NOTE: Numerous pictures may make this thread slow to load!
A friend of mine in Cape Town phoned me up some time ago and asked me to design a set of floorstanding speakers for him.
A key directive was the need for a reasonably sized speaker, so after much deliberation, we settled on a 2.5 way design using choice bits from 18Sound and B&C. My friend wants to build himself, so I need to come up with the design and crossover before he can start on his side. Whilst it's possible to do this on paper, the best results can only be achieved by building a set myself.
Depending on how this goes, I may decide to make the design available in kit form at a later stage. At this point I am working on a total of 4 speaker kits at the same time, so things tend to become a bit heavy!
For drivers, we have the 18Sound HD1050 compression driver for the tweeter:
spec sheets, etc: http://www.eighteensound.com/index.aspx?mainMenu=view_product_simple&pid=192
The HF horn selected is a cast aluminium B&C ME20:
Mid/bass and bass drivers are 8" 18Sound 8MB400:
Spec sheets, etc: http://www.eighteensound.com/index.aspx?mainMenu=view_product_simple&pid=228
As per all 18Sound products, the MB400 is a very nicely designed and built driver. Cast aluminium frame, treated paper cone, and a seriously strong motor. Here you can see a pic of the magnet - pack of 20 Marlboros on it for scale:
Highlights of this driver include Qts of 0.38, Mms of 18 grams, Fs of 64 Hz, and linear xmax of + and - 5.8mm (excellent for an 8" HE driver).
So, onto the cabinet building. I decided to use 18mm marine plywood for the build, and after giving it some through, have also decided to apply only clear paint to the enclosure, therefore showing the plywood off a bit. That means I need to work really carefully, as there is no way to hide any problems with fillers and things. It also means I need to be a bit more creative to make it look good.
The cabinet design I settled on is tapered front to back in order to minimize standing waves. I have also decided to house the mid/bass and bass drivers in separate enclosures, and made the internal separator at an angle as well - again to minimize parallel surfaces and thereby minimize standing waves.
Many clamps are required - because I can't use any fastners such as brad nails or screws (because I can't hide them later), it's biscuits and glue with clamps only:
Next, I added some H-bracing into the cabinets. The high grade marine ply is plenty stiff and rigid without it, but a bit of extra bracing can only make things better!
Not that it's really needed, but I decided to recess the HF horn onto the front baffle. Because it's a square shape, I had to make up a routing jig for it. Here you can see the jig on top of the baffle:
Here you can see the recess routing done and dusted (but not yet sanded):
Test fit - looks pretty good!
Next, I glue the baffles on. Each cabinet has double thickness baffles. Because the 8MB400 driver needs around 14mm worth of recess, which will only leave 4mm of wood behind it to mount on, I doubled up so we now have 22mm worth of marine ply for the driver to be bolted to securely:
And here you can see the glued up, but unsanded cabinet:
As stated above - because I am not going to veneer or paint this speaker (other than clear coats), I decided to spice it up a bit by routing some detail onto the side panels:
And herewith seen from another angle. The top of the speaker is the nearest side shown below:
To make the top a bit more interesting to look at, I cut up a whole load of 30mm wide strips of the plywood, and glued them together such that the end grain shows. Here you can see the pieces being clamped:
After the glue dried, I did some sanding and this is what the results look like:
After that, I placed the piece on top of the speaker cabinet, and marked the correct dimensions after which I applied the saw liberally. This is the result:
There is still a lot of work I want to do to the top piece before gluing it on, but here you can see roughly what it will end up looking like:
And finally, a before and after pic of the top pieces:
Here you can see the two cabinets standing back to back:
That's all the pictures I have for now - more to follow later on.
Cheers,
Ian.
A friend of mine in Cape Town phoned me up some time ago and asked me to design a set of floorstanding speakers for him.
A key directive was the need for a reasonably sized speaker, so after much deliberation, we settled on a 2.5 way design using choice bits from 18Sound and B&C. My friend wants to build himself, so I need to come up with the design and crossover before he can start on his side. Whilst it's possible to do this on paper, the best results can only be achieved by building a set myself.
Depending on how this goes, I may decide to make the design available in kit form at a later stage. At this point I am working on a total of 4 speaker kits at the same time, so things tend to become a bit heavy!
For drivers, we have the 18Sound HD1050 compression driver for the tweeter:
spec sheets, etc: http://www.eighteensound.com/index.aspx?mainMenu=view_product_simple&pid=192
The HF horn selected is a cast aluminium B&C ME20:
Mid/bass and bass drivers are 8" 18Sound 8MB400:
Spec sheets, etc: http://www.eighteensound.com/index.aspx?mainMenu=view_product_simple&pid=228
As per all 18Sound products, the MB400 is a very nicely designed and built driver. Cast aluminium frame, treated paper cone, and a seriously strong motor. Here you can see a pic of the magnet - pack of 20 Marlboros on it for scale:
Highlights of this driver include Qts of 0.38, Mms of 18 grams, Fs of 64 Hz, and linear xmax of + and - 5.8mm (excellent for an 8" HE driver).
So, onto the cabinet building. I decided to use 18mm marine plywood for the build, and after giving it some through, have also decided to apply only clear paint to the enclosure, therefore showing the plywood off a bit. That means I need to work really carefully, as there is no way to hide any problems with fillers and things. It also means I need to be a bit more creative to make it look good.
The cabinet design I settled on is tapered front to back in order to minimize standing waves. I have also decided to house the mid/bass and bass drivers in separate enclosures, and made the internal separator at an angle as well - again to minimize parallel surfaces and thereby minimize standing waves.
Many clamps are required - because I can't use any fastners such as brad nails or screws (because I can't hide them later), it's biscuits and glue with clamps only:
Next, I added some H-bracing into the cabinets. The high grade marine ply is plenty stiff and rigid without it, but a bit of extra bracing can only make things better!
Not that it's really needed, but I decided to recess the HF horn onto the front baffle. Because it's a square shape, I had to make up a routing jig for it. Here you can see the jig on top of the baffle:
Here you can see the recess routing done and dusted (but not yet sanded):
Test fit - looks pretty good!
Next, I glue the baffles on. Each cabinet has double thickness baffles. Because the 8MB400 driver needs around 14mm worth of recess, which will only leave 4mm of wood behind it to mount on, I doubled up so we now have 22mm worth of marine ply for the driver to be bolted to securely:
And here you can see the glued up, but unsanded cabinet:
As stated above - because I am not going to veneer or paint this speaker (other than clear coats), I decided to spice it up a bit by routing some detail onto the side panels:
And herewith seen from another angle. The top of the speaker is the nearest side shown below:
To make the top a bit more interesting to look at, I cut up a whole load of 30mm wide strips of the plywood, and glued them together such that the end grain shows. Here you can see the pieces being clamped:
After the glue dried, I did some sanding and this is what the results look like:
After that, I placed the piece on top of the speaker cabinet, and marked the correct dimensions after which I applied the saw liberally. This is the result:
There is still a lot of work I want to do to the top piece before gluing it on, but here you can see roughly what it will end up looking like:
And finally, a before and after pic of the top pieces:
Here you can see the two cabinets standing back to back:
That's all the pictures I have for now - more to follow later on.
Cheers,
Ian.
