What Sensitivity with Tube Components?

I've been told that my 89db (sensitivity) B&W speakers will not work all that well with tubes and that at best, speakers should have at least a 90-91db sensitivity to used with tubes.

wcc10  - curious to know where you heard something like that ?  

It depends. you need to provide more info.
Which B&W speakers (model);  how big is your room and how are speakers placed in the room; How far away do you sit from them and how loud is it (average)  ?

Do you listen to all music genres or any specific ones ? 

If you can answer those questions I can make some suggestions. 

Cheers 



 
 

24 x 24 room - nice....
On a bookcase - against the wall ? 
are one or both speakers along one bank of windows ?
CM6s2 ?  like these 

http://www.u-audio.com/shopimages/gmosp156/0000000045302.jpg

what are you looking to improve upon and whats the current amp? 

Those speakers are extra hard to drive - inefficient - due to the small box and B&W trying to make more bass with it.

B&W Manual
88dB spl (2.83V, 1m) its not a straight 88db spl (1.00v, 1m) comparison.
So they are actually worse.
Do the windows have curtains ? if so have you tried closing them.
The manual also says they need to be at least .5 meters 1.6 feet from the back wall and side walls.
A Big TV between them makes it worse too - not sure if that is the case. 

Your amp makes 100 watts at 8 ohms. and only 120 watts at 6 ohms. Your speakers go down to 3 ohms to make their bass.
The speakers are making your amp struggle imo with the bass. This throws off the tonal balance. Makes the speaker therefore sound bright.

If you buy a SS amp make sure the specs show doubling going down - 100 wpc 8 ohms, 200 wpc 4 ohms.
if you buy a tube amp makes sure it has 4 ohm connectors on the back.
I would go with as many watts as you can afford which ever way you decide to go.
important.
try to bring the amp home for trial. if you can't do that bring your speakers to the store and listen there set up as close as possible to your home.

my 2 cents.

briefly looked at the manual. So you are using pure direct mode, cd direct amp ?When I said the 4ohm setting earlier I was implying for the tube amp. but this is an interesting amp.  

I have not tried this setting in the "Low" (4 ohm) setting but maybe it would be worth a try?

I am not familiar with that amp but would say - Yes.
See the wording here.  

http://hometheaterhifi.com/reviews/receiver-processor/receivers/yamaha-r-s700-stereo-receiver/

the R-S700 is bi-wire ready. In this case, it uses both sets of internal amplifiers (Speakers A & B) for one pair of bi-wired speakers. This implies a true bi-wired scenario, where separate discrete amplifiers are used for the tweeter/mid-range and woofer section of your bi-wire-able speakers.
Note that if you do use this bi-wiring feature, it is important to select the proper impedance (high or low) setting for the receiver. The high setting allows bi-wiring speakers with 6 Ohm impedance or higher, while the low setting allows bi-wiring of speakers rated 4 Ohms and higher. Similarly, the high/low impedance switch needs to be properly set for standard wiring too.

As far as wattage - B&W benefit from more good wattage.   I would try the above settings first and see how you like it. I believe you will get more oomph - and it will be a warmer sound.    

Do I consider Class A, B, AB Tube amplification?

That can become a long discussion.  there are real amp experts here that can help you out more.
Push Pull a/b tube amp works well from my own experience with lower efficiency bass needs.  And yes stands would improve things alot - but thats a no due to your wife saying so.    

It is unfortunate that today you can spend $2,000.00 on speakers and not be satisfied.

Sure, in the total these are inexpensive speakers and maybe I expect too much?

wcc010 - imo - Those are not inexpensive speakers. And they definitely will not replace what a 12" woofer will do.

I am curious to know what happened when you switched to the low impedance speaker setting on your amp ?  Did it change anything? 

Cheers

  Perhaps I will try a true bi-wire set up with the switch set to low. Worth a try.

Hi wcc10 according to yamaha amp manual this is what has to happen to test that feature setting.  Even Yamaha recognizes different speaker impedance's and it is the reason they included that feature in your SS amp. Give it a try - costs nothing.  

from that earlier link.

the R-S700 is bi-wire ready. In this case, it uses both sets of internal amplifiers (Speakers A & B) for one pair of bi-wired speakers. This implies a true bi-wired scenario, where separate discrete amplifiers are used for the tweeter/mid-range and woofer section of your bi-wire-able speakers.

 
So give it a try definitely. 

But and this is a big but..... someone that is used to a 12 inch woofer like yourself - it can be like mothers milk you know ...  if infants could talk when being switched from mothers milk to artificial I am sure they would say - ew ,  yucky, phewy.

If the above doesn't work I would switch speakers, or get your wife to approve a sub to bring balance to the music.Those speakers in a space surrounded by windows is a challenge.

Let us know how you make out - good luck