Suitable midrange cone, for bandpass mid in Unity horn.

[Patrick Bateman]

Originally Posted by SEdwards

Thanks for the plots Sheldon. Looks like 1 driver can work pretty well.

I have an idea that I want to run by you guys. First all all, keep in mind that I like listening from the floor. Chairs = work.

In a system with perfect symmetry (like the L/R symmetry of a horn) we should be able to cut it in half and get the same result. With a 100% reflective screen along the axis the virtual sources from reflections should equate to the real sources from the other side.

So I should be able to model a horn with only 2 sides, closed by the floor. Imagine a folded book standing up (angled). Add another boundary and 1 of the 4 sides of the pyramid should do.

Has anybody tested in this way? The compression driver at the throat breaks the symmetry of the mids, but still, it would be very interesting to compare with a full horn.

I imagine that the 50% horn would work for my floor use.

If I'm not mistaken, the 'mirroring' thing will increase output at low frequency, but as frequencies grow higher, you're still going to get the peakiness that results from a horn that's too small.

If you're trying to reduce the footprint of a horn, I've generally found that the most effective way to do that is to use a boundary to extend the output. For instance, when I put my Summas flush with a wall, the wall seems to become 'one' with the speaker. Whereas when the speaker is a foot or two from the wall, the soundstage is not as good.

[SEdwards]

In principle, I think that peakiness can only sneak in as the symmetry is broken. With corner loaded woofers, the long bass wavelengths allow a lot of fudging. In an ideal world with an ideal point source placement at the corner, the gain should work at all frequencies since there is no length scale in the problem until we add one with asymmetry.

I admit that the highs might be tough to get right but it should be doable with some care at the throat. The mids should be pretty immune to sloppy termination with the boundary.

Looks like I have an experiment to perform.

EDIT: Even if I don't find a nice HF solution, I think that this kind of boundary reinforcement should be helpful for estimating mid response with 1 of the 4 sides.

[Patrick Bateman]

Originally Posted by SunRa

Hi Sheldon, I can't recall, or fin in this thread, have we established what's the Misco 5" midrange used in the original unity? This one: JC5RTF-B ?

About a year and a half ago I posted some pics of the original Lambda Unity, and made an (incorrect) guess as to the origin of the woofer. (I'm too lazy to look up the link right now, but it's in this thread.)

Tom corrected me, and said the woofer was from Misco. The JCRTF5-B is the only one from Misco whose parameters match, and it looks virtually identical to the Lambda Unity, so I think it's safe to assume it's the same woofer. It's possible that there were some changes made for the Lambda run, but someone would have to run their drivers through a woofer tester to be 100% sure. (IE, if the power handling was different, that would show up as a change in the QES)

[SunRa]

Thanks for confirmation and also for the clarification on conic vs os profiles.

I am somehow going a different route for my eventual unity build.

I've noticed JLH for example is more concerned to get the midranges work higher, so that the compression driver crosses at around 1.2Khz, even higher and he is not very interested in going low with them. That's why, I guess, he is using the 3" Misco's, to better integrate them with the CD.

My goals are somehow different, I would like to get the unity work from 200-300Hz if possible.

Therefore I think I would compromise on using a 1.4" CD so that I can cross at around 800-900Hz and dsp the top end. And I would be using 5" mids to achieve that. I need start doing some ackabak sims and calculate cross-sections to see if this is going to happen. Mounting 5" mids near a 1.4" apperture might not allow me to meet the 800-900Hz crossover point I am hopping for and keep the point source behaviour.

[JLH]

The local area of expansion (flare rate) dictates how low the mid will play. The cross sectional area dictates how high you will get high frequency loading from the horn. This is a different issue than the 1/2 wave length cancellation notch. The area the mid taps into needs to have a circumference less than or equal to the wave length of highest frequency of interest. For 900Hz you want to tap into the horn where the area is approximately 115cm^2 and 146cm^2 for 800Hz. You have to balance the 1/2 wave length cancellation notch, the local area of expansion, and the area of the tap in point all simultaneously to get a Unity or Synergy horn to work correctly.

[Patrick Bateman]

My Paraline experiments inspired me to try something which is basically equivalent to an unfolded paraline. A Paraline is a horn with a coverage angle of zero degrees that radiates in 360 degrees. If you take a ninety degree slice out of that, you end up with this:



Details here:DIYMA Car Audio Forum - View Single Post - Creating The Perfect Soundstage

[SunRa]

Cool, oblate spheroid and unity back again

[PTrim]

I ordered some of the Visaton M10 drivers and just measured the specs-

FS=629
VAS=0.2ltr
QTS=3.24
QES=5.19
QMS=8.58

I measured 2 of the drivers and obtained similar results with both. The VAS was measured with the added mass method. If anyone is interested I got my drivers through this company- M 10 - 8 Ohm

I am going to have a go at designing a Synergy horn now I have these specs.

Cheers Paul

[SunRa]

I'v plugged-in the data you measured (thanks for publishing this) in John's Unity Midrange Spreadsheet and it's a bit off compared to the original midrange used in Unity.

Please post the results of your build, I'm curious of what you can get with this driver!

[Patrick Bateman]

I know there's a lot of people reading this thread that don't have the time to build a synergy horn, or the space that's required to get it to play down to 300hz. Here's an alternative you might consider:




This is the satellite from a KEF KHT1005. Here's a list of reasons you might consider it in lieu of a Synergy horn:

1) after screwing around with Unity horns for over half a decade, I'm convinced that their fundamental goodness has little to do with their efficiency, and a LOT to do with the near-perfect transition from midrange to tweeter. Basically a Unity/Synergy horn fools our brain into thinking it's one wide-bandwidth driver.
2) Once you hear this done properly, conventional two-ways will never sound the same; I can't listen to a conventional two-way without *immediately* knowing that something is wrong. Literally the second I walk into a room.
3) The KEF UNI-Q isn't perfect, but it has a LOT of the Unity goodness. I think this is due to (you guessed it) the near-perfect transition from midrange to tweeter. This is especially notable on vocals and percussion.





4) One way to determine if a loudspeaker has some of that Unity goodness is to look at the polar response. The graph above shows the polar response of two loudspeakers. The first is a conventional two-way (Focal Chorus 807V) and the second is a Kef UNI-Q (Q900).

Note how the transition from the Kef's midrange to tweeter is nearly perfect? To the microphone, it seems to be one driver. There's a little 'wiggle' at 5khz where the midrange hands off to the tweeter. But that 'wiggle' isn't as severe as the noticeable widening of directivity that occurs with the Focal two-way. (Note how the Focal directivity gets much broader at 4khz? That's because the tweeter is much smaller than the woofer, and so has wider directivity. In the Kef, the midrange cone acts like a waveguide for the tweeter, so the directivity change is verrrrrrrry slooooooow.


I couldn't find any directivity plots of the KHT1005 online, but I'm willing to bet it's comparable to the Q900 that was measured by Stereophile.


Here's a frequency response measurement of the KHT1005 satellite, from Home Theater magazine.


Last but not least, I think that one of the most important reasons that Synergy horns don't sound like regular speakers is that they're symmetrical. For instance, a regular two-way speaker is generally optimized for good horizontal directivity (if it's optimized at all.) It's hard to get good vertical directivity from a two-way, due to the fact that the pathlength differences vary greatly depending on angle. The Synergy horns don't have this problem; if you flip an SH-50 on it's side, the directivity is the same.

The same is true with a Kef UNI-Q, at least down to 300hz or so. (Synergy SH-50 is admittedly symmetrical down to a much lower frequency.)


If all of this has piqued your curiosity, the final icing on the cake is that the UNI-Q can be had for about $50 per satellite for the next 24 hours. Newegg has them on their Black Friday flyer. Even if you DIY, it's pretty easy to spend $50 per channel on a Synergy horn *crossover*, and that doesn't even factor in the cost of drivers, labor, failed experiments, and anti-depressants when your midranges don't work

I'm putting my money where my mouth is, and buying ten

http://www.newegg.com/Product/Produc...-82156028-L06A

promo code is EMCJJHF34 and it's good for 24 hours.

Happy Thanksgiving!