I would go with SB65 in smaller premade horn with 2in throat - after several attempts with other drivers in the Bookshelf Horn thread, Bushemeister and I found that the SB65 has smoothest and most predictable response through the horn. I have used Faital and TC9 in larger throat with tractrix and that works too. Regarding sensitivity, the horn will add about +10dB so can work well despite being 84dB.
Btw, read the section on how to shape the adapter. That is critical to a smooth response and was arrived at by a lot of testing. Don’t reinvent the wheel.
https://www.diyaudio.com/forums/multi-way/285030-bookshelf-multi-source-horn-125.html#post4644522
Btw, read the section on how to shape the adapter. That is critical to a smooth response and was arrived at by a lot of testing. Don’t reinvent the wheel.
https://www.diyaudio.com/forums/multi-way/285030-bookshelf-multi-source-horn-125.html#post4644522
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H-5 Рупор 2" компании ГОРН-Якубович . Купить по цене производителя с бесплатной доставкой по Украине - 2", 450 х 250 х 195. But disgusting ugly nasty 
plastic.
plastic.The shape looks reasonable to me*. Note that a fair bit of DIY is still needed.
If you can't get those SB drivers, IMO, the Peerless NE65 drivers are also good. They are roughly equivalent (copper caps, nice FR plots etc), and I also like:
- the sleek neo magnet and nice looking frame (low reflection).
- it can be ordered on Digikey, who (so far) have delivered free and fast, with nothing broken on arrival - their delivery has been my best experience of buying products from overseas.
In a horn, this driver sounds much better than the couple of 1" drivers (e.g. JBL 2425J, which I'd had high hopes for) I compared them to. The comparison was done as evenly as possible, with EQ to get the FR similar, and playing in the same room, same distance, with the same LF setup.
I've tried the NE65 on an off the shelf (but modified) horn, and a home made (prototype) straight-walled synergy style horn. It worked well on both. This FR plot is from the latter.
I applied 7dB of EQ to balance out the LF boost the horn gives, and two
+5dB peaks to counter notches at 8kHz and 12.5kHz. These notches might be from the slightly rough throat transition on my prototype horn.
Most CD drivers would need more EQ than this (when mounted on a similarly wide, straight-walled horn).
*OT, but an aesthetic suggestion: rear mount it, and use a high contrast colour scheme, and you'd get something like this:
Synergy Horn | Parts Express Project Gallery
I have some good P.Audio gear, but I do not trust their spec sheets very much. That FR plot has been smoothed so much that the only meaningful info left is the amount of HF droop it has.
That droop is pretty normal for a 2" CD. What's also normal for a 2" CD is a series of breakup peaks all through the HF.
This plot shows a (new) NE65 cone driver on the same horn and conditions as an (old) JBL 2" compression driver.
Many of the anomalies, such as the midrange spikes (2.5 and 3.5kHz) are present on both plots, and are probably caused by the horn, and/or interactions with nearby objects.
The 6.5kHz dip + 7kHz spike, and all the other anomalies which only show on the JBL plot, are due to it's relatively large titanium diaphragm (breakup modes). Similar spikes will be present on the P.Audio driver, which uses a similar diaphragm - they've just smoothed their plot until those peaks don't show up.
Also note that, if you simply compared the sensitivity numbers from spec sheets, you'd see 111dB @ 1 watt vs 82.7dB @ 1 watt, a nearly 30dB difference.
...but if you look at the FR plots I've presented, the gap is much smaller. If you were to use EQ to squash down the JBL's midband & many peaks, to make it flat from (say) 750Hz-15kHz, the efficiency gap would be much smaller again.
In my opinion, aiming for response literally to 20kHz is pointless. Try it for yourself - listen to some HF test tones between 10kHz and 20kHz, and see where your hearing ends.
Most men have hearing that begins to fail well before 20kHz: a typical hearing check only tests up to 8kHz, and a typical 40 year old man is -10dB at 8kHz on those tests.
Women usually have (much) better HF hearing, but in my experience, the main impact this has on speaker design is that it they prefer smoother HF, not more extended HF (i.e. women can hear, and thus dislike, HF spikes like those shown above, more clearly than men can).
So a real world goal, in my opinion, is to aim for fairly flat response to about 10kHz, and then smooth (meaning non-peaky, but not necessarily 100% flat) response to wherever your hearing fails.
I've got an kinda similar horn, except for the driver mount, a copy of the PH-942 but behaves very much like the PH-642, measurements do not differ very much except for the dispersion angle. It does, indeed, work much higher up, with a (slow slope) response up to ~16k, steeper drop off and narrower beaming after that. While it does keep the radiation pattern quite well up to there, the radiation pattern starts to get uniform at around ~700-750Hz, the 90° version starts very likely higher.
The question is, what's your development goal? What drivers do you want to use? With a 1.4" or even 1" driver + horn you can easily get that low too for HiFi and still reach 20k with excellent sound and resolution, that means you won't profit much from the synergy horn (if at all), the driver will feel bored to death anyway.
If you have PA in mind, the question is still what benefits you'd expect from a synergy build. If you want cones for the mid, they'd have to be very small, there's only space for a 4-4.5" cone with not much horn length left, which means you'll have neither low crossover capabilities nor spl gain, benefits in dispersion control/directivity or power. And you have to modify the 2" throat and build a reduction flange to a 1" driver too. Apart from that, you'd have to remove the stiffening ridges on the sides of the horn too.
In both cases you'll have to deal with more amp and dps channels or with a lot of crossover parts, with makes it in both cases much more expensive than going for a 1" or 1.4" driver + horn, not to speak about the effort and time you have to invest. I'm sorry, but to me it looks like you'd get a lot of work for none of the benefits. If you want to experiment with a synergy horn, build a longer (than the P.Audio horn) conical horn from plywood. If you don't have a good circular saw, let a carpenter build it, that's a lot more promising and won't be expensive either.
Edit: Sry, I've missed a lot of clearifying answers I unfortunately only saw after I posted, my browser didn't load the whole page.
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I decided to go with SB driver. Ordered it at madisound. Agree on that very high freq is not really necessary, just decided to go with a proven recipe.
Thanks for sharing other thoughts, though.
I want all the benefit of the Synergy horn in a smal room. Low distortion, controlled directivity with less reflections from the walls, point source behaviour, dynamics (this is why i went with Beymas) etc. It will be used as a monitor for my main listening position - at my desktop. Yeah, it is an overkill in terms of bulkiness and SPL, i know
But i do intend to use it for some outdoor listenings from time to time. It is a two way synergy and some modifications on the horn body are, of course, necessary.
This is how it is going to look schematically:
Of course, it will require some cutting, use of epoxy and what not, but this is DIY
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H-5 Рупор 2" компании ГОРН-Якубович . Купить по цене производителя с бесплатной доставкой по Украине - 2", 450 х 250 х 195. But disgusting ugly nasty
Yeah, saw it. Even discussed the shipping terms, but then decided to go with P.Audio horn. Due to the looks of the former, i guess
Sweet. Not 'proven' since the different horn will change the response a bit, but as long as you can measure + apply EQ, you should be fine.
I was under the impression you were unable to buy / ship the SB to your country "couldn't find the parts the guys used in the build".
Of course, it will require some cutting, use of epoxy and what not, but this is DIY
I think your build will be substantially easier than the xBush build, since your horn walls are flat: no filler needed + the mid taps will be shorter.
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