# DIY Synergy horn



## paulspencer (May 11, 2007)

Hi guys. Thought some of you might be interested in some Synergy horns that I've been building - two of them so far, S1 and S2. Both prototypes, before I build one that I will actually paint and install flush in some corner bass traps. 

You can read about the whole thing on my blog:
http://redspade-audio.blogspot.com/2011/03/diy-synergy-horn.html

S1, my first prototype:










This is a 60 x 60 degree horn, it has a B&C DE250 compression driver at the throat and four 5" closed back mids loading the same horn, at the mouth it's half a metre wide. I use DCX for the crossover then it crosses to an Eminence Magnum 18LF 18" woofer with Rythmik subs below. S1 was my first attempt, when I wasn't entirely sure my hornresp sim would work, so I kept it simple.

It measures very nicely!










You can see it controls directivity down to about 500 Hz. It took some time to adjust to the different sound. It's very clear and detailed, clean at very high levels, very dynamic. The narrower dispersion seems to be part of the clarity, being a bit more dry and free from room sound. Ideal for a really bright difficult room. 

S2, was the next step, about twice the size - now 1m wide, 45 x 90 degree dispersion with 6 drivers (much harder to mount) and a second flare angle, which prevents beaming. Here it is on my polar measurement rig:










And it measures even better than S1:










At this point the main question in my mind is "what's next?" The final horn will probably get made out of ply and be spray painted glossy red, set flush into a big corner bass trap. But before that, I just might build some more ...


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## StereoClarity (Apr 22, 2008)

Those look like a TON of fun! What sort of efficiency are you measuring at 1W?


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## paulspencer (May 11, 2007)

I haven't measured the sensitivity, but sims for the mids are 100 for S1 and 103 for S2. CD is 109db and extension is to around 230 Hz. Less than 1w into the mids is very loud.


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## foolio (Nov 27, 2011)

Amazing that people can build these.


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## GranteedEV (Aug 8, 2010)

Paul;

I think your build is very inspirational and truly in the spirit of DIY - and I'm guessing based on your great blog that you matched the exit angles too! I'm curious how you went about modeling something as complex as a synergy horn. Did you just wing it, or can the hornresp / akabak type programs do this?

I wanna do something like this. I was thinking of using the CSS Planar 2 tweeter and removing the built in horn with a unity type waveguide. Do you think something like that could be pulled off?


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## paulspencer (May 11, 2007)

Thanks!

Hornresp does a decent job, but you can easily start to move away from its capabilities and so the results won't necessarily match perfectly. What I've found is that it's close enough that you can make it work with the crossover, but you won't be entirely sure about extension of the mids on each end. 

Your project sounds like an interesting one and could have some potential. One question though - does your tweeter retain the qualities you like in this design? Or does it mostly take on the sound characteristics of the horn itself, in which case a compression driver makes more sense. It's hard to say without trying.


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## GranteedEV (Aug 8, 2010)

paulspencer said:


> Your project sounds like an interesting one and could have some potential. One question though - does your tweeter retain the qualities you like in this design? Or does it mostly take on the sound characteristics of the horn itself, in which case a compression driver makes more sense. It's hard to say without trying.


...i don't have a clue. When it comes to horns i am a neewwwb!! What little I know is just broken bits and pieces reading forum posts and blog entries including your own. It would be a total learning process from the start. 

All I know is that the Planar 2 is a flat diaphram that can play down to 1khz @ LR2 in its current horn, but that horn doesn't appear to have much directivity control.

As far as compression drivers, I'm leaving that for the SEOS-15 and that project is a lot more within my level of comprehension at the moment. The planar 2 is less of a project and more of my imagination...I don't know how the planar would even load the horn. It's just my gut feeling here that it's something I want to hear.


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## paulspencer (May 11, 2007)

It's a project worth trying. You will need to be able to work out the physical form, simulate the mids in hornresp, measure and design the crossover. The thing that most may find most difficult is actually working out the 3D form, how it fits together, how to build it.


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