Hi there fellas, I'm getting into the final stages of constructing my first diy speaker.
Speaker consists of RAAL Ribbon for highs, Accuton c50 for mids and scanspeak illuminator 6.5" woofer.
I have built the cabinets already out of 18mm plywood, with the front baffle being 36mm thick.
I have put on a few coats of bitumen paint on the cabinet walls, as well as covered them in this. Butyl Based Sound Deadening Material | Jaycar Electronics
I have also purchased this 650gsm Acrylic Speaker Dampening Material | Jaycar Electronics.
The speaker kit that I'm building calls on using 8-10mm thick of parts express Sonic barrier to line the cabinet walls.
In Australia (located in Tasmania) I don't have access to any of that stuff locally. What else can I use that I can source locally to line the cabinet walls.
That acrylic material from Jaycar, would probably be used as stuffing right?
How would a layer of fiberglass batting or glass wool work stuck to the cabinet walls work instead.
I have also heard of people using recycled felt moving blanket things to line the speaker walls, though I can't find any place locally selling them.
The speakers are also front ported if it helps.
Speaker consists of RAAL Ribbon for highs, Accuton c50 for mids and scanspeak illuminator 6.5" woofer.
I have built the cabinets already out of 18mm plywood, with the front baffle being 36mm thick.
I have put on a few coats of bitumen paint on the cabinet walls, as well as covered them in this. Butyl Based Sound Deadening Material | Jaycar Electronics
I have also purchased this 650gsm Acrylic Speaker Dampening Material | Jaycar Electronics.
The speaker kit that I'm building calls on using 8-10mm thick of parts express Sonic barrier to line the cabinet walls.
In Australia (located in Tasmania) I don't have access to any of that stuff locally. What else can I use that I can source locally to line the cabinet walls.
That acrylic material from Jaycar, would probably be used as stuffing right?
How would a layer of fiberglass batting or glass wool work stuck to the cabinet walls work instead.
I have also heard of people using recycled felt moving blanket things to line the speaker walls, though I can't find any place locally selling them.
The speakers are also front ported if it helps.
Attachments
Take a stroll down Bunnings insulation isle. Another source for the same material will be farm supplies or just about anywhere they deal with horses and support equipment. I found a source for some dampening foam at a camping supply, a ground mat for a swag, its thicker, but does the same thing and far cheaper.
What he said:
...but what I'd suggest is the ute bed liner: a roll of 5mm thick rubber, made from recycled tyres.
Fibreglass and other fuzz absorbs more + to a lower frequency if used to fill large spaces, not just as lining on cabinet walls.
...but what I'd suggest is the ute bed liner: a roll of 5mm thick rubber, made from recycled tyres.
Fibreglass and other fuzz absorbs more + to a lower frequency if used to fill large spaces, not just as lining on cabinet walls.
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Bunnings (Sydney) sell rolls of the felt and also sell the moving blankets (quilted cover). IMO that acrylic stuffing is not going to do too much damping of lower freq...
I'm also doing DIY cabinets for a 3-way and have taken the approach of using different materials like cork, lead and felt on the walls.
I'm also doing DIY cabinets for a 3-way and have taken the approach of using different materials like cork, lead and felt on the walls.
Airstep Cushion Pad, Bitumen Paint and Raw Wool
I have been struggling with the same issue. I ended up using Bitumen Rubber Paint from bunnings and then Airstep Cushion Pad which is an Australian made felt underlay from 30% wool. It is 9mm thick (v Bunnings 4mm).
I also purchased Merino raw wool fleece (as you would use for spinning) for loose fill of the sealed chambers, it has similar effect to Acousta-Stuff.
The Bitumen paint made a big difference when you knock on the box, seals everything up nicely too. Only just got the felt so haven't tried it yet. Have been using the wool on its own temporarily while I wait and it has worked well. Will use both now that felt has arrived.
See here for Underlay and here for Bitumen
I have been struggling with the same issue. I ended up using Bitumen Rubber Paint from bunnings and then Airstep Cushion Pad which is an Australian made felt underlay from 30% wool. It is 9mm thick (v Bunnings 4mm).
I also purchased Merino raw wool fleece (as you would use for spinning) for loose fill of the sealed chambers, it has similar effect to Acousta-Stuff.
The Bitumen paint made a big difference when you knock on the box, seals everything up nicely too. Only just got the felt so haven't tried it yet. Have been using the wool on its own temporarily while I wait and it has worked well. Will use both now that felt has arrived.
See here for Underlay and here for Bitumen
I'm getting a bit impatient, since I first started building these speakers nearly 6 months ago. I would rather try and get all remaining materials locally.
That parts express sonic barrier is an open cell foam right?.
Would bunnings have something similar or work I be better off getting something recommend in some of the above posts. Also with regards to the fibreglass would I use it as stuffing to replace that acrylic stuff from Jaycar or could I use it to line the walls in conjunction with using the Jaycar material as stuffing.
That parts express sonic barrier is an open cell foam right?.
Would bunnings have something similar or work I be better off getting something recommend in some of the above posts. Also with regards to the fibreglass would I use it as stuffing to replace that acrylic stuff from Jaycar or could I use it to line the walls in conjunction with using the Jaycar material as stuffing.
Just finish it 
You could fuss forever with options and get a barely measurable difference.
I made a mistake before, and assumed that Sonic Barrier was another layer of dense (mass loading) material. After actually checking out the blurb, it appears to be a (light, fluffy) open cell foam with a thin skin layer - the "embossed surface finish".
The published absorption values don't seem particularly good. It is not any better than normal stuffing - just neater.
If you want to clone Sonic Barrier (without waiting for shipping), you should be able to DIY it locally - e.g. I got a sheet of open cell foam from an aquarium shop. It is used in aquarium filters. Glue on some thin felt as the skin layer.
...but why bother, if Sonic Barrier is no better than ye olde stuffing? I'd just use a pillowcase full of fibreglass, or the Jaycar stuffing, old blankets or wool garments (from op shops) to fill the box.
You could fuss forever with options and get a barely measurable difference.I made a mistake before, and assumed that Sonic Barrier was another layer of dense (mass loading) material. After actually checking out the blurb, it appears to be a (light, fluffy) open cell foam with a thin skin layer - the "embossed surface finish".
The published absorption values don't seem particularly good. It is not any better than normal stuffing - just neater.
If you want to clone Sonic Barrier (without waiting for shipping), you should be able to DIY it locally - e.g. I got a sheet of open cell foam from an aquarium shop. It is used in aquarium filters. Glue on some thin felt as the skin layer.
...but why bother, if Sonic Barrier is no better than ye olde stuffing? I'd just use a pillowcase full of fibreglass, or the Jaycar stuffing, old blankets or wool garments (from op shops) to fill the box.
The mid and tweeter are closed back units correct? so you'll likely get away with it but I would have sealed them off in their separate enclosure. That leaves the woofer primarily and IMO panel or box resonances to damp. The bitumen will see you right and the butyl sheets are much of the same thing... fine to use both though.
I'd try them as they are to begin with... you could also lightly stuff with the acrylic if you wanted. A suck it and see and go from there.
As a comparison I have used cork on the walls of the upper chamber filled with fibreglass bats and (Jaycar) vinyl on the walls of the woofer enclosure with felt over the top... yet to hear the results though.
Good luck
Edit: I agree with hollowboy... posted prior to mine.
I'd try them as they are to begin with... you could also lightly stuff with the acrylic if you wanted. A suck it and see and go from there.
As a comparison I have used cork on the walls of the upper chamber filled with fibreglass bats and (Jaycar) vinyl on the walls of the woofer enclosure with felt over the top... yet to hear the results though.
Good luck
Edit: I agree with hollowboy... posted prior to mine.
Haha fair enough. The mids and tweeter are closed back units.
The woofer has an open basket.
I'll likely head to bunnings tomorrow then and get some felt or whatever they have. If not I'll put some fiberglass batting sheets on the walls with some spray on adhesive followed by the Jaycar acrylic stuff.
One my thing should I chamfer the woofer cutout?
The baffle is quite thick 36mm or is this not necessary. The scanspeak 18wu driver I'm using is pretty open at the back, unlike the sealed midrange and tweeter.
The woofer has an open basket.
I'll likely head to bunnings tomorrow then and get some felt or whatever they have. If not I'll put some fiberglass batting sheets on the walls with some spray on adhesive followed by the Jaycar acrylic stuff.
One my thing should I chamfer the woofer cutout?
The baffle is quite thick 36mm or is this not necessary. The scanspeak 18wu driver I'm using is pretty open at the back, unlike the sealed midrange and tweeter.
That sounds like a good idea - if you later need to reach inside the box, you'll be touching acrylic, not fibreglass.
I'd chamfer it. Generally good practice + that's the kick I'm on at the moment. I see your nice woofer as more incentive to chamfer - why not put the effort in, if you've already put the $ in?
This link shows a chamfered hole giving smoother response and slightly better LF sensitivity:
chamfering driver holes
This is my rambling - not really on topic, except that it lead me to buying some new drivers, largely because of their nice, streamlined frames - which may have been copied from the Illuminators (see pic in post 21).
paper cone open frame driver for front horn
Ok, correct me if I'm wrong but since the mid and tweeter are closed units, the only thing to dampen really is the woofer, since I'm guessing it would create a sort of back wave, that should be absorbed/damped as much as possible.
Should I make the layers of damping material behind the woofer extra thick for this?
Due to the way I designed the cabinet and my inexperienced, reopening the cabinet after all the drivers have been installed would be a pretty big hassle.
Should I make the layers of damping material behind the woofer extra thick for this?
Due to the way I designed the cabinet and my inexperienced, reopening the cabinet after all the drivers have been installed would be a pretty big hassle.
Give your local carpet shop a call. They might have some offcuts like the “Airstep cushion pad” I got. Much better than the Bunnings stuff it is really thin. If you are going to go to Bunnings I would get the removalist blanket
Baffle thickness is very important and yes chamfer the rear of the cut outs for the woofer. They don't have to symmetric by the way.
Bitumin and felt serve different purpose
There is quite some confusion here regarding the role of bitumin ( panel damping ) vs felt and foam ( cabinet acoustic damping). Bitumin will damp the panels increasing mass to stiffness ratio, like in a car body. Felt won't do that but on the other hand will absorb internal waves.
You may think the end results will be the same but panels aren't vibrated by internal standing waves alone. More troublesome is structural borne vibrations, originating from the baffle. Felt is useless there. You need bitumin ( bbc style), woofer decoupling and / or rigid cabinet.
There is quite some confusion here regarding the role of bitumin ( panel damping ) vs felt and foam ( cabinet acoustic damping). Bitumin will damp the panels increasing mass to stiffness ratio, like in a car body. Felt won't do that but on the other hand will absorb internal waves.
You may think the end results will be the same but panels aren't vibrated by internal standing waves alone. More troublesome is structural borne vibrations, originating from the baffle. Felt is useless there. You need bitumin ( bbc style), woofer decoupling and / or rigid cabinet.
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