B&W 803d, Martin Logan Spire, Klipsch P-37F?

I do like the tone of the mids on B&W speakers. They have a very sweat sound that is very special on female vocals. I do how ever find the mids a little unnatural.

I have had a hard time putting my finger on what the unnaturalness is but the problem seems to be in the upper most part of the mids.

B&W's use their 6 inch Kevlar midrange up to around 4 Khz. A driver this size starts to beam at 1 Khz. This means there is a roll off in the off axis sound field from 1 Khz to the point where the tweeter kicks in. B&W do not appear to use a waveguide on the tweeter so the tweeter dispersion is very wide and even when it kicks in.

So what doses this design choice mean?

In an anechoic space you hear only primary sound so it won't matter but in an average room you hear a combination of primary and reflected/reverberant sound (70% to 30% or as much as 30% to 70% depending on your setup/room size) - so it will matter. The discontinuity between the midrange and tweeter will place undue emphasis on the tweeter and a "scoop" in the midrange (lack of emphasis). There is also a school of thought that says the ears/brain are somehow able to tell when off axis reflected engery does not match on axis response...the effect is that the sound loses some of its "naturalness" but in return you get a "hi-fi" sound that is more detailed/precise with super tight imaging - you can observe this especially on acoustic guitar where string plucks which can seem over emphasized... and on male vocals which may seem too recessed compared to the bass and treble (whilst female vocalists may jump out at you).

Clearly, the benefits well outweigh the drawbacks for the many B&W fans around the world. The design is clealry a success and it certainly differentiates B&W sound from others.

I hope this helps...

and on male vocals which may seem too recessed compared to the bass and treble (whilst female vocalists may jump out at you)

These were my precise observations with all of my B&W speakers (803D, 804S and N804).

That concerns me as I do not feel like male vocals are recessed on my current RF-7s

The RF-7 is crossed over at 2200 Hz. So it is much like many two ways - except the horn will probably play way louder and cleanly. The 10 inch woofers will still beam however the tractix horn will cause the tweeter to beam also. I suspect Klipsch will have matched the two at 2200 Hz and hence you will have a very smooth off axis response throughout the midrange (they claim "smooth response and consistent coverage" but I have not seen a plot...so this is speculation).

Here is a table of woofer size and beaming
Woofer Beaming begins to occur at (Conservative limit)
18" 576 Hz
15" 720 Hz
12" 863 Hz
10" 1079 Hz
8" 1.23 KHz
6" 1.73 KHz
5" 2.16 KHz
4" 2.58 KHz
3" 3.45 KHz
2" 5.18 KHz
1" 10.36 KHz

In practice, you will begin to notice a significant difference in off axis versus on axis sound as you step to the side of any speaker which flouts these upper limits by more than 50%.

You may have noticed that large single driver speakers often have a "whizzer cone" (think Fostex): this is to try to overcome the beaming problems of a large driver. Other designs may include an acoustically reflective "phase plug" which helps reduce the detrimental effect of beaming (think Seas Excel woofers). Another trick is to let the cone itself flex...remember all those concentric rings on TAD woofers...at higher frequencies the cone flexes and the inside moves more than the outer edge (reducing beaming)

It begs the question: Why in the world would designers ever use woofers at frequencies where they beam? Well the challenge is that drivers need to move a hell of a lot of air as you go to lower frequencies. For example, tweeters do NOT like to be driven at lower frequencies (they just don't work well - either they distort at low SPL's or users fry them too easily). A horn is one option to get a tweeter (a small compression driver actually) to play lower but then it beams by its very nature - so not much of a cure. Another option is to use more drivers (three way) or build robust drivers (big motors and expensive) that are small but still capable of playing low frequencies at high SPL's.

Hope this helps...

So would everyone agree that 803d would have superior midrange to the RF-7? I don't like the ideo of a recessed midrange.