DIY Broadband Bass Trap – How To Build Your Own 8″ Monster Trap

DIY Broadband Bass Trap – How To Build Your Own 8″ Monster Trap

With some basic diy skills and for a fraction of the cost of retail bass traps, you can quite easily build effective broadband bass traps to tame those offending low frequency reflections in your studio. Follow the step by step guide below and you’ll transform the sound of your studio in no time.

To make a single bass trap you will need the following materials and tools.


4 x Rockwool RW3, Rocksilk RS60 or Owens Corning 703 Acoustic slabs: 1200mm (48 inches) x 600mm (24 inches) x 50mm (2 inch) with a density of 60kg/m3

4 x 38mm (1.5 inch) Angle brackets

Pack of 25mm (1 inch) crosshead screws

Any breathable fabric to cover the traps with. If you can blow through the fabric without it offering much resistance, then the fabric is suitable for the trap.

2 x lengths of timber 1200mm (48 inches) x 32mm (1.25 inches) x 20mm (0.75 inches)

2 x lengths of timber 546mm (21.5 inches) x 32mm (1.25 inches) x 20mm (0.75 inches)


1 x saw

1 x screwdriver – preferably electric

1 x heavy duty staple gun with a couple of packs of 12mm (0.5 inch) staples

1 x pair of scissors

1 x pair of gloves

1 x face mask

Step 1

Cut your lengths of timber to size and lay them out on the floor to create a rectanglular frame. The shorter lengths at each end should be inside the longer lengths.

Step 2

Position the angle brackets on the inner side of the frame in each corner and screw them into the timber. If you are using an electric screwdriver, screw slowly to avoid splitting the wood.

Step 3

Lay some of your material out on the floor and place your timber frame on top.

Step 4

Fold the material over the edges of the frame and staple it down along each edge.

Step 5

Trim off any excess material.

Don’t worry if the frame looks a little crude at ths stage.

Step 6

Lay out some more material on the floor and place your 4 x 50mm (= 8 inches) acoustic slabs on top of the material. Wear gloves and a face mask when handling the acoustic slabs.

Step 7

Lay your timber frame on top of the acoustic slabs with the front side facing down.

Make sure it lines up at the edges and corners.

Step 8

Fold the material up and over the acoustics slabs. Pull it tight and staple it along each edge of your timber frame.

Staple the remaining edges down and trim off any surplus material.

Your finished bass trap will look like this from the rear ..

and like this from the front.

Position your bass traps where you need them.

I made ten of these for a total cost of around £250 ($400). It took approximately 8 hours to build them all.

Thanks for reading. If you have any questions or comments please leave them below.


  1. Dave

    Great design! Thank you for this technique.

    I want to point out to anyone with a commercial home project studio that, in addition to all the other concerns one has doing business from the home, the materials for these trap fabrics (and gobos, etc., too) have to be fire-retardant!

    It's not like the Fire Marshall is stalking us, but a recent events demonstrate that if there's a fire, you need to demonstrate that you followed fire code….

    1. Thanks for your comment Dave. You are absolutely right to point out that using fire retardent materials is a must. A solution for traps/gobos that you have already built is to purchase a fire retardent fabric spray. I believe they are readily available and will have a negligable bearing on the performance of your trap.

  2. Val

    Hi everybody!
    well I followed the guide and built my bass traps. I build 10 1200mm (height) + 4 2300mm traps to fill the corners entirely. they works perfectly.
    Now I have a BIG question for you. Reading various forum it's quite clear that rock wool is dangerous for health.
    Try to explain: rock wool release micro fibers, particularly when it is "sollecitated" (It's obvious that we all have build our traps for acoustic matter and our traps are constantly sollecitated by our music low and sub frequencies). We inhale the above micro fibers as our music "shake" the rock wool and unfortunately our body is unable to expel them. In long term this may causes cancer.
    As I have 72 rock wood panels in my control room (covered, as usually, only with fabric) I'm very scared for my health and think the only thing I should do to reduce the "cancer matter" is to seal the rock wool inside a not breathable thing (plastic, nylon, cellophane) and then cover it with fabric. Reading here and there seams this solution doesn't affect the low frequencies absorption of our bass traps.
    Can anyone confirm this?

    1. Hi Val,

      assuming you've used the right fabric ie, one that is of a tight weave but yet breathable, you should have no problem with rockwool fibres escaping. I can't comment on the health effects of breathing in rockwool dust as I'm not a medical expert but I have not had any problems with rockwool dust escaping into the atmosphere and have not found any build up of dust on the surfaces in my studio.

      Regarding covering the bass traps first with a thin membrane such as cellophane and then covering with material; this is ok to do (as long as the cellophane is very thin) but not for traps that are positioned in your early or secondary reflection points as this will cause issues with comb filtering and ultimately skew your recordings and mixes. covering the traps in this way will not affect the low frequency absorption but will make your room sound a little brighter which may or may not be desirable.


  3. Val

    Hi Simon,
    Thank you for your reply!

    Regarding the fabric I wasn't sufficient clear in my prev post. The matter of fibers not concern what your eyes can see (all the fibers or dust you can see your body can easily expel and a tight wave fabric protect you against them) but instead concerns what you can't see. Reading various articles seems that wood rock release micro particles (too small to be visible by eyes) which, after inhalation, remains in our lungs forever (as our body physically can't expels them). Seems that, in log terms, the above micro particles should causes lungs cancer in human.
    The only thing we should do to protect us against particles is to completely seal the rock wool inside a not breathable materials (doing so the rock wool can't spread the micro particles in the air we breath in our studios).
    Please don't consider me a paranoid. I spend 10/12 hours per day in my studio and thinking the air I'm breathing could be dangerous for my health doesn't fell me very well 🙂

    Regarding comb filtering few of my traps are placed in "the wrong place" (early and sec reflection) so should it be ok to: seal the wood rock, cover with fabric and then apply a sheet of pyramid foam?


    1. Hi Val,

      I guess there's a balance to find between keeping the fibres in and maintaining the acoustic properties of the traps. One alternative is to redesign your room so that it works acoustically without using traps of this nature. A room designed with splayed walls and ceiling for example, altough you need plenty of space and this can be costly. You could use foam bass traps, however, the problem there is that even the best foam traps do nothing much below 300Hz and will generally make your room sound too 'dead' and 'strange'.

      The best solution for the early reflection points in my opinion is broadband absorbers. Pyramid foam may or may not work well. I guess this is going of be a question of trial and error.


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