Rotel RMB-1585 MKII & RMB-1587 MKII Power Amplifier Overview

Company History

Rotel is a company we know well. Started by Mr. Tomoki “Tac” Tachikawa, the company started modifying televisions from the US to work in the Japanese market. After a company reorganization in 1961 Rotel went into the audio OEM business. After years of perfecting in-house designs, the company decided to go into business under its own name to make high-end but affordable audio. Rotel knew there were many products out there in the ’70s that were marketed on features instead of sound quality. Instead of following that trend, they focused on 3 basic principles: musical accuracy, build quality, and affordability. Rotel knew there was a market for audio products that performed admirably and did not cost a fortune. Designing and building many of their own parts in-house allowed them to do just that.

Home theater receivers have been a staple in home theater for years providing a one-box solution that handles all the processing and power amplifiers in one chassis. While there are excellent receivers out there that deliver high performance there are compromises. Having everything in one chassis leaves less space for each circuit. With all of this tech packed into one enclosure the power amplifier section is generally the area that gets compromised. Less space for transformers, capacitors, and transistors means the manufacturer has to put smaller components in for the amplifier section. While these amplifiers are still capable they will not have the power reserves within them to handle today’s more complex and dynamic movie soundtracks. Taking cues from high-end two-channel audio separate power amplifiers that had 5 or 7 channels of amplification soon hit the market to give people options when they wanted to step up in amplifier performance. These multi-channel amplifiers had large chassis that could fit all the needed oversized components in them to be able to put out rated power at all channels driven and have the capacitance needed for dynamic peaks.

Rotel has had multi-channel amplifiers in its inventory for years giving music and home theater lovers power and dynamic headroom not found in home theater receivers. These amplifiers have stood the test of time providing the sound and reliability Rotel built its reputation on. The RMB-1585 and RMB-1587 have been Rotel’s premier multi-channel amplifiers for years to much acclaim due to their rock solid reliable build quality and value giving owners years of trouble-free service and the dynamic headroom to play their favorite movies with real-life dynamics and sound quality.

With recent launches of the MKII versions of their integrated amplifiers, preamps, and source components, Rotel thought it was time they updated their premier line of multi-channel amplifiers with new components and architecture to take advantage of their research and development.

Features & Technology

Having the ability to produce most of the parts in their equipment gives Rotel the ultimate control over what goes into their products. This allows them to build these amplifiers to high tolerance to give the best performance. Giving these great amplifiers the MKII treatment meant upgrades in both the power supply and amplifier stages giving these amplifiers even better performance.

Power Supply

At the heart of any high-end power amplifier is the power supply. Having clean solid power delivery is critical in allowing the other components in the amplifier to work at their best providing the best performance.

Having an oversized Toroidal transformer, the RMB-1585 MKII and RMB-1587 MKII have the juice needed to make rated power plus. This allows these amplifiers to produce the dynamics of a movie soundtrack without running out of power or clipping keeping distortion low at all volumes.

Along with these oversized transformers, These large class A/B amplifiers have 120,000µF of filter capacitance. These Slit Foil capacitors do two main jobs within the amplifier. First, when the transformer sends power through the rectifier, it is changed to DC voltage pulses. These pulses are smoothed through the capacitors into a nice even DC voltage for the amplifier circuits. The second job is to provide a power “reservoir” for peak signals. When you have a very dynamic passage in a movie or music that puts a heavy load on the amplifier the capacitors will help the power supply provide extra power for these peaks. Having these power reserves in place is part of what gives these amplifiers their “effortless” sound quality and enjoyment. The power output of the RMB-1585 MKII is 210 watts/channel at 8 Ohms, 340 watts/channel at 4 Ohms all channels driven, and 440 watts/channel at 4 Ohms driving 2 channels. The RMB-1587 MKII is 155 watts/channel at 8 Ohms, 250 watts/channel at 4 Ohms all channels driven, and 335 watts/channel at 4 Ohms 2 channels driven. Seeing the power ratings with all channels driven is a great sign that these amplifiers will power your multi-channel speaker system to its fullest as most receivers and home theater integrated amps only rate their power into 2 channels.

Inputs

Both the RMB-1585 MKII and the RMB-1587 MKII have smart auto-switching XLR and RCA inputs allowing installation to be both easier and compatible with any home theater processor or receiver that has multi-channel outputs. The amplifier can tell which input for each channel you are using whether it is a RCA or XLR and automatically switch to use that input method. This makes installation a simple plug-and-play process.  

There is a 12-volt trigger input and output on the rear of the amplifier allowing on and off control to be triggered from your processor or receiver if it has trigger outputs. Having an output on these amps also allows you to connect other amplifiers or components to the trigger chain allowing multiple component control allowing the processor’s power switch to act more like a main on/off switch.

Outputs

The 5-channel outputs on the RMB-1585 MKII and the 7-channel outputs on the RMB-1587 MKII use high-quality gold-plated binding posts for each channel allowing you to choose banana plugs or spades. This gives users the option to use any cables they would like and get the best connection possible. These outputs are well-marked and correspond with the inputs so that there is no confusion on installation.

Keeping Cool

Both the RMB-1585 MKII and RMB-1587 MKII have 4 thermostat-controlled variable speed low-noise fans to keep these amplifiers cool when playing dynamic soundtracks. Many installers and home theater lovers will install large equipment racks to house all of their home theater equipment. These racks are great as they keep everything tidy and allow users to get to their equipment in one place — usually in a back room or closet. The bad thing about them is that all the equipment is put together only inches apart from each other which can create a lot of heat. Heat being the enemy of amplifiers, Rotel decided to add 4 strategically placed fans inside of each amplifier. These fans have a thermostat function that controls fan speed as the amplifiers heat up. This keeps them cool and allows them to function in tight rack spaces. There is a switch on the rear panel that allows users to turn off the fans if these amplifiers are placed in the listening room and are well-ventilated to keep any fan noise from being heard. 

Expert Advice: Ask our knowledgeable staff about your placement options and if turning off the fans is an option as it will make the amplifiers run hotter and could shorten their lifespan if the fans are turned off without proper ventilation.

Bi-Amp Option

The Rotel RMB-1585 MKII has another option that should interest you if you have difficult-to-drive main speakers or you just want to get the most out of your speakers. Using channels 1,2 and 4,5 you can select an option using a switch on the back panel for bi-amping. What this does is take your stereo inputs for channels 1 and 5 and allow you to use 4 channels of the amplifier to power a compatible main speaker. This turns this 5-channel amplifier into a 3-channel amplifier giving 4 channels of power to your main speakers as well as a dedicated channel to the center channel speaker. It is well known that separating the bass channels and midrange/tweeter channels can have benefits when it comes to both sound quality and output capability. We think this is a well-thought-out touch to an otherwise well-appointed amplifier that will give users options on how they use it. (Note: the RMB-1587 MKII does not have this ability).

Performance

We started our evaluation in a two-channel music system to get a taste of what these amplifiers can deliver to music lovers.

Thelonious Monk’s 1962 album Monk’s Dream is a jazz classic that showcases the ability of an amplifier with natural instrument tone. Playing the title track “Monk’s Dream” showed us that both the RMB-1585 MKII and RMB-1587 MKII amplifiers have the low distortion clarity to let this track shine. The drums had great detail with the bass drum sounding realistic with the quick response that solid-state amplifiers are known for. Cymbals had body and great detail without any edge or grain. And the snare drum was dynamic. Monk’s horn also had great detail and body giving the music the drive it deserves. Soundstage and imaging were solid only being battered by much more expensive amplifiers that are dedicated to two-channel audio.

Blue Tofu’s 2001 album Blue Tofu is a great album and the song “The Woman Singing” can really test an amplifier's ability with dynamic bass. The bass drum hits in this song are immense and can overwhelm lesser amplifiers. There is a bass guitar line that runs right with the bass drum that can get lost in the mix on some amplifiers and speakers. Both of these Rotel amplifiers showed us this detail allowing us to fully enjoy this track. The Rotel multi-channel amplifiers handled this task easily and made good work showing all of the dynamic bass in all of its glory. Vocals had good clarity in the mix and sounded very natural giving the music realism. Playing this track showed us how well-rounded these amplifiers truly are and why the RMB series has been very popular with Rotel. With either the RMB-1585 MKII or the RMB-1587 MKII you get a classic class A/B solid state sound that lets you hear the detail and solid foundation of the music. If you like a warm and buttery tube sound or want the holographic presentation of great class-A designs then these Rotel’s will not be for you, but if you want and neutral sound without any bloat or want a powerful amplifier for your multi-channel theater system both the Rotel RMB-1585 MKII or the RMB-1587 MKII could be the perfect amplifier.

Having evaluated these amplifiers with music we decided to try them in a theater environment to see how they stacked up. Running a 7-channel speaker system the RMB-1587 MKII  was at home driving a theater system. Movie soundtracks had the effortless power on tap to allow the speakers to produce the loudest of passages without the strain or clipping found in receivers or lesser amplifiers. Both of these amplifiers had a solidity to their sound that you won’t find in some of the inexpensive class D multi-channel amplifiers out there. Rotel knows class A/B solid-state amplifiers well and it is apparent with these models.

Overall Recommendation

We enjoyed our time with the Rotel RMB-1585 MKII and RMB-1587 MKII Power Amps and think they are a solid option for people wanting to take their theater system to the next level. They have built-in thermostat-controlled fans to help keep them cool when they are installed in equipment racks with a switch to turn the fans off for 2-channel listening or when installed in a well-ventilated area. With the RMB-1585 MKII’s ability to be configured in bi-amp mode, it gives users the option to use this amplifier to drive less sensitive speakers to their full potential. These amplifiers have the build quality and attention to detail that Rotel is known for and should provide users years of trouble-free enjoyment. If you are in the market for a multi-channel amplifier to take your theater to the next level or want to try bi-amplifying your main speakers we recommend these amplifiers. If you have any questions or would like to discuss how the RMB-1585 MKII or RMB-1587 MKII could improve your system, our knowledgeable staff at Audio Advice is here to help!

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Audio Advice has been in the industry since 1978, and throughout the years, we’ve developed a team of professionals who live and breathe all things audio and video. We spend countless hours testing and reviewing every product we sell to be sure it stands up to our extremely high-quality standards. With our state-of-the-art home theater audio lab, we can become product experts and provide our customers with in-depth, honest feedback. 

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