Paul Spencer Posted August 16, 2011 Share Posted August 16, 2011 (edited) My next mains still in design stages will be a coaxial hybrid horn/waveguide arrangement. It is based on the Danely "Synergy horn" which is actually a range of speakers, they are all something like this: I've written about it on the blog: http://redspade-audio.blogspot.com/2011/03/synergy-horn.html Why this one? I'm after a couple of things that don't easily come together in the same speaker: suits a built in studio soffit style install very high efficiency ~100 db 1w1m controlled directivity low distortion extreme dynamics phase coherent point source with sharp image focus and a big sweet spot drivers operated well away from breakup range No other speaker can do all that. Direct radiators use large drivers to get efficiency up and they are all offset a fair amount in their vertical spacings - they fall short on most of those goals. Horns lack the coherence but do some of those things very well. FR drivers have the coherence but have issues with directivity, breakup. Don't get me wrong, I'm not saying the alternatives aren't valid, or that this is the best speaker in the world, just that it seems to meet all my goals without compromising any of them. I had intended to build something like a Gedlee Summa which uses a 15" pricey pro driver up to 1k. Instead I'll be using 4 x 5" drivers per side - much easier to get it to work. I was stalling on this project as I couldn't figure out how to simulate it. Finally I realised I could do it with Hornresp quite easily: So it will feature: B&C DE250 compression driver at the apex of the horn/waveguide 4 x 5" closed back mids (250 - 1k) Then it will cross to my "Black widow" active woofers (current project) and dual Rythmik subs under floor tapped horns (future project). So lots of audio projects happening at the moment! I'll be having some GTGs to show them off when show worthy, hopefully when the weather warms up and we hit the season for BBQs and GTGs. Edited August 16, 2011 by Paul Spencer Link to comment Share on other sites More sharing options...
mondie Posted August 16, 2011 Share Posted August 16, 2011 Wow. That is insane, looking forward to following your progress on this one Paul. Link to comment Share on other sites More sharing options...
Drizt Posted August 16, 2011 Share Posted August 16, 2011 Wow. That is insane, looking forward to following your progress on this one Paul. Agreed, on both accounts. Link to comment Share on other sites More sharing options...
Frizzo Posted August 16, 2011 Share Posted August 16, 2011 I like it! Link to comment Share on other sites More sharing options...
caddisgeek Posted August 16, 2011 Share Posted August 16, 2011 Agreed, on both accounts. I agree with your argreement Link to comment Share on other sites More sharing options...
Antripodean Posted August 17, 2011 Share Posted August 17, 2011 Paul, great to see it is taking shape. Seems like you have decided on the Pyle drivers. My understanding from the DSL team is that the mids need to be damped down more for home use to achieve a flatter FR across a broader range. Hence, I think you will need all the midrange sensitivity you have. I will be good to see your akabak script for this one :o I'm just wondering why you say "coaxial" as there are no coaxial drivers used in the build? Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 17, 2011 Author Share Posted August 17, 2011 The Synergy is a "coax horn" - I wanted a more generic term as not everyone will know what the Synergy is. Coax could refer to the drivers it's true, but in this case it's about the horn itself. Yep, decided on the Pyle drivers. Max predicted SPL is 120 dB, that is 10 db headroom at THX reference. They are slightly less effective based on lower BL and higher mms. If modelled with low mms and higher BL the efficiency at the top comes up, but I will just use EQ, I'd rather it droop at the top end rather than the bottom. I've modelled in hornresp only, too impatient to learn Akabak just yet. I could spend more time coming up with an Akabak sim than it would take me to build and measure the real thing. I can also try in a prototype some different options. It's been enough waiting already! Last night I altered the black widow port to try to tune it higher and it resisted my efforts. You find out that stuff when you build and measure it and I don't always trust the model too much. So there might not ever be an Akabak model from me! We'll see ... Now do you remember our nearfield measurments of your Unity? The response was dead flat, almost perfect. I don't know if that means the crossover is compensating, or that the model isn't quite right. Link to comment Share on other sites More sharing options...
Gee Emm Posted August 17, 2011 Share Posted August 17, 2011 Your endeavors never fail to impress me Paul It will be great to catch up chew the fat at Bathurst re all your little (?) projects Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 17, 2011 Author Share Posted August 17, 2011 Looking forward to it ... wow, we're almost there! Link to comment Share on other sites More sharing options...
Antripodean Posted August 17, 2011 Share Posted August 17, 2011 The Synergy is a "coax horn" - I wanted a more generic term as not everyone will know what the Synergy is. Coax could refer to the drivers it's true, but in this case it's about the horn itself. Now do you remember our nearfield measurments of your Unity? The response was dead flat, almost perfect. I don't know if that means the crossover is compensating, or that the model isn't quite right. I have to agree that there is a lot of benefit in building to see what you can achieve. Nothing like measuring the actual. As always, if you need help building just let me know I always think of coaxial on the same axis hence why I don't see the synergy horns as coaxial, except a couple of the mid models like the SM60M. For me the idea of drivers acting as a point source due to time alignment and ensuring the driver overlap on the horn is within 1/4 wavelength is how I picture it. No matter, it's the results that count I think the crossover on the Unity Horns, as used by William Cowan and myself, is pretty darn good :o Here's Cowan's in room FR unsmoothed. Excellent! [ATTACH=CONFIG]35224[/ATTACH] Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 17, 2011 Author Share Posted August 17, 2011 Coaxial - depends if you are looking at the orientation of the drivers themselves or the actual outputs of the drivers. They do share a common axis in terms of their radiation. I think Danley has called them a coaxial horn somewhere. Considering the woofers don't want to run up to 300 Hz without a fight, I might have to run the horn down lower. I can supersize it to reach 250 Hz. The surround woofers actually sim quite well as mids in the horn as well. Link to comment Share on other sites More sharing options...
Gee Emm Posted August 17, 2011 Share Posted August 17, 2011 Damn this is getting exciting. Link to comment Share on other sites More sharing options...
Guest Posted August 17, 2011 Share Posted August 17, 2011 Damn this is getting exciting. +1 ,will be very interesting .But Paul really needs to pull his finger out :o. Cheers Link to comment Share on other sites More sharing options...
jaspert Posted August 17, 2011 Share Posted August 17, 2011 You have been talking about this for a while. I hope it won't be completed at "56oval" diy project time frame :o as I hope to have a listen in the near future. Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 17, 2011 Author Share Posted August 17, 2011 I've been stalling because I hadn't figured out how to simulate it. Now I've sussed it out well enough to knock up a prototype, I should have a first crack working some time in the next few weeks. I have a friend helping out with some CNC work. A Synergy horn can be relatively simple, but I'm making the throat a bit more elaborate. It starts out as a 1" circle for the compression driver at the apex. Normally it's a conical pyramid horn shape, but I'm wanting to do an oblate spheroid profile. Basically it's a conical with a radius at the start as seen in profile. With a conical horn you have a sudden transition from the narrow angle in the compression driver to the wider angle in the horn. Discontinuities are never a good thing in horns. The oblate spheroidal profile that Earl Geddes has championed seems the ideal profile out of the few constant directivity options, but it's tricky to transition from circle to square while at the same time doing an oblate profile! I'm hoping that the CNC guy can figure out the transition. In theory I can make the mouth as wide as 1.2m if needed. Bigger horn means the mids will be loaded to a lower point, otherwise I might have a hard time getting mids to meet the woofers. I want to avoid more woofers to bridge the gap - things are already complicated enough as 3 way + subs. Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 24, 2011 Author Share Posted August 24, 2011 Drivers arrived today! All in little boxes. 8 x 5" closed back mids and also 2 x 8" midwoofers for the surrounds. Ahhh the temptation to test and fire them up right now! Instead they sit by my PC to distract me all day. Link to comment Share on other sites More sharing options...
ehtcom Posted August 24, 2011 Share Posted August 24, 2011 Well, where's the picture? Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 24, 2011 Author Share Posted August 24, 2011 This is all of them ... ... minus the other 2 compression drivers and the other 18 that are in the system. Looking forward to the weekend! Link to comment Share on other sites More sharing options...
Drizt Posted August 24, 2011 Share Posted August 24, 2011 Very cool. I look forward to seeing / hearing the end result. Link to comment Share on other sites More sharing options...
ehtcom Posted August 24, 2011 Share Posted August 24, 2011 Nice, thanks Paul Link to comment Share on other sites More sharing options...
Gee Emm Posted August 25, 2011 Share Posted August 25, 2011 Holy snapping ar$eholes Batman! Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 25, 2011 Author Share Posted August 25, 2011 Looking forward to the weekend! Next step is a test box for the surrounds (the other project) and my first crack at a Synergy. I've been learning a few new tricks. The Synergy likes to have narrow dispersion or the bottom end loses efficiency and drops off. I can compensate for that with more drivers, ie step up to 6 per side. 90 degrees seems to be a challenge, it seems to want to be a 60 degree horn. Extension is another issue. They will go to 300 Hz easily, but I'd prefer more like 200 Hz which makes the crossover to the woofers so much easier. The woofers don't really want to run up to 300 Hz, but 200 - 250 Hz is much easier. Lots of juggling going on. Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 27, 2011 Author Share Posted August 27, 2011 Ok I'm no longer looking forward to the weekend. Trying to figure out the angles of this darn horn is killing me! It's a weird 3D mitre that is doing my head in! Oh the joys of geometry! Link to comment Share on other sites More sharing options...
Paul Spencer Posted August 28, 2011 Author Share Posted August 28, 2011 Finally managed to work out the mitres today and started cutting. No pics this time, but they will come when all the bits are cut. My dad figured out the mitres by trial and error, cutting little samples and adjusting til they fitted together. I figured them out by building it in CAD, but we both came up with different angles. I came up with 14 degrees, he came up with 33! We couldn't make sense of it all, but we decided to go with what he worked out as we had the physical example that it actually worked. Well, today I figured out the answer. Dad mitred all pieces equally, but on CAD I had done it with only half of them. The result either way is the same, but the CAD version is quicker to build. Fortunately we worked that out before wasting any time. Now it will be some time before I can touch this project again, I think it's going to drive me nuts! Link to comment Share on other sites More sharing options...
Paul Spencer Posted September 3, 2011 Author Share Posted September 3, 2011 What day is today? Speaker Saturday ... let the horn building continue! Hoping to have something that makes some noise today. We'll see ... Link to comment Share on other sites More sharing options...
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