priced well below Western gear, for reasons Srajan fully explores in his article.

Ovation Audio is a relatively new HiFi retailer situated in the lovely town of Aurora, about one hour north of Toronto. It wasn't long before Ovation became one of my fav haunts, not so much for the gear carried but for the very amiable owners Mike Hamelin and Rickey Yan who, together, have twenty-five years of experience in the HiFi retail business and are terrific to deal with. The sign of a good retailer is not just the range of equipment. It's also the time they take to build relationships with customers.

I walked in one Saturday to pick up a couple of CDs I had ordered. As I strolled in, I spied a cute little tube amp, hooked up to a pair of PMC IB1s. It all sounded quite good, a big, nice, warm, enveloping sound. Mike asked me how much I thought the amp cost. I opined approximately CDN$3000-3500.

You can imagine my shock when Mike divulged that this little amp sells for a mere CDN$1650 (approximately US$1200). I knew that it wouldn't be long before I sussed out a way to snag it for a closer listen. That amp, the subject of today's review, was the Houston Mini-2 Integrated Amplifier.

Top International Electronic Ltd is a major, well-known (at least in Asia), and respected Hong Kong based HiFi company that offers a rather large range of tubed products in three separate lines: Duntonic, Houston and Audio Space (I hear that Top makes a killer copy of the famed Marantz Model 9). As you can imagine, Houston is aimed predominantly for North American markets. Why Houston, you ask? I don't know - but it sure beats Scranton, Flint or Poughkeepsie. If you think I'm just picking on American towns, then how about Kamloops, Medicine Hat or Sudbury? Yeah, Houston sounds fine to me, too.

The Houston Mini-2 is a class A/B push-pull tube integrated amp that can dish out 32 watts of thermionic glory in ultralinear mode or 15 watts of triode bliss.

Tube complement is 4 x EL34s, 2 x 12AU7s and 1 x 12AX7. The unit is 240mm wide, 345mm long and 175mm tall and weighs in at 12 kg. The EL34 is commonly used in affordable tube amplifier designs due to its low cost and higher power output. Direct-heated triodes such as the 300B are expensive and can't dish out the watts like its more powerful cousin, but they are highly regarded for their rich, musical sound. A neat feature of the Mini-2 is its ability to change the EL34s' pentode performance characteristics to that of a triode via a toggle switch. You get the best of both worlds and the ability to customize sonic performance.

On the back of the Mini-2, there are three line level inputs, a 3-prong IEC power inlet, 4 and 8-ohm speaker jacks. All connections are gold-plated and appear to be of high quality. The binding post nuts are plastic but quite solid and I had no issues with them. The power switch is on the left side near the rear. The feet appear to be unique - a Sorbathane ball, or material like it, is set into a traditional circular footer. I suspect that Top considers this footer superior to the standard hard plastic feet seen on just about everything else. On the front, there are two brass rotary knobs to control volume and input selection. Between them are two metal toggle switches. One flips the Mini-2 from 'ultralinear' to 'triode' mode. The other adjusts negative feedback from 'low' to 'high'.

Unfortunately, the English portion of the manual does not explain what triode and ultralinear are, or their operational criteria. The same is true for the negative feedback adjustment switch. Negative feedback is used in amplifier designs to reduce distortion. Some listeners believe that this circuit degrades sonic performance while others disagree. Houston allows the user to choose between low and high levels of negative feedback.

Unless you experience hum, leave it in low mode as the Mini-2 sounds more alive with greater presence. I would also recommend to run the Mini-2 in ultralinear mode for the majority of listening, unless you wish to listen at lower volumes or to less complex music such as a string quartets. There is an LED in the front to indicate power status. Why you would need a LED on a tube amp is beyond me. Geez, just look at the tubes or stand next to it. You'll know if it's on or not. In a darkened room, the lovely orange tube glow is somewhat offset by the intruding LED. Otherwise, fit and finish are first-rate. I experienced no difficulties or mishaps with the Mini-2. The only issue I had was the lack of English instructions explaining the functions of the feedback and operating mode switches. The unit needs to be opened up to perform biasing. If you aren't handy with a multimeter, any decent HiFi shop should be able to do it for you.

The sample I received from the good folks at Ovation Audio was fully burned in. I could get down to business in short order. I hooked up my Kestrel 2s to the 8-ohm taps via a double run of JPS Labs Ultraconductor, installed the supplied three-prong power cord, connected my trusty Rotel RCD-971 CD player and the overachieving Music Hall Maverick SACD player as modified by the Parts ConneXion (stay tuned for a review of that killer piece). My disc spinners were wired up with JPS Labs Ultraconductor and Superconductor+ respectively. I let the Houston warm up for a half hour before lighting up some tunes. I dropped in a fave recording of Bach's Cello Suites [Channel Classics CCS 12298] and Pieter Wispelwey's baroque cello exploded from my Kestrels with elemental force. Wow.


The cello was a palpable presence in my room. I could feel the wooden resonance of the cello as I have never felt it before. It just added to the feeling that a living, breathing musician was playing in a real acoustic space. Next up was The Doors (not the anemic Elektra release but the Steve Hoffman DCC version, GZS 1023). The Doors were literally in my living room. Each instrument was a fully fleshed out, three-dimensional entity. The sound of Robby Kreiger's guitar was so thick that I could cut it with a knife. I spent the next several hours going through my music collection pulling out CD after CD. Another Steve Hoffman mastered DCC disc made its way to my player, Presley's 24 Karat Hits (GZS 1117). Elvis was definitely in the building.

My wife joined me on several occasions during my time with the Mini-2 (that rarely happens) and proclaimed that she had never heard anything so wonderful. Soundstaging was first rate. Music and voices were spread out across a well defined 3D soundstage with good lateral spread, depth and height. Nothing was bunched around the speakers, nor was there the dreaded hole in the center. In fact, some images extended beyond my Kestrels. In Sinatra's Songs for Swinging Lovers [MFSL UDCD 538], Frank was front and center while his orchestra was arrayed behind him. The palpability was, again, exceptional.

The Houston possessed a beguiling warmth that was tough to resist. Individual instruments were fully fleshed out, especially stringed instruments . Electric guitars sounded terrific on the Mini-2. When grooving to the sleaze of the Stones' Exile on Main Street [Virgin 2438-47864-2], the twin axes of Richards and Taylor were rendered wonderfully ragged. I could almost taste the bourbon, cigarettes and certain illicit substances that I'm sure were abundance during the sessions.

The Houston drove my Kestrels to party levels with nary a blink. That didn't surprise me as Meadowlarks have relatively benign impedance characteristics and moderately high sensitivity, making them ideal transducers for tube amps.

However, the Mini-2 may not be the most detailed or transparent amp around. I did detect a slight veiling of details. Its bass response, while going fairly deep, was definitely not what I would call tight. Highs were a little rolled off, just enough to take the glare off of high hats, strings and voices. Oh, but that midrange! It just draws you in. I preferred triode mode for chamber music and solo instruments, ultra linear mode for more demanding music. Tonally speaking, they were about the same. But triode mode gave a wee bit more palpability and smoothness.

The low or 0-feedback mode was the optimum setting for all music. When negative feedback was switched back in, the soundstage shut down and the presentation became distant. Most of the time, I forgot about being critical and got lost in the music instead. Every time I tried to expose faults, the Mini-2 whispered into my ear and seduced me with its warmth and musicality. If it was generating euphonic distortion or artificially juicing up the midrange? So be it.

I did try more demanding music than the aforementioned discs. I dropped in the likes of the Screaming Trees, Thievery Corporation and Moby. At last, I found the Mini-2's Achilles heel. How big a problem that may present for you depends on your choice of music and listening preferences. I detected some congestion on more complex music, especially anything with driving, deep bass. This was also evident in dense orchestral works such as Pierre Boulez's awesome recording of Bruckner's 8th Symphony [DG 289 459 678-2]. While the strings sounded absolutely gorgeous, especially in the Adagio, I felt that the bottom end was somewhat disembodied - a little sluggish and lagging behind the music. But it really didn't matter. The Mini-2 was so captivating that I could overlook its few shortcomings and just groove to the tunes.

I was dreading the inevitable shoot-out between the Mini-2 and my Bryston B60. I feared that my solid-state integrated would sound so lifeless and boring that I'd have to send it packing. Well, your mind can play nasty tricks on you. The B60 didn't do as badly as I thought it would. The Mini-2 had a more seductive way with voices and solo instruments. It also projected music further into the room than its silicon-based companion. However, while the Houston surpassed it in shear palpability and presence, the wee Canuck amp beat it in control and extension at both ends of the frequency spectrum.

The svelte Bryston also delivered more rhythmic snap. There wasn't any music, no matter how complex, that the B60 couldn't make its way through. The bass was the biggest difference. It was more extended and controlled. The little black box simply grabbed a hold of those Peerless woofers and showed 'em who was boss. It also sounded more laid-back. Musical details were noticeably more realized. The presentation was clearer. When I say clearer, don't confuse that with analytical. The Bryston has an uncanny way of serving you the music straight up but without sounding analytical or cold. It surprised me how warm and natural it managed to sound compared to the Houston.

Neither amp is necessarily better than the other. It's a matter of which presentation you prefer. Think of the Bryston's vision as Apollonian, the Houston's as Dionysian. Think of the B60 as Aunt Lucy, the librarian who is steady, dependable, always in control but maybe a touch too reserved. Envision the Mini-2 as Uncle Ernie, the gregarious relation whom everyone loves, who knows how to kick back, enjoys life, farts in public, gets into trouble now and then. Take yer pick. I like 'em both.

Why can't I have both Apollo and Dionysus? I want my cake and eat it too. I can now understand why some audiophiles spend their lives chasing the genie, continuously switching from solid state to tubes and back again. I can appreciate why some folks choose to use a tube pre-amp and solid state power amp, in an attempt to combine the best of both worlds. Maybe the answer lies with a hybrid solid state/tube integrated amp, such as the Unison Research Unico? Perhaps there are solid state and tube amps out there that can do it all? I'll let you know. I shall be reporting on the Underwood/Parts ConneXion modded Unico and the Blue Note Steroid Signature amp, which supposedly does the impossible -making solid state sound like glowing bottles.

One of the cool things about tube gear is its tweakability. You can spend a lifetime swapping tubes or changing caps to alter sonics. To illustrate that activity, Mike and Rickey provided two matched pairs of Electro-Harmonix EL34 tubes. After a few days, I swapped out the stock tubes for the upgrade 34s. When I fired the amp up, I heard a flat, two-dimensional, thin sound. No surprise there. I put the Maverick on repeat and left it alone for the next 20-30 hours before listening again. Well I'll be darned if I didn't hear an improvement. I detected more extension at the frequency extremes, more sweetness, more detail and a more holographic soundstage. Mind you, it wasn't an enormous jaw-dropping improvement but one quite noticeable and, for $100, ultimately a no-brainer upgrade. I'd buy the amp and upgrade tubes.

It wasn't long before I removed the stock power cord and replaced it with the Wireworld Aurora III. Ah, even better. I easily detected a quieter background, images were a touch more focused. I also tried some Black Diamond Racing Cones and Audio Prism Iso Bearings. In both cases, I preferred the stock feet.

As impressed as I was by the Mini-2, I shall temper my enthusiasm with the knowledge that it was the first tube product I've spent quality time with. It would be premature to claim giant-killing status. There are many more amps in this price range that may or may not do better. However, as far as I know, the only competitors the Mini-2 faces at this price are the Jolida and ASL products. While I haven't heard any of them yet, neither product line looks as sexy as the Houston. Perhaps I shall return to the Mini-2 for a follow-up some day. That shouldn't be hard to arrange - my parents bought one! Mom and Dad are definitely not what I'd call audiophiles. They haven't a clue what I'm talking about most of the time and no doubt worry about my sanity. The bottom line? No matter what short- comings this amp may have, it's just so darn involving that you'll be hard pressed to worry about what it cannot do.

As you have no doubt figured out, I really liked this amp. The Mini-2 is fun. It's got build quality to die for, it looks great, sounds indecently good and all that not for a lot of money (CDN$1650 or approximately US$1200). This amp should fly off the shelves as it packs a ton of musicality in a cute, diminutive package. If you don't have a penchant for a steady diet of Heavy Metal or Dub -- or an unhealthy obsession with hearing every little detail on a recording -- then do give the Mini-2 a listen. It may seduce the pants right off ya.