Do you have access to CNC? (looks like a plug cut on the tweeter) This is how I do rebates, with reduced mass between the screw holes, chamfered as well. I have been thinking if this could be improved by having a small lip to hold the driver (no lugs for the screws), but have a 3D printed ring behind the baffle that could have machine thread inserts and be nice shape.
For other isolation mounting as suggested in The Loudspeaker Design Cookbook is to use Well-Nuts, sorbothane inserts with metal threads that expand like Rawl plugs to fill a void and acoustically isolate. I have used these between speaker and base and they work well.
No CNC but I do have a 3D printer that I've used for both jigs to saw facets on the fronts of the baffles and for routing templates. The tweeter cutouts were template routed, then squared off a bit with a jigsaw (my only straight bit is 1/2" so I needed the jigsaw at those inside corners). I plan on following chamfering both openings - the mid-woofer to avoid the transmission line effect that Troels documented, and probably the tweeter for the little bit of recovered volume in my compact (10 L after a generous allowance for crossovers).
I like the way you left material just around the screw heads. It would have been easily done with a template!
I've thought of the 3D printed (there would be other ways as well) back ring. It had not occurred to me that it would allow leaving out the screw holes altogether
though I did figure on oversized holes lined with soft material. Meanwhile, my distortion data is consistent with Lars' report that experiments suggest torquing screws carefully and putting efforts elsewhere. On the other hand, I can see "soft mounting" approaches being more immune to changes with thermal or humidity cycles.
Thanks for the Cookbook reference as well.
I like the way you left material just around the screw heads. It would have been easily done with a template!
I've thought of the 3D printed (there would be other ways as well) back ring. It had not occurred to me that it would allow leaving out the screw holes altogether
though I did figure on oversized holes lined with soft material. Meanwhile, my distortion data is consistent with Lars' report that experiments suggest torquing screws carefully and putting efforts elsewhere. On the other hand, I can see "soft mounting" approaches being more immune to changes with thermal or humidity cycles.Thanks for the Cookbook reference as well.
I actually CNC'd some jigs to try and sell them (specific for Mark Audio drivers), but have now bought a 3D printer to make some better designed ones.
It looks like Purifi have engineered a really strong frame that's only 5mm thick. The older mark audio drivers were 10.5mm or so there wasn't a huge amount of material left in a 18mm baffle. But 13mm or so for the Purifi should be enough to torque it well with normal screws
These are the Well-Nuts described in the book. It would be very easy to have these secure into a 3d printed back based, and they have a natural lip which would further isolate the driver from the baffle. It does open up the ability to use nice anodised bolts instead of wood screws.
It looks like Purifi have engineered a really strong frame that's only 5mm thick. The older mark audio drivers were 10.5mm or so there wasn't a huge amount of material left in a 18mm baffle. But 13mm or so for the Purifi should be enough to torque it well with normal screws
These are the Well-Nuts described in the book. It would be very easy to have these secure into a 3d printed back based, and they have a natural lip which would further isolate the driver from the baffle. It does open up the ability to use nice anodised bolts instead of wood screws.
Whoa! That is exactly what I am planning to do!
The Jern enclosure is a rare beast, apart from the reflection from the tweeter almost all is great, I can't imagine designing a less resonating box.
The 5.25" will fit like a glove and I plan to try the Hiquphon first but I also have a pair of Bliesma T26Bs that are tempting, certain Textreme offers are the next step, I am not going back to passive ever again.
If it shows the promise I expect the Purifi/Jern combo might be magical and active will allow me to test the best of tweeters to compliment that set.
You use a DSP? How do you like the speaker now?
The Jern enclosure is a rare beast, apart from the reflection from the tweeter almost all is great, I can't imagine designing a less resonating box.
The 5.25" will fit like a glove and I plan to try the Hiquphon first but I also have a pair of Bliesma T26Bs that are tempting, certain Textreme offers are the next step, I am not going back to passive ever again.
If it shows the promise I expect the Purifi/Jern combo might be magical and active will allow me to test the best of tweeters to compliment that set.
You use a DSP? How do you like the speaker now?
Cool journey! I use a minidsp DDRC-88D with BM plugin so I have both crossovers and dirac live in that box (if you are not using dirac live you miss out!) Signal then goes to a dac8 PRO from octo research (from this I adjust volume) and then to a 4 channel 1ET400A from Audiophonics. What I said about the volume adjustment is mostly not true, in practice I set a max volume in the dac8 and then adjust it in software with my bluesound streamer.
Its actually a hotted Jern 11 so I cant compare with a plain 14 EH. But I do enjoy this set up, its so easy on my ears. I really just picked a suitable crossover point I think around 2,2 kHz, applied 24db/octave filters, gain matched the drivers not by measurement but from charts! Also did some time alignment with the help from a minidsp guide. Rationale for this simpler approach is that then I let dirac live do its magic. Once again, and especially if you live in a concrete box as many of us do, use dirac or I guess similar and treat your room modes (plus other stuff it helps with)
I have thought about testing out a 5.25 inch but probably next thing in my hifi journey I will wait until purifi comes out with something I can use as an open baffle "subwoofer" and add two more channels of amplification + crossovers settings (perhaps one 2*8 inch puri in a push pull per channel is enough for my room!?). I dont need the decibels and once I tried dirac I certainly dont want room modes back ever again... Therefor I think open baffle bass and Jerns as top end is a perfect match
I might also want to try out what you mentioned Lars:
"our coming tweeter in the 104mm faceplate version will fit right in"
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In the coverage of AXPONA 2024 show I became aware of another brand using Purifi drivers in a commercial offering.
OePhi https://oephi.com/loudspeakers
![06393[1].jpg](https://www.diyaudio.com/community/attachments/06393-1-jpg.1302599/ "06393[1].jpg")
OePhi https://oephi.com/loudspeakers