ScottG said:
I thought Genelec used an EBS alignment with traditional low Fs drivers (Peerless).
Bagend seems to have parallels to your design but uses sealed over ported and therefor has much larger drivers (21"). Similar idea though with the use of EQ to extend the response to 9hz or something like that.
ShinOBIWAN said:
Yeah.. I thought that would be a problem..
You know - you could go with a bend in the pipe..
I don't like the idea, but IF its between the basic construction I spec'ed and a straight pipe - then bend the pipe. HOWEVER if you do so then marginally increase the diameter (..and of course the length).
Is that acceptable?
ScottG said:
I'll draw another model up and see how I can sensibly dimension this now that I can do a bend in the pipe.
Could I lessen the sand wall too? Say 2" instead of the 4" on each side?
ShinOBIWAN said:
It could be..
There are however somethings that are "odd"..
1. the drivers are mounted fairly high on the baffle (..relative to a boundry).
2. distortion is incredibly low at lower freq.s (at least from the two plots I've seen).
Neither fact seems normal for a standard EBS design, (..though when you think about it the B&C design here is more of an actual EBS than what is normally termed an EBS).
Also, are you sure about peerless? (..that would certainly invalidate my thoughts here.)
ShinOBIWAN said:
Sadly the most important part is the top..
So yes, you could decrease to 2" on the *sides*, but from experience for some reason unknown to me - the 4 inch amount on top makes a difference.
What about making what I will call a single layer "surface" mounted MATRIX along all internal "walls" - very effective both acoustically and resonanse dampening, and doesnt vaste much space
BTW, very interesting this using woofer only below Fs, if I understand it correctly
BTW, very interesting this using woofer only below Fs, if I understand it correctly
ScottG said:
TBH, I'm going on what I've seen in photo's. I've heard other mention this to so I could be jumping to conclusions. The HTS4 uses what looks to be a XLS12 with dual PR's and HTS6 appear to use the same drivers but in a quad configuration and sans PR's. Is the HTS6 ported or sealed? I always assumed ported but...
AVTalk has a few photo's of the HTS4:
http://www.avtalk.co.uk/forum/index.php?t=msg&th=13929&start=0&rid=4491&SQ=1154046893
Looks like Peerless.
ScottG said:
Top part is doable in 4"
Where's the best place to mount the driver BTW? Low down for a bit of floor loading or up high? I'll be doing forward firing.
I've decided to compromise on the video side of things and raise my screen up to allow a cabinet of 72cm height - which is exactly the height of the Perceive's minus the sat enclosures so it should have some good continuity. I'm keeping the baffle fairly slim at around 35cm but with a good amount of depth ~50cm.
Also can you elaborate on the plinth details? As I understand your saying that I should 'fence' in the port/plinth cavity and just have one exit point between the enclosure and the plinth. What dimensions? Port's relative postion? Any taper to this fencing? Can it be dimensioned to be used as an extension to the ports length or is that detrimental?
ShinOBIWAN said:
Up higher for the driver..
hmm, plinth? 😕
platform and airspace?
platform 1 inch thick and the same length and depth of the cabinet.
on top of platform are 4 spikes. The spikes support the cabinet. They create an effective airspace between the cabinet of about an inch to an inch and a half thick. (..should be variable to raise and lower cabinet.) No surrounding "fence" for this airspace (..unlike the avalon loudspeakers design which I originally recomended).
or are we talking about..
pipe within pipe port construction?, or
baffle construction and the driver loading airspace?
The port itself should "exit" to the near, (but off-"dead"-center), center of the base of the cabinet. It isn't terribly important exactly where, but you should keep it at least 7 inches from any cabinet "outer" edge.
ShinOBIWAN said:
If the HTS6 and the 7073 are identical then the HTS6 is ported.
Stereophile spec'es the drivers as "kevlar", but it could vary well be that they are mistaking the nomex fibers for kevlar.
I don't think you are jumping to conclusions - what you have suggested sounds about right.
What I find strange is the distortion difference between the HTS4's 95 db level at 20 Hz and the HTS6's 105 db level at 20 Hz. Perhaps I'm calculating the gain of 9db for the 4 driver config. over the 1 driver config. wrong? IF I'm doing that calculation correctly then the HTS6 is meaningfully different. (..perhaps if there is a port its firing at the floor and thats the difference?)
(..oh, and when I was referring to the genelec sub I was talking about the HTS6.. not the HTS4.)
Scott,
Do you plan on posting all the sub enclosure dimensions online? ie blue prints for us wanna-be's?? My friend already bought two of those subs and wants me to get started ASAP. How important is the cement?? Would triple thick 3/4" MDF be okay?
Do you plan on posting all the sub enclosure dimensions online? ie blue prints for us wanna-be's?? My friend already bought two of those subs and wants me to get started ASAP. How important is the cement?? Would triple thick 3/4" MDF be okay?
alexcd said:
Hi Alex,
I was working on a rough scale diagram yesterday it doesn't currently have dimension but I could add them.
I've still got some work to do on it but will post it later on.
That's great but now I'm confused. Didn't ScottG already build one or were those just guidelines? Either way I will be awaiting your drawings. 🙂
alexcd said:
The design has never been built, Scott made the suggestions and I'm trying to come up with a cabinet that's reasonable enough quality to his vision justice but without ending up with something so large and heavy that its impractical. Striking a balance isn't easy unfortunately and Scotts design outline is rather demanding.
OK, I this is the direction I'm headed, this is to scale BTW:
Sorry Scott but I've had to ditch the sand idea, I'll be really really struggling for room otherwise and I'm not prepared to make that compromise yet, even if the sound is better. I've ensured a rather hefty matrix bracing but this is obviously inferior to the very extensive construction of your suggested design.
The base in the diagram is a work in progress and was based upon the idea of enclosure the port with a single exit point. This will be revised when I get a little more time.
If you can see anything that could do with tweaking or improving please let me know.
Alex:
I'll also add dimensions to those diagrams once they're finalised. I'll do a cutting list too.
The slightly angled top section can be squared off to give a rectangular cabinet for simplicity, the volume increase is negligible(less than 1.5ltrs) and won't require any further changes. I only styled the subs that way to match my mains.
Sorry Scott but I've had to ditch the sand idea, I'll be really really struggling for room otherwise and I'm not prepared to make that compromise yet, even if the sound is better. I've ensured a rather hefty matrix bracing but this is obviously inferior to the very extensive construction of your suggested design.
The base in the diagram is a work in progress and was based upon the idea of enclosure the port with a single exit point. This will be revised when I get a little more time.
If you can see anything that could do with tweaking or improving please let me know.
Alex:
I'll also add dimensions to those diagrams once they're finalised. I'll do a cutting list too.
The slightly angled top section can be squared off to give a rectangular cabinet for simplicity, the volume increase is negligible(less than 1.5ltrs) and won't require any further changes. I only styled the subs that way to match my mains.
I dont really care about size since these will probably end up being my friend's end tables to his couch but the general size would be helpful. I think I will go with the sand idea in that case. Good thing these are in the basement or he would have to reinforce the floor.
alexcd said:
Glad your doing the sand route, I can imagine it creates the most impossibly dead and well damped cabinet. I'm also sure that Scott will be pleased someone is recreating his vision entirely 🙂 I felt kinda guilty throwing it out after all the work he'd clearly put into it, at least now it wasn't a waste.
The internal dimensions for 63ltrs for my cabinets are 54.2cm(H) x 30cm(W) x 48cm(D). Don't forget those sizes takes into account the volume taken up by the port and bracing, the Gross volume is around 81ltrs but the NET is just a shade under 63ltrs.
You'll need to add another 27.2cm to each of those dimensions if your doing the 18mm MDF + 100mm(4") sand + 18mm MDF.
Those internals will work nicely for me. Thanks.
My memory fails me, does Scott's design use internal bracing?
My memory fails me, does Scott's design use internal bracing?
alexcd said:
No fixed dimensions for a "clonus". There should be enough information here to do one yourself. When I get a stable net connection (which should be by the middle of next week), you can always tell me the cut dimensions and I'll review them to see if there are any issues that need alteration. (..ping me here for that, to give me a "heads-up", but start your own thread on the subwoofer section and I'll respond there.)
No, 3/4 MDF is NOT ok.. MDF material is FAR to compliant. You want lots a rigidity here. (..note those big @ss metal rings on the wilson audio XS. You will also see similarites with a few other designs as well on this point.) We also want to move vibration quickly away from the frame - and added mass helps here.
However, you don't need to make the cylinder driver chamber part of the cement baffle. (..its preferable, but only marginally preferable.) THAT makes the baffle a LOT more easy to form from cement. (i.e. its just a thick board with holes then - and don't think store bought cement board.. that stuff is cr@p.)
The cylinder would effectivly then be made of mdf "rings" in a constrained layer combination, (to build-up thickness), to span the distance from the intererior of the exterior box to the exterior of the interior box.
Going back to the platter and cup example..
Just make the "platter" out of cement, the "cup" would be mdf stacked rings between the 2 boxes.
The cylinder doesn't have to be made of mdf either - it could be something like sonotube.
Nor does the baffle need to be cement.. it could be made of something like 3/4 inch steel plate.
ONE FINAL NOTE:
You want as much weight as possible - specifically you do *NOT* want the thing moving back and forth even by less than a 10th of a mm.
So don't go thinking "roller" footers to move it around, UNLESS they are removable for a fixed position after geting it to the spot you want. Much like an infommercial add.. for a sub you want to:
"set it, and forget it".
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