[KJ]

Weez,

One thing I should mention is that although B&W's specs list their Nautilus 800 line at 8ohm impedance, I was told by another B&W dealer that they measure lower (~4 ohms).  Looking at B&W's site, they do show a minimum impedance of 4.6 ohms for the N805s you heard (88db sensitivity).

Beebop,

This might indicate that the B&Ws are slightly easier to drive with the 60wpc of the B60 compared to your current speakers.  On the flip side, Bryston's wpc rating is almost always conservative.  I own a 3B-ST which is rated at 120wpc and use it to drive B&W Matrix 805s.  Yet, the amp came with just over 150wpc from the factory according to the build sheet.

So, on one hand your speakers might be more difficult to drive than what Weez auditioned.  On the other, you'll most likely get a little bit more power than 60 wpc.

Maybe I'll swing by Dave at AE on Tuesday to ask about the impedance ratings since I work only 1/2 mile away from his store.  Sadly, I've been a frequent visitor to his store and one of the providers of his kids' college funds.

-KJ

[WEEZ]

KJ,

The impedence of the 805's might dip into the 4-ohm range at certain frequencies, but also probably has higher impedence at other frequencies-hence the 8-ohm "nominal" rating. Don't know.

All I can say is, the little B60 is an impressive amp and IMHO, should produce enough juice with any "reasonable" speaker in any "reasonable" room at a "reasonable" volume level. Sound reasonable?

BeeBop,

What speakers will you be using? Is your room huge? I think some of us would be interested to learn of your intended use of the B60, I know I would.

WEEZ

[WEEZ]

By the way, 4-ohm speakers are not necessarily easier to drive- they take more current from the amp. All things being equal; an 86db 8-ohm speaker will give the same volume as an 89db 4-ohm speaker.

(read that somewhere.... )

WEEZ

[WEEZ]

Actually,

I might have that backwards--

Anyway, a 4-ohm load is harder on the power supply of the amplifier, so I think the B60 would be happier with an 8-ohm speaker. The bigger amps probably wouldn't care as much.

Oh well...

My point is that the B60 drove the 805's in that large listening room very well. I was impressed.

WEEZ

[BeeBop]

KJ,
What speakers will you be using? Is your room huge?WEEZ

ACI 25th Anniversary Sapphires. Room is not huge - 20' by 16' and filled with overstuffed furniture, bookcases, etc..  Mostly I listen to Jazz/Classical/World music. Every once in awhile I get a bellyfull of whiskey and dig out my old rock, only rarely.

I'd really like to get a 3BSST and BP25 but can't afford it. Well mayyyybe used. Was hoping the B60 would do it at least for awhile.

[WEEZ]

BeeBop,

Nice speakers. If I recall correctly, the new Sapphires are rated at 86db as you indicated- but the important thing is that they don't dip below 6-ohms, so they present an easy load for an amplifier. That's a good thing IMHO.

I started this whole thing asking about the sonic signature of the B60- not having a chance to audition one locally. After hearing a new model last week, I must say that I was impressed. (Too bad I still haven't been able to hear one in my system, though). The B60 is absolutely quiet. It seems to have a neutral presentation with no grit or grain whatsoever. Very smooth.

Maybe you could use a B60 for a pre-amp with your "future" 3BSST- and enjoy it as an integrated in the meantime. That thought has crossed my mind......

WEEZ

[WEEZ]

By the way, the optional phono stage is quite good also. Too bad the DAC option can't be had with the phono option at the same time. Oh well...

WEEZ

[KJ]

Actually, I might have that backwards--

Anyway, a 4-ohm load is harder on the power supply of the amplifier, so I think the B60 would be happier with an 8-ohm speaker. The bigger amps probably wouldn't care as much.

WEEZ

I believe you are correct.  The impedance rating of the speaker indicates the measured electrical resistance.  Therefore, you would not want a speaker to have a lower impedance than what a ss amp is capable of.  Otherwise, I believe you are at risk of frying the amp's output transistors.

-KJ

[BeeBop]

... the important thing is that they don't dip below 6-ohms, so they present an easy load for an amplifier ...

Thanks WEEZ. You're right. Nominal impedance is 8 ohms; minimum impedance is 5.8 but I wouldn't expect it to hit that more than once in a blue moon.

[nicolasb]

Otherwise, I believe you are at risk of frying the amp's output transistors.

Most even half-way decent amps will limit their output under those conditions. You're actually much more likely to damage the speaker if you have an inadequate amplifier. Many amplifiers will "clip" - i.e. hit a ceiling and suddenly go from (say) a rising edge to a flat signal. Signals like this, with sharp corners, are impossible for a speaker to handle, because the cone has to try and go from rapid movement to being stationary (or vice versa) in no time at all. In attempting to do this, it may well damage the suspension of the cone.

It's usually the tweeters that blow out, as they're more fragile.