I 'll make a pair of active dsp-controlled floorstanders, big and loud this time! Speakers will be made with my heavy metal fan son, for indoor home listening.
https://en.toutlehautparleur.com/coaxial-speaker-rcf-cx12n251-8-8-ohm-12-6-inch.html
a pair of 12" woofers, closed box, xo around 200Hz
Hypex FA123
I found these pro coaxials at THLP, I was searching for ones with a fixed horn. I couldn't find directivity or any other independent measurements, so going blind this time! More detailed plans during Christmas holidays and first measurements in test baffle in January!
Here is link to photo album of the project https://photos.app.goo.gl/hGFkqajgoVwWrzL59
https://en.toutlehautparleur.com/coaxial-speaker-rcf-cx12n251-8-8-ohm-12-6-inch.html
a pair of 12" woofers, closed box, xo around 200Hz
Hypex FA123
I found these pro coaxials at THLP, I was searching for ones with a fixed horn. I couldn't find directivity or any other independent measurements, so going blind this time! More detailed plans during Christmas holidays and first measurements in test baffle in January!
Here is link to photo album of the project https://photos.app.goo.gl/hGFkqajgoVwWrzL59
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Inspiration comes from my good experience from coaxials and these projects
Taipuu company started making speakers with a kimmosto desing mega speaker 15" coax+18" woofer
https://taipuuspeakers.fi/en/taipuu-speakers-dsp-active-speakers/
Javad Shadzi's Lyceum Optimus
Taipuu company started making speakers with a kimmosto desing mega speaker 15" coax+18" woofer
https://taipuuspeakers.fi/en/taipuu-speakers-dsp-active-speakers/
Javad Shadzi's Lyceum Optimus
I always wondered if a driver like this could fire the woofer through a round slot. The baffle could be flush with the horn but leave a calculated gap between the edge of the baffle and the edge of the horn. Sort of like the Genelec monitors. Then the horn might behave better. I just can’t tell if the horn sits proud enough of the frame to let it happen.
Anyhow, looking forward to this build. Hopefully some videos too!
Anyhow, looking forward to this build. Hopefully some videos too!
Sure! Though this particular one would ideally need a flared opening to ~mirror the HF's exterior, expanding a bit further like is done in some circular segmented heat duct grill concepts and realized by RCA for this coax compound horn.
Video
Video
I took a close look at these a while ago but decided I liked KEF coax's better. Attached is a directivity report for RCF NX12SMA Stage Monitor which, I believe, uses the CX12N251. I got it from RCF tech support in response to my request for directivity info on the '251. I think these have potential but if you look at the directivity, you see effects from the edge of the waveguide at around 1.4 khz. Find a way to fix/mitigate that and you have a winner and it may not be too bad as is.
Attachments
I did some really crude abec sims to model that gap between the woofer cone and the baffle. Without any treatment you get a big discontinuity. The best result I got was to assume that the gap was filled with felt which would keep the HF out of the gap between the woofer and the waveguide and act as an acoustic low pass filter for the woofer crossover. Easy say; harder to do - have to find a felt thickness that works and a means to keep it in place.
this report is for their TT25-CXA stage monitor that uses their CX15N351. Same issue with the WG edge but lower in frequency. Still, its got to be better than using the woofer cone as a waveguide; certainly up top, and it doesn't degrade with woofer excursion. I'm wondering why I didn't go this way. I think I just wanted to end up with a narrow cabinet.
Yes, I noticed this directivity mismatch problem actually with every 12" coax with horn. But these were on sale! Let's see how it'll go. I have one minidsp 2xHD extra for tests. 12" coaxes without a plastic horn have their problems too, even MoFi 10" was a tour-de-force for Andrew Jones. Here is a nice interview
https://www.soundandvision.com/content/interview-andrew-jones-mofi-sourcepoint-10-loudspeakers
https://www.soundandvision.com/content/interview-andrew-jones-mofi-sourcepoint-10-loudspeakers
You can 3D print an extension flange that rolls the waveguide around behind the woofer (assuming your woofer enclosure is small enough), with some holes to allow radiation from the woofer diaphragm. You can make the holes elliptical to reduce the diffraction impact on the HF, and potentially put some felt on the leading edges also.
Easiest way for me is to make the front baffle in sandwich layers. Base should have recession for the flange of the driver. Second layer will cover the flange and the cutout is tapered to continue the cone profile, etc. with increasing angle. I don't have access to 3D machinery so I must do machining by electric hand tools, finishing with files and sandpaper. Old school...
Starting tapering with a 12" driver would mean a pretty wide baffle! I must consult my son about this. I have seen wide curved baffles in my dreams for many years - Sonus Faber Stradivari style https://www.stereophile.com/floorloudspeakers/105sonus/index.html But my son lives in a rather small apartment and has a long way to living in a penthouse or a manor. Some kind of temporary intermediate solution this time!
Mummy speaker shape is out of question for me too, but a sarcophag of a black coffin should be ok!
Starting tapering with a 12" driver would mean a pretty wide baffle! I must consult my son about this. I have seen wide curved baffles in my dreams for many years - Sonus Faber Stradivari style https://www.stereophile.com/floorloudspeakers/105sonus/index.html But my son lives in a rather small apartment and has a long way to living in a penthouse or a manor. Some kind of temporary intermediate solution this time!
Mummy speaker shape is out of question for me too, but a sarcophag of a black coffin should be ok!
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The 12" coax midrange-tweeter must have a small closed subcabin. Twin 12" woofers will use rest of the box.
I have been thinking about SLS12 8R parallel for woofers. https://en.toutlehautparleur.com/speaker-peerless-sls-p830669-8-ohm-12-inch.html
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FYI/FWIW/YMMV, forget now who made a new WG w/slots, rim damping for the Urei studio monitors to replace the original Altec 604 coax/duplex's HF horns to greatly improve frequency, polar responses. Manual.