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post #121 of 139 Old 09-23-2014, 04:26 PM
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On a scale of 1-10 what is the difficulty in DIY synergy or unity horn ?

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #122 of 139 Old 09-23-2014, 05:15 PM - Thread Starter
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I think it is 8-9, lots of stuff going on. Multiple horn loaded bandpass calculations, you have the issue of where the midrange ports should be placed in order to get proper mid/HF time alignment. Both don't always match up perfectly with simulations so you have some extra fun thrown in there. The general construction/assembly is much more difficult then a regular speaker box. Crossover design can be a little tricky too. Overall much easier to get good results with more conventional approaches.
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post #123 of 139 Old 09-29-2014, 06:11 AM
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You think active Xover would be a better fit for a project like this ?

If you were starting over with a $650 budget on drivers per speaker , today what parts might you choose ?

Based on what you've learned would you change anything and why ?
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post #124 of 139 Old 01-01-2015, 02:40 PM - Thread Starter
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I have been meaning to dig these out for a while and finally did get to them the past month or so. They had been sitting for about two years half pulled apart while I was deciding what I would do with them go active/passive hybrid but finally decided I did not want to go through the hassle of setting them up active with 4 amps channels with an external DSP and preamp every time I do go to listen to them since these are not going to be permanently setup anywhere. So I decided to go in and redesign the full passive crossover.

In case you did not read through the thread the woofers on these were some 10" buyouts from PE that cost $5, the final configuration had them in a 4th order band pass situated towards the back of the enclosure firing into up/down into a sealed chamber in the center that housed the mids and CD. The front chamber was large enough and tuned low enough (105hz) to get the benefit of the acoustic low pass down into the woofer's pass band. You can see some pictures of how it looks back on post #82 : The very low budget DIY synergy horn build

Well I decided to try out a pair of Dayton PA255-8's I had laying around instead as I was afraid of cooking the little 1" VC on those buyout woofers. They worked out a little better then the buyouts so I ordered up another pair for the second speaker and went ahead with the crossover design. I had a tough time getting the drivers to blend well as there is very little if any overlap between the woofers/mids and mids/hf. I also ran into a problem with conventional crossover design causing the impedance to dip severely try the cross the woofers at 250hz to the mids. After a few iterations I finally managed a crossover that is very efficient across the board and utilizes the woofers impedance peak to gain 3dB more output at that range. I believe final sensitivity is roughly 100dB at 80hz with 2.83v input 4pi! The pair of 10" woofers in the band pass configuration should be capable of nearly 130dB above 90hz where they are not excursion limited, about 127dB at 80hz. Average impedance above 250hz is about 12 ohms, minimum of 3.5 ohms at 90hz:



Here is a quick FR measurement I did indoors at about 1.5m, 1/24th octave smoothing:





Dynamics in the midrange and midbass are insane, even off an old low end AVR.

I'll have to get a few photos of the guts and show you guys the crazy crossover, most parts I have ever used in a design. Had to assemble parts of the crossover inside the enclosure because I could not fit a prebuilt board anywhere even if split in three.
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post #125 of 139 Old 01-01-2015, 03:25 PM
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Matt, it would be wonderful if there is kits & flatpacks for this synergy horn
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post #126 of 139 Old 01-01-2015, 04:14 PM
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Originally Posted by WereWolf84 View Post
Matt, it would be wonderful if there is kits & flatpacks for this synergy horn
I don't want to speak for Matt, but when this idea has come up in the past it usually dies a quick death due to the issues of Danley's patents and intellectual property - it's one thing to build these for yourself, but another thing to start selling kits. Probably not going to happen.
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post #127 of 139 Old 01-01-2015, 05:59 PM - Thread Starter
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Besides the patent issue I feel something like this would be quite difficult to do in flat pack form, one mistake while gluing it up and the rest won't go together. Just gluing the horn together can be quite difficult. I don't even know how many separate pieces my enclosures have, I think it is around 40. Over 110 screws in each as well and that's just for access panels and drivers.

Then you have the crossover, a bit more complex then most regular speaker designs:


Here are a couple shots with the new woofers:


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post #128 of 139 Old 01-01-2015, 06:17 PM
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Amazing work. Let me be on the record as first to beg for one of your famous outdoor videos once these are wrapped up to your liking.
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post #129 of 139 Old 01-14-2015, 12:44 PM
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Amazing work. Let me be on the record as first to beg for one of your famous outdoor videos once these are wrapped up to your liking.
+1
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post #130 of 139 Old 01-14-2015, 02:10 PM
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Ok, mtg, I'm impressed. Nice frequency response on those!

So, how come you're not using them for your main system?

BTW, I talked to Erich about selling flatpacks for just a wooden conical horn (without the Synergy ports), that could be used either for single driver or as basis for a Synergy. Suprisingly, he doesn't seem to have any spare time to be taking on anything else!

DIY Synergy horn spreadsheet http://libinst.com/SynergyCalc/
XSim -free crossover designer and simulator http://libinst.com/Xsim/XSimSetup.exe
Easy and cheap sound diffusers (the "Depot Diffusers") making-easy-diy-depot-sound-diffuser-panels-step-step.html

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post #131 of 139 Old 01-14-2015, 03:17 PM
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Quote:
Originally Posted by bwaslo View Post
Ok, mtg, I'm impressed. Nice frequency response on those!

So, how come you're not using them for your main system?

BTW, I talked to Erich about selling flatpacks for just a wooden conical horn (without the Synergy ports), that could be used either for single driver or as basis for a Synergy. Suprisingly, he doesn't seem to have any spare time to be taking on anything else!
Bill, Erich & Matt, let's make that happens

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post #132 of 139 Old 01-14-2015, 03:40 PM
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I'd cut them up if I knew where to drill the holes.

My next project. I gotta get my learn on.
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post #133 of 139 Old 01-14-2015, 04:37 PM
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Quote:
Originally Posted by Mfusick View Post
I'd cut them up if I knew where to drill the holes.
In my designs so far, I can never get the holes too close to the CD throat. So arrange for the holes to be placed as close-in as you can, then work from there. Using a MiniDSP and a set of amps (Tripaths amps work well), along with a way to make response measurements of course, simplifiy crossovers a LOT. The mechanical outline of the mid drivers will define how close in you can get. That's why I try to use small midrange drivers (and another reason is that I like to use CDs that don't go so low, but that have very short built-in throat lengths).

DIY Synergy horn spreadsheet http://libinst.com/SynergyCalc/
XSim -free crossover designer and simulator http://libinst.com/Xsim/XSimSetup.exe
Easy and cheap sound diffusers (the "Depot Diffusers") making-easy-diy-depot-sound-diffuser-panels-step-step.html
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post #134 of 139 Old 01-15-2015, 09:06 PM - Thread Starter
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Thanks Bill,

If I could find a way to use these in my main system they would be used there. Unfortunately I am somewhat limited in the size of the speakers I can use so theses will just have to sit off to the side and get pulled out whenever I want to have a listen to them.


Any chance for a flat phase response on these went out the window when I decided to move the woofers back into the cabinet. Making that a low tuned (105hz) 4th order band pass does some nice things with filtering out harmonic distortion and reducing woofer excursion but it added a lot of delay. I believe there is >1080 degrees of phase shift in the design however it still sounds great to my ears. BTW if anyone is in the Chicagoland area and wants a demo give me a holler.

I am going to try making a DIY budget synergy V3. This one will use all off the shelf drivers while staying very affordable. It will be fairly compact as well, ~16-18" wide and high maybe 13-16" deep. Dual 8" woofers, two 4" mids, 1" CD. Should be capable of 120+ dB, f3 about 80hz, ~98-99dB @ 2.83v. I plan on making it similar to the one above with the 4th order band pass woofers. I need to build a simple horn and do some testing of the mids to figure out if they will cover the required pass band before I go further with it. If everything goes well I try and document the build so that others can replicate it, that is one of the reasons for choosing off the shelf drivers. If they turn out well I'll build three and use them for my LCR.
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post #135 of 139 Old 01-16-2015, 06:02 AM
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Wow Matt very nice. I'll be following that for sure.
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post #136 of 139 Old 01-17-2015, 03:23 AM
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Quote:
Originally Posted by bwaslo View Post
In my designs so far, I can never get the holes too close to the CD throat. So arrange for the holes to be placed as close-in as you can, then work from there. Using a MiniDSP and a set of amps (Tripaths amps work well), along with a way to make response measurements of course, simplifiy crossovers a LOT. The mechanical outline of the mid drivers will define how close in you can get. That's why I try to use small midrange drivers (and another reason is that I like to use CDs that don't go so low, but that have very short built-in throat lengths).
Bill, would it be possible to build the horn bigger in order to accommodate somewhat better mids that might otherwise be too big in the original enclosure? Of course I know that you are not going to build a totally new horn, I am just talking, in theory, would it work to increase the depth, height and width of the horn to have more flexibility in choosing drivers?
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post #137 of 139 Old 01-17-2015, 05:39 AM
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Making the horn bigger won't change the midrange situation. The only benefits that I see to a larger horn is lower pattern control, lf loading, and you can use more/larger lf drivers. We need small mids (3-5") to get them close to the throat of the horn. There is a reflection from inside of the cd that determines the hf response of the mids, along with other factors. If the distance of the mid port to the reflection point in the cd is 2" then you'll get a notch at about 1687hz. 13500/(2*4)=1687.5. You'll need to cross a bit before the notch but you can see at these small dimenions a bigger horn doesn't gain any ground with the mids. Also, the mids need to be close enough to the throat such that the flare rate of the horn will give enough hf loading, but I don't think this is usually a problem.

These things are all covered in the patent http://www.goodsoundclub.com/PDF/Synergy_Patent.pdf

As far as using "better" mids I don't see it that way. A Synergy is not like a typical box speaker. In a regular speaker you might consider using a Goldwood woofer vs a ScanSpeak Rev. Budget not being a concern obviously the Scan is the better driver if it fits your criteria. With a Synergy the bandpass chamber on the mid acts as a low pass filter which acoustically lowers distortion. Couple that with the fact that you're likely using 4 mids that are loaded on a horn and the efficiency is increased dramatically. I think these things negate the need for high tech/expensive drivers. Not to mention that the more expensive mids don't have the necessary parameters to work on a Synergy. You can't just slap any mid on there and expect it to work.
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post #138 of 139 Old 01-17-2015, 11:51 AM
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Some seemingly-contradictory replies --

MTG, I guess I don't see the need for a 18" Synergy horn, a BA750 driver will drive a SEOS18 horn down to its pattern control frequency already won't it? Except for maybe getting the woofers closer, that might be a good reason, I guess. Seems like a 2-way might work then. After getting linear phase working, I'm pretty sure it isn't much of a factor, if any at all. And if you want linear phase, an easier way to do it (after you have a Synergy type horn working) is to use an FIR DSP like one of the pricier MiniDSPs.

Tip24/96, making the horn bigger doesn't help, the midrange cut-in (assuming a highish crossover) occur down in the first few inches of the throat no matter how big the horn. I think that's in line with what Nate Hanson said.

Nate, I couldn't agree more. People need to avoid the "more expensive is better" mode of thinking with Synergies. Priorities in the design are much different than in normal speakers.

DIY Synergy horn spreadsheet http://libinst.com/SynergyCalc/
XSim -free crossover designer and simulator http://libinst.com/Xsim/XSimSetup.exe
Easy and cheap sound diffusers (the "Depot Diffusers") making-easy-diy-depot-sound-diffuser-panels-step-step.html
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post #139 of 139 Old 01-17-2015, 06:02 PM - Thread Starter
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I am seeing an advantage in that I can cram a lot of output into a relatively small enclosure using less expensive drivers. My design goals for this new one are less geared towards directivity control down low and more to the effect of getting great bang for the buck. Without giving too much away a PAIR of these new v3 synergies could possibly be built for less then a single BA-750 and SEOS-18. Staying with the low budget diy synergy roots on this one.

I'm my experience the synergy design allows otherwise cheap not so great drivers to outperform much more expensive direct radiating designs. The distortion of the $0.69 mids in my v2 synergy is crazy low as it's effectively a 10" horn loaded driver with the acoustic low pass of the bandpass style loading helping to further reduce distortion.
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