[guest2521]

I would take the IB1 even over the N800. They are much more neutral and even handed even though the B&W is very good on piano music and vocal. However I feel on rock the PMC is streets ahead and sounds much cleaner and tighter. The PMC also sounds very balanced at low volume level due to the TL loading and the very sensitive midrange unit.  The mid-range is more important than the tweeter IMHO. The human ear cant tell a sine wave from a square wave at 10 khz . Some people will prefer the Nautilus range of course and they are undoubtedly a huge technical achievement in many ways.

I use PMC MB2s with a bryston 7b-st and 4b-st per speaker to give passive tri-amping. Its a HUGE improvement over just using the monoblocks. Bryston stereo amops have excellent channel seperation - in fact they are state of the art in most measurement areas. Triamping always sounds better than any single amp equivalent with the pmc, i.e. triamping with 3bs will sound better than monoblocking with 7bs. In fact all the Bryston amps sound pretty much identical as I am sure James will attest. The difference is just the power level.

[Andrew B.]

If you are ready to spend serious money and don't mind a simpler setup, then you should look at some active ATC monitors. Active is theoretically a better way of driving speakers than passive (bi/tri amped or not) because each amp serves just one driver with the result that distortion levels should be much lower. Passive bi/tri amping still involves a passive crossover in the signal path. In practice, some do active badly and some do it well. ATC do it well.

Try the SCM50 ASL (around £7k) or if you have a large room then move up to the 100s or 150s. I think the 50s will be enough from what you have said so far. You will be able to sell your power amps and if you have a Bryston pre then you just need some XLR cables to connect to the ATCs, which have balanced XLR inputs.

http://www.atc.gb.net/scm50/scm50.html

Don't get too hung up on the stats. Mine go down nearly flat to 20 Hz in room. They also play extremely loud, if you want to party. They are awesome.

Andrew

[guest2521]

Or you could go for active ib1s. I will be activiting my system in the next month or two. It is the best way to go. Check out the active pmc ib1s v atc scm100a.

[dan_lo]

Try the SCM50 ASL (around £7k) or if you have  ...

I compared the Active ATC50 to a Bryson/PMC (4BSST, IB2/MB2) setup, when I auditioned both. I had high expectations from the ATC's ( I also found the active package attractive).
Anyway, there was no contest. The PMC's were way better. Much better bass and dynamics.
I still think the active 50 is a good deal at £7k.

biovizier - Are you really taking out the crossover from the ib1?

[guest2521]

The active ib1 is about £6k so slightly cheaper than the atc scm100a.

I too found the passive pmc beat the active atc - by a wide margin.

[PavelL]

So, WHAT is channel separation of Bryston amps /4B sst /? Still no answer... Can anyone tell me? Mr. Tanner? :I'm already considering an upgrade. May be a pair of 7B sst ))

[BrunoB]

I've not listened to B&W's diamond tweeters in person, but everyone who has has simply raved about them. The distortion figures are astonishing: <0.5% THD at 100kHz. That's hardly "useless voodoo". The 802D is generally reckoned to be at least as good as the old Nautilus 800 (better in the treble, not so good in the deep bass), and a very large jump ahead of the Nautilus 802. In fact, even the 803D is supposed to match or surpass the old N802. I own Nautilus 803 speakers myself, and it's the tweeter  ...

I have listened to the B&W 805s and 802D. IMHO, the treble of the 802D is way better and is similar to a ribbon tweeter  in term of speed and detail.

Bruno

[ctviggen]

I think that <0.05 THD at 100kHz is useless voodoo, since any of us are lucky to hear anything at 20kHz let alone 5 octaves higher than that, and your CD player isn't producing anything at that level.  That doesn't mean the tweeter isn't great, just that that statistic is useless.

[James Tanner]

So, WHAT is channel separation of Bryston amps /4B sst /? Still no answer... Can anyone tell me? Mr. Tanner? :I'm already considering an upgrade. May be a pair of 7B sst ))

The typical channel separation on the 4B SST is about -110dB

james

[PavelL]

So, WHAT is channel separation of Bryston amps /4B sst /? Still no answer... Can anyone tell me? Mr. Tanner? :I'm already considering an upgrade. May be a pair of 7B sst ))

The typical channel separation on the 4B SST is about -110dB

james

Thanks for your prompt reply. One of the reviews /in Stereo Magazine/actually said "The stereo channel separation is in order: 52 dB at 10 Kilohertz and five Watts" Did not really sound "work-of-ARTish" at all. I was a bit worried. Would you comment?

[James Tanner]

Gee I have no idea how that measurement came about.

The typical channel separation on the 4B SST is about -110dB in the lower and midband frequencies, decreasing to about -90dB at 20KHz. In other words, crosstalk is extremely low, close to negligible.

james

[nicolasb]

I think that <0.05 THD at 100kHz is useless voodoo, since any of us are lucky to hear anything at 20kHz let alone 5 octaves higher than that, and your CD player isn't producing anything at that level.  That doesn't mean the tweeter isn't great, just that that statistic is useless.

Two octaves. But, in any case, nothing in life is ever that simple.

It is true that a person with normal hearing cannot hear anything if you play him a sine wave tone with a frequency much above 20kHz. However, it does not follow from this that the ultrasonic components of the signal are useless. It has been fairly well established now that the ear is actually sensitive to "transients" which include ultrasonic components.

What is a transient? An example would be someone hitting a snare drum. If you model the sound pressure level following a snare drum hit, the signal you get is very close to vertical: it goes from nothing to about 130dB in almost no time at all. If you filter out all components above 20kHz then you cannot represent a rising edge this steep - it can't rise any faster than a 20kHz sine wave does. And the ear is actually sensitive to the difference between a 20kHz sinusoid rising edge, and the much steeper rising edge that you get with (say) a snare-drum hit. If you extract the component above 20kHz and repeat that pattern, then you don't hear anything - but the initial attack is audibly different without the ultrasonic portion of the signal.

Now, it has to be said, if you're listening to a music CD, it won't contain anything above 20kHz anyway, so you'd have to be listening to something like DVD-Audio or SACD for steep rising edges like this to actually be preserved in the recording.

The other point, of course, is that a tweeter capable of very low distortion at 100kHz will be producing even less in the 5-20kHz range, and even very small levels of distortion in that range are very audible indeed. One of the comments I've heard from people who have head the diamond tweeters in action is that they're one of the few speakers to really reproduce human speech perfectly - especially consonant sounds and particularly sibilants ("s" sounds). A spoken "s" has a lot of frequency components up in the high-tweeter range that a lower-quality tweeter messes up, and makes the speaker sound as if he or she has a very slight lisp.