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Unison SR-1
Hybrid Integrated Amplifier

− review −

The Good Life

Isn't it said about tubes and solid-state that never the twain shall meet?  Well, M.K.Chong discovers that you can get this odd couple to work together, and carefully mixed and matched, the combination can be wonderful indeed ...

"Sometimes in the chaos that typifies our urban struggle, we forget that there are better things in life. Like staying up all night to behold the radiance of daybreak, the smell of a newborn baby's hair, or that lone sunbeam peaking through the clouds after a midday drizzle.

A few weekends ago, I chanced upon one such magical experience. After a good day's worth of prep time and hosting friends over for dinner, we were just plum worn out. Dead tired but too keyed up to sleep just yet, we snuggled in front of the system with the remnants of what turned out to be a six-bottle and three-cigar evening.

With Tony Bennett playing under the auspices of the Unison Research SR1's twin glowing tubes and between sips of cabernet sauvignon and slow puffs of Cohiba, we arrived at a definitive moment of rightness. For that moment, everything was right with the world.

I've had a few moments like this before, but I have to admit that this one was special.

- A Hybrid Conundrum -

Renowned Italian tube amp maker Unison Research has struck gold in the SR1. Admittedly having chocked more accolades for its single-ended triode designs, this vacuum tube-solid state combination opens a new chapter for the company.

The first hybrid to come forth from its stables, the SR1 still embodies classic Unison characteristics. Up front, the SR1 proudly displays its distinctive Unison pedigree; keenly crafted (nay, sculpted) hard wood accents, finely brushed stainless steel ski-slope tube platform, gregarious styling, gorgeous chassis work and, of course, tubes - matched 12AX7/ECC82 dual-triodes.

Here's where the familiarity ends though. Instead of massive transformer cans, there's a brace of massive heatsinks. For dyed-in-the-wool Unison fans that proudly wave the SET banner, this may spell for a tragedy of Shakespearean magnitude. Fear not, there's some logic to this madness.

The preamp stage is a pure triode input stage coupled to an active bias-controlled second triode driver stage wherein those matched ECC82s are enlisted. The 80-watt per channel muscle comes courtesy of a pair of complimentary power MOSFET devices. Running in what Unison terms as Dynamic Class A, these MOSFETS run hot, as a cursory tap will well attest.

As the SR1 only needs 15 minutes of warm-up time to reach optimal operating temperatures, Unison does not advise owners to keep the amp on continuously. Nonetheless, diehard tubeheads can do so but do note that the SR1 at full song draws 290 watts from the mains per hour.

At 270 x 450 x 150mm (w/d/h), the SR1 can be a challenge to place in conventional fixed rack systems. It is even more difficult to manoeuvre it when most of its 15 kg heft is distributed over its rear end - just about where its monster C-core transformer resides.

Though not a fully decked out AV amp with bells and whistles, the SR1 does have jacks for four line-level inputs and tape in/outs. The SR1 also features a remote control, but, for the life of me, I couldn't get it to work. This little doohickey, which has two buttons for volume control, looks like a car remote alarm clicker but feels like some kid's RM3 thingamajig from PSB (Petaling Street Boutique, for those not in the know).

Setting up the unit is pretty easy. Just plug-&-play, almost. Unison has designed built-in protection systems that kick-in on powering up and serve to ensure that user excess and temperature mishaps do not result in catastrophic (read expensive) events. When everything checks out, the signal LEDs will turn green from amber, signifying it's ready to roll.

- Hybrid Dreams -

Yes, this amp put a smile on my face. Ear to ear, buddy. To be sure, I did harbour concerns about its hybrid design; most of the hybrid amps I've listened to before have invariably demonstrated distinct tube and solid-state characteristics with marked transitions between the two. The SR1 registers none of these problems, presenting a seamless sound with tight integration across the band.

The overall flavour is decidedly tube-like, which I assume was a Unison design goal from the get-go. The warmth of voices and instruments is particularly noteworthy.

From Mary Black to Ute Lemper, voices had a rich visceral quality, endearing listeners to immerse themselves in the recording. Rebecca Pidgeon played over and over again, and my wife and I often ended up going through a whole stack of CDs before a night was through. This physical tangibility of vocals conferred a very agreeable "right-there" feel without over romanticising the sonics, as some 300B based amps are wont to.

Definition of sonic images was clearly delineated within a lusciously open soundstage. Pushing the cobwebs aside, the width of the reproduced space extended beyond the physical confines of the room. Natural recordings of choral works were just magical, giving sufficient breadth and dimensionality to the performers within the acoustic. Cloistered recordings blossomed with the largesse that the SR1 accorded while retaining appropriate sense of scale.

Transients were finger-snapping fast. Snare drums and sitar were just so immediate. Minutiae were well preserved; the gentle drag of fingers over steel guitar strings and soft vocal inflections were readily presented. Again, this brought marked results to well recorded works over complex studio recordings. Categorically, some recent pop CDs featuring mainly post-pubescent men did not fare well with the SR1.

Turn up the wick and the SR1 begins to show its weak legs. Don't get me wrong; the SR1 can go loud and has bass aplenty (and tight at that). The bass dynamic is of warmth and richness as with the mids and treble but the lack of absolute attack at lower extremities meant that stuff like Nirvana and Limp Bizkit are probably not that good an idea. Mind you, at neighbour unfriendly levels, and before you reach terminal hearing impairing SPLs, the SR1 will exhibit mild distortion and clipping.

- Conclusion -

Putting doubts about hybrid systems aside, the Unison Research SR1 cuts a convincing argument for real world tube applications with desirable tube sound and solid state dependability. What I particularly enjoyed was the overt lack of artificiality with this amp. This is indeed a surprise, and scores it many points in the overall sense.

Indeed, there's little doubt that this amp will make a lot of people happy. I would be tempted, if it were not for the fact that I'm keeping my sights on that mint Unison Research Simply 845 waiting for me out there. Till then, I'll be stocking up on some vino and looking to good times ahead. This one is recommended, and then some.

For: Lucid presentation; generous warmth; loads of air; excellent detail retrieval; glorious build.
Against: Will not bite when required; absolute bass could be more authoritative; wife thinks it looks like a bug from the front perspective."M.K.Chong

−  Established 1973  −
"love what you listen with"
Los Angeles, California USA


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−  Established 1973  −
"love what you listen with"
Los Angeles, California USA
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