Hi all,
Still in the planning phase of maybe building a synergy horn.
Has anyone tried to build one without midrange cone drivers and using midrange compression drivers instead?
- They do not need a compression chamber, as they already got one, optimized with a phaseplug and all.
- They can be placed on the corner of the horn making coupling better.
- If one were to rethink the horn shape, one could match the exit angle of the compression driver in each corner, and optimizing the coupling to the horn in the midrange area too.
Has it been done?
Is it a bad idea?
Still in the planning phase of maybe building a synergy horn.
Has anyone tried to build one without midrange cone drivers and using midrange compression drivers instead?
- They do not need a compression chamber, as they already got one, optimized with a phaseplug and all.
- They can be placed on the corner of the horn making coupling better.
- If one were to rethink the horn shape, one could match the exit angle of the compression driver in each corner, and optimizing the coupling to the horn in the midrange area too.
Has it been done?
Is it a bad idea?
There was a short thread on it a year or so ago. The problem is the midrange compression drivers have a fairly high diameter which prevents them from being placed close enough to the apex to support XOs high enough for typical 1" CDs.
The problem isn't the difficulty of creating a bandpass chamber; its minimizing loss of bandwidth due to the implicit bandpass chamber. You will be using a 1.4" to 2" exit CD on the SEOS30, which typically can be used down to 500 Hz or so. You shouldn't have a problem because its easy to get cone drivers to play this high.
Really, you don't want midranges on your SEOS30 - you want woofers, 8" or larger that play from 500 Hz down to 100 Hz or even lower, depending on the size of woofer holes through the horn walls you are willing to have.
The problem isn't the difficulty of creating a bandpass chamber; its minimizing loss of bandwidth due to the implicit bandpass chamber. You will be using a 1.4" to 2" exit CD on the SEOS30, which typically can be used down to 500 Hz or so. You shouldn't have a problem because its easy to get cone drivers to play this high.
Really, you don't want midranges on your SEOS30 - you want woofers, 8" or larger that play from 500 Hz down to 100 Hz or even lower, depending on the size of woofer holes through the horn walls you are willing to have.
Adam,
1) It has been discussed several times, IIRC no one has actually done it.
2) The phase plug is optimized for a specific exit size and wide bandwidth, not for use in a Synergy type horn.
3) Better than what?
4) Sounds like you would "rethink the horn shape" into something that would have terrible high frequency response.
5) Multiple entry mid-range compression drivers have been used for low-fidelity speech applications for many decades.
6) Yes, bad idea.
The chamber in front of a midrange cone driver creates an acoustical LP filter, reducing distortion, simplifying the crossover. The small exit of the band pass chamber has minimal effect on the HF driver's response. A cone driver is not limited by the very minimal excursion of a typical "midrange" compression driver (usually less than <1mm), so is capable of far more output for a given diaphragm size, and a lower crossover point, relaxing the constraints of the LF and HF drivers.
Cheers,
Art
I think people tend to overlook the fact that in effect we are creating compression drivers out of regular cone drivers with the bp chamber/port exit on a Synergy horn. Imo I really don't see any advantage to using a CD as a mid. As it is now I'm getting about 10dB more output from two 4" closed back mids than my 1" compression driver after CD EQ on the latter.
1) Where?
2), 3) and 4) My thought was matching the corners of the horn to exit angle of the mid-CD. Imagine a narrowing of the corners like some of the JBL waveguides.
5) I'm asking if it has been done for synergy horn or similar horns. Has it?
6) Ok, thanks for your opinion
The chamber created for the cone driver, as far as I can see, does not utilize a phase plug.
A mid-cd would, as it is build in, and optimized for the specific driver. How does one do that DIY for a cone midrange with out going though 100's of weird looking tries, and can they be replicated without a 3d-printer? - I'm asking.
2), 3) and 4) My thought was matching the corners of the horn to exit angle of the mid-CD. Imagine a narrowing of the corners like some of the JBL waveguides.
5) I'm asking if it has been done for synergy horn or similar horns. Has it?
6) Ok, thanks for your opinion
The chamber created for the cone driver, as far as I can see, does not utilize a phase plug.
A mid-cd would, as it is build in, and optimized for the specific driver. How does one do that DIY for a cone midrange with out going though 100's of weird looking tries, and can they be replicated without a 3d-printer? - I'm asking.
I'm not settled on the SEOS30.
If a design using a 1 inch CD with 4 mid-CD's could work it would not compromise the high end as much as using a bigger HF-CD.
I've never seen any advantage of using a midrange compression driver, and there are MANY disadvantages:
1) it's significantly more expensive
2) The primary advantage of a midrange compression driver would be higher efficiency. But we rarely need more efficiency in the *midrange* of a Synergy Horn. In fact, we're frequently padding down the high frequency compression driver because the midrange array is so insanely efficient!
3) The upper limit of the midranges is dictated by the geometry of the Synergy Horn. IE, the phase plug on a midrange compression driver wouldn't make any real improvement.
4) The throat of a midrange compression driver is too large. The midrange taps on a Synergy Horn are 3/4" in diameter, much smaller than the throat of a midrange compression driver
lots and lots of disadvantages, no real advantages
If you want to build your own midrange compression driver, the Dayton RS52 is a pretty good start. That's something I've wanted to do for some time. It's really well suited to horn loading. Bruce Edgar used to horn load the Dynaudio dome midrange.
1) it's significantly more expensive
2) The primary advantage of a midrange compression driver would be higher efficiency. But we rarely need more efficiency in the *midrange* of a Synergy Horn. In fact, we're frequently padding down the high frequency compression driver because the midrange array is so insanely efficient!
3) The upper limit of the midranges is dictated by the geometry of the Synergy Horn. IE, the phase plug on a midrange compression driver wouldn't make any real improvement.
4) The throat of a midrange compression driver is too large. The midrange taps on a Synergy Horn are 3/4" in diameter, much smaller than the throat of a midrange compression driver
lots and lots of disadvantages, no real advantages
If you want to build your own midrange compression driver, the Dayton RS52 is a pretty good start. That's something I've wanted to do for some time. It's really well suited to horn loading. Bruce Edgar used to horn load the Dynaudio dome midrange.
I've looked at that one, too. Looks good, except that it only has a 2"dia surface, but eats up 5"dia of mounting space, while sticking way out in the back. I couldn't see a reasonable way to mount it on a Synergy horn, but the time you've got it mounted far enough back to not hit the tweeter driver you'd have to have the exit from it's front volume chamber be way offset from it's center for a decent crossover point. Though maybe with one of the newer tiny neodymium HF drivers?
Oh, I should've mentioned, you have to hack it to pieces lol:
You remove the faceplate to make the overall size smaller. Then you saw the back cup in half, to reduce the volume. Then you seal it back up. This raised the Fb and the overall efficiency.
At this point, it's possibly the best "hifi" midrange for a Synergy Horn. It has the correct specs, but best of all, it has very low QTS and it has a shorting ring for reducing distortion.
The main reason I've never gone any further is that it's still a fairly expensive driver. $156 for a set of four:
Dayton Audio RS52AN-8 2" Reference Aluminum Dome Midrange
I'm using those $2 Gentos in my current Synergy Horn project.
You remove the faceplate to make the overall size smaller. Then you saw the back cup in half, to reduce the volume. Then you seal it back up. This raised the Fb and the overall efficiency.
At this point, it's possibly the best "hifi" midrange for a Synergy Horn. It has the correct specs, but best of all, it has very low QTS and it has a shorting ring for reducing distortion.
The main reason I've never gone any further is that it's still a fairly expensive driver. $156 for a set of four:
Dayton Audio RS52AN-8 2" Reference Aluminum Dome Midrange
I'm using those $2 Gentos in my current Synergy Horn project.
I only use one on the SmallSyns (on the bottom wall), vertical symmetry wasn't bothered much at all*. The hole is near or under a quarter wavelength from the other wall at crossover, so it's effectively in the same place.
*and the vertical pattern isn't all that much worth keeping symmetrical, since directivity is lost quite high in frequency because of the narrower angle and short height
*and the vertical pattern isn't all that much worth keeping symmetrical, since directivity is lost quite high in frequency because of the narrower angle and short height
of course that could work - lots of examples, just none with so large a horn unless you build a conical out of plywood, which won't have as nice polars as a SEOS. SEOS30 is just a short but expensive path to a large horn.
Thanks Patrick!
That cleared up why people are not using mid-cd's in Synergy horns. Your idea with the midrange dome sounds interesting. But maybe a bit to advanced for me when taking the cost and potential fail from my part, into account.
I'm keeping my eye out for your dome-experiments though.
That cleared up why people are not using mid-cd's in Synergy horns. Your idea with the midrange dome sounds interesting. But maybe a bit to advanced for me when taking the cost and potential fail from my part, into account.
I'm keeping my eye out for your dome-experiments though.
I don't trust those cheap closed back mids people have been using either. I especially don't trust the ones PE sells as buy outs. Its hard to argue with the results people have gotten with the Celestion TF0410MR, however, now that they are obtainable - unless you want to do a 2-way Synergy instead of a 3-way. Then it makes senses to spend more money and getting something larger with more excursion and with an open back. Then the field is wide open but you have to have a system design or performance requirements in mind before you can make a statement about the suitability of a particular driver.
The Scan Speak you mention looks similar to the Faital Pro 4FE35 that I have used successfully in a Synergy, but twice the price.
The Scan Speak you mention looks similar to the Faital Pro 4FE35 that I have used successfully in a Synergy, but twice the price.
There are a number of open back small drivers that can do well for synergy mids. 3FE22 is one that I've used with good effect.
But the problem is that it's not easy to enclose the back of the cones tight enough You end up doing a lot of messy gluing of plastic or stiff cardboard over openings, not easy to do cleanly and you always wonder whether something dripped inside onto the cone. Usually covering it with a tube isn't tight enough (a 2"D mailing tube over those cheap 2" Gento SP99023A cones is an exception.... but still not easy. And their sensitivity is poor, so you do need 4 of that type if you use them.) You could never do a kit with that method. Lots of promising drivers would require you to bring the voice coil wires off off terminal strips and through an added wall, a job needing some skill if not some spare drivers to mess up.
But the problem is that it's not easy to enclose the back of the cones tight enough You end up doing a lot of messy gluing of plastic or stiff cardboard over openings, not easy to do cleanly and you always wonder whether something dripped inside onto the cone. Usually covering it with a tube isn't tight enough (a 2"D mailing tube over those cheap 2" Gento SP99023A cones is an exception.... but still not easy. And their sensitivity is poor, so you do need 4 of that type if you use them.) You could never do a kit with that method. Lots of promising drivers would require you to bring the voice coil wires off off terminal strips and through an added wall, a job needing some skill if not some spare drivers to mess up.
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I should point out that one thing I like about the 4FE35 is that there is no need to try to convert it to a closed back mid for use in a 2-way Synergy. Its got a Qts of .84, which is high enough for open baffle use. The result is that it almost doesn't care what its enclosure volume is - anything from a couple of liters per driver on up. So long as the 4FE35s aren't sharing the volume with woofers it can be used open back in almost any convenient volume.
So why a 2-way Synergy instead of 3-way? Art Welter's SynTrip was just about full range in 2 ways using 10" woofers and a 1.4" CD. Cask05's MEH on the K-402 with 2" CD and 15" woofers went even lower. Others, including the original Unity, have taken the woofers off of the horn and paired them in vertical symmetry above and below it to extend the vertical directivity.
In general, you can get a more refined high end with a 1" CD, which usually implies a 3-way Synergy. An exception would be using the 1" BMS4550 CD with 4 Faital 4FE35s and the woofers outside the horn. Depending on the age of your ears, you may not benefit from the so called more refined high end of a 1" CD and be more than satisfied with a good 1.4" or 2" CD. I suspect that solution costs more however.
So why a 2-way Synergy instead of 3-way? Art Welter's SynTrip was just about full range in 2 ways using 10" woofers and a 1.4" CD. Cask05's MEH on the K-402 with 2" CD and 15" woofers went even lower. Others, including the original Unity, have taken the woofers off of the horn and paired them in vertical symmetry above and below it to extend the vertical directivity.
In general, you can get a more refined high end with a 1" CD, which usually implies a 3-way Synergy. An exception would be using the 1" BMS4550 CD with 4 Faital 4FE35s and the woofers outside the horn. Depending on the age of your ears, you may not benefit from the so called more refined high end of a 1" CD and be more than satisfied with a good 1.4" or 2" CD. I suspect that solution costs more however.
Similarly, loading a higher end cone full range to the horn with some synergized LF augmentation has been shown to work well too. Especially if you don't need much greater than roughly 100 dB/1 meter peak output. (I haven't looked in a while at max output of ~2in/50mm drivers so consider this a trend rather than a definitive statement)
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