Quoting a decades long member that I haven't seen posting for awhile now, 'Sound is Round', so round overs are superior to truncated and only really effective when fairly large relative to the speaker width, i.e. a 24" baffle has a ~13543/2/24 = ~282 Hz, so for it to not happen requires: ~13543/pi/282/2 = ~7.64" radius/side. 24 - ~15.28 = ~8.72" to mount the driver, so just not practical for the typical DIYer around here. Higher frequency ones get 'swamped' by the LF WLs, room modes, so renders them more cosmetic than anything acoustically useful.
In short, no, in theory the driver ideally should be in the vent.
The angled vent termination increases its pipe end correction = shorter vent for a given tuning and when the vent is a very high aspect ratio [> ~9:1], it becomes increasingly resistive to the point where it starts 'choking' from way too high a vent mach, so large pipe end correction smooths it out somewhat, just like extending a horn's mouth can smooth out ripples in its response.
Alternatively, one can add a foam 'horn'/pipe extension, though getting the optimal density and/or thickness can be a bit tedious.
Goodmorning everyone
on Rokikiki's request, I share in the thread a drawing with the dimensions I gave to Chris Templer's TNT project, however it should be noted that these measurements were obtained by redrawing with the CAD "on the" original photo of the Coral project, compensating for the drawing obtained with Templer's statements about his measurements .... so, it is not certain that what I got is exactly what Templer built (and as I said, I wrote to him without ever having any answer from him on the doubts I had .. .).
So take this drawing with the right attention, to those who want I can also send the CAD file privately, so that everyone can make changes or improvements to share here ...
PS: Dimensions are in centimeters, red lines indicate wooden profiles (25mm thick birch plywood) and purple lines indicate Axiom 201 speaker size.
on Rokikiki's request, I share in the thread a drawing with the dimensions I gave to Chris Templer's TNT project, however it should be noted that these measurements were obtained by redrawing with the CAD "on the" original photo of the Coral project, compensating for the drawing obtained with Templer's statements about his measurements .... so, it is not certain that what I got is exactly what Templer built (and as I said, I wrote to him without ever having any answer from him on the doubts I had .. .).
So take this drawing with the right attention, to those who want I can also send the CAD file privately, so that everyone can make changes or improvements to share here ...
PS: Dimensions are in centimeters, red lines indicate wooden profiles (25mm thick birch plywood) and purple lines indicate Axiom 201 speaker size.
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Hi Eric
These are very nice built, mine are like this and are looking soon for a new home
Eric
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hi to everyone
no, unfortunately I have not yet built anything, I was waiting for some clarification on how to proceed to solve the problems of the measures that did not convince me, but in the meantime many things have happened in my life beyond the hifi and each one brought a small stone under which to bury this project ... I'm almost thinking about selling my axiom and stop thinking about it: in Italy they say "out of sight, out of mind" ...
very beautiful your projects, which speakers did you use? I see in your photos a concentric speaker ...
Thank you, will report to my carpenter
Have bypassed the attenuator, the L pad is still present and in use a new 1mF cap (original 1.5mF?) only, so the tweeter works as auxiliary speaker.
Hello landrupp
These are indeed concentric drivers without the issue if time alignment. Mine are Triaxiom 212c.
Eric
Forgot to mention, that the woofer is now working as fullrange with my x-over mod.Thank you, will report to my carpenter
Have bypassed the attenuator, the L pad is still present and in use a new 1mF cap (original 1.5mF?) only, so the tweeter works as auxiliary speaker.
new sound coming out of my Goodmans after swapping the triode amp with the ACA. The response with the ACA and the Goodmans has much improved in the lower region in a way, that the body of bass drum, toms, acoustic bass a. o. can be 'seen' much better and with high speaker levels, I can hear the peaks with less distortions. The quality of sound is not far from some 'exotic' and high priced stereo sets, which I've heard at a HiFi-show recently.
Eric
Hi @100ohms
Do You have maybe some photos of the inside construction and grid? Maybe opinion about fabric (red or green one)?
I made some ARU-s based on the pictures I found on the net. But I am not sure 100% that is as goodmans...
It is not easy to find the mesh and fabric as it was decades ago.
Do You have maybe some photos of the inside construction and grid? Maybe opinion about fabric (red or green one)?
I made some ARU-s based on the pictures I found on the net. But I am not sure 100% that is as goodmans...
It is not easy to find the mesh and fabric as it was decades ago.
Thanks
I think that I had this one.
I put the fabric (red) from some material for the kitchen cleaning. 1mm cca. And these braces are about 6mm. I used standard Al mesh that i can find in the stores similar to this. I used clasic neoprene glue to mesh and attach the fabric.
Overall dimensions can be extracted from the hole from original plans.
I will try to find pictures with dimensions of mine diy ARU-s
.
Can You measure the braces and the fabric?
I think that I had this one.
I put the fabric (red) from some material for the kitchen cleaning. 1mm cca. And these braces are about 6mm. I used standard Al mesh that i can find in the stores similar to this. I used clasic neoprene glue to mesh and attach the fabric.
Overall dimensions can be extracted from the hole from original plans.
I will try to find pictures with dimensions of mine diy ARU-s
.
Can You measure the braces and the fabric?
Hi Zoran
The mesh wire is on the backside and on the frontside, there is a kind of ‚sliced and stretched foil‘.
The fabric seems to me a little thinner than 1mm. Probably between 0.5 and 0.25mm.
Eric
The mesh wire is on the backside and on the frontside, there is a kind of ‚sliced and stretched foil‘.
The fabric seems to me a little thinner than 1mm. Probably between 0.5 and 0.25mm.
Eric
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Yes the fibric is thinner about 0.5mm as You said.
I found some photos of my diy ones...
There are 2 metal mesh inside in mine, the distance between them is 5mm.
As from I can estimate...
Could You estimate the distance between the outside and inside mesh?
.
Also another set of braces in the same positions after the inside mesh.
The space in the center cell between the meshes is empty. (As Your photos indicated too.)
.
But is the rest of the space around the center "mesh hole" empty or filled with something?
And this outside mesh, is the something glued on the surface or is just the "empty" mesh?
I found some photos of my diy ones...
There are 2 metal mesh inside in mine, the distance between them is 5mm.
As from I can estimate...
Could You estimate the distance between the outside and inside mesh?
.
Also another set of braces in the same positions after the inside mesh.
The space in the center cell between the meshes is empty. (As Your photos indicated too.)
.
But is the rest of the space around the center "mesh hole" empty or filled with something?
And this outside mesh, is the something glued on the surface or is just the "empty" mesh?
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My ARUs are without distance between the sliced and stretched metal sheet (which is made for estetical reason? - my opinion) and the mesh wire. The light shines through too. If space is between the mesh wire and the metal sheet, this could prevent any rattle or noise, caused by vibrations at high speaker volume. I've found some more pictures and informations on my drive. There is also an early ARU version, without that 'estetical' metal sheet, with mesh wire only and probably much bigger in size.
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