THX-Ultra Certified Five-Channel Power Amplifier
Rotel
is one of those companies that is recognized for their affordable audiophile products.
The RMB-1075 is no different, offering a moderately priced five-channel THX-Ultra
certified power amplifier rated at 120 watts per channel into 8 ohms or 200
watts per channel into 4 ohms. Better
yet, this amplifier has a flat frequency response out to 100 KHz, making it ideal
for high bandwidth formats such as SACD and DVD-Audio. This attractive amplifier
has large finned vertical heatsinks on both sides of the front panel with LED
indicators for power as well as individual channel status in the event the protection
circuits activate. Internal heatsinks also occupy both sides of the chassis, each
of which contain two channels of amplification. The remaining channel uses the
front panel heatsink. A large power switch is located in the lower center of the
face of the unit. During power on, relays are used to delay the activation of
the input signal to prevent speaker thump.
The RMB-1075 uses one large 1,500VA toroidal power transformer. Power rails are filtered with eight 10,000uF British-made slit-foil capacitors. Each output channel uses four bipolar transistors (two 2SA1492s and two 2SC3856s) for a total of 20 output devices, each rated at 130W/15A.
The
rear of the unit has five gold-plated RCA connectors along with a DB-25 input
connector. Speaker outputs use color-coded 5-way binding posts for maximum convenience.
The 12 volt trigger input with pass-thru capability is a great feature enabling
a preamp to activate the power. The non-grounded detachable power cord was a nice
addition to this product.
Setup
Our
setup had a Parasound AVC-2500u THX-Ultra A/V controller with the 12 volt outputs
used to trigger the amplifier. UltraLink Platinum Ultima MkII interconnects were
used throughout the system. The speaker system consisted of three Miller &
Kreisel S-150THX speakers across the front channels and a pair of SS-250 Tripole®
for the surround channels. Each of the five channels present 4 ohms of nominal
impedance to the amplifier making it a fairly difficult load to drive. We used
a Sony DVP-NS900V for CD and multi-channel SACD source material. DVD-Audio was
handled by our Kenwood DV-5900M DVD changer.
We drove our speakers rather hard to see what limitations may exist with this amplifier, but even at relatively high levels, the performance was excellent. Detailed transients were evident in many of our high resolution recordings as well as excellent imaging qualities. The amplifier worked very well with our A/V controller, which uses a THX Linkwitz-Riley crossover set at 80Hz. The subwoofers begin to take over below this frequency. The transition between the main channels and subwoofers was smooth and without any noticeable voids or bumps in the bass response.
The
Rotel RMB-1075 performed amazingly well in our system, especially given the list
price of under $1000. The THX-Ultra badging ensures adequate drive capabilities
for most speaker systems. The looks and performance of this multi-channel amplifier
proves that great sound quality can be had by those on a budget.
-
Kevin Nakano