This seems to be the best place to ask, because most people here tend
to have a realistic technical view on things.

I have a surround system based on the B&W Nautilus 805 and HTM2. I am
currently driving then with some old Rotels, the 991 and 993 with a TAG
AV32 pre. These are hefty 200wpc amps. I am currently thinking of
"downgrading" to an Arcam AVR300 receiver, for the simplicity of it,
and because I have had it with "high-end" separates.

So, will a first-class 100wpc receiver be able to get the most out of
my 5 year old 805s? I have asked this question in some other forums and
always get the same predictable answer. No, these are magical
"high-end" speakers. They require at least 200wpc to perform their
best. You should consider upgrading those Rotels to
Krell/Bryston/Levinson whatever instead. A receiver will make them
sound worse.

Now, I don't know much about amps and do not have much experience
comparing them. I have never tried my 805s with anything else than the
Rotels. But I have to wonder: how much juice does it take to drive a
small two-way speaker with a nominal 8ohm impedance (dipping at
4.8ohms) 88db sensitivity to normal listening levels? Considering the
fact that I will mostly be crossing them at 80hz and I don't like to
listen very loud, not even when playing movies? Is the 805 such a
difficult load just only because it happens to be a "high-end" 2-way?
What else is there besides the sesitivity and the 4.8ohm lowest
impedance? Phase? Any other tricks that a "high-end" speaker might play
on an amp that makes it more fussy? I don't know but I just thinks it
smells funny.

I will not have the chance to try the Arcam with 805s before I buy it.
I just want to know if there is any sound technical reason why I should
worry doing this amp downgrade.

wrote in message ...
This seems to be the best place to ask, because most people here tend
to have a realistic technical view on things.

I have a surround system based on the B&W Nautilus 805 and HTM2. I am
currently driving then with some old Rotels, the 991 and 993 with a TAG
AV32 pre. These are hefty 200wpc amps. I am currently thinking of
"downgrading" to an Arcam AVR300 receiver, for the simplicity of it,
and because I have had it with "high-end" separates.

So, will a first-class 100wpc receiver be able to get the most out of
my 5 year old 805s? I have asked this question in some other forums and
always get the same predictable answer. No, these are magical
"high-end" speakers. They require at least 200wpc to perform their
best. You should consider upgrading those Rotels to
Krell/Bryston/Levinson whatever instead. A receiver will make them
sound worse.

Now, I don't know much about amps and do not have much experience
comparing them. I have never tried my 805s with anything else than the
Rotels. But I have to wonder: how much juice does it take to drive a
small two-way speaker with a nominal 8ohm impedance (dipping at
4.8ohms) 88db sensitivity to normal listening levels? Considering the
fact that I will mostly be crossing them at 80hz and I don't like to
listen very loud, not even when playing movies? Is the 805 such a
difficult load just only because it happens to be a "high-end" 2-way?
What else is there besides the sesitivity and the 4.8ohm lowest
impedance? Phase? Any other tricks that a "high-end" speaker might play
on an amp that makes it more fussy? I don't know but I just thinks it
smells funny.

I will not have the chance to try the Arcam with 805s before I buy it.
I just want to know if there is any sound technical reason why I should
worry doing this amp downgrade.

First, the Arcam AV300 is one of the best sounding receivers out there...and
should handle your 4.8 ohm dip okay. Some of the mass market receivers
might choke on it...which is the root source of the advice you have been
given, probably.

Secondly the fact that you are driving them in an "all small" mode with
self-powered subwoofer does relieve strain on the amps.

And thirdly, the fact that you don't play music or movies all that loud also
mitigates in the Arcam's favor.

Obviously this is just an opinion, but I'd say to go ahead...and I'm not a
"mass market" guy. But neither is the Arcam a "mass market" receiver.

wrote in message ...
This seems to be the best place to ask, because most people here tend
to have a realistic technical view on things.

I have a surround system based on the B&W Nautilus 805 and HTM2. I am
currently driving then with some old Rotels, the 991 and 993 with a TAG
AV32 pre. These are hefty 200wpc amps. I am currently thinking of
"downgrading" to an Arcam AVR300 receiver, for the simplicity of it,
and because I have had it with "high-end" separates.

So, will a first-class 100wpc receiver be able to get the most out of
my 5 year old 805s?

As long as it's not driven to clipping, there ought not to be any problem.
My prefernce, would be to keep the available power as high as possible,
simply to avoid clipping.

I have asked this question in some other forums and
always get the same predictable answer. No, these are magical
"high-end" speakers. They require at least 200wpc to perform their
best. You should consider upgrading those Rotels to
Krell/Bryston/Levinson whatever instead. A receiver will make them
sound worse.


Not unless driven to clipping. This has been shown repeatedly to be the
case. There are plenty of receivers that can drive loads as low as 2 ohms,
but they tend to be a bit pricey compared to others.

THX certification is a good sign so if you must change, look for it.

Now, I don't know much about amps and do not have much experience
comparing them. I have never tried my 805s with anything else than the
Rotels. But I have to wonder: how much juice does it take to drive a
small two-way speaker with a nominal 8ohm impedance (dipping at
4.8ohms) 88db sensitivity to normal listening levels?

Depends on the size of the room. The bigger the room the more power you
need.

Considering the
fact that I will mostly be crossing them at 80hz and I don't like to
listen very loud, not even when playing movies? Is the 805 such a
difficult load just only because it happens to be a "high-end" 2-way?

Not likely.

What else is there besides the sesitivity and the 4.8ohm lowest
impedance? Phase? Any other tricks that a "high-end" speaker might play
on an amp that makes it more fussy? I don't know but I just thinks it
smells funny.

You'd be right. There is a large amount of mythology in audio, and about
amps in particular.

I will not have the chance to try the Arcam with 805s before I buy it.
I just want to know if there is any sound technical reason why I should
worry doing this amp downgrade.

AFAIK the only real concerns a
1. Is there enough power to drive the speakers to the spl you require
without clipping?
2. Is there a problem with the speaker that makes it difficult to drive
with an amp that
doesn't have high current capability?
3. Will a receiver be able to provide all the fucntions you need?

Most audiophiles, would not reduce the power output to their speakers,
simply because they like the idea of the extra headroom from having the
extra wattage. There are now many recievers that can drive virtually any
speaker. Your speakers are not difficult to drive and you will not suffer
any degradation in sound quality by consolidating your functions into a
reciever.

You might wish to consider other receivers having the same functions and
power output just to see (and hear) if there is any reason to pick the Arcam
over another.

These are some of the actual opinions regarding the 805s and the AVR300
from other forums:

"No. Nautilus series B&W speakers like lots of current. They may sound
'OK' with a relatively cheap AV receiver but they're really meant to be
driven by serious amplification of the Krell/Chord variety. I drove a
pair of 805s and an HTM2 with a Roksan five-channel amp (which,
relatively speaking, had lots of current). It sounded reasonable.
Upgrading to a 200W Krell really showed what these speakers are capable
of. Trust me. An AVR300 will only show you 30% of what those B&Ws can
do."

"I'm sorry but bi-amping the AVR300 won't bring out the best in a pair
of 805s. The 805s totally outclass the AVR300. B&W Nautilus are less
sensitive (at some frequencies) than people expect. I'd look for a
power amp which, ideally, doubled its wattage as the speaker's
impedance halved. Anything else and you're really wasting much of your
investment in those speakers. It's like transplanting a Mondeo diesel
into a Porsche IMO."

Could someone give me a sound techical explanation as to why this guy
might be right? I just don't see it. I'm more on Harrys line of thought.

wrote in message ...
These are some of the actual opinions regarding the 805s and the AVR300
from other forums:

"No. Nautilus series B&W speakers like lots of current. They may sound
'OK' with a relatively cheap AV receiver but they're really meant to be
driven by serious amplification of the Krell/Chord variety. I drove a
pair of 805s and an HTM2 with a Roksan five-channel amp (which,
relatively speaking, had lots of current). It sounded reasonable.
Upgrading to a 200W Krell really showed what these speakers are capable
of. Trust me. An AVR300 will only show you 30% of what those B&Ws can
do."

"I'm sorry but bi-amping the AVR300 won't bring out the best in a pair
of 805s. The 805s totally outclass the AVR300. B&W Nautilus are less
sensitive (at some frequencies) than people expect. I'd look for a
power amp which, ideally, doubled its wattage as the speaker's
impedance halved. Anything else and you're really wasting much of your
investment in those speakers. It's like transplanting a Mondeo diesel
into a Porsche IMO."

Could someone give me a sound techical explanation as to why this guy
might be right? I just don't see it. I'm more on Harrys line of thought.

Here's a quote from the Stereophile review of the 805s:

"My estimate of the Nautilus 805's B-weighted voltage sensitivity was a
little below specification at 85.5dB/2.83V/m. However, its impedance plot
(fig.1) revealed it as being very easy to drive, with a minimum value of 4.8
ohms at 200Hz and a generally low phase angle, other than in the upper bass.
The midbass "saddle" in the magnitude trace indicates the tuning of the
unique dimpled port to lie at 42Hz, implying only moderate bass extension"

I assume this the speaker you are talking about, it's a bit difficult to
determine if they mean 805s or if they mean 805's.

Assuming that the above review snippet is your speaker, then any decent
quality amp should have no problem driving it.

I cxan only assume that if it were difficult to drive, someone on this group
would let you know. I can't find anything from any reasonably objective
source that claims it is difficult to drive.

Whatever quibbles I have with SP, they do seem to do honest measurements.