I do not know what a CLD construction is.
We did discuss that, but it has advantages (theoretical) and disadvantages (theoretical).
In my opinion a separate mid range unit decoupled form LF will not benefit from the sheer mass of the total enclosure.
The best part of the original design (see link above) is its midrange. I think that next to great components it is the stability and mass of the total enclosure that helped making this stand out. The total speaker will also become larger. I know benefit from the space behind the midrange to be added to the LF volume.
We did discuss that, but it has advantages (theoretical) and disadvantages (theoretical).
In my opinion a separate mid range unit decoupled form LF will not benefit from the sheer mass of the total enclosure.
The best part of the original design (see link above) is its midrange. I think that next to great components it is the stability and mass of the total enclosure that helped making this stand out. The total speaker will also become larger. I know benefit from the space behind the midrange to be added to the LF volume.
CLD is constrained layer damping, arguably the best way to dampen panel resonances. I won't repeat what already has been written quite a few times. But take it that a small midrange unit with adequately damped separate enclosure walls is superior to integrating the midrange in the main enclosure. Main enclosure equals big panels equals much sound contribution from panel resonances. Just my 2ct.
Ahhhh yes I have looked into that a few times, and I have heard some nice demo's that proved it worked, but these were all fairly light constructions.
This speaker will weigh around 150kg
What you don't see in these renders is that we will use a rubber seal between aluminum and internal MDF structure (mainly to cope with stress on the rods if part of the structure expands/contracts more than others. The angled midplane that separates mid from LF will be strengthened and all panels will get lead bitumen layers and of course several forms of absorption layers like technocell.
In my experience mass will be equally or better than having a seperate fairly light structure holding mid.
And from the inside outward on the sides. Technocell, Lead bitumen, 15mm MDF, 13mm HDF, 18mm Walnut
This speaker will weigh around 150kg
What you don't see in these renders is that we will use a rubber seal between aluminum and internal MDF structure (mainly to cope with stress on the rods if part of the structure expands/contracts more than others. The angled midplane that separates mid from LF will be strengthened and all panels will get lead bitumen layers and of course several forms of absorption layers like technocell.
In my experience mass will be equally or better than having a seperate fairly light structure holding mid.
And from the inside outward on the sides. Technocell, Lead bitumen, 15mm MDF, 13mm HDF, 18mm Walnut
I kind of do, but I leave more mass in the midrange section that helps dampening resonances. The fairly thin part of your midrange section is more prone to vibration
I agree the 10 rods have more than enough stiffness and strength for this application. My concern is the opposite... there is a risk of over-tightening the threaded connections and compressing the wood structure to failure. With 10 bolts, it would be very possible. Are you planning to use a torque wrench to control the level of pre-load applied to the rods? I would recommend that.
Another advantage to this design is being able to alter the preload on any given rod. This allows deal with cabinet resonances by tuning the cabinet stiffness to get the least possible resonance signature. Overall, it is a very robust and impressive cabinet design.
It is a very high-end absorption material. Self adhesive. And gives better absorption than the typical black egg box foam
Nice Project.
I disagree rectangular bracing is stronger than round hole. Example is colosseum or bridges. Without arch those buildings would collapse. Simple as that.
You can remove quite some wood in round hole and the bracing would still be rather strong. It you don’t, bracing is VERY strong even when twisting.
I believe general advise/rule of thumb is minimum 50 % of membrane of driver to let driver breathes through bracing.
General advice: MDF is bad for bracing (and generally main quality is that it is cheap) and I suggest you use high quality ply.
If you are open to more suggestion, you could think of using WG. I think even cheaper tweeter in optimized WG runs corners with non-WG tweeter.
I highly suggest you experiment with clean carted wool especially in midrange.
Next we have mounting of drivers, where I suggest experimenting with midrange driver mounted from behind. A lot of companies do that nowadays, even cheaper speakers. It looks great and from sim (can’t find post), optimized shape has better dispersion then mounting driver flush. In both scenarios corners were rounded. Not so easy to build.
The baffle thickness was 55mm. The thin part was 25mm thick actually, 30mm thick alu wg was mounted above midrange. Definitely not limiting factor in any way.
Hi Rokytheman,
Thanks for your reply. I share this with you guys not just to show off
but to be challenged and get feedback like this.You have a point here but I like to still argue it. An arc was used in ancient history to help building a span between two pillars as the arc kind of supports itself during the construction.
But here we want to reduce vibration (and I can tell you my previous design is dead). To me, just using logic as an electrical engineer, the function of the bracing is connecting the opposite walls with a beam. Ideally a few beams as every time you half the width of the panel it resonance frequency doubles but half’s in amplitude. As individual beams are unpractical to mount we use panels with holes. The strength of the beam wil be linear to intersection area of that beam. My logic tells me that round holes with the same breathing area then square ones will produce thinner beams.
My theory is followed by Magico and the Kef Reference 5 (where I stole the M8 rods idea from)
I understand that for a DIY project with no CNC round holes are more practical as you can see on the extremely informative pages of Troels Gravesen.
Oh and most of the internal bracing is constructed with 1100kg/m3 HDF (Finsa Compac Plus)
I am sorry that I have to disagree on another point 50% breathing area is not enough as I had a secondary impedance bump in a previous design because of the limited area in a two bass speaker design.
The waveguide subject also came up. But this tweeter is so nice in a flush mounted curved baffle spanned with a fairly soft leatherette that this was a no brainer to copy from the original design.
Yesssss long hair wool in the midrange as filler
We also looked at rear mounting the drivers. It sure looks good. The problem is the relative thin area you have to mount the units into. Again plain logic tells me that this ruins the whole stiffness of the baffle. That is why the thinnest part of the baffle is still 15 mm but where the mounting screws are it is 40mm. Having units mounted behind a 15mm baffle will definitely cause diffraction errors. A thinner residual thickness will cause mounting issues. Or the need for strange clamping hardware like Magico uses. And these clamps interfere with the minimum inside space I have to make the enclosure as narrow as possible.
These are all compromises in the end and personal preference and practicalities dictate the choices I made.
But the challenges, disagreements and tips are very much appreciated.