Why don't people build more coaxial systems?

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#121
I'm thinking of building a set of 3 front speakers (LCR) for my home theater using the Beta-10cx and D220T. I would place the center speaker behind an acousticly transparent (AT) projector screen, so it would need to be as shallow as possible.

Any reason not to do this?
Perhaps I could do it based on the Osprey ii by @Michael Chua if he would be kind enough to share details. Or if people have other suggestions I'm open to that.

I have a separate subwoofer so the new speakers won't need to have much below 80Hz.

The setup will be part of my home theater, which I also use to listen to music.

Thanks!
 
#123
No good reason not to since its HF is supposed to be at 2/3 screen height, though the mains should be too, so at the same height and at least stretch some screen cloth over them, 'gapped' to match to maintain tonal balance.
 
#125
My view is that there aren’t any fantastic coaxial drivers for DIYers to work with.
By great I mean something with a nice smooth response past 2x Fc for the mid, good sensitivity (90+dB/2.83V) and a tweeter that’s well behaved on and off axis.

Like the UniQ. KEF have been refining that for over 20 years…

Here’s the 2022 model:

1711844899443.png1711844915303.png

Reference:
https://www.erinsaudiocorner.com/loudspeakers/kef_blade2_meta/

This is what can be accomplished when you're vertically integrated, and have the resources of design talent and manufacturing capacity; and can build drivers, waveguides AND cabinets all in house.

So I would take the Blade 2 Meta, take out the standard woofers, load it with a quad of Purifi PTT6.5X drivers, take out the passive crossovers, give it the ol’ spinorama treatment, DSP + tri-amp it, add delays to the M/T section. You in @bikinpunk ?

Awhile back I did say to Jack
“O! Mate! Can we all have a full copper sleeve in the next update, pretty please? Coz, you know, it’ll get pesky H3 down below H2”

1711868846387.png


He wrote me and said “R u sure?”
I sez “yeah! Me cobber @5th element knows so, coz he’s made 3 coaxials from B&W, Satori and SBA drivers”

So he says “Orr righty then, since you’re buying the next round, I’ll get me minions to look into it”

Something to look forward to…
 
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#127
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#130
I got a hold on a set of Coax from KEF R3. It was not until 2018 that they figured out the rubber ring between the coil and the cone, to reduce the break-up in the midrange - so everything is still quite "new".

Having several drives and DIY designs behind me, I can surely say that the KEF coax have given me the most listening pleasure in my room. This could be partly because my room is a little wonky in shape and with respect to reflections - but also because the KEF coax is an excellent design - if you filter it properly, so that you take full advantage of having the same response in all off-axis's.

I run it actively and believe the issue with several of the cheaper models from KEF, is the poorer filter and uneven response, which many times is easy to counter with EQ - but still best with the right filtering.

I would consider buying a set of used KEF R3's, to just take out the Coax and use it in a DIY - rather than use any other coax. If not possible to get a used set... I would maybe stick to smaller midranges and waveguides - maybe the Sica 5" coax - since I've heard it and was quite surprised by its performance.
 
#132
tktran303 said:
My view is that there aren’t any fantastic coaxial drivers for DIYers to work with.
By great I mean something with a nice smooth response past 2x Fc for the mid, good sensitivity (90+dB/2.83V) and a tweeter that’s well behaved on and off axis.

Like the UniQ. KEF have been refining that for over 20 years…

Here’s the 2022 model:

View attachment 1292829View attachment 1292830

Reference:
https://www.erinsaudiocorner.com/loudspeakers/kef_blade2_meta/

This is what can be accomplished when you're vertically integrated, and have the resources of design talent and manufacturing capacity; and can build drivers, waveguides AND cabinets all in house.

So I would take the Blade 2 Meta, take out the standard woofers, load it with a quad of Purifi PTT6.5X drivers, take out the passive crossovers, give it the ol’ spinorama treatment, DSP + tri-amp it, add delays to the M/T section. You in @bikinpunk ?

Awhile back I did say to Jack
“O! Mate! Can we all have a full copper sleeve in the next update, pretty please? Coz, you know, it’ll get pesky H3 down below H2”

View attachment 1292921

He wrote me and said “R u sure?”
I sez “yeah! Me cobber @5th element knows so, coz he’s made 3 coaxials from B&W, Satori and SBA drivers”

So he says “Orr righty then, since you’re buying the next round, I’ll get me minions to look into it”

Something to look forward to…
Click to expand...
I had a similar thought about the Blades 2 Meta’s, but if you were cloning them then I’d go with 2 of the new Purifi 10” drivers instead of the 4 x 6.5 😉
 
#133
Studley said:
I had a similar thought about the Blades 2 Meta’s, but if you were cloning them then I’d go with 2 of the new Purifi 10” drivers instead of the 4 x 6.5 😉
Click to expand...
4 smaller drivers are chosen for directivity and CC distance to the coax - as far as I know. And there is no real need for some of the most expensive 10" drivers in such design, since there is so much else going on in the design. KEF also live happily with "special" drivers. Using off the shelf drivers is not the best choice, for many reasons.
 
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#134
ddanj said:
I'm thinking of building a set of 3 front speakers (LCR) for my home theater using the Beta-10cx and D220T. I would place the center speaker behind an acousticly transparent (AT) projector screen, so it would need to be as shallow as possible.

Any reason not to do this?
Perhaps I could do it based on the Osprey ii by @Michael Chua if he would be kind enough to share details. Or if people have other suggestions I'm open to that.

I have a separate subwoofer so the new speakers won't need to have much below 80Hz.

The setup will be part of my home theater, which I also use to listen to music.

Thanks!
Click to expand...
No reason not to……if you can get the crossover right, that will be a fantastic LCR setup

On a side note the CX12 is a little easier to work with as the cone breakup isn’t nearly as aggressive. These pro coax drivers from Eminence are smoother the larger they get.
 
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#136
Just do it, for home cinema they are perfect. I assume you will have a few subs to cover the low end?

For your info I’ve played around with both the 10” and the 12” beta CX and with different CD drivers APT50, ASD1001, PSD2002 and the selenium. All with the stock crossover from Eminence. I have a large thread on this but to summarize I find the ASD1001 to work great with the 10” giving a smooth sound. The PSD2002 works good with the 12” and play a lot more dynamic but with a slightly rough response. I prefer the dynamics over flat response myself so I currently only use the 12”. I don’t like the selenium one bit, it rings in my ears.
 
#137
Besides Kef, what about Tannoy? Buy this 5" dual concentric, remove driver, build a separate box, cross over at 300hz to an 8" or 10"?

https://www.ebay.com/itm/234742036643


This one is even cheaper (but uses a 4.5" driver, same blue color, and may not matter if cross to a woofer handling lower range of frequency). Actually, this looks like a perfect atmos speaker in the ceiling.

https://www.ebay.com/itm/266592006331
 
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#138
ddanj said:
My concerns are complexity of the crossover, losing sensitivity, and beaming. But maybe I should just commit to it and try it out.

How shallow could I make the box? How much space is needed directly behind the drivers?

Thanks!
Click to expand...
There’s designs out there with the Betas…..just look around for em. Shouldn’t beam at all if crosses around 1.2k. Sensitivity will be limited to the cone of course………for LCR duty, wide baffle or in wall…..no need for BSC. For your purposes, box depth isn’t an issue…..just maintain enclosure volume needed for your F3.
 
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