RMB-1085 Setup and Listening Tests

Setting up the Rotel isn't exactly rocket science. You'll need to connect RCA cables from your preamp/processor/receiver to the amp and speaker cables out to your speakers. I used Blue Jeans Cables. There is a 12 volt trigger cable supplied if you are planning on using that function. One thing that sort of irritated me was the configuration of the speaker terminals. Switching the order of the positive and negative just seemed like an unnecessary step that was just begging for someone to reverse polarity on their rear speakers. Plus, the grouping made everything a little tighter than it could have been. I'd much prefer a visual separation (like a line on the back panel) with as much room given to space out the inputs and outputs as possible. One of the things I hate about most receivers is how you need to have the hands of a 12 year old anorexic boy to get to the speaker terminals. I expect one of the bonuses for paying for external amplification is more room to move. The grouping of the left and right main and surrounds on the RMB-1085 felt nearly as cramped as some receivers I've used.

As a reviewer, I often do things that others wouldn't. I needed to test how the amp worked with and without the 12 volt trigger. So I connected the 12 volt trigger cable and just flipped the switch back and forth from "Off" and "On". What I found was that while in the "Off" position, with the cable attached, the amp was still affected by the component connected via 12 volt trigger (in this case it was a Denon AVR-2307CI). For a while this made me think there was something wrong with the amp. While this isn't likely to be a real world issue since most people will not connect the trigger cable unless they are planning to use that feature, it is worth mentioning. Rotel states that the amp shouldn't do this but I had two units do the same thing. There was never any audible sound as the amp switched back and forth from standby mode and it was suitably responsive to the 12 volt trigger. The RMB-1085 was always powered up before the receiver could finish its power up cycle. The amp went from cold to ready in about 2 seconds if the lights on the front are any indication.

The RMB-1085 is 100 watts by five channels - fairly modest power from an external amp standpoint. What is important, of course, is how "clean" the power is. If you are getting an honest 100 watts - that is much better than some of these other receivers whose claims are dubious at best. One thing I noticed was that even if I ran my speakers full range at outrageous volumes, the power consumption on my APC H15 never got higher than 20% (which isn't that much higher than with the amp off). That's pretty impressive!

With only five channels, it is unlikely that someone would want to bridge the amp but it is possible. Unfortunately, the RMB-1085 is not bridgeable. Add to that the lack of balanced inputs and some of the more serious audiophiles might think twice about this amp. Rotel claims that the RMB-1085 is perfect for medium and large sized rooms. I would argue that this claim would be dependant on the speakers you own. Speakers with low sensitivity are going to require more power. The manual for the RMB-1085 suggests not pairing them with speakers with impedances that dip lower than 4 ohms which might be a concern for some. All you electrostat owners will have to look elsewhere for your amplifier needs.

One thing the Rotel RMB-1085 really does have going for it is size. You don't know how many potential amplifier reviews I've turned down simply because there wasn't anywhere in my theater that I could locate another receiver-sized box. This, of course, is the joy of Switching amps - their usually physically smaller than their linear amp counterparts. At less than three inches high, you can pretty much put it anywhere. Rotel suggests a minimum of four inches of clearance and proper ventilation for the amp and I agree. If you are thinking that Switching amps run cool so you can shove them under your couch you're going to be disappointed. While I wouldn't say the Rotel ran hot, it definitely wasn't cool. I had it located in a cabinet with a fan blowing directly on it and after a few hours it was warm to the touch. So warm that I thought I'd burn my hand? No. But definitely hot enough that I thought it was too hot for a Class D amp. I wouldn't mind seeing Rotel put some of that unused real estate in the RMB-1085 to use with a few heat sinks to help cool it off.

Listening Tests

As mentioned above, the Rotel RMB-1085 was fed by a Denon AVR-2307CI which was in turn fed by either a Motorola DCT3416I for HDTV, a Toshiba HD-A2 for HD DVD, or a Denon DVD-3910 for DVD-A. It was all powered and protected by an APC AV H15. All connections were accomplished via Impact Acoustics HDMI with the Oppo HM-31 providing switching duties. Since the AVR-2307CI sports 100 watts per channel, it was fairly easy to do a comparison. Unfortunately, this required manually switching the speaker cables which pretty much guarantees that only the most obvious of differences could be noticed. For speakers I used the Emotiva ER-series speakers consisting of three ERM-1s across the front and two ERD-1s set in dipole configuration for surround duties.

HDTV: Terminator: The Sarah Conner Chronicles
Before I really got into the more serious tests of the Rotel, I wanted to finally finish watching the season finally of the Sarah Conner Chronicles which had been sitting on my DVR for months. One of the joys of HDTV (for me at least) is the surround sound. With some programs it isn't much of a bonus but with an action oriented show like Terminator, it can make a big difference. Plenty of bass, pans and enveloping music elevate this series past most of the audio drivel on TV these days (especially with the canceling of this years 24).

While most of the vocals are centered in the front, what makes a big difference is the music. Whenever a terminator (good or bad) shows up, the soundtrack kicks in full force in all speakers. The Rotel RMB-1085 kept me involved and never ran out of power even when I cranked the volume. As we all know, advertisers love to bump up the volume on their ads compared to the shows. The Rotel didn't hiccup as the local car dealer started screaming at me and I went diving for the remote. Thank goodness for the DVRs and the fast forward button. This wasn't the most strenuous of tests but it did give the Rotel a chance to warm up for some of the other tests I had planned.

HD DVD: Stardust
There are so few movies that are both available in the now defunct HD DVD format AND I want to see, that I'm quickly running out of titles to order from Netflix. I wasn't really excited about this movie even though Neil Gaiman, one of my favorite comic book writers, wrote the novel it was based on. Honestly, if it wasn't for the HD DVD version, I probably would have skipped this movie. All in all, it was about what I expected - moments of brilliance complete obscured by poor casting choices (Robert De Nero as a gay pirate?) and a ridiculous premise (a guy promises a falling star to this girl and when he finds out the star is really a different girl, he still wants to give her to the first girl). This movie would probably be enjoyable by young children but for everyone else, it just sort of doesn't make sense.

Of course, the reason I was using this movie in the review was because of the enhanced audio. While it didn't have Dolby TrueHD, the Dolby Digital Plus was a nice step up from the usual audio I experience when watching a DVD. The first thing you'll notice when you step up to the higher definition audio formats is an increased dynamic range. The Rotel didn't disappoint providing all the power needed for the quick volume changes. Surrounds weren't used a lot during this movie though when they were it was to good effect. Each of the effects was well placed in the soundstage and separation was excellent. I was especially impressed with the lightning effects and how realistic they sounded. Even during the peaks which were a good 10dB louder than anything else on the soundtrack the Rotel never seemed strained.