Question Bowers and Wilkins CM10 S2

Discussion in 'Home Cinema Speakers' started by brett7365, Jun 9, 2015.

  1. brett7365

    brett7365
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    Hi All

    So I am nearly ready to pull the trigger on a Pair of CM 10 S2's, I took my Rotel RMB-1575 and my NAD M51 to Sevenoaks in Sheffield and spent a good 3 hours listening to them with my amp. They sounded amazing, and I commented to the sales guy that in terms of sound quality I would put them 100 % better sounding then my Kef q500's, obviously they are 3 and a half times the price and should sound that good, but their was a comment that was made by the sales man that has got me thinking, he said that he has the cm10's at home and a nad M51, but that he had the top end Parasound amp (i didnt get the model number) at home that was about £8000, he said that this was the first time he had heard the Class D rotel amps and that in his opinion my amp was just as good as his parasound and said that his amp couldn't go as loud as mine could, but we both agreed at that level the highs were starting to sound a little hard. He said the Parasound had a slightly softer sound but that he felt it was maybe 2 - 3 % better than the rotel. Now comes my question.

    So I was told that with my amp is not revealing enough to power the 800 series speakers, specifically 804 and 803 Diamonds but what do you guys think? Unfortunately Sevenoaks don't have the 800 series speakers so I can't audition, what's your guys view? are the 804's worth nearly double the price of the CM10 and could my amp power them?
     
    Last edited: Jun 9, 2015
  2. Arcam_boy

    Arcam_boy
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    You'll find as you move further in to the higher end territory the gains will become smaller and smaller.

    I'd take a listen to various amps yourself rather than listen to a salesman as although he's saying your amps good he's listening to it in a different room and after maybe a several week gap. Also the comment about yours being louder maybe down to harshness or distortion from your amp making it sound louder.

    You should be able to power a set of 804/3's from the Rotel. It certainly wouldn't hurt you to get a better amp (think a second hand classe power amp) if you was thinking of the 800 series and it'd probably make the most of the CM10's too!

    Its all good fun but once you start getting to 800 series and eeking an extra 1 or 2% from them it all gets very very expensive!!
     
  3. brett7365

    brett7365
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    Yeah id been thinking the sigma series, the other thing i thought of doing was selling the 1575 and getting a 1585, the nad m27 and m17 looks intersting too, the reason i didnt get the 1585 to start with is because of the size, but i do have a massive enclosed cabinet in the lounge, im starting to think of getting some computer fans in the back of it to push fresh air in and extract from the top, then i could consider some big class a/b amps. Thing is though i do really enjoy the sound of my amp, id hate to regret letting it go
     
  4. harry_houdini

    harry_houdini
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    I ran a 1575 with the B&W 803D + HTM2D and it was fantastic - you'll make tangible gains by getting some good sound proofing in your listening environment then spending more on amps. I still regret selling my 1575 as it was a great all round amp for its price point.
     
  5. brett7365

    brett7365
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    Thanks for the response, im going to have to find a company that has 800 series speakers and go have a listen with my amp! I found a company called moorgate acoustics that are not far from me, they have 800 series, but they dont do av just 2 channel stuff
     
  6. BlueWizard

    BlueWizard
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    "...I was told that with my amp is not revealing enough to power the 800 series speakers..."

    Revealing and Power are not related. Very revealing amps can have modest power, and very powerful amps are not necessarily revealing.

    With 250w/ch, the 5-channel Rotel RMB-1575 has more than enough power to drive all but the rarest of speakers. However, in multi-channel amps like this, the limiting factor is not the power limit of the individual amps, but the power limit of the Power Supply. According to the specs sheet for the Rotel RMB-1575, the power supply tops out at 600w. 250w x 5 = 1250w, but again the spec sheet says -

    Power Consumption: 600 Watts

    Home Theater System Surround Sound Amplifier DVD Player - Rotel PRODUCT SPECIFICATIONS

    That is actually very common in multi-channels AV Amps. The under-powered power supply is based on the fact that you are never going to drive all 5 channels to full power at the same time.

    Myself If I had serious money to spend, I would use a 2 channel Parasound Power Amp (A21) for the Front 2 channels and a 3-channel Parasound (A31) amp for Center and Rear. Each of those amps would have its own separate power supply. And generally Stereo amp over-rate their power supplies. For example a 100w/ch Stereo (200w total) might have a 300w power supply.

    Or perhaps in a 7-channel system, I might use a 2-channel for the Front Channels and a 5-channel for the remaining channels. Or use two 2-channel and a single 3-channel. It would depend on if I had any space limitations. Alternately, a Parasound A31 3-channel for Front and Center, and two Parasound A23 (125w/ch) for the remaining four Surround channels.

    As an example, the maximum power rating for the Parasound A31 250wx3 is 1800 watts (1.5KVA) -

    Power Maximum: 1800 Watts
    with 60 amps peak current capability.

    So, 750w in the 3 amps, but more than double that in the Power Supply.

    Though Class-D amps are extremely efficient, and the power supply power can be much closer to the amp rated power, 1250w vs 600w is a pretty substantial difference.

    But again, this is very common in multi-channel amps for AV use.

    So, whether the Rotel are revealing enough for the B&W 800 series or not, is a different issue than whether the Rotel is powerful enough to drive the speakers.

    The Rotel RMB-1575 5-channel is about £1700.

    The Parasound A51 5-channel is rated at 250w/ch with ALL CHANNELS DRIVEN, and costs £4950, and has a maximum power consumption rating on the Power Supply of 3000w (2.2KVA).

    Just trying to lend some perspective.

    Steve/bluewizard
     
  7. brett7365

    brett7365
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    Thanks for the informative response Steve, Ive always thought that the power consumption must be related, av receiver's with there 170 watts X 9 only consuming 400 watts lol. We can put the revealing and power comment down to me getting carried away with my typing and not taking the time to get exactly what I mean written down, my apologies. What the Bowers and Wilkins support team said was (This is a copy and paste of the relevant section of the e-mail I got from them)

    "From our experience the RMB-1575 can offer a very good performance all the way up to a set of CM10's.
    However, once entering the B&W Premium 800 Series territory, the speakers demand a superior level of amplification (as a consequence of their very revealing nature) to warrant their capabilities and justify their pricing level."

    I think that what they mean is that the 1575 is not revealing enough to get the most out of the 800 series speakers and I would not get the benefit of the 800's over the cm series, so it would be a waste of money.

    I probably need to forget about 800 series for the moment, get the CM's and enjoy it, when the kids have grown up and moved out then look at the 800 series and more powerful amps etc.
     
  8. hifix

    hifix
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    If you wanted a power amp to suit the CM series now, and the 800 series later, then look at the Classe Sigma. We've had the two channel model powering the KEF Blade 2s with no issues at all - never sounding compressed or harsh.
     

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