Rotel RB 1090 Stereo Power Amplifier

      Date posted: September 15, 2000

Rotel RB-1090 Power Amp
Sugg. Retail: $3000 (CAN)
Distributor: Equity International
54 Concord St.
North Reading MA
Ph. (978) 664 2870
Fx. (978) 664 4109

(Reprinted from the Summer/Fall 00 Audio Ideas Guide)

      Let’s be frank. Rotel isn’t really known for their power amps. Not as this price anyway. “Sure great mid market CD players, but amps? Maybe for the home theater but not for my audio
system” is a common refrain. I’m sure some of you are turning up your noses at the very thought of a Rotel power amp feeding your speakers.

      The RB 1090 represents Rotel’s all out assault on exactly this kind of thinking, combining their trademark of high value with serious audiophile credentials. The 1090 is definitely a serious amp. It even looks serious, standing 9.5″ tall and wearing all that intimidating heat sinking right on its big, black face. Pick it up (if you can) and you’ll know it means business, tipping the scales at just under 85 lbs. How many amps have you encountered that include wheels? No joke, tilt er’ back a few degrees and this Rotel rolls on a pair of wheels tucked discretely under the back of the chassis. Considering the weight, it’s a very clever design feature.

      Responsible for all that mass is an electrical engine capable of producing 380 watts of juice into 8 ohms. Apparently stable down to 2 ohms the 1090 pumps out over 1000 watts when confronted with that load. Essentially two separate power amps sharing the same box and (detachable) cord, the 1090 also has two totally independent power supplies fed by “two 1.25 kVA toroidal transformers and four 22,000 uf Slit Foil storage capacitors. This enormous potential feeds an output stage with four pair (sic) of power transistors, each rated at over 200 watts with more than 17 amps current capability.” Should you grow tired of the sound of the 1090 it’s comforting to know that you can at least use it to power your arc welder.

      Controls and connections are simple but allow considerable flexibility. Included are balanced and single ended ins (I used the SE inputs exclusively), two sets of binding posts for each channel (well separated, but not of outstanding quality), and a front mounted power toggle flanked by a clipping indicator for each channel. Build quality is very good, on par with that of the 991 CD player, but the amp isn’t an exotic hand-built and doesn’t look or feel it. Despite the manual’s claim that the 1090 consumes 800 watts, it turns on gently and runs very cool with zero noise, electrical or physical. This leads me to suspect that this rating is based on the amp running at full capacity, which, unless you’re the owner of Apogee Synchillas and have a penchant for metal (a pretty unlikely combination in itself!), is something you’d be hard pressed to make it do for long. A class A/B design, the 1090 is (thankfully) not drawing that kind of power all the time.

      Don’t let its big size and big numbers give you the wrong idea. It will be easy for many to write off the 1090 as a simple brute, another megawatt amp with all the poise and finesse of a diesel locomotive,
but anyone who spends some time with it will quickly realize that this beast wears velvet gloves and moves most gracefully indeed. In terms of watts the 1090 is certainly overkill for most systems, including mine, but I think it’s important not to fixate on its power rating, just as single ended triode freaks don’t kvetch about underpowering their speakers. 8 watts? So what? It’s beside the point. Forget the numbers, how does it sound?

      It would be a shame to see an amp this good going only into the systems of people with “difficult” loudspeakers, because it sounds so damn good with easy loads like my Energy Veritas 1.8’s (6 ohm nominal impedance
and 87 dB sensitivity). I expected it to be effortless in the macrodynamic sense and to be possessed of powerful and well controlled bass, and it was. But I wasn’t expecting the smoothness, the subtlety, the liquidity, the vast and enveloping soundstage or the sheer musicality that emerged from the 1090. The impressive level of transparency and resolution was also an unexpected bonus, the Rotel painting an extremely neutral and balanced sonic picture with what seemed like as much detail as the source could provide.

      I listened to all the components reviewed in my Summer/Fall 2000 Column through the 1090, which not only helped me get a
firm handle on their respective sonic signatures in comparisons, but also helped them sound their best. As a result the comments made about the Rotel RCD-991, Anthem Pre 1P, and Rotel RQ 970BX can be applied to the 1090, which faithfully communicated all that musical information to the speakers. Like many excellent solid state amps, the Rotel has almost no sonic signature of its own, it just gets out of the way and does as it is told. Tonal and timbral colours emerged vivid and detailed, soundstages appropriately huge and deep when called for, highs detailed, smooth and never fatiguing or etched, and bass deep, tight, and effortlessly powerful.

      One of the things that has re-energised my listening at home is the way my system has been able to communicate what is perhaps best described as the “ebb and flow” of music, the subtle cues that make it breathe, the tiny changes in scale and intensity that make it sound real, and therefore satisfying and involving. No small amount of credit
goes to this amplifier. I’ve never before had the sense that the system was tracking the waveform with such scrutiny and agility, responding
to every peak and valley in that wave instantly, as it if were anticipating it, no matter if it was a mighty broadband transient burst or the most delicate solo pizzacato. Maybe it’s all that available current, or a divinely synergistic match with the 1.8’s, but this amp sounds not only fast, but like it’s reading a page ahead, knows what’s coming and has long figured out exactly how best to deliver it. Combine that
with the dynamic omnipotence of 380 watts and you’ve got a sledgehammer you can tune your watch with, a top fuel funny car that can rip it up at the N�rnbergring, brute force and supple grace artfully fused. I’ve heard amps with more satisfying bass (the Anthem Amp-2 I reviewed last time out comes to mind), silkier highs,
more transparent mids, but none that make music as convincingly as this one.

      Like the 991 CD player the 1090 sounded its best with a little help in the AC department. In this case the Foundation Research LC 1 dedicated power conditioner played an important part in coaxing the best possible sound from the 1090. Without it some of the subtle effortlessness evaporated, and the amp went from sounding magical to just plain excellent. If you’re willing to spend $3K on this amp then spend the extra few hundred bucks to get the most out of it.
In the case of the 1090 it improved the sound enough to more than justify its $695 price tag. Even if you were to consider it part of the 1090’s price, this amp would still be a steal. Combine the breathtaking sound with the fact that it can drive almost any speaker on the planet, and it becomes a major heavyweight (literally!) at its price point and well beyond. If I hadn’t spent some time with it my prejudices might vary well have kept me from considering this amp a serious contender. If you’re shopping, don’t make this mistake.

Aaron Marshall

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6 Responses to “Rotel RB 1090 Stereo Power Amplifier”

  1. SAAudiophile c-unknown Says:

    I used the Rotel RB 1090 for roughly 12 months to drive my Infinity RS 9 Kappa speakers and I agree with most of what Aaron says in his review with regard to what the amp sounds like. I would however like to comment on Rotel’s claim that the RB 1090 can drive “even the most demanding speaker”, as in my experience it unfortunately did not live up this claim. Under normal stereo listening conditions at moderate volume, the Rotel’s protection circuits often activated. When watching a movie this problem became even more apparent due to the increased dynamics. I contacted Rotel in UK and they advised that the RB 1090 should not be used to drive speakers with an impedance lower than 4 ohms, which in my opinion is a total contradiction to their claim of driving “even the most demanding speaker”. As a matter of interest, I replaced the Rotel with a Sunfire Signature 600 Two and problem solved. The Sunfire not only seem to have limitless power, but the sound quality is in a different league to that of the Rotel - I would go so far as to say that there’s no comparison - the Sunfire has better control, the soundstage is wider and deeper, the detail is far superior, the noise floor is lower and the overall musicality of the Sunfire is streaks better. It’s honestly like chalk and cheese.

  2. Aaron Marshall c-us Says:

    That’s interesting SA Audiophile. Unfortunately I didn’t have a challenging load like your Infinity’s to put the Rotel up against and I’m surprised that it couldn’t swing enough current to drive them. The Sunfire, a version of which our editor uses in his home theater system, is a very good choice for those speakers with its unique power supply circuitry. Not many speakers that it couldn’t drive to very high levels, I suspect.

  3. j baran c-unknown Says:

    i have a adcom gfa5802,also i have a pair of the original amp killers kappa 9s,at only 300wpc it drives them with ease,i dont what wattage your amp is the rotel has more power than my adcom ,and has know problem driving them,your comments are helpful,because i thinking about buying a rb 1090.

  4. RobC c-us Says:

    SA Audiophile, most of the Infinity RS 9 Kappa’s have a switch on the back beneath a black cap (just above and to the right of the x-over plate), which allows you to select “normal” or “extended” mode for the woofers. Very early models do not have this switch (they are permanently “extended”), and those with it are sometimes referred to as 9A’s. In extended mode the 9 Kappa’s will dip as low as 0.8 ohms. Bass will be deeper, but without a very high current amp to tame it, it will lack a bit of tightness.

    Assuming you have a later model with the switch, you may want to set it to “normal”. This mode will be far more friendly to your amp. I have used my own RS 9 Kappa’s in “normal” almost all of the 17 years I have owned them, and can confirm that bass response is still very pleasing. Similiar to J Baran, I also use an Adcom GFA-5802 to drive them. The 5802 does a good job in normal, which I suspect is how J Baran is using his. It will also struggle on bass heavy music (try out 2001 a space oddessy from Telarc’s “Time Warp”) when the 9 Kappas are in “extended”.

    A final note on the RS 9 Kappa’s. These speakers truly come into their own when they are bi-amped. A big part of it is that each individual amp has to deal with less crossover complexity, and impedance difficulties. I suspect that if you had your speakers in “normal” mode, and used a second amp (perhaps an RB-1080) on the highs, with the RB-1090 on the woofers you might have been happier. Still, I do understand your disgust with the statement by Rotel claiming to drive “even the most demanding speakers”. Many marketing departments will throw that phrase on their collateral, and I always chuckle and think, “you have never heard of the Infinity RS 9 Kappa”.

  5. Charles Fortin c-ca Says:

    Hello Everybody. My name is Charles Fortin. I’m a electrotechnicien. I have to: 1 Rotel RB-1090. It’s a good deal for the price. But the real problem about this product it’s the only 8 outputs per chanel for 380 watts. A good amplifier have 12 outputs per chanel for 250 watts. A high-and amplifier have sometime 24 outputs for 250 watts. I modify mine and now it’s a 110 watts per chanel not 380 watts and my frends don’t beleve it: the amp play louder whit less distortions and have the same bass control has my Mark-levinson no:27 with 1 ohms not 4 or 8 and it never come hot only cool to warm. First; before you buy a high power amplifier ask the seller what number of outputs stages the amplifier have. And if he can’t: don’t buy the product. Because after your purchase it’s not the time to have a problems whith power and the load of your speakers. I repair and modify over 990 amps and my experience told-me; more the power is high more problems to comes and to much watts for less dollars it’s not very good. Never forget that; all compagny never give you a miracle dream product for less money. You dream in colours. Talk to another real expert in electronic. Somes audiophiles talks about a minimum outputs stages for great musicality. It’s not really true because when I multiply the number of outputs stage the output courant do more and the sound stage come more palpable and live and like true and like real orchestra. The speakers ares under control and the woofer don’t go away because the amplifier can’t do a real good job. If you thik I’m direct! You right. I don’t like lies. King Regards. Charles.

  6. Lawrence c-unknown Says:

    Lets hope at this point we can all agree that finding the right amp for a pair of speakers can be a real challenge? I bought a RB 1090 for a pair of JBL 4430’s and the match was perfect. I had several other amps at my house and I played with several variations, including the Sunfire Signature 600 Two that someone mentioned above. I even used other Rotels, the RB 1092 and the mono block 1091’s which are basically the same thing. The class D amps didn’t come close to sounding as full as the RB1090’s 380 wpc. I have a fairly large living room and I even brought the whole system outside for a party or two and the match held up nicely in both environments. The Sunfire didn’t play well with my JBL’s, but it loved my Martin Logans in my listening room upstairs. I’m a huge fan of the RB 1090 amp and I’m in the market to buy a second one. For the price it’s going to be tough to beat.

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