How much power is enough for B&W Nautilus 804's?


Hello all ... from a recommendation in an earlier post, I went with bi-amping my Nautilus 804's (120 wpc Bryston 3B-ST on tweeters, 250 wpc Bryston 4B-ST on woofers). Per that post, plenty of power on the low end does wonders. It does sound great, but still find the bass not all that (bass player since I was 12 - a few yrs ago). In your opinions, would there be anything to gain by adding another 4B-ST to the mix on the low end? In bridged mode, each pumps 800 wpc into 8 ohms. Would I be doing anything other than putting my 804's into harm's way?

Your advice appreciated. Ed
ekurilla
Almarg,
excellent comments & observations esp. #1 as I was also thinking along the same lines. I've bashed B&W enough here (despite being a former B&W owner OR maybe because I was once a B&W owner) that I decided to stay away. ;-)
Then I noticed that you were thinking along the same lines & just had to pipe in..... :-)

One more thing - just because the Bryston amps are high wattage does not mean that they can source large amounts of current. I did not find any specs for the 4B-ST (tho' I did find a 1992 Stereophile review of the 4B). If the 4B-ST is anything like the former 4B then I read that the DC rails of the power amp are 85V! Meaning that the power transformer must be 60VAC. I have no idea what the VA rating of the power transformers are for the 4B-ST but that would have give some idea of the power delivery capacity. At any rate, the output transistors must be fantastically high voltage rated to run at 85V. IOW, at 85V the current handling capacity of some BJT power transistors is severely degraded i.e. they cannot handle much current while remaing inside their safe operating area (SOA). Thus, you have the high wattage of the 4B-ST but might not have the current delivery capability that B&W speakers so -l-o-v-e-. Hence a bass that is lacking heft.
Looking at the 4B-ST chassis leads me to believe that this thought process is on the correct track.
If the 4B-ST was a current delivery power-house the chassis would have looked like a Pass Labs 350 power amplifier Or a Plinius SA-250, for example.
I haven't owned N804's, but I've owned several b&w's, inc. Matrix 802's. No matter HOW much power I fed the 802's, the bass was never tight or coherent enough.

I sold them & bought Totem Mani 2's, way better bass (& almost everything else). So you might want to check out other speakers, & not necessarily floor-standers IMO.
Exactly, if you want bass similar to open E string of double-bass Bowers will be your worst investment.
Thanks all for the info! This was 1st post on AudiogoN. Took me a while to find where responses live.

Other details on my kit: low end Bryston preamp (.4B), only source is PS Audio DAC 3 w/ Cullen Phase 4 mod, RCA connectors thru out including Y adaptors from pre to amps for bi-amping, no electronic X-over

Seems to me I have 4 courses of action to consider:

1) get different, more bass-capable speakers
2) add a subwoofer (heard REL Stratus III is particularly well suited to 804)
3) add electronic Xover(s) to take advantage of possible bridged 4B-ST's
4) learn the electronics in play to REALLY understand / improve these system choices!

Again thanks all. Great stuff!

Ed