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Let's discuss bass trap solutions on the cheap
Old 1 week ago
  #1
Lives for gear
Lightbulb Let's discuss bass trap solutions on the cheap

One of the biggest mixing hurdles that's difficult to overcome.

Last edited by goom; 1 week ago at 10:02 PM..
Old 1 week ago
  #2
I live near Chicago so shipping wasn't too bad. Roxul 80 is what you want. It's cheap and the most absorbent material for bass. It works great.

https://www.atsacoustics.com/item--R...f-6--RB80.html
Old 1 week ago
  #3
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bowzin's Avatar
I used Roxul Safe N Sound because it was available locally at Lowe's, no shipping. Also have a few boxes of OC703 I got from someone on Craigslist.

-Should be obvious but use NON-outdoor-treated wood, as it's cheaper, lighter, and not loaded with heavy metals and chemicals.

-I went through a bunch of designs, ultimately the easiest/most-flexible is 1x6 or 1x8 lumber, cut to make a "box" that fits the dimensions of the absorber material. So for the Safe N Sound that's interior dimensions of ~30" x 46" so you can fit two 15-16" panels side-by-side, and then 2 or 3 layers deep. I tried a bunch of reinforcement options... but with decent wood I ended up just -pre-drilling about 2-3 screw holes with beefy ass wood screws (had tons of exterior structural deck screws) right into the corners. If you pre-drill it wont split as easily, and they ended up being plenty strong, kind of surprised actually. If you can't make it work, triangles add structure, or even just a piece of 2x2 in the corners to give you something more substantial to screw in to. I was trying to keep weight to a minimum though.

-Making complete "boxes" means I can stack 'em. Once wrapped completely, I often screwed an additional larger 1x? board to the bottom and/or as a footing. The top board was a nice platform to stack another, or a useful/inevitable "table" for keys, picks, etc. I just quickly spray painted them flat black, sometimes I got more fancy.

-Wrap it completely, including the back, you dont want this crap coming out of the traps. Don't allow people to smack it or beat on it, leave it undisturbed. For this reason, I don't like burlap, it's too "breathable." I once used really cheap muslin, it worked well, but I noticed I could see through it with only one layer, so I doubled up. Still absorbs highs just fine.

-Guilford of Maine has fire ******ancy, pretty important if in a commercial situation. Cotton is super flammable, wood is flammable, mineral wool and fiberglass is fire resistant up to certain temps (usually pretty high) but the damage may already be done if a whole wall of cotton goes up in flames because of an electrical fire or something. Something to consider.

-IMO just wrap the outsides of the wood box, using a staple gun. A lot of people try to leave the wood exposed, it adds a lot of complexity, and you have to paint/stain the wood.

-I did drill a bunch of 1-2" holes in the wood frame on a few, if you do the math, its a free way to add a lot of additional exposed area, especially for free-standing gobos, or any use where sound can be coming from multiple angles. If they're going up on walls or corners or something, not really as necessary.

-Depth is critical, deeper the better but there is a limit, at that point switxhing to less dense material will be better. Cant say without onowing the material, but it'saround the 15"-20" mark, often switching to super cheap "pink fluffy" normal insulation is better at those depths, for example simple stacking rolls of pink fluffy in corners, maybe putting them in fabric "bags," is pretty easy and effective.

-For Roxul safe n sound, it is 3" deep. Specifically sleaking of Roxul Safe N Sound, 3" does not "sound good" to me, it is not a smooth absorption curve but rather all the place. 6" or 9" or even a few 12" depths all performed way better. IMO 9" on the ground, and 6" hung or stacked, was a good compromise.

-On the backs, put two screws on either side about 60% of the way up, and use good wire to make a hanger. When hanging, it's common knowledge to leave an "air gap" on the back, and it's not a bad idea to also vary that air gap, so basically it's "hanging" forward off the hanger.

-When I used ultra cheap garbage wood (mistake), it warped a lot over time, and I had to add more horizontal support bars. Use decent lumber, not the cheapest crap in the store which is usually intended more for trim. It ends up not saving you money.

-Hard to overstate, table saws are the most dangerous things in the shop, and severely misunderstood... watch a number of youtube videos specifically regarding table saw safety, or better yet, dont get a table saw. If you do, use the bleeping riving knife, understand about kickback, that the fence must be perfectly parallel and not pushing stock into the blade (keep pressure toward the fence, NEVER the blade), etc. etc. etc. This is serious business, a table saw can launch wood back at you at around 150mph, likewise it can drag your hands into the blade at the same speed. Your "reflexes" will not save you. SawStop brand is popular and expensive for a reason, even that isn't always 100% effective. I recommend either a simple hand saw, or a miter saw. A miter saw can still be very dangerous though, dont do stupid sh** with it, use clamps, never "freehand" anything into it, etc. A handheld circular saw can be dangerous too without experience, a lot of people are really way too cavalier with this stuff, it's like watching the idiot at the gun range with no muzzle discipline, it hurts to watch and while something bad may not happen that day, the odds of bad things happening go from like 1 in a 100,000 to 1 in 50 really fast if not following proper procedure. You might get away with bad form for years, but... it's low probability, high consequence.

Last edited by bowzin; 5 days ago at 06:36 PM.. Reason: Spelling
Old 1 week ago
  #4
Here for the gear
 

Can’t remember where I heard about this, but if you make a typical broardband absorber box it is much more effective if you sandwich some thin plywood between two half depth layers. So where you might’ve used 100mm you use 2 * 50mm with a thin plywood layer in the middle and it is much more effective at absorbing low frequencies but no larger.
I could be completely wrong though as I have very little experience in this
Old 1 week ago
  #5
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Quetz's Avatar
I'd read about people using coffee sacks that they'd just put slabs of rockwool into, but it always looked a bit messy, and when I went to a market in London to actually eyeball the sacks they weren't anywhere near big enough to put a 4' x 2' (120cm x 60cm) slab into.

I decided to prototype a few traps using the materials I had to hand as budget was non-existent, and re-appropriated an old bookcase and a couple of Ikea under-bed drawers as the frames, and then use the coffee sacks as the fascias with a cheap breathable fabric bought in the same market as the backing.

Below are some images to show you the (very simple) process.

This is the smaller of the under-bed drawers before removing the unnecessary parts, I didn't take a picture of the bigger one at the time before stripping it but it looked exactly the same just bigger, obvs:



Here's the simple frame that's left:



So all you need to do is seal off the front with a coffee sack that's been unstitched to get the right dimensions, here we're seeing the bigger one being worked on:



The only tools you need are a Stanley/craft knife to unpick the coffee sack stitching and a decent staple gun.
You could also drill large holes all over the frame to increase absorption but I didn't have the right drill piece at the time.

Coffee sack is now stapled taut across the frame from the inside:



Next you just drop your absorber material in, I'm using 4" (100mm) thick 60Kg/m3 rockwool that I bought on ebay from someone who had a surplus from home improvements.
I got two new packs (4 x 100mm slabs in each pack) for a total of £20.
The surplus sacking was used to ensure a snug fit:




Here we have the lightweight and super-breathable fabric for the backing:



Which is also simply stapled to the frame to make a sealed back.
A natural gap is created between the absorber material and the wall it'll be put against which helps raise efficiency:



And here's what it looks like finished:



And here's the smaller one finished:




Then I started casting around for more frame candidates and decided to cannibalise an old book/junk shelf:



This already had openings in the side panels, so all I had to do was remove the middle shelf and move the top and bottom shelves to the ends of the bookcase, which were screwed into place.

Once that basic frame was made, the process was the same as before and ended up with this:



This was taken before the rockwool was put in which is why it doesn't look as taut.

There you have it.
Cheap, effective.
The coffee sacks were £4 each, the bookcase was free from someone getting rid of it and the Ikea drawers cost me £25 new for the pair; I got 2 years use out of them as actual drawers before converting them so I feel they were essentially free!
To buy the timber (cut to size) to make four frames in the same style as the bookcase would cost less than £10, so even when buying the wood, these are extremely cost-effective.
Old 6 days ago
  #6
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avare's Avatar
 

Quote:
Originally Posted by Rewolf View Post
Can’t remember where I heard about this, but if you make a typical broardband absorber box it is much more effective if you sandwich some thin plywood between two half depth layers. So where you might’ve used 100mm you use 2 * 50mm with a thin plywood layer in the middle and it is much more effective at absorbing low frequencies but no larger.
I could be completely wrong though as I have very little experience in this
That is complete BS.
Old 6 days ago
  #7
Gear Maniac
 
standup's Avatar
I stacked unopened rolls of r15 pink fluffy fiberglass in the corners. The back wall has moving blankets hung up, rolls of fiberglass behind. I’m in a basement, and between the open joists I stuffed 4 inches rock wool.

Overall it’s a dead room. But the fiberglass rolls noticeably killed the low end resonance. Before I put them in, a kick drum was a massive overwhelming sound, after it was not bad.

I kinda wonder if I should slice up the plastic on the side facing the room so that sound hits fiberglass instead of a layer of plastic, but I also think the low frequencies go right through thin plastic as if it wasn’t there.
Old 5 days ago
  #8
Lives for gear
Quote:
Originally Posted by standup View Post
I stacked unopened rolls of r15 pink fluffy fiberglass in the corners. The back wall has moving blankets hung up, rolls of fiberglass behind. I’m in a basement, and between the open joists I stuffed 4 inches rock wool.

Overall it’s a dead room. But the fiberglass rolls noticeably killed the low end resonance. Before I put them in, a kick drum was a massive overwhelming sound, after it was not bad.

I kinda wonder if I should slice up the plastic on the side facing the room so that sound hits fiberglass instead of a layer of plastic, but I also think the low frequencies go right through thin plastic as if it wasn’t there.
For some reason, I don't think the low end waves are effected by the surface. I'd love to see a photo of that stack. How many did you end up using?
Old 5 days ago
  #9
Gear Maniac
 
standup's Avatar
Quote:
Originally Posted by goom View Post
I'd love to see a photo of that stack. How many did you end up using?
So it looks like there are 6 of them. And in the corner, suspended over the sump pump, are a couple of small mini-chunks I made at a different time.

And with the curtain closed it looks much nicer. You can see a couple of random purple foam towers I got off Craigslist cheap, and one of the 4" 703 baffles that are scattered around the room.

It's a pretty dead space, but I can get OK recordings down here. Real engineers have told me drums "don't" sound like they were recorded in a basement.
Attached Thumbnails
Let's discuss bass trap solutions on the cheap-img_1766.jpg   Let's discuss bass trap solutions on the cheap-img_1767.jpg  
Old 4 days ago
  #10
Lives for gear
Quote:
Originally Posted by standup View Post
So it looks like there are 6 of them. And in the corner, suspended over the sump pump, are a couple of small mini-chunks I made at a different time.

And with the curtain closed it looks much nicer. You can see a couple of random purple foam towers I got off Craigslist cheap, and one of the 4" 703 baffles that are scattered around the room.

It's a pretty dead space, but I can get OK recordings down here. Real engineers have told me drums "don't" sound like they were recorded in a basement.
Nice. I had the same idea with the rolls, but I wimped out. I need to do this.
Old 4 days ago
  #11
Gear Nut
 
Strick9's Avatar
 

My solution was pretty simple. I made boxes out of four 2”x2”x8’ pieces screwed into square pegboard pieces. Then I stuffed eight pieces of Safe N Sound into them, four on bottom and four on top. Everything came from Lowes. Then I wrapped it in the blue Guilford of Maine fabric that my other panels are wrapped in.
Attached Thumbnails
Let's discuss bass trap solutions on the cheap-863ed6f1-afda-46fe-a750-54ce6da0007c.jpg  
Old 4 days ago
  #12
Lives for gear
Quote:
Originally Posted by Strick9 View Post
My solution was pretty simple. I made boxes out of four 2”x2”x8’ pieces screwed into square pegboard pieces. Then I stuffed eight pieces of Safe N Sound into them, four on bottom and four on top. Everything came from Lowes. Then I wrapped it in the blue Guilford of Maine fabric that my other panels are wrapped in.
How many corners did you end up with? How high do they go?
Old 4 days ago
  #13
Gear Nut
 
Strick9's Avatar
 

Quote:
Originally Posted by goom View Post
How many corners did you end up with? How high do they go?
They're just an inch or two shorter than 8 feet tall. That's how the 2"x2"x8' boards come.

My room only has 3 corners that I could put the traps in, because the door is in the 4th corner.
Old 4 days ago
  #14
Lives for gear
Quote:
Originally Posted by Strick9 View Post
They're just an inch or two shorter than 8 feet tall. That's how the 2"x2"x8' boards come.

My room only has 3 corners that I could put the traps in, because the door is in the 4th corner.
You got me hyped. I'm going to do this.
Old 3 days ago
  #15
Gear Nut
 
Strick9's Avatar
 

Quote:
Originally Posted by goom View Post
You got me hyped. I'm going to do this.
Let me know if you have any questions. I'm happy to help.
Old 3 days ago
  #16
Lives for gear
 

Quote:
Originally Posted by Quetz View Post
I'd read about people using coffee sacks that they'd just put slabs of rockwool into, but it always looked a bit messy, and when I went to a market in London to actually eyeball the sacks they weren't anywhere near big enough to put a 4' x 2' (120cm x 60cm) slab into.

I decided to prototype a few traps using the materials I had to hand as budget was non-existent, and re-appropriated an old bookcase and a couple of Ikea under-bed drawers as the frames, and then use the coffee sacks as the fascias with a cheap breathable fabric bought in the same market as the backing.

Below are some images to show you the (very simple) process.

This is the smaller of the under-bed drawers before removing the unnecessary parts, I didn't take a picture of the bigger one at the time before stripping it but it looked exactly the same just bigger, obvs:



Here's the simple frame that's left:



So all you need to do is seal off the front with a coffee sack that's been unstitched to get the right dimensions, here we're seeing the bigger one being worked on:



The only tools you need are a Stanley/craft knife to unpick the coffee sack stitching and a decent staple gun.
You could also drill large holes all over the frame to increase absorption but I didn't have the right drill piece at the time.

Coffee sack is now stapled taut across the frame from the inside:



Next you just drop your absorber material in, I'm using 4" (100mm) thick 60Kg/m3 rockwool that I bought on ebay from someone who had a surplus from home improvements.
I got two new packs (4 x 100mm slabs in each pack) for a total of £20.
The surplus sacking was used to ensure a snug fit:




Here we have the lightweight and super-breathable fabric for the backing:



Which is also simply stapled to the frame to make a sealed back.
A natural gap is created between the absorber material and the wall it'll be put against which helps raise efficiency:



And here's what it looks like finished:



And here's the smaller one finished:




Then I started casting around for more frame candidates and decided to cannibalise an old book/junk shelf:



This already had openings in the side panels, so all I had to do was remove the middle shelf and move the top and bottom shelves to the ends of the bookcase, which were screwed into place.

Once that basic frame was made, the process was the same as before and ended up with this:



This was taken before the rockwool was put in which is why it doesn't look as taut.

There you have it.
Cheap, effective.
The coffee sacks were £4 each, the bookcase was free from someone getting rid of it and the Ikea drawers cost me £25 new for the pair; I got 2 years use out of them as actual drawers before converting them so I feel they were essentially free!
To buy the timber (cut to size) to make four frames in the same style as the bookcase would cost less than £10, so even when buying the wood, these are extremely cost-effective.
Awesome post w/ instructions on how to repurpose stuff for bass traps. Very awesome and thrifty!
Old 2 days ago
  #17
Lives for gear
 
BrentA's Avatar
 

One of the best is also one of the cheapest. Hang faced R19 on your walls and then cover it with tapestries. Hang it the faced side out for the best low end absorption. The recycled denim insulation works really well too.
Old 1 day ago
  #18
Here for the gear
 

Quote:
Originally Posted by bowzin View Post
-Hard to overstate, table saws are the most dangerous things in the shop, and severely misunderstood... watch a number of youtube videos specifically regarding table saw safety, or better yet, dont get a table saw. If you do, use the bleeping riving knife, understand about kickback, that the fence must be perfectly parallel and not pushing stock into the blade (keep pressure toward the fence, NEVER the blade), etc. etc. etc. This is serious business, a table saw can launch wood back at you at around 150mph, likewise it can drag your hands into the blade at the same speed. Your "reflexes" will not save you. SawStop brand is popular and expensive for a reason, even that isn't always 100% effective. I recommend either a simple hand saw, or a miter saw. A miter saw can still be very dangerous though, dont do stupid sh** with it, use clamps, never "freehand" anything into it, etc. A handheld circular saw can be dangerous too without experience, a lot of people are really way too cavalier with this stuff, it's like watching the idiot at the gun range with no muzzle discipline, it hurts to watch and while something bad may not happen that day, the odds of bad things happening go from like 1 in a 100,000 to 1 in 50 really fast if not following proper procedure. You might get away with bad form for years, but... it's low probability, high consequence.
I find it easy to understand a table saw.

On the other hand, I'm a much more accomplished fabricator and craftsman than a recording engineer.

I'm really none of a recording engineer.

But back to table saws, with a reasonable amount of care they are practically safe as milk.

If you have that care and technique you don't need an expensive Saw Stop that will wreck your blade if your wood is too moist.

I haven't had much use for a riving knife either.

The push to stop power switches are nice, especially if they are located where you can hip-check them.

I say this having done high risk jobs with a table saw. For example, cutting 1/4" aluminum plate. If that kicks back and you are standing in the wrong place, it will cut you in half. You can't use a Saw Stop for that, the conductivity of aluminum will set it off and ruin your blade. You can't twist aluminum enough for a riving saw to do anything before it will kick back so if you are relying on that for safety, you are doing it wrong.

Once you know how to do it right, you can do it all day long with minimal risk.

If you can figure out how to cut aluminum with a table saw, wood is cake.

Use pusher pieces so your hands don't get near the blade, set up your saw and fence properly. If you can't afford a new saw with a nice fence, look for a used one on Craigslist, eBay or whatever and fix it up. A good sign of quality is a table saw with cast iron wings. Stamped steel is a sign of a low end machine. Don't buy a small one or "portable" unless you need to move it a lot, those smaller machines are harder to use for many jobs. I bought a nice older saw in need of a little TLC for $150. It will go head to head against most new machines that cost 3x the price. I'm working on an 80/20 extrusion saw fence that will let me add good stuff like feather boards and sprague clutch rollers. When that is done it will still be a lot cheaper but it will have a really nice fence (maybe even with a DRO).

When someone tells me a tool is dangerous, a lot of times I think it is just them. Sometimes it is.

If you are that type of person, lay down the tools and back away.

The sad thing is there are a lot of that type of person who don't recognize it and think the tool is dangerous.
Old 1 day ago
  #19
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bowzin's Avatar
Quote:
Originally Posted by Pod person View Post
I find it easy to understand a table saw.

On the other hand, I'm a much more accomplished fabricator and craftsman than a recording engineer.

I'm really none of a recording engineer.

But back to table saws, with a reasonable amount of care they are practically safe as milk.

If you have that care and technique you don't need an expensive Saw Stop that will wreck your blade if your wood is too moist.

I haven't had much use for a riving knife either.

The push to stop power switches are nice, especially if they are located where you can hip-check them.

I say this having done high risk jobs with a table saw. For example, cutting 1/4" aluminum plate. If that kicks back and you are standing in the wrong place, it will cut you in half. You can't use a Saw Stop for that, the conductivity of aluminum will set it off and ruin your blade. You can't twist aluminum enough for a riving saw to do anything before it will kick back so if you are relying on that for safety, you are doing it wrong.

Once you know how to do it right, you can do it all day long with minimal risk.

If you can figure out how to cut aluminum with a table saw, wood is cake.

Use pusher pieces so your hands don't get near the blade, set up your saw and fence properly. If you can't afford a new saw with a nice fence, look for a used one on Craigslist, eBay or whatever and fix it up. A good sign of quality is a table saw with cast iron wings. Stamped steel is a sign of a low end machine. Don't buy a small one or "portable" unless you need to move it a lot, those smaller machines are harder to use for many jobs. I bought a nice older saw in need of a little TLC for $150. It will go head to head against most new machines that cost 3x the price. I'm working on an 80/20 extrusion saw fence that will let me add good stuff like feather boards and sprague clutch rollers. When that is done it will still be a lot cheaper but it will have a really nice fence (maybe even with a DRO).

When someone tells me a tool is dangerous, a lot of times I think it is just them. Sometimes it is.

If you are that type of person, lay down the tools and back away.

The sad thing is there are a lot of that type of person who don't recognize it and think the tool is dangerous.
Well sure, I certainly wasn't directing my comment to "an experienced fabricator" so I'm sure this is all old news to you, but to someone inexperienced or who's watching some dumbass in a YouTube video. Saw one vid the other day made me absolutely facepalm and probably precipitated my comments. Agree with what you're saying, still kind of reiterates my original point about being smart and paying attention, or like you said just don't attempt it. I do carpentry, never metal, or at least extremely rarely and nothing too major.

Agree about the value of finding an older table saw with a big heavy-duty metal deck, did the same thing. These small portable ones on sale for $110 or whatever for "Black Friday" at Harbor Freight or some place, where it's 90% plastic everywhere, makes me cringe and these are the ones people are buying up big time.

Touchy subject for me because my musician buddy cut three of his finger tips off in a tablesaw kickback incident, despite being experienced it just took one instant. He got phenomenally, one-in-a-million-lucky and was able to reattach/save his finger tips and is basically completely healed at this point many years later. Insanely lucky there were no long term effects after having his guitar-playing, left-hand finger tips dragged into a 10,000 RPM table saw, almost puked when I heard. Was a serious time and still took years to get back to normal. Just try to stay frosty since then, and kind of surprises me how poorly understood table saw issues are. Serious biz IMO. I tell folks to get a miter saw first, the saw can only go up/down, and the blades spin away vs. toward you on a table saw. Obviously can't do everything on a miter saw, but can do quite a bit, including make bass traps.
Old 23 hours ago
  #20
Here for the gear
 

Well, if you lose fingers due to table saw kickback, you're doing it wrong. Kickback throws your workpiece (back) across the shop, your fingers would only get close to the blade if they were directly behind it. That's not a reasonable saw technique.

You cut off fingers if you push your fingers through the blade. Sometimes you get kickback afterward when you let go of the workpiece.

I would disagree about a chop saw being safer than a table saw. You can lose a thumb if you use a chop saw wrong. If you think it is safer and use less care, you are more likely to take chances and injure yourself with the tool.

I guess I was just lucky because I had an interest in making things and learned how to work with power tools when I was young. On the other hand, the table saw was one of the easiest to learn. I would say it's about a 5 minute lesson to learn basic techniques and safety, then about 10 minutes of cutting to get comfortable with the tool.
Old 18 hours ago
  #21
Gear Nut
 

I did the entire soffit in my room with fluffy attic insulation. I made a box 8 x 24 inches with 1 x 2 wood then covered it with bed sheets same deal with 3 big clouds. good and cheap.
Old 15 hours ago
  #22
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Bob Ross's Avatar
 

I've followed Ethan Winer's remarkably simple solution for rigid fiberglass corner traps (see https://ethanwiner.com/acoustics.html and scroll down to the section titled "FIBERGLASS BASS TRAPS" and Figure 3a) in several rooms, all with excellent results.

The hardest part is making them look attractive.
Old 3 hours ago
  #23
I used to work in a factory when I was younger. A guy lost his three middle fingers down a food mincer. They reattached the ring finger where his index finger should be. The rest were lost. I was there when it happened. Terrible.
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