So I am sure some of you will remember the crazy month earlier this year where I spent a mad few weeks knocking out a really nice 'little' synergy horn using a full range driver (the SB65WBAC25), two 8 inch woofers (SB23NRXS45) and a SOTA CD horn (XT1464) under the expert guidance of Xrk - master of computer simulations!
It ended up having rather good measurements and sound (It is my favorite speaker and I have some rather good ones).
![536587d1457613073-bookshelf-multi-way-point-source-horn-polar.jpg]diyAudio](https://www.diyaudio.com/forums/attachments/multi-way/536587d1457613073-bookshelf-multi-way-point-source-horn-polar.jpg]diyAudio)
The one problem with it was the way it looked...........
So, I have spent the last 6 months thinking and planning how I can make this thing look half decent......
This won't be everyone's cup of tea I am sure, and my progress pictures are likely to look fairly poor before it looks better, so bare with me.😀
CLICK ON IMAGE TO VIEW CORRECT ASPECT RATIO
So take one spherical planter:
Usually a sphere shaped enclosure is not great for internal modes. This is due to the overwhelming single internal dimension - the diameter - causing a large resonance. Fortunately, due to the design of a synergy horn - the horn sits right inside the enclosure - subdividing the space up and breaking up any resonances:
Try horn for size with a bit of cutting:
Strengthen further - just because I can......with two layers of fiberglass, then a 2cm thick layer of structural two part car body filler......
make a 3mm aluminium/6mm MDF/3mm aluminium CLD baffle ring:
take one heavy gauge peony plant support, turn it upsidedown, angle grind off the legs, and spray it black....
Getting there - nearly finished with the Mark 1 - white box for comparison......
It ended up having rather good measurements and sound (It is my favorite speaker and I have some rather good ones).
The one problem with it was the way it looked...........
So, I have spent the last 6 months thinking and planning how I can make this thing look half decent......
This won't be everyone's cup of tea I am sure, and my progress pictures are likely to look fairly poor before it looks better, so bare with me.😀
CLICK ON IMAGE TO VIEW CORRECT ASPECT RATIO
So take one spherical planter:
Usually a sphere shaped enclosure is not great for internal modes. This is due to the overwhelming single internal dimension - the diameter - causing a large resonance. Fortunately, due to the design of a synergy horn - the horn sits right inside the enclosure - subdividing the space up and breaking up any resonances:
Try horn for size with a bit of cutting:
Strengthen further - just because I can......with two layers of fiberglass, then a 2cm thick layer of structural two part car body filler......
make a 3mm aluminium/6mm MDF/3mm aluminium CLD baffle ring:
take one heavy gauge peony plant support, turn it upsidedown, angle grind off the legs, and spray it black....
Getting there - nearly finished with the Mark 1 - white box for comparison......
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Soooo. Take one 51cm diameter spherical polystone planter....... Volume - 60L.
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The polystone sphere is about 6kg. It appears to have a hard polystone outer layer, with a 4mm fiberglass inner which is orange. It is fairly light for it's size but very strong - I can sit on the side of it without any deformation.
Cut away rim in two areas to allow 8 inch woofers to slot in....
Cut away rim in two areas to allow 8 inch woofers to slot in....
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X - I know - you are always so polite......but deep down in my heart.....I knew they were hideous. 😉
I will likely spray the aluminium baffle matt black and blend in the wave-guide to make it look uniform.
My plan is to sit the 'globes' on a ring hairpin plant stand like this:
Inspiration taken from these:
My plan is to sit the 'globes' on a ring hairpin plant stand like this:
Inspiration taken from these:
Does anyone know of a nice way of cutting a perfect 40cm diameter circle in 5mm aluminium sheet?!?
CNC water jet / laser - the water jet will leave some minor burring, but that'd easily be remedied
sometimes it pays to have tricky work done elsewhere
sometimes it pays to have tricky work done elsewhere
Try a circle jig and a carbide router blade. Wesayso cut holes in thick aluminum plates with a wood router until the cows came home. Carbide should cut Al nicely - just don't take too much off at a time.
Jasper Circle Jig Model 200
There are other brands of course...
Rockler Circle Cutting Jig - Rockler Woodworking Tools
There is always a hand held jig saw and then files or rotary sander (large Dremel type drum).
Jasper Circle Jig Model 200
There are other brands of course...
Rockler Circle Cutting Jig - Rockler Woodworking Tools
There is always a hand held jig saw and then files or rotary sander (large Dremel type drum).
are you looking for a single flat disc with no center hole, or a torus for mounting flange?
compass jigs need a pivot point - usually a screw hole, but a temporary block could be hot glued to the metal if you're wanting to avoid the penetration
if cutting aluminum that thick with a router, I'd certainly recommend a variable speed motor set to well below the standard speed (e.g. Porter Cable 690 = 27,500 RPM)
and take precautions - full face shield - not just glasses, work gloves, and hearing protection
a small shard of metal can do a lot more damage than a splinter of plywood or MDF dust
compass jigs need a pivot point - usually a screw hole, but a temporary block could be hot glued to the metal if you're wanting to avoid the penetration
if cutting aluminum that thick with a router, I'd certainly recommend a variable speed motor set to well below the standard speed (e.g. Porter Cable 690 = 27,500 RPM)
and take precautions - full face shield - not just glasses, work gloves, and hearing protection
a small shard of metal can do a lot more damage than a splinter of plywood or MDF dust
OK, now I am getting worried.
I might look into other 5mm sheet substances.....possibly G10 or micarta....
I might look into other 5mm sheet substances.....possibly G10 or micarta....
Don't panic - aluminum is a perfectly valid choice - but with any material, there are considerations in machining, and safety should always come first. What is the exact intended function and size / shape of the piece you have in mind here?
I'm not a huge fan of it for an entire speaker enclosure, but any particular reason why not MDF in this instance? It's dirt cheap, and far more easily machined with standard wood working tools and bits than any of the high density plastics / thermoset resin materials.
I'm not a huge fan of it for an entire speaker enclosure, but any particular reason why not MDF in this instance? It's dirt cheap, and far more easily machined with standard wood working tools and bits than any of the high density plastics / thermoset resin materials.
Thanks Charlie and Chris,
I did consider MDF - but the baffle needs to be quite thin - no more than 6-8mm to ensure the synergy horn sits down in the sphere and the woofers don't hit the rim - if that makes sense.
So I thought aluminum would be perfect.
I have hit upon serendipity just now on a certain auction site - the baffle circle needs to be exactly 400mm diameter to fit the top - and a chap is selling two laser cut aluminum 400mm diameter discs which are 3mm thick for about £25....
So I am thinking I could make the baffle with some CLD techniques - 3mm aluminium/constrained layer ~1mm (?epoxy) /3mm aluminium = total thickness of 7mm.
From some CLD work and research I have done for previous projects - I am pretty sure there are some good epoxy products that work well in CLD with aluminium - it needs some thing stiffer than the usual stuff you would CLD with wood if I remember right.
I did consider MDF - but the baffle needs to be quite thin - no more than 6-8mm to ensure the synergy horn sits down in the sphere and the woofers don't hit the rim - if that makes sense.
So I thought aluminum would be perfect.
I have hit upon serendipity just now on a certain auction site - the baffle circle needs to be exactly 400mm diameter to fit the top - and a chap is selling two laser cut aluminum 400mm diameter discs which are 3mm thick for about £25....
So I am thinking I could make the baffle with some CLD techniques - 3mm aluminium/constrained layer ~1mm (?epoxy) /3mm aluminium = total thickness of 7mm.
From some CLD work and research I have done for previous projects - I am pretty sure there are some good epoxy products that work well in CLD with aluminium - it needs some thing stiffer than the usual stuff you would CLD with wood if I remember right.
I think 1mm sorbothane sheets that you have should work nicely with aluminum. Use contact cement to bond it all together. The rim should have some screws to keep form coming apart but driver mounts naturally do that.
Water activated Loctite PL Premium adhesive could work too. Spritz it with water mist prior to clamping down.
Water activated Loctite PL Premium adhesive could work too. Spritz it with water mist prior to clamping down.
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Thanks X!
Will have to look back through my research - for some reason I thought sorbothane was more likely to work as an isolating layer rather than a constraining one due to the aluminium being so stiff.
But you are right - given I was going to use sorbothane as an isolating gasket, I could also use it for the constraining layer - not tried using contact cement with it....
I will start experimenting. 😉
Will have to look back through my research - for some reason I thought sorbothane was more likely to work as an isolating layer rather than a constraining one due to the aluminium being so stiff.
But you are right - given I was going to use sorbothane as an isolating gasket, I could also use it for the constraining layer - not tried using contact cement with it....
I will start experimenting. 😉
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