Bass
Absorber
Published by Acousc Fields Copyright © 2016
Allrights reserved.No part ofthis document may be used or reproduced by any means,graphic,electronic,or mechanical including photocopying,recording,taping,or by any informaon storage retrievalsystem without the wrien permission ofthe publisher.
D
Download Edion License Notes
T
This document is licensed for your personalenjoyment only.This document may not be resold or given away to other people.Ifyou would like to share this document with another person,please purchase an addionalcopy for each person you wish to share it with.Ifyou are reading this document and did not purchase it,or ifit was not purchased for your use only,then you should return to
AcouscFields.com and purchase your own copy.Thank you for respecng
respecng the authors'work.
DISCLAIMER
These are build plans.They are not blueprints.Some dimensions may vary.They are to assist you with layout and one method ofassembly. Dimensions willvary with unit,usage and build methodology.Please consult with Acousc Fields prior to building the units to make sure you are using the correct acouscaltool.
Alldocuments and drawings remain the sole and exclusive property ofAcousc Fields. Copies can be obtained at:www.acouscfields.com
Contents:
ToolList ...4
MaterialList ...6
Cut-Sheet ...8
Setup & Cabinet Fabricaon ...10
Metric TechnicalDrawings ...27
T
Tabl
e
of
Fi
gures:
Figure 1 - MaterialSupported ...11Figure 2 - Cut off jig ready to go.Set depth correctly ...12
Figure 3 - Cut off jig in acon ...14
Figure 4 - Truining Edges ...14
Figure 5 - Run only managable pieces through saw ...15
Figure 6 - Fabbed and ready to go ...16
F Figure 7 - Dry fit showing face frame ...18
Figure 8 - Wood front frame ...18
Figure 9 - Dry fit with allscrews installed ...20
Figure 10 ...23
Figure 11 ...25
Tool
Li
st:
Sturdy saw horses (not the cheap plasc kind from the home
center).
4- 8'2x4's (this willbe your cut table)(10'or 12'is be er because
you don't have to pick up the sheet while cu ng.There is room for both halves on horses).
7 1/4" corded circular saw.Heavier duty the be er.
A new combinaon blade for this saw.DeWalt make great blades
for about 8 bucks.
8'circular saw cut off jig (see page for making one ofthese,and
instrucons for cu ng these sheets).
Table saw (portable or staonary).
Cordless drill(2 is op malbut not necessary).
18v impact driver (op onal). 1/8" drillbit.
Countersink.
#2 Phillips driver for drywallscrews.
Combinaon square (used for checking edges ofMDF,and truing
Framing square and drywallsquare. Caulking gun.
7 1/4" corded circular saw.Heavier duty the be er.
Belt sander or means oftruing edges (electric hand planer is ideal). 2 Pipe clamps 20" wide (op onalbut very helpfulin assembly). Staple gun.
2 smaller bar clamps (for holding ply wood cutoff jig). Sharp chisel.
Pu y Knife.
Basic carpentry tools.(Pencil,accurate tape measure,hammer,
chalk line,common sense tools).
N
Note:Icannot stress enough how important it willbe to have a good tape,good combinaon square,framing square,and drywallsquare. Without these three tools you willbe flying blind.Keeping pieces square, and theiredges square willbe the difference in good and poorresults.If you have not built a cabinet before Iwould experiment with these techniques on scrap plywood.It willminimize pilot error.
Materi
al
Li
st:
For the laminated BDA using 1/2" and 3/4" Medium Density
Fiberboard (MDF).There is no actual"wood" in this project.Use only MDF.MDF comes 49" x 97" and is fullnominalthickness.
1 Fullsheet of3/4" MDF plywood.(The term plywood is only used
to delineate sheet goods).
1 Fullsheet of1/2" MDF plywood.
1 Halfsheet Peg board at 1/4” thickness.
A dozen or so 3" drywallscrews.(Allscrews coarse thread only no
galvanized or weather coated).
1lb.box of1 5/8" drywallscrews. 1lb.box of2" drywallscrews.
1lb.of1" drywallscrews (this is a specialty item.Ace Hardware,
True Value or h p://www.mcfeelys.com
Liquid Nails - quart tube or 3-4 smaller tubes.(Look for the
Acousc Fields Acousc Foam
www.acouscfields.com/product/acousc-foam/ This is essen al for op mum performance on both the front and as the internalfill material.Ifyou are outside the USA/Canada then you can use
Thermafiber Fillas an alternave fillmaterial.(This is also a specialty item and can be found at a drywallsupply store.i.e.not a home
center item).
Speaker grille cloth - h p://www.rockler.com/speaker-cloth 4 casters from the home center (hardware department).
16- pan head screws sized to the appropriate holes on caster
moun ng plate not to exceed 11/4",no less than 7/8".
16 corresponding lock washers.
2" Open Celled Acousc Foam (enough to cover the front air space
(15 1/2" x 46").This unit was designed for Acousc Fields 2” thick foam technology.
SmallBox 1/4" staple gun staples appropriate for your staple gun
Cutsheet:
Quan ty Descrip on Size 2 Side Pieces W:13 7/8” H:1” L:55” 2 Top + Bo om W:13 7/8” H:1” L:27” 1 Back W:27” H:1” L:55” 1 W:25” H:1/4” L:55” 1 1 W:26 1/4” H:1/4” L:55 1/2” 2 PEG Board W:25” H:1/4” L:55” 4 Frame Cut to fit 2 Foam W:25” H:2” L:55” NOTES:Ifyou cannot locate 1” MDF you can use 2 x 1/2” boards or 1/4” + 3/4” (or any combinaon equalto 1”).
W
We have recently discovered that our 2” foam technology willwork in place ofthe Thermafiber fillthat was specified in the originalprototype build secon.It is easier to work with and less toxic whereas
Thermafiber must be purchased in 100 sq. .rolls.With only 8 sq. . needed per BDA unit,this creates a lot ofwaste.To address this issue, we tested our 2” foam and found that it not only works as an addion to the face but willalso work for the internalfillmaterialand can
repla
replace the Thermafiber.We can offer you a box of4 pieces offoam, each measuring 25” W x 18,5” H x 2” D to fit your BDA unit for $79,97 plus shipping to your locaon.
Layered
Vi
ew:
Setup
&
Cabi
net
Fabri
ca on:
This secon is designed to illustrate the step by step procedures involved with the build out process.Allmeasurements for the actualbuild are to be taken from the cut sheets secon in part 1.Do not use the measurements shown in the prototype build secon.To see an
assembly video showing how to complete your unit once allthe pieces are cut,please go here h p://www.acouscfields.com/diy-bass-traps-diy-bass-absorber-kit-guide/
U
Unless you have access to a cabinet shop,or have your own,that has great ven laon,MDF is a materialbest cut and fabricated outside. Let's take a moment to talk about shop safety.There is no substute for experience.Having lile to none,Iwould try some smaller
projects before tackling this one.MDF is very heavy,very slippery and smooth,the dust is aggressive,and it is difficult to fasten. S
Supporng this materialwith the 4 2x4's on both sides ofthe cut equally willgreatly reduce poor quality cuts.As you cut through a sheet,ifit is not supported,at the end ofthe cut,it willbreak.Having sharp new blades are a must.Old blades and dulltools are a safety hazard.For moving the sheets around,having help is always a plus. Hearing protecon,eye protecon,gloves with a grip,and breathing protecon are a must.
C
Cut this MDF in a well-ven lated area.Sweep off the sawdust a er every cut.During assembly,vac ups allthe dust.Saw dust between the joints willgive poor results during glue up.Use low odor Liquid Nails.It willsay,“Subfloor" over a green label.And last but not least put your paence shoes on.It is not a race.Clear your mind.You are going to be using power tools.When used properly they can be terrific.When rushed and unfocused,they are dangerous and can "bi
"bite".So allow yourself,plenty of me to perform said tasks.Ifyou get fagued stop,it willbe there tomorrow.
So let's get started.Set up you strong sawhorses up oh let's say 4-5'apart.Depends on the length of2x4s you use.As Isaid ifyou use 12's then when you cut your sheet in half,you can push one halfto the le and work on the right side.A er the first sheet is cut up,slide the other piece in front ofyou and con nue.Limit liing (work
smart).Space 2x4's equaldistances apart on the horses,as to
support an en re sheet across its width.(Always make sure you have 2x
2x's on either side ofthe cut).Now toenailwith one ofyour 1 5/8" drywallscrews through the edge ofthe 2x4 into the saw horse.
(Screws through top face,saw blades and screws don't mix)Do both edges,on both saw horses,ofthe two outer 2x4s.You want the middle 2 to float so you can posion them on either side ofthe rip cuts.When Isay rip it means to cut the length ofa board or plywood, and wellcross cut is exactly what it says it is.It cuts across the width o
ofa board.
A er you have set yourselfup a stable cut staon,and purchased your MDF,you are ready to start fabricang pieces for this project.It is important to note that focusing on cu ng the MDF at this me is allyou need to worry about.This project is divided into four stages. Set Up,fabricaon,assembly,and finishing.To jump back and forth is not producve.
So take a deep breath,and realize that these dimensions are important.First ofallthis cabinet is designed based on a set of calculaons with size,arrangement,and density alltaken into
account.So you are building an engineered en ty.No substu ons ofmaterial.Secondly,these dimensions have been tried out,and are accurate to 1/16th or less.It is important to keep corresponding widths and heights the same,or assembly willbe a nightmare. Assembl
Assembly willconsist oftwo parts.Dry fit,and glue up.
So,pullout your cut list,and your plywood diagram showing how to layout each sheet to maximize producvity and minimize waste. You willhave about a 1/3 ofa sheet of3/4" MDF le over,however much less 1/2".
Set the piece of3/4" MDF on the horses.(Check factory edges carefully at the home center.No digs,dings puffs)make sure it is flat. Ifyou are storing it un lyou start the project,store it in such a way that it willremain flat.Here is layout and cut by cut.
Pullfrom the right and measure 46" and mark it with your pencil.(the edge closest to you,and furthest from you.Take your drywallsquare line up the marks and scribe the line.It should be
square,(drywallsquares are off by a bit some mes).So always double check widths before you cut to ensure parallelto the opposing edge. Set your cut off jig on the line,clamp (make sure saw blade is square to base plate).Set your depth ofcut to 1 5/8",and rip your first piece at
at 46".
This piece willbe your Back #1,le and right sides.
Note:It's important NOT to lay out allthe cut lines at once on each half. Yourpieces willbe progressively off by the thickness ofthe saw blade.So you willcut,layout the next line,fora side,cut,and layout forthe last
Figure 3 - Cutoff jig in acon.
So layout using your drywallsquares the width ofthe back at 16 1/2".(16 1/2" w x 46"l)and rip the back piece with the cut jig.
Layout 12 1/2" width on the off fall,and rip the 12 1/2".Repeat this for the other side.
Take allthree pieces lay them flat together make sure they are exactly the same height.Ifit is off,you can correct this now by
clamping these pieces together.Flush one end ofthese three pieces together,and with a belt sander or electric planer make adjustment carefully.
Figure 5 - Run only manageable pieces through the saw.Clamp saw down.
Take the back out ofthis pile and make sure the sides are exactly the same width.Check the alledges for square with your
combinaon square.A power saw willhave some run out,however avoid extreme bevels.(It is important to make sure your saw blade in your saw is square to the base plate before starng).Once these are acceptable set them aside.
Set the remaining 3/4"(a smallpiece)off fallfrom the first sheet aside,and layout an 18 3/16" rip,and cut.These are the top pieces and are deliberately oversize a bit.You willflush two sides when installing,and sand the other two sides flush a er dry fit with the 1/2" on there as well.These are the 3/4" tops.They willget a layer of 1/2" as wellduring assembly.
Set the larger piece ofthe 3/4" MDF aside and crosscut 2- 13 11/16" on the newly ripped piece.Set allthe fabbed 3/4" material aside.Set the off fallaside you are done cu ng 3/4".
Now set 1/2" MDF on the horses.Reset (reduce)the depth ofyour saw to allow for the reduced thickness ofthe material).
Layout 46" on sheet and crosscut 46" on the 1/2" sheet.Slide off fallout ofway.
Layout 16 1/2"on this piece and rip your piece 16 1/2" x 46".This is your interior panelthat the foam mounts to.
Set sheet you just ripped aside and layout 18 3/16" and rip on the remaining big piece.Crosscut this piece to 48 1/2”.(Fullperimeter back ofcabinet).
Get out table saw.(Now’s a good me to have some help.)Set fence up for a 2 1/4" rip.
Rip 4 pieces to 2 1/4" x 46" set aside (air space fillers).
Set saw for 3 1/2" Rip 2 pieces to 3 1/2" x 46"(absorber filler strips).
Rip two pieces at 2 3/4" x 46" (front filler).
With the remaining 1/2"set up for a 1 1/4 rip.(Face frame for grille,rip sample check thickness with the 1/2" and 3/4" together.) Rip three pieces at fulllength.Yielding R/L and T/B ofgrille face frame.
Use the same techniques you did with the cut off jig when cu ng the Peg board.Two pieces at,16 1/2" x 46".NOTE:Peg board varies in thickness.The width laid out here is for Peg board 3/16" thick. With thicker Peg board and you willhave to adjust the width ofyour front filler strips.They must be flush with the cabinet front edges. Also you want your Peg board to not run past the top ofthe sides and back.It willprevent the tops from screwing on flat.)So check this during
Figure 7 - Dry fitshowing face frame on frontedges and screw pa erns.
Allscrews willhave pilot holes with the 1/8" bit.You willdrill through the first piece and a lile into the second.Carefularound front edges,MDF likes to split.Carefulnot to over drive the screws. When a bit goes through MDF it puffs out the back side.Scrape that puff with a chisel.It willmess you up during assembly ifyou don't.
DE
DETAILS!!Allface side holes to be countersunk to allow for the screw head.No screw heads above the cabinet surface.Allscrews spaced 6" apart or a lile less,but no more.
So take the back and two sides.Put the back between the two sides.Have someone hold it while you clamp it together with the pipe clamps.Just ght enough.Flush up the side edges with the back face.Take framing square and check the box on the outside.The sides willhave a tendency to move towards each other on the
unclamped edge.So cut a piece ofscrap 2x or something at 16 1/2" to use a spacer for the front.Get it as square as you can.It willmake a di
difference.With clamps at the top and bo om ofthe back,set your combinaon square at 3/8"(center for the back edges).The screws willgo through the sides and into the back edges.(You want to be dead center when screwing into the MDF edges!!).One inch in on each end,and spaced roughly 6 inches apart (more screw is ok,less than this is not).See screw pa ern page.Once allyour holes are laid out,drillthrough the side and a touch into the edge ofthe back. C
Counter sink and drive 2" drywallscrews.Repeat un lthe back and sides are joined.
Remember this is dry fit.No glue yet.(Puffs on back side are eliminated because it is clamped together).
Now you willpre drillthe strips that willseparate the interior compartments.Find center ofeach strip’s width,set combinaon square to this distance.This willspeed up marking centers ofeach strip.Measure in 1" from the edge marks,and again space holes roughly 6" apart between these marks.Drillyour 1/8" through holes. Counter sink.Turn over,and pare off the puffs with your chiselor they won't lay flat.You can "gang" together strips ofthe same width, and
and drillthrough holes saving some me.Remember to check for tear out on the back side.(This goes for allthrough holes,in all components).
Now lay the cabinet on its side with the front facing you.We will now make the back air space.Take one pre drilled 2 1/4" strip;place it in the locaon as per drawing.Screw to the inside ofthe le side. Next take two strips ofPeg board place it next to the strip you just installed.These willbe used as spacers for the Peg board panel.Use your pu y knife as a lile extra space for the Peg board to slide in during dry fit.Next to be screwed to the side is the spacer for the “Thermafiber” (see drawing).Once this is completed,remove the strips,and place them against the edge ofthe strip you just installed, and repeat process with the next strip to be screwed.Now use a couple
couple of1/2" strips ofMDF (for the thickness ofthe interior MDF paneland screw the last strip ofthis side to the carcass.This piece should be flush to the front edge ofthe cabinet.
Turn cabinet over and repeat this process.When you are finished, these sides should be mirror images ofeach other.Now take a
moment,and with a magic marker make witness marks,and notes on these components to orient you for glue up.Do not try to a ach these strips with the sides un assembled.The willnot be indexed properly.
Take allfour tops and check them for square.Measure the
diagonals and check with framing square.These need to allbe the same.For both ends,take the two pieces flush to each other,and align the front and side edges flush to the "top" face,and align one side face.The top and bo om caps are purposely oversized.Once you have one side and front flushed,a ach the top to the sides and back top edges.You willbe hanging over the back and one side hop
hopefully by a scant 1/8".These willbe belt sanded (80 grit)flush to the carcass.
Screw top or bo om on with 3" screws slide your Peg Board panels and MDF panelin.Check fit.(make adjustments iftoo tall).
A ach other end,and checks to make sure other lids are lying flat. Back piece should be oversized the same way the top and bo om were.Flush two sides,a ach,and sand the remaining sides flush. Mark cabinet with witness marks and notes.Take notes ifyou have to on paper ifyou have to.Confusion during glue up is not good.Sub floor glue skins very fast so you must work quickly.
Note:It is vitalyou pay a enon to materialthicknesses!
Screw Length Schedule:
- Back to sides = 2". - Strips to sides = 1".
-- Top and bo om through top and bo om edges ofcarcass = 3" 1/2". - MDF fullperimeter back = 1 5/8" (through edges ofback).
- 1" through the panelporon ofthe back.See diagram.(6” inches spacing).
Cut a very even p on you sub floor glue with your u lity knife. Disassemble cabinet.With help,place a thin bead ofglue on the back 46" long side edges.Orient sides to back,align screw holes and
witness marks,clamp and screw.
Glue and screw rear 2 1/4" strips.Right and Le sides at same me.Lay cabinet on back.Run a bead ofglue down the edges ofthe strips.Lay in first Peg board panelflush to bo om and top edges. Draw a bead down the Peg board where the next spacers willgo. Glue up back of3 1/2" spacers align and screw in place.
Swipe edges ofinstalled 3 1/2" pieces.Lay in "Thermafiber" ba , lay in Peg Board,another swipe ofglue on Peg Board and cabinet side,glue back ofnext strips and a ach.
Glue edges ofinstalled strips to carcass,lay in MDF panel.
Now take a moment.Place finalstrips in.Check for flush to front face.Make appropriate adjustments on width before gluing and screwing these strips into the sides.
Orient tops and bo oms.Liberally glue the two surfaces together (1/2" and 3/4" top then other end when me for other cap).Place glue on top edges ofcarcass,and a ach.Repeat for bo om.
Thinly but liberally,put glue allover the back ofthe carcass.Make some circles;this willcreate sucon between the two pieces.Orient and a ach.(As per screw layout).
Figure 12 - Spread glue evenly with pu y knife Glue and screw together the Grille frame according to the
perimeter ofthe front face ofthe cabinet.(miters or bud joints for frame your choice)Staple grille cloth as per layout on drawing. A ach foam to front MDF par on.
Installcasters.(Op malinstallon casters is to morse caster plates into MDF).Space casters 3"- 4" in from the corners.
N
Note:MDF is fragile.Skinning this with some 1/4" plywood is opmalor some sort ofcovering.At the very least two orthree coats ofPoly
Urethane.Do not use acrylic.The waterin the acrylic willaffect the binders in the MDF.
Techni
cal
Drawi
ngs:
Ifyou prefer working in metric sizes,the following technicaldrawings should act as your guide.
