Rotel RMB-1095 Amplifier Review

Rotel RMB-1095 Introduction

My wife and I like to occasionally go out and treat ourselves to a nice dinner. On these nights the baby gets sitted and the checkbook opens up for some special culinary delights. Home theater enthusiasts like to splurge too, and when it's time to spice up a mid-priced receiver or processor, Rotel is here to offer an affordable upgrade - one that will definitely improve the amplification stage of your system.

Rotel's 5-channel RMB-1095 is THX Ultra certified and boasts 200 watts into 8-ohms (20Hz-20kHz) with all channels driven. It can drive any speakers rated at 4-ohms or greater and has 116 dBA SNR (more on this later). Weighing in at 75lbs and standing over 9" tall there are no smoke and mirrors to be found here.

Rotel RMB-1095 Build Quality

Inside the Box

Open up the RMB-1095 amp and you'll be greeted with a densely-packed assembly of solid state technology. The first thing that should catch your eye is a large 1.2kVA toroidal transformer. What you may not see is its twin, an identical transformer situated directly below it. Filling out the rest of the power supply are eight 80V 15,000 uF capacitors. You won't be able to get a good look at them due to their location within the enclosure, so take my word on it. These are what are now known as slit foil capacitors, named for the tiny slits that are cut into the aluminum strips of the cap. The Rotel also employs thirty 150 watt, 15 amp Toshiba bipolar transistors as output devices. 15 are configured as PNP and 15 as NPN making a push-pull class AB amplifier design.

Rotel sports some very cool features and design practices with this monster amplifier including:

• Six high current complementary output power BJT's per channel - paralleling multiple BJT's is a good method of ensuring amplifier output impedance is low enough to deliver high current while driving low impedance loads
• Multiple high voltage capacitors ( 8 x 15,000uF = 120,000uF total!) In order to do 200wpc a minimum recommended cap voltage of sqrt(2)*40 + 5 = 63V should be used. Using 80V gives them plenty of design margin and added headroom. Using multiple smaller sized caps like Rotel employed ensures low ESR caps for minimizing power supply ripple and achieving a stable and clean power source.
• Dual 1.2kVA transformers ensures this amp can utilize the full rated power from the wall outlet (120V,20A) if called upon.
• Excellent SNR spec of 116dBA (full power) which translates to about 116 - 20*log(40/2.82) = 93dBA at one watt. It's important to have a low noise floor at low power levels where the amp spends most of its time. In this regard, the Rotel did not disappoint both on paper or during real world listening tests.

I believe the interior to be well laid out, with heatsinks arranged around 3/4 of the chassis' circumference. The heatsinks are visible on the front of the unit only, giving it a "we mean business" sort of look. Some prefer their heat dissipation to be hidden on the sides, however I think Rotel's design adds to overall look of the unit, especially when offsetting an aluminum center console (also available in black.)

The center console highlights the included thermal protection circuitry which protects the amp in case of faulty operating conditions. There is also independent Left, Center and Right channel protection which engages when load impedances drop below 2-ohms, such as when a speaker wire is shorted, the unit overheats, or a highly reactive or extremely low impedance speaker load is encountered. Activation is indicated by LEDs above the power switch. This circuitry automatically resets after a cool-down period.

The power switch is a convenient pushbutton that matches the center column, which is available in aluminum or black. It has a nice snap to it that leaves the impression of a well-made component.

Rear Panel & Connections

Taking a look at the rear of the Rotel RMB-1095 will show off the high-quality WBT 5-way binding posts. These are the premium kind, and really do a lot to dress up the rear of the amplifier. In addition, should you choose to utilize bare speaker wire, the holes in each of the speaker connector shafts are situated so that all cables will be vertically-oriented - a nice touch, resulting in a cleaner cable assembly.

The RMB-1095 allows for both balanced XLR and unbalanced RCA input signals, so if you have a high-end processor with balanced XLR outputs you can maximize your potential. One additional input option is the DB25 connector which is essentially a neater way to integrate five unbalanced channels. Primarily used in custom installations, this connection must be used in conjunction with five open-circuit RCA plugs which ensure proper impedance.

A 3.5mm 12V trigger connection for the amplifier is provided. It accepts anything from 3-30 V and must be engaged via an on/off switch. There is also a 12V trigger output jack for daisy chaining the 12V signal to other components. To use the 12V trigger, the amp must be on. Disengaging the front power button turns off all power to the amplifier regardless of trigger inputs.

Rotel RMB-1095 Setup, Listening Tests & Conclusion

Setting up the Rotel amplifier involved sending the multi-channel preamp outputs from the Yamaha RX-V2500 to the RCA line level inputs of the RMB-1095. Since I was only using 5.1 plus the Yamaha's presence channels, the lack of the two additional amplifiers for 7.1 did not bother me or affect my setup. When using a receiver as a preamp you also gain the advantage of being able to utilize the onboard amps for additional channels not covered by the receiver. For example, I utilized the Yamaha's amplifiers for the presence speakers which I engage during certain movies where I feel it would be nice to experience additional DSP effects.

The first thing I noticed upon connecting the Rotel and powering up the system was a very loud ground loop buzz coming from my speakers. After some basic troubleshooting I realized that it was a ground loop between the cable TV line and the Rotel amplifier ground. This is probably the most common ground loop encountered by many adding an amplifier with a three prong power cable. Adding a cable TV ground isolator from Jensen Transformers fixed the problem entirely. I was so impressed by the transformer that I actually wrote an article depicting the problem and highlighting the solution. If you encounter this in your system, don't pull your hair out. Simply disconnect your cable TV line from the wall. If the buzz goes away then buy this product.

The Rotel amp didn't really run hot for me during the testing period, and I provided it tons of ventilation. The heatsinks did a great job and to be honest, the amp is built so well, you really have to feed it a lot for it to break a sweat. Putting it into a cabinet requires at least 10" of clearance so you'll have to avoid wimpy racks and may need to reposition your shelving to allow for adequate heat dissipation. One of the coolest physical features on the amp is the presence of two rear low-profile casters that allow the amp to roll back into place once you have it inserted into a shelf or rack. This is a life-saver and shows some excellent design thinking on the part of Rotel

Listening Tests

So far the Rotel RMB-1095 has shown itself to be a versatile, well-constructed, powerfully-equipped device with the look of a serious home theater component. Its sound was next on the list and I decided to start with some very familiar material. As ever, I strove to provide a real world experience, so I compared its sound to a $1000 receiver - a likely upgrade waiting to happen.

CD: Steely Dan Gold
Popping in Steely Dan's Gold Album, I queued up Track 1 "Hey Nineteen" and listened carefully to the first minute of the song. There is some very tight instrumentation within this track and lots of room to observe distortion and an amplifier's ability to effectively control the loudspeaker. What I found was that the receiver provided a softer sound, slightly muddied in the lower midrange. The RMB-1095 rendered the intro so cleanly compared to the receiver, an unprepared listener may think something was missing.

Editor's Note
I placed the receiver into Pure Direct mode so that all DSP was bypassed and the main channels were handling full range signal. While I will talk about 5.1 home theater later, all of my direct comparisons were done in this method using only two-channels. An SPL meter was used to ensure a ballpark equivalent SPL was maintained when comparing between the receivers internal amps and the Rotel.

In truth, the Rotel amplifier is giving you a more accurate representation of the soundtrack. It's not a fair comparison, really, but it is important to occasionally demonstrate why a good amp is so highly prized by audiophiles especially when the loudspeaker is demanding of it.

CD: Casting Crowns - Casting Crowns
For some additional two-channel listening I fed the Rotel some tracks from Casting Crowns' self-titled album. Track 10 "Your Love is Extravagant" is a beautiful track and one of the cleanest tunes on the album. The bass line and gentle guitar picking were presented with much detail and imaged well within the soundstage. I played with much more in terms of two-channel but the bottom line is that a dedicated high-quality amplifier will breath new life into your CD collection if you're coming from a mid-priced receiver or other lower-quality amplifier.

Movies

For subjective 5.1 testing we left the realm of critical listening and entered the "raw power" zone. I cranked up several scenes from The Empire Strikes Back, Shrek, Farscape Season 4, and Lord of the Rings: The Return of the King. IN particular, I tried to find scenes that utilized the main and surround channels without necessarily driving the subwoofer too hard - after all, we're evaluating the Rotel, not my subwoofer's amp. I found that (in order of appearance) starship flybys, dragon battles, close-quarter combat scenes, and large hoards of attacking orcs could be played back at floor-shaking levels while sounding pristine on Reference System 3. It was exciting to be able to have so much dynamic range and headroom, and not have to encounter audible distortion or situations where the system was overdriven. The RMB-1095 certainly does not disappoint and provides ample clean power with room to spare - a trait shared by many THX Ultra and Ultra 2 products due to the nature of the certification process.

Conclusion

Lack of distortion and tight control over my low impedance 4-ohm RBH Sound 1266-LSEs really made a difference and quickly showed off the advantages of a high-quality amplifier.

It should be noted when considering an amplifier upgrade from a receiver there are several dependent variable to consider:

• Loudspeaker Impedance - speakers with dips below 4 ohms tend to be driven better by a high quality amp such as the Rotel.
• Loudspeaker Efficiency - speakers with lower than 87dB SPL @ 1 meter tend to benefit from a dedicated power amp
• Room Size - rooms larger than 2000cu ft require solid amplification which can sometimes exceed capabilities of mid-priced receivers
• Room Acoustics - depending on the liveliness of the room, a well damped room can eat amplifier power
• Listening Preferences - if you like to blast music and movies to THX or even ear bleeding levels, depending on the variables above a powerful amp like this Rotel can certainly make the difference.
• Whether or not you apply bass management to your Loudspeakers and utilize dedicated powered subwoofer(s) - most of the power in a home theater system is in the bass. When utilizing full range speakers, a robust amplifier will deliver more control and drive to the speakers.

There's really no magic going on, you're simply getting what you pay for - good clean power. By my calculations, the 5-channel Rotel costs just over $26/pound. For that price I'd say skip the Maine lobster and order up a Rotel RMB-1095.

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Frequency Response Linearity
SNR
Output Impedance
Measured Power (8-ohms)
Measured Power (4-ohms)
Multi-channel Audio Performance
Two-channel Audio Performance
Build Quality
Fit and Finish
Ergonomics & Usability
Features
Performance
Value