[Zero]

The main things that I listen for include:

-  How closely a product can recreate (my interpretation) of proper instrumental and vocal timbre.
-  How fluid the integration is between the main frequency bands.
-  Any polarity or phase issues that stem from the components (and not the listening space).
-  Imaging.  Be it on-axis, off-axis, or what have you.
-  Lastly, I listen for whether or not the product is adept at handling a wide variety of music types. 

There's plenty more that I hone in on while listening to expensive Hi-Fi exotica, but since I'm shooting from the hip at the moment, I'd have to say the above list is my 'top 5'. 

[kingdeezie]

I just have to say, I couldn't disagree with this more.  IMO tonal balance is determined primarily by the first impulse, as is the majority of how we perceive a speakers sound.  When I take speakers (and we make models with very well controlled and even off-axis response) between my 3 different rooms, the overwhelming characteristics of how they sound remain intact.  What changes in how well they image and disappear into the room.

Consider me completely unknowledgeable on this subject, and this is being asked as an honest question of anyone here.

When you are talking about controlled and even off axis response, wouldn't this predictability between rooms only apply to frequencies above a certain range?

Said in another way, considering how bass frequencies tend to propagate differently than midrange or high frequencies, how is it possible that overall tonality doesn't change between rooms?

I have always struggled with bass reproduction in my small room, even with significant amount of treatments.

These bass issues have most certainly changed the tonality of the speakers, as positioning and treatments have had significant impact on the sound I hear. When there are nulls and peaks in the bass, it seems the entire range is effected in some way or another.

How does the off axis response over the full frequency spectrum provide insight into how a speaker will ultimately sound room to room, when bass response can vary so drastically?

[Nyal Mellor]

Freo-1,

Boy all that seems so right, but the ATC prices are all so wrong ($4990/pair for the cheapest active ATC, the small 2-way SCM20ASL PRO MK2).   

Considering the sound quality you get from the ATCs I think the prices are very competitive with other speakers in the market. Those SCM20ASLs do need subwoofers for a full range system but sound in one word awesome. The SCM19/20 also measure really well; the mid/woofer is a very clever design, where the outside of the cone decouples from the inner at higher frequencies. Notice the "two tone" coloring of the cone...that's the two different materials in use. Plus the large soft dome dust cap. And the massive underhung magnet!

[poseidonsvoice]

Nyal,

That is a beautiful feat of engineering from ATC. I long have respected their driver technology.

Another link of relevance here from Audioholics along with points by Duke and Dr. Toole:

http://www.audioholics.com/loudspeaker-design/measure-loudspeaker-performance

Don't forget the Acoustics Frontiers blog here (all the links within are relevant):

http://www.acousticfrontiers.com/category/blog/acoustics/speaker-directivity/

Best,
Anand.

[Duke]

I tracked down Ken Kantor's paper on the Magic Speaker: http://www.kenkantor.com/publications/magic_speaker/magic_speaker.pdf

Thank you for finding and posting that!

There was another article in Audio from that era, a two-part look at the live end/dead end approach to room treatment.  The first part, dealing with the underlying theory, was very informative.  The authors were Pisha and Bilello, but I've been unable to find a copy online. 

Another link of relevance here from Audioholics along with points by Duke and Dr. Toole:

http://www.audioholics.com/loudspeaker-design/measure-loudspeaker-performance

Don't forget the Acoustics Frontiers blog here (all the links within are relevant):

http://www.acousticfrontiers.com/category/blog/acoustics/speaker-directivity/

Yeah I was lucky enough to exchange a few posts with Floyd Toole in the thread at the first link, that was pretty sweet.

Nyal's series of articles on speaker directivity is excellent.   He threatened to do one on dipoles, and I've been hoping he would do so and maybe include bipoles too. 

How does the off axis response over the full frequency spectrum provide insight into how a speaker will ultimately sound room to room, when bass response can vary so drastically?

Suppose we have a 6.5" two-way speaker with a 1" dome tweeter, crossed over at 2.5 kHz.  Suppose this speaker's response is essentially "flat" on-axis.   Here's an approximation of what's happening off-axis in the 2.5 kHz crossover region (the exact numbers will vary a bit with woofer diaphragm material and cabinet geometry): 

At 30 degrees off-axis, the woofer is -3 dB and the tweeter is -1 dB, so the tweeter is 2 dB louder.

At 60 degrees off-axis, the woofer is -9 dB and the tweeter is -2 dB, so the tweeter is 7 dB louder.

At 90 degrees off-axis, the woofer is -18 dB and the tweeter is -7 dB, so the tweeter is 11 dB louder.

So the more of this off-axis energy the room returns to us in the form of reflections, the louder the speaker will sound at the bottom end of the tweeter's range, ballpark 2.5 to 4 kHz, right smack where the ear is most sensitive.   Emphasis in this region can make a speaker sound forward, bright, and even harsh. 

[Nyal Mellor]

Nyal's series of articles on speaker directivity is excellent.   He threatened to do one on dipoles, and I've been hoping he would do so and maybe include bipoles too. 

Suppose we have a 6.5" two-way speaker with a 1" dome tweeter, crossed over at 2.5 kHz.  Suppose this speaker's response is essentially "flat" on-axis.   Here's an approximation of what's happening off-axis in the 2.5 kHz crossover region (the exact numbers will vary a bit with woofer diaphragm material and cabinet geometry): 

At 30 degrees off-axis, the woofer is -3 dB and the tweeter is -1 dB, so the tweeter is 2 dB louder.

At 60 degrees off-axis, the woofer is -9 dB and the tweeter is -2 dB, so the tweeter is 7 dB louder.

At 90 degrees off-axis, the woofer is -18 dB and the tweeter is -7 dB, so the tweeter is 11 dB louder.

So the more of this off-axis energy the room returns to us in the form of reflections, the louder the speaker will sound at the bottom end of the tweeter's range, ballpark 2.5 to 4 kHz, right smack where the ear is most sensitive.   Emphasis in this region can make a speaker sound forward, bright, and even harsh.

I will do one on dipoles at some point, though I think Linkwitz has covered most of it on his website. Bipoles I had not considered but is another one to add to the list.

Here's one of my blog posts on cone size: http://www.acousticfrontiers.com/speaker-off-axis-ka-and-driver-diameter/

[JLM]

A couple of weeks ago Duke PM'd me with a suggestion for adding LCS (Late Ceiling Splash) to my large floor-standing single driver speakers via use of a parallel tweeter/cap laying on the floor behind each speaker.  So I've cobbled together a relatively close facsimile from local/borrowed/on-hand parts and have been listening for a couple of days.  I likey.  Seems to lift the treble, adds spaciousness, and solidifies imaging.  So I dropped $70 and ordered Duke's recommended parts from Madisound and Parts Express and will write a review in the next few weeks.

Thanks Duke!!

Note that I've also been experimenting with speaker placement as friends and the CD (Controlled Directivity) crowd have recommended, so it's been a bit of a roller coaster ride of impressions over the past month.  Went from Cardas equilateral near-field to pulling them about 12 inches farther - same distance from listener and toeing them in in front of me - had been compromising with the primary listening position and my desk directly behind to having them cross between both positions.  Any farther apart (before LCS - will have to experiment again) and the center of the soundstage disappears.  But now the soundstage is much wider/deeper from the primary position (had always exhibited very defined imaging) and from the desk sounds like "regular" (multi-driver, far-field, maybe even O.B.) speakers.

[werd]

A couple of weeks ago Duke PM'd me with a suggestion for adding LCS (Late Ceiling Splash) to my large floor-standing single driver speakers via use of a parallel tweeter/cap laying on the floor behind each speaker.  So I've cobbled together a relatively close facsimile from local/borrowed/on-hand parts and have been listening for a couple of days.  I likey.  Seems to lift the treble, adds spaciousness, and solidifies imaging.  So I dropped $70 and ordered Duke's recommended parts from Madisound and Parts Express and will write a review in the next few weeks.

Thanks Duke!!

Note that I've also been experimenting with speaker placement as friends and the CD (Controlled Directivity) crowd have recommended, so it's been a bit of a roller coaster ride of impressions over the past month.  Went from Cardas equilateral near-field to pulling them about 12 inches farther - same distance from listener and toeing them in in front of me - had been
compromising with the primary listening position and my desk directly behind to having them cross between both positions.
Any farther apart (before LCS - will have to experiment again) and the center of the soundstage disappears.  But now the soundstage is much wider/deeper from the primary position (had always exhibited very defined imaging) and from the desk sounds like "regular" (multi-driver, far-field, maybe even O.B.) speakers.

I find this interesting. Have you tried batching the 2 tweeters together for use as a single point. Then put them in the middle of your 2 speakers?