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How to improve the HPM-100/900 cabinet

So long as the flanges are recessed into the baffle such as to be flush with the surface, it will be different, but not inherently bad. You're already doing "different" by unclustering the drivers.

Your major problem with that design is that you have the top three drivers on the centerline. Offset them to one side and the other by a couple of inches and put both ports on the other side.

Why? Because you have equal distances to the cabinet edges, which will reinforce deliterious edge diffraction effects for each of those drivers. You want them to occur at different frequencies so that they will not sum....
 
Zilch said:
So long as the flanges are recessed into the baffle such as to be flush with the surface, it will be different, but not bad. You're already doing "different" by unclustering the drivers.

Your major problem with that design is that you have the top three drivers on the centerline. Offset them to one side and the other by a couple of inches and put both ports on the other side.

Why? Because you have equal distances to the cabinet edges, which will reinforce deliterious edge diffraction effects for each of those drivers. You want them to occur at different frequencies so that they will not sum....
Click to expand...

Talking with Dave Newman in Chat brought this same thing up. He didn't explain why only suggested it would be better to use an off set. The Woofer can only be set over a tiny bit as it's size is pretty close to the cab size. I hadn't thought of or Dave didn't mention the Woofer needing an off set. But I can certainly do that to some degree.

How about this layout, (using the computer to hack up my rough sketch leaves something to be desired LOL)
 

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No reason to move the woofer over. I mentioned diffraction as the reason, but it's the same reason I recommended not using a grill, and doing a roundover on cabinet edges. :)
 
Mark W. said:
How about this layout, (using the computer to hack up my rough sketch leaves something to be desired LOL)
Click to expand...
There's no need to move the woofer off the centerline, and you've moved the others too far to the side in my view. You'll need to consult Dickason for guidance as to what may be optimum, but I suggest more like one or two inches offset.

[The more you move them over, the more you tilt the plane of time-alignment with the woofer.... :yes: ]
 
Gibsonian said:
Why no grill and what do you propose to protect the drivers in it's place?
Click to expand...

Well since soon this house will be filled with a couple of grand daughters (the first one is about to be crawling) protecting the gear is being well thought out.

I will have very HPM-100/900 looking black cloth grills on them most of the time but during dedicated listening sessions I would be able to pull them off and squeeze a tiny bit more from the speakers. We have been talking in Chat about using tiny rare earth magnets to hold them in place with the ones in the cab set under the veneer so hidden when the grills are removed.

The reason as I understand it for no grills is to reduce any reflection back on the drivers from frame work or even the cloth.
 
OK the latest layout ideas. The mid range and tweeters are set 2" off the center line. And I'll go back to the original single Port. Though I will make it quite different then the Pioneer original is I don't like the ring around the opening it actually step down to the Tube ID causing a step at the opening.

I'm thinking about rounding the edges of the face with about a 1" radius I can do this with a Router bit I already have and using my router table can do a very nice job of it. I'll use a Solid piece of walnut around the front edge so I get a nice transition.

I'm currently thinking I will make the 1.25" thick boards using a 3 layer laminate glued up with a layer of Std duty Chip board 1/2" thick on the inside then a layer of 1/4"T 9) layer Birch Aircraft grade plywood in the middle and finally a 1/2" T layer of MDF on the outside. Then line the inside with a layer of 1/16th" T soft Balsa (which is as dead as a wood can get it's so soft and light NO RING what so ever)

I'll go with a nice Hopefully redish tint Walnut 2 ply NBL veneer wraped over the cab so it has the same grain line from the bottom of one side to the bottom of the other side.

I'll vary the depth of the cabs to achieve the proper volume I can go as deep as 16.5" which is almost 1.5" more then stock and the 2" added height will also add volume to allow more bracing.

Anyway here is this go arounds layout drawing
 

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Mark W. said:
For those who know the Pioneer HPM-100 or HPM-900 speakers a question.

First the back story.

Kelly an AK member decided that I should be the guy to receive a pair of HPM-900's he was playing with. They have as virtually all of these do destroyed cones in the woofers.

I'm thinking seriously about having GordonW (another AK member) rebuild the woofer with a special paper cone he has figured out.

BUT the cabs on the 900's are not only beat but lack even the structural design of the 100's. So I'm thinking about building my own cabs for the HPM-900 drivers and crossovers.

Due to the requirements of our system and living room the cabs will have to be exactlyt he same size as the HPM-100's cabs they would be replacing. 15.5" X 15" X 26"

So do I try to duplicate the 100's better cab? Or do I try to improve on something? heavier walls? more internal bracing? Different Porting?

I will be doing the cabs with either real veneer over some type of particle borad or Plywood (do I want a stiffer cab?) or I have thought about layering particle board with 1/4" Walnut plywood over top using solid walnut corners and edges.

So anyone who's into speaker cab design got any ideas on how to improve a HPM-900's cab?

So you know I have pretty much any woodworking tools or skills needed to do almost anything.
Click to expand...

It looks like I'm bringing this thread back from the dead... but did you follow through with new cabinets?

I've been tinkering with the idea of having a woodworker friend do something similiar for my and my HPM-900's :thmbsp:
 
Looks like I gave those 900's to the right person. Hurry up and get them done so I can come drink your wine and listen to the final product. :thmbsp:
 
Paging Mark W. Paging Mark W. :

kfa888, no fair asking him to give 'em back after you hear how good they sound :lmao:
 
Kinda wondering myself, Changing to HPM 900 drivers myself, Less the woofer.
Took awhile to collect all that stuff.
 
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