Stereo Power Amplifier with bridging option
Power output: 50 watts per channel into 8Ω (stereo), 150W into 8Ω (mono)
Frequency response: 15Hz to 100kHz
Total harmonic distortion: 0.03%
Damping factor: 280
Input sensitivity: 1V
Signal to noise ratio: 116dB
Speaker load impedance: 4Ω to 16Ω
Dimensions: 444 x 86 x 336mm
If you have any problems opening files please read the download FAQ. All files are provided under strict licence and reproduction without prior permission or for financial gain is strictly prohibited.
If you have additional documentation please consider donating a copy to our free archive.
Reviewed Mar 03rd, 2014 by bwcarter
This amp has a superior sound that even my old ears could hear - a dramatic improvement over many if not most of the other vintage power units I've been able to listen to. Which number 40 to 50 - in $1000 or less (mostly a lot less) range. I put the 850 in top 20% for sound quality, and for build quality as well.
I was using the matching Rotel RC-850 preamp, which I've reviewed separately - I discuss further using it with this amp.
Sound improvements were definite. Bass was dramatically improved - much more visceral and deeper reaching, plus smoother and cleaner. Sound overall was cleaner with more presence or something. Can hear the difference across a 25 foot room at low volumes - the smooth bass carries.
I've heard that these have a rep for being built like a tank and reliability - which has value. It's a heavy piece, and I think it has dual power supplies. Switch is high quality, and fittings on rear seem so as well.
Note that these are designed to be easy to bridge for double plus power - little switch on rear of amp. The owner's manual says they go from 50 watts in stereo to 150 watts bridged. That may be a typo - as usually it's a doubling of the stereo output. But what do I know? I know that 100 watts of this quality power will drive a lot of the more demanding speakers. I do have 2 myself, but haven't even used them bridged as yet. Have been comparing a single to other vintage 40-60 watt power units.
Also heard they are unusual in having the ability to perform well below 4 ohms and not suffer quality losses or heat up. Down to 2 ohms even. This low end grunt may indeed be a factor in the superior sound. I had a similar experience with a Quad 33/303 set - and it too is noted to handle very low ohm loads.
Perhaps I'm gushing a bit, but after spending about 2 years recently diving deep into the hobby/addiction of vintage audio - and buying literally dozens of pieces, it's not often I find a power unit that I can for sure hear a difference in. Especially at this very affordable price point.
Used a set of vintage B&W DM5 speakers which have great clarity and sweetness - but aren't super fancy and have limited bass. They really worked well with the Rotel 850s.
Note that I'm not a real audiophile - rather a 60+ working man with typical hearing limitations, and limited money to spend. Am exploring/searching for great sound, but also looking for value. I recently tiptoed into a higher realm of expense - and quickly came screaming back to my proper place in the lower kingdom. Bought a Kenwood 700 set (Supremes - all 3) and Tannoy Berkely 15 - $5000 worth. Dissapointed with the sound for the money and sold/selling it. The 700M amp does stand out and is worth the $1000 or so - and rest may do well as investment and eye candy, but don't perform well in the value department for me.
Fair market value as of Feb 2014 is about $250-300 per amp or preamp in excellent condition. I say this is great value and that you should definitely buy one if you get the chance - prefably with matching preamp, but am confident in the amp alone - you just may not get the full benefit.