Amp Selection for B & W Speakers

[BigBlue1974]

Hey there...also my first post here. Reading these forums really makes me jealous of some of your setups!

So I'm in the planning stage for adding amp(s) to my home theatre setup.

Currently I have the following from the B & W CDM NT line:
CDM 9NT for my front speakers
CDM CNT for my center
CDM 1NT for my rear channels

I am looking to buy another set of CDM 1NT speakers and go to 7.1 for my completed home theatre room.

So here's the decision. I was contemplating going with a Rotel 1080 for the fronts and a Rotel 1095 for the remaining speakers. The other option would be to get a Rotel 1077 which could then drive all 7 speakers.

Just curious what other members opinions are on which would be the better choice and why?

[musman]

I would say go with the RB 1080 then the 1095. The reason is the 1080 will sound much better do to the fact that it is a much more powerful amp, not just in power but in it's ability to put out lots of current to your speakers. The damping factor is 1000 on the RB 1080 & 400 on the 1077.

Also I think the RB 1080 will double it's power into 4 ohms or at least close to that. So in turn it will control your speakers better. The 1077 is sharing one power supply so with all channels driven I really don't think it will put out it's rated spec into all channels. Going with the 1080/1095 is the only way to go.

[mike c]

I believe the 1077 was bench tested and the result was 125wpc x 7 all channels driven. also, i think the 1077 will double output in 4ohms.

[Kevin D]

Musman,

I highly suggest you check out some of the user and magazine reviews on the 1077; 100 watts on a 1077 isn't like 100 watts on anything else.

The 1077 actually produces more power per channel, all channels driven, then it's rated power. The 1077 also doubles power into 4ohms (and doubles again down into 2ohms). Ohm swings do not matter to the 1077 and it in turn will have more control over the speaker as it will not struggle or creep close to distortion trying to equally drive all frequencies.

Saying something will sound better based on dampening factor and wattage is an opinion, but without experience it's definitely not the only way to go.


With that out of the way, I currently have CDM9's, CDM1's, & Sig 7's (inwall CD1's). Don't have a center channel. I had a 1095 and a bridged 1066 running them. Took a gamble on the 1077 and have never regretted it. It hands down feels like more power, more control, better bass, and it will go a lot louder and cleaner then the 1095.

Now, they do sound different. Then 1077 is slightly more relaxed on the highs (I used to run -2 on the treble, now I'm at 0) and the sound-stage is more forward. Both things I liked. You need to try and setup a demo between a 1080 and a 1077 and pick which sound you like the best. The 1080/1095 on CDM's is still awesome and would be great if you liked the sound of the 1080 better. But I personally enjoy the sound of the 1077 more, and that extra 10-20% of power and control is just a side benefit.

Kevin D.

[musman]

I would like to see proof that the 1077 will double into 2 ohm or even a 4 ohm load with all channels driven. I know you own one & no one want to think they could have gotten something better for there money & I don't want to offend you. But there are Krells out there that will not double into 2 ohms with one channel driven. If you look at the Rotel spec sheet they say 100 wpc 8 ohms all channels driven then they say 200 wpc into 4 ohms, they leave out the words *all channels driven*. In fact the RB 1090 or the RB 1092 have no 2 ohm rating. Believe me if it doubled into 2 ohms they would put it in writing.

As far as the damping factor goes, no I would never purchase a amp based on that alone but it is the internal impedance of the amp & it does have allot to do with it's ability to provide current to the speaker & control the woofers.

Peace.

[WI Rotel]

I vote for the RMB 1075. SInce your system is a 5.1, there is no true need for 2 extra channels. Although these 6 and seven speaker formats are the rage I truely don't see what the hoopla is all about. Ive listened to all three and still think the 6 and the 7 are just a waste of money. Please note that recordings are 5.1, the six and seven channel doodas are "processed" variations of 5.1 recordings. No studio is at this time planning to make any other format other than 5.1. Furthermore, even the dolby and DTS music surround modes are a waste. IMO none of them sounds as good or offers better fidelity than Rotel's 5 channel stereo DSP mode. I like it so much that I essentially never listen to regular 2 channel stereo anymore!

[Kevin D]

In the right room 7.1 makes a huge difference. If you have to compromise to get a 7.1 system, put your money to a better 5.1 system.

WI, should we direguard DTS-ES, a true discrete 6.1 system that's been out for years?? What about DD TrueHD and DTS-HD coming out with HDMI 1.3, which will be true 7.1 systems. Recordings will no longer just 5.1 anymore.

Kevin D.

[Kevin D]

If you look at the Rotel spec sheet they say 100 wpc 8 ohms all channels driven then they say 200 wpc into 4 ohms, they leave out the words *all channels driven*. In fact the RB 1090 or the RB 1092 have no 2 ohm rating. Believe me if it doubled into 2 ohms they would put it in writing.

Peace.

OK, the doubling into 2ohms was an exageration. But power does increase of 4ohm, plus simple fact that it will drive a 2ohm load easily makes up for it. Can't do that that with a RB-1080. Plus the 1077's distortion hardly rises when driving a 4ohm load as well.

Kevin D.

[BigBlue1974]

In the right room 7.1 makes a huge difference. If you have to compromise to get a 7.1 system, put your money to a better 5.1 system.

WI, should we direguard DTS-ES, a true discrete 6.1 system that's been out for years?? What about DD TrueHD and DTS-HD coming out with HDMI 1.3, which will be true 7.1 systems. Recordings will no longer just 5.1 anymore.

Kevin D.

When you say compromise to get a 7.1 system, could you clarify on that? Is it more in terms of space in the room or layout etc?

[musman]

The RB 1080 is far more suited to drive a 2ohm load than the 1077. Call Rotel & ask them i am sure that's what they will tell you. Actually they will tell you neither should be hooked to a 2ohm load.

As far as the distortion ratings go most people are not able to hear 2% distortion let alone a slight rise when the amp is working harder.

From Rotels web site >>

"Speaker Impedance 4 ohms minimum".

Peace:

[WI Rotel]

When you say compromise to get a 7.1 system, could you clarify on that? Is it more in terms of space in the room or layout etc?

If you are going to have to buy cheaper components in order to get 7.1 might as well stay with 5.1 with better components. I agree.

[Kevin D]

I've found it's essential that you stick with the spec'ed layout for 7.1 for you to truly benefit from it. If you're room dictates having the center rears right on top of you or all four rears in line with each other, just spend more on a better 5.1 setup.

A 5.1 setup can create a truly awesome surround effect, a 7.1 setup can create an even better one. A compromised 7.1 setup will collapse it pretty quick.

Kevin D.

[BigBlue1974]

Ah ok. Well I'm planning to still get another set of 1NTs to have 4 total for the rears so I don't think that should be too bad. You mention the spec'd layout. Any link to a site that shows what the appropriate spacing etc should be? My room that I'll be working in will be 15 X 15 which seems like it should be large enough but perhaps I'm going down the wrong path if I want 7.1 in there...