How hard to clone the Orions?

[AJinFLA]

Sorry sdclc,

I type slower than molasses, so you posted as I was typing up that last one
The speaker behind the one I posted above. Here is a closeup of the XT-19.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

Sorry about my crappola camera

 

[sdclc126]

AJ - I've seen your speaks on other threads - great job & nice "Variation on a Theme" - but I still don't know the brand of tweet that is - never seen it before. Looks like almost the same diam as the mid, but I guess that's not a radiating surface - a dispersion cone/horn?

Anyway, why did you choose this over the SEAS Mills & how do you compare/contrast the sound characterisitcs (and where did you buy them?)

I'll be patient for your reply, Mr. Molasses!

 

[AJinFLA]

CLC,

I guess you didn't catch it in my post above.

Here is a closeup of the XT-19

I'm not refering to the speaker system, thats the tweeter - a Vifa XT-19. It being loaded by a waveguide.
http://www.d-s-t.com/link/vifa/data/XT19TD00-04a.htm
Now take a look at how it (remember without the waveguide) compares to the Millennium (test grp 8)
http://206.13.113.199/ncdiyaudio/mark/Tweeter test group 4/ow2xt19mdt30start.htm
Open both drivers in two windows side by side for comparison. Look at the response between 10-20k. Notice how the XT-19 exhibits better off axis response typical of a smaller dia driver (the Millennium is very good, but more typical of a 1" dome). What this translates to often is more "air" in the treble. Now take a look at both linear and non-linear distortion. Here is where things get very, very complicated. Starting with how the testing was done, etc. then ending with -well how does this translate "sound" wise. I won't pretend to understand all the complexities involved, but the bottom line is this. The XT-19 is excellent, the Millennium is among the very, very best - if not THE best, as found by SL. It's no match at the low end, again the bigger dia. dome has the advantage here. (the dual concentric drivers like the XT are curious in that although it is a 19mm (3/4") driver, the actual diaphram is more like 1", hence (partially) the very low (unmodified) Fs of about 700Hz - but I digress). But thats where the wavguide comes in. It allows me to do many things. The 1st is the loading allows (when corrected) reduced distortion. Look at what someone intelligent enough to know what they are doing and properly record/measure the entire procedure (my polar opposite ) found:
http://www.zaphaudio.com/hornconversion.html
Then there the shaping of the directivity (response) of the driver to more closely match the directivity of the midbass (@XO) so that are more constant directivity can be achieved. There is much more, but I'm running out of gas here, so I must go. Oh yes I forgot my quick conclusion, whereas you can reduce distortion (ala WG), you cannot improve dispersion (without ill-effect, NO a phase shield IS too compromised). Whew. FYI, there is an interesting thread on the Mad board right now that you should also read. The real experts (Guru's - something I am NOT) are chiming in http://www.madisound.com/cgi-bin/discuss.cgi?read=349868
read the entire thread, there is good info there. I probably missed quite a bit in my description here, but it should give you some idea of my thinking WHETHER WRONG OR RIGHT. I'm out...

Cheers,

AJ

 

[sdclc126]

Thanks for all that great info AJ!

Sorry but the model # meant nothing to me without the "Vifa" in front of it. I own one Vifa driver - a little 4.5" midwoof for my HT center channel speaker - for the price I'm quite pleased with it.

Just surprised that the tweet would compare so favorably with the Mills - at a significant price difference. I'm still a novice in terms of a lot of the technical stuff - X-over design, measurments, etc. - so much of it still goes over my head; but your post begged the question (to me anyway) - might the Millenium (or other dome tweets) also benefit from a waveguide? I wonder how it and the Vifa would compare then? More like apples to apples that way? Maybe we could start a new threat with this - I haven't seen too much about it here, but I haven't searched either.

Also if you wouldn't mind, please direct me to any threads about your Orion "knock offs" - what do you call them anyway? Are the woofs the XLSs? And also, how did you come up with the design for the baffle for the mid & tweet? Quite a departure from the Orion there - was this purely an architectural exercise, or was there a method to your madness? What effects has this baffle imparted on the sound of the speaks?

Thanks again for all the details.

 

[Drew Eckhardt]

Do you find them a bit unforgiving with typical non-audiophile approved recordings?

No with one exception: _Presto_ by Rush is too thin sounding, although the excessive top end is not accentuated beyond what's on the recording.

Bass at lower listening levels may be a bigger issue: power response from the woofers is a lot more like what it is at higher frequencies than with a box speaker, SBIR produces a dip instead of a peak, and they couple less to room modes. Acoustic recordings played at levels closer to live are exceptionally natural, but without the boost from those factors the Fletcher-Munson curves work against you and you loose the bass.

The audiophile answer is to listen at more realistic levels. The practical answer may be a loudness contour. YMMV.

I'm not yet sold on the idea of dipole midrange, it seems to me that from an accuracy point of view one aims to eliminate the rear wave of the driver. Conventionally this is done within the box. With a dipole you are allowing it to enter the room, and attempting to delay and attenuate the rear wave so it's perceived as ambience.

Counter-intuitively the dipole's off-axis response adds less to your listening experience than a monopole's. The dipole is more accurate.

As catapult noted, the dipole adds less ambiance than a monopole because its total power response is 4.8dB lower for a given on-axis SPL.

As you drop down through the human vocal range the sound waves become large compared to a domestically acceptable speaker's baffle: over a foot at 1000Hz (mezzo top end), and 11 feet at 100Hz (barritone low end). The box speaker approaches pure mono-pole behavior with the same SPL level behind it as an open baffle speaker.

In a typical room the the dipole gains its advantage at more interesting angles than 180 degrees.

I have a pretty typical room - 13x19x8', speakers on a short wall 4' off the front and 8' apart, listening position 11' off the front wall, 30 degree toe-in.

First reflections are

front wall 8ms delay, -6dB attenuation from distance, 19 degrees
229 degrees off-axis total
dipole difference: -3.7dB
total attenuation: -9.7dB

ceiling 4ms delay, -3.5dB attenuation from distance, 45 degrees
45 degrees off axis total
dipole difference: -3dB
total attenuation: -6.5dB

side wall 3.4ms delay, -3dB attenuation from distance, 37 degrees
67 degrees off axis total
dipole difference: -8.2dB
total attenuation: -11.2dB

Timber changes from comb filtering and image shifts are _much_ less severe with an open baffle speaker in such a typical room than they are with a box.

The Orion is a bit more complex than a pure dipole - 1440Hz on up are covered by a dome tweeter and the midrange drivers's response 180 degrees off axis is attenuated some at the top by its basket and magnet structure. There's a range where it has more output arround 180 degrees off-axis than a box speaker; although at -6.7dB below and 9ms behind the direct sound this second reflection is a lot less important than the side-wall and ceiling reflections.

 

[paulspencer]

I think if I went with dipole bass, I'd be pretty demanding. I have a kind of custom loudness contour of sorts on my sealed monopoles already! With ultracurve I use dynamic eqs that add a loudness contour at lower volumes. At medium to high volume levels, this does not come in. I tend to like a bit more bass than most ...

But when I've heard my subs without a box, I like how they sound. There is a natural dynamic quality.

Drew, when you talk about "dipole difference" ...

front wall 8ms delay,
-6dB attenuation from distance,
dipole difference: -3.7dB

Do you mean the dipole has 3.7db less SPL going into that reflection?

Hmmmm, maybe I should try out a bit of a dipole test. Put my AV12s in the H frame I'm not currently using, make up some MTM baffles for my vifas, I probably do have enough eq and filters to get it all calibrated flat ...

I have an active xo that I'm not using which crosses at 80Hz and 2.4k. It's a 4LR which I don't use since I figured it wasn't enough by itself, however the 80Hz HPF for the mids would be needed on an OB.

 

[Drew Eckhardt]

Drew, when you talk about "dipole difference" ...

Do you mean the dipole has 3.7db less SPL going into that reflection?


With my room dimensions, speaker placement, and listening position the dipole front-wall first reflection is 3.7dB less than it would be with a monopole.

Dipole polar response is 20 log cosine alpha.