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Multi-Way Conventional loudspeakers with crossovers

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Old 11th February 2014, 07:15 PM   #111
Zvu is offline Zvu  Serbia
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That is why i wrote "if we count out dedicated suwoofers". Compared to LMS-R15, 15TBX100 really is a lot lighter.

I am working on something similar to Summa's but with Beyma 15K200 and using DE250 for tweeter. Xover should be 24/18dB/o and at 900-1000 Hz. Beyma has Mms of 107gr and i think that even that is a lot to reproduce lower mids with proper dynamics.
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Old 11th February 2014, 07:22 PM   #112
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In the original post I was referring to the possibility of raising the QTS of the 15TBX100 by increasing QES and QMS. Basically it would be hard to get it up to 1.0 because it's hard to add enough weight or enough resistors to make it's parameters ideal for an OB.

But it's all a bit academic; with miniDSP you don't have to bother, just 'dial in' whatever frequency response you want and skip any driver modifications.
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Old 13th February 2014, 02:38 AM   #113
dr suad is offline dr suad  United States
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Patrick,

Excellent write up on the Pyle horn unity. I like the idea of modifying an existing horn instead of having to build a horn from wood. if it works out that the measurements are OK with your project, I may use it to replace the tweeter and horn of my modified Klipsh Cornwall speakers. All I would need to do it simply seal the ends of the ND91's and cut a hole for the Pyle horn.

One neat thing about this project is that you could cut the mounts for the ND91's out of masonite and then simply glue it it using loctite "repair putty". We use this stuff all the time in industrial applications to hold up 2 pound brackets directly mounted to machines. Its and industrial epoxy that molds like clay and in 5 minutes, its has hard as a rock, bonding to nearly anything. JBweld makes a similar product, but has steel filler. Its available at walmart and home depot.

Nick McKinley of Lambda acoustics use to be based in my hometown of Melbourne, FL. I remeber going to his place one time to listen to the Unity speakers he built. I never heard anything quite like it!
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Old 13th February 2014, 03:51 AM   #114
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I understand horns for the car but the beaming effect I couldn't live with for too long, same with ribbon tweeters... good luck anyway.

and whatever you find out im using for my car..
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Old 5th August 2014, 06:58 AM   #115
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Quote:
Originally Posted by Patrick Bateman View Post
This isn't equalized, but here's what it looks like at zero, 22.5 and 45 degrees off axis:

Click the image to open in full size.

Basically we see that the beamwidth is narrowing at high frequency, just as expected.
Note that the vertical range in this measurement is compressed to 40dB to make the variations clearer. (The other measurements used a 50dB window.)

I'm kinda stoked that the dipole radiation doesn't seem to be creating and weird lobes off axis, with the possible exception of a dip at 1khz.
Obviously the response will change quite a bit once I add a baffle, and I plan to make it cardioid-ish also.
User DJK posted an interesting patent over in the 'study of dipole/cardiod horn' thread. Apparently Cerwin Vega had a patent on a Unity-style cardioid horn, almost fifteen years ago. (Patent US6038326 - Loudspeaker and horn with an additional transducer - Google Patents)

I believe it predates the SPL Labs Unity horn by a few years, and Danley references the Cerwin Vega patent in his patent.

Interesting stuff.

Click the image to open in full size.

a second electroacoustic transducer disposed outside said compression chamber, said second electroacoustic transducer being mechanically and acoustically coupled to said horn whereby, when radiation of said second electroacoustic transducer is added to radiation of said first electroacoustic transducer, radiation output in front of said loudspeaker is a dipole and in phase augmentation sharing the monopath of the output of said first electroacoustic transducer and in rear of said loudspeaker is out of phase of with the output of said second electroacoustic transducer so that said combined monopole and dipole produces a cardiode-shaped wave.
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Old 5th August 2014, 12:33 PM   #116
bwaslo is offline bwaslo  United States
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But in the CV patent, throat and offset drivers cover the same frequency range, it is not a way to split up an audio band among drivers (more math needed for that).
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Old 5th August 2014, 03:03 PM   #117
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Quote:
Originally Posted by bwaslo View Post
But in the CV patent, throat and offset drivers cover the same frequency range, it is not a way to split up an audio band among drivers (more math needed for that).
It's complex:
In a horn with sealed back drivers, like a Synergy horn, the Fb of the midranges is somewhere around 500hz.
In a horn with open back drivers, like a back loaded horn, the Fb of the midranges is significantly lower. For instance, if you remove the back off of those sealed midranges, the Fs will drop to something like 150hz.

OK, so I've established that the same driver will have a different bandwidth depending on whether the chamber is on the driver.

Here's where things get tricky:

Removing the back chamber ALSO lowers the efficiency. For instance, a 5" midrange with a backchamber will have an Fb of around 500hz and an efficiency of about 95dB. Remove that backchamber and the FS goes down to about 150hz, but the efficiency also drops significantly; perhaps as low as 87dB or so.

Someone really needs to build one of these things, and I unintentionally came close when I built this:

Click the image to open in full size.
(note that two of the midranges are dipole, and one is sealed.)


Due to the efficiency difference between the sealed midranges and the dipole midranges, I think you need about 3-4 times as many dipole midranges. But the geometry of a Synergy horn is well suited to this setup; you could have three midranges that are open back, and one midrange that's closed back.

Click the image to open in full size.

Bill, you've noted that the frequency range of the drivers is the same. I don't think this is true. The sealed back driver has higher efficiency, narrower bandwidth, and a higher F3.

But this is actually a GOOD thing! Because the dipole midranges will play much much lower. For instance, the pathlength from the front of the dipole midranges to the rear of the dipole midranges is about 60cm. That means that there will be a 1/4wl resonance at 140hz.



All of this is academic obviously; but I truly found that my cardioid Synergy horn was probably my BEST sounding Synergy horn that I've ever built. The configuration combines a lower F3 than you'd get with sealed back drivers, with a radiation pattern that's more directional.
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Old 7th August 2014, 06:34 AM   #118
xrk971 is online now xrk971  United States
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Default The Legis Synergy & PP Tapped Pipe

In case folks may have not seen this build going on in the Subwoofer forum, I think you may be interested in what I think is one of the coolest and biggest Synergies to be built. Monster Massive seems an appropriate name for this implementation using 15 in Deltalites for the mid driver and a 2in JBL for the CD. Pair that with an all new design for a tapped pipe push pull sub using a pair of 18 in drivers, it is massive.

Check it out here:
Study of a Dipole/Cardioid Bass Horn

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
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Old 8th August 2014, 12:20 AM   #119
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Quote:
Originally Posted by Patrick Bateman View Post
Seems to work for Gradient.
Their papers explain it better than I can - you really have to hear them.
Gradient admittedly uses a waveguide with a much broader pattern than mine.

Tipping the waveguide back also does a few other things:

1) The main thing is just making the speaker shorter. I have a 100' projection screen, so I'd really like to keep the loudspeakers below the screen
2) I've been screwing around with Beolab type lenses this year, and it's remarkable how far back you can tip a speaker, and it will still sound good. I don't like the sound of having a speaker firing straight up, but even 45 degrees backwards sounds quite good. (The Beolab uses a lens to redirect the very top octave into the forward lob.)

Haven't tried it with the Summas, but I should.
Stig ,Carlsson got good reults from low placed drivers, and ive gotten surprisingly good results from a "joke" 10 minute project with nude tilted Seas tv21's and planar or AMT tweeters, actively crossed over. the tilting is good!
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