Suitable midrange cone, for bandpass mid in Unity horn. - Page 65 - diyAudio
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Old 11th January 2013, 04:54 AM   #641
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Originally Posted by Patrick Bateman View Post
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:

Click the image to open in full size.
Click the image to open in full size.

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.

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
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.

Click the image to open in full size.
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

Newegg.com - KEF KHT1005.2SE Home Audio Speaker System w/ White Satellite Speakers

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

Happy Thanksgiving!
If anyone is interested in the Kefs, here are some updates on them:

1) Newegg has them on sale again, for the next 96 hours. For $249 you get a powered 8" sub and five 3" coaxial satellites. A screaming deal, considering that the Seas H1602 is $160 each.

2) I measured mine. Here are the parameters:
fs = 149.4hz
qms = 1.083
qes = 0.6459
qts = 0.40
bl = 2.2
sensitivity = 87dB
le = 0.34
sd = 25cm^2

I didn't measure the VAS; I'd guess it's around one liter, based on the VAS specs of comparable drivers from Peerless and Audience.

One thing that surprised me about the Kef drivers was how fragile they are. The cone is probably the thinnest aluminum I've ever seen. Compared to the Peerless 3", I'd estimate it's cone is about half the weight. This has some 'neat' advantages for DIY, because it makes it a good match for a horn. I'm guessing Kef used a very light cone to get sensitivity up, since the very small size of the cone will lead to low efficiency. I simmed the sensitivity using Hornresp, so it may be off by a dB or two. But 87dB is still pretty good for a 2.5" driver.


Here's a couple ideas for the Kef drivers:

1) Stick them in a back loaded horn. Planet10 has some neat designs, and I think the Kef is nearly a drop in for many of the Fostex drivers. The Kef has the advantage of having a seperate midrange and tweeter. Or that could be a disadvantage, depending on how you look at it.

Click the image to open in full size.
2) If you're *really* brave, I think you could do a low-efficiency clone of the Danley. If you tinker around in hornresp you'll find that you can get the efficiency of the Kef into the 90s if you horn load the midrange and add a coupling chamber. On the downside, the tweeter will limit your SPL. Might just be better to go with a back loaded horn!

Note that the price of $249 includes five passive xovers too, which saves a ton of trial and error.





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Old 11th January 2013, 12:13 PM   #642
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It seems to me that getting used to lower volumes is really one of the best approaches, since physics is so much more on your side. I'd like to really lower the noise floor at my place so that I can get some threshold shift. Something like 6dB is so much extra energy but so little perceived volume with our hearing mechanism.

Phase coherency really opens up as an option, then. I know it's important to ave enough volume for a realistic experience but 90 dB sounds like 100 dB when it wakes you up at night.

So you get as much satisfaction (or close to it) with those little guys, as with your more powerful speakers?

Last edited by SEdwards; 11th January 2013 at 12:14 PM. Reason: typo
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Old 11th January 2013, 02:25 PM   #643
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Originally Posted by SEdwards View Post
It seems to me that getting used to lower volumes is really one of the best approaches, since physics is so much more on your side. I'd like to really lower the noise floor at my place so that I can get some threshold shift. Something like 6dB is so much extra energy but so little perceived volume with our hearing mechanism.

Phase coherency really opens up as an option, then. I know it's important to ave enough volume for a realistic experience but 90 dB sounds like 100 dB when it wakes you up at night.

So you get as much satisfaction (or close to it) with those little guys, as with your more powerful speakers?
I bought the tiny little Kefs for purely cosmetic reasons.
Basically I used to live in a 2800' house, and when I downsized I had to move my Gedlee Summas into the garage. (There's just no way to fit them in the living room of my new home, and I don't have spare rooms in the new house like I used to have in the old.)

So I bought the Kefs as a 'placeholder', basically something to tide me over until I could get into a home that's better suited for high end audio. (My lease is up in five months )


But...

A funny thing happened:

1) I noticed the Kefs image better than anything I've ever owned
2) I noticed the Kefs are really articulate, and work well in small spaces



Both of these things are important to me, particularly item two. I write software for a living, so I spent HOURS in front of a computer monitor every day. So the ability to place a speaker very close to me, and still have it sound good, is a big advantage.




I'm wary to compare the $10,000 Summas to a $600 set of Kefs. Definitely apples and oranges here. In particular since I generally prefer to listen to music with the speakers very close to me. (IE, the Summas were never *designed* to be a nearfield monitor. The Kefs excel in this application because the center-to-center spacing between the tweeter and the woofer is less than three centimeters!)
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Old 11th January 2013, 08:01 PM   #644
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I understand the downsizing thing completely. I went from a whole house with HT room in Australia to one room here Germany.

My placeholders are 3" units until I can move back (this year hopefully). I have permission to direct funds from my wedding to a horn build. Planning on AMTs at the mouth. I'll try the 3"s as mids. I tend to wonder how big the upgrade will end up sounding...worth it, I hope. I'll make speakers that can get just loud enough for the wedding but are better suited to a house.

I also much prefer nearfield listening, or headphones. Physics is on your side then. We can't change the relative frequencies of sounds but we can scale what's making them and how far away the transducer is.

Do you have the center playing music too, or is it more ambio at the moment?

Btw, hope you have some nice Cherry switches under your fingertips.
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Old 12th January 2013, 07:53 PM   #645
winslow is offline winslow  United States
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The KEFs have been Klippel tested and the results are on DIYMA.
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Old 15th January 2013, 10:23 PM   #646
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The KEFs have been Klippel tested and the results are on DIYMA.
I found a review of the Q100 on zaphaudio and a review of the HTS3001SE from diyma member 'bikinpunk' here:

Kef’s HTS3001SE… I cracked the Egg! | Medley's Musings

But both of those drivers are larger and more expensive than the one I have. Also, the small cheap Kef driver, the one I bought, is quite a bit better suited to horn loading. This is because the cone on the cheap one is much much lighter, yielding a horn-friendly qts value.
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Old 16th January 2013, 01:14 AM   #647
Pallas is offline Pallas  Pakistan
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Originally Posted by Patrick Bateman View Post
A funny thing happened:

1) I noticed the Kefs image better than anything I've ever owned
2) I noticed the Kefs are really articulate, and work well in small spaces
Seriously, try the 3005SE's. (I know "bikini" Erin is selling the pair he tested...)

I have some of both the 1005.2's (I think that's the number) and the 3005SE's, as well as Q100's. Imaging is a step above, perhaps due to the proto-Tangerine phase plug on the tweeter. Not to mention the extra octave of extension. They're the best thing in that size class I've ever heard. The Q100's better them when playing loud, especially in the upper midrange (much stouter tweeter), but none of these little drivers are really designed for "loud."

Quote:
Originally Posted by Patrick Bateman View Post
But both of those drivers are larger and more expensive than the one I have. Also, the small cheap Kef driver, the one I bought, is quite a bit better suited to horn loading. This is because the cone on the cheap one is much much lighter, yielding a horn-friendly qts value.
The limiting factor there will be the tiny tweeter. Though the small tweeter is the limiting factor on the 3005, too.
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Old 18th January 2013, 09:43 AM   #648
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found this on ebay 2pcs RT4 4x4 SEALED Back Midrange | eBay
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Old 14th February 2013, 09:43 PM   #649
tinitus is offline tinitus  Europe
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I never understood those small holes for the midrange driver

but looking at a bandpass sub it suddenly struck me... they are 'just' bandpass front ports, and can be calculated as such he, thats cool, I want one for my bass guitar

cheers
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Old 15th February 2013, 08:03 AM   #650
tinitus is offline tinitus  Europe
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thinking about using the same small widerange as main driver in the unity horn, replacing the CD tweeter ....nah, thats just rubbish, and wasted energy ...or is it
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