Rotel RB 985, a good buy or a blunder?

Is Rotel 985 good enough to drive difficult speakers like B&W DM302?

  • Yes

    Votes: 2 50.0%
  • No

    Votes: 2 50.0%

  • Total voters
    4

Kreshna

...but I have to know.
I'm building a mini home theater system to play old computer games. My speakers are five B&W DM302s, whose soundstage depth is excellent, but impedance drops to as low as 3 ohms at certain frequency ranges.

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B&W DM302's impedance curve compared with that of JBL L20T.

Originally I tried to drive a pair of DM302s with my 25 wpc Sansui A-40, but the sound distorted heavily at loud volumes. Such thing didn't happen when using the Sansui to drive a pair of JBL L20Ts. It seems the impedance drop is the cause. A buddy of mine said that the impedance drop demands more current, and when the amplifier cannot handle such low impedance, THD increases.

Also, a fellow AK members told me that B&W loves power.

Then I replaced the Sansui A-40 with Yamaha RX-V663, which has considerably more power than Sansui A-40 (95 wpc vs 25 wpc, more than triple). The Yamaha does a fine job driving a pair of DM302s, but it seems I'm going to run out of juice in five channel mode, especially with speakers as difficult to drive as DM302.

I originally aimed for three Crown Com-Tech 210 or 410, in parallel mode (instead of bridged mode), to drive my LCR DM302s.. Those Crowns are cheap and plentiful on ebay, but then I realized the S/H cost is hugemongous! Not to mention ebay's racketeering fee (which claims to pay your customs fee, but in fact way higher than the said customs fee).

So I settled with Rotel RB 985 instead.

I have read opinions on audioreview saying the 985 is good enough to drive 4 ohms speakers. However, the specs doesn't mention anything about 4 ohms load. The B&W DM302's nominal impedance is actually 8 ohms; it is the 3 ohms dip that worries me.

What do you think? I already bought the Rotel anyway, so the purchase cannot be cancelled. But if the Rotel isn't powerful enough to drive the DM302s, I could use them in living room to drive the JBL titaniums (JBL 120Tis, JBL 4410 center, and JBL L20Ts). Those JBLs are easier to drive than the B&Ws, albeit less sensitive.

The planned mini home theater system, on the other hand, will be in small room. I would sit no more than 1.8 meters from the front L-C-R (rear speakers would be even closer). The DM302s, despite difficult to drive, is pretty sensitive at 91 dB / watt / meter. And based on Crown Power Calculator, I would only need 81 watts per channel to achieve THX level (85 dB continuous with 20 dB headroom) at my sitting position.

So, is the Rotel 985 good enough for the purpose?
 
Since you already bought the Rotel. Try it and find out for yourself in your system in your room. Only way to really find out. Of course take some precaution and don't do anything stupid. I'd start a low volume, take it slow and easy at first. Your ears will be a better judgement than my ears which are 3000+ miles away. It's music dude not rocket science. Me like or me no like will do.
 
How are you going to run out of power at 110 watts per channel. The 985 is a superb sounding THX spec amp. Keep it well ventilated though because this unit will run quite hot.
 
How are you going to run out of power at 110 watts per channel. The 985 is a superb sounding THX spec amp. Keep it well ventilated though because this unit will run quite hot.
Well actually mine is the 100 wpc Mk I version, instead of the 110 wpc Mk II version, but I guess I won't miss the extra 10 watts, no?
 
How are you going to run out of power at 110 watts per channel. The 985 is a superb sounding THX spec amp. Keep it well ventilated though because this unit will run quite hot.

I just bought a Rotel RB 985 second hand and I'm quite surprised how good it sounds. I've never owned Rotel amps before. Was wondering how it stacks up to their current lineup?
 
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