DIY 2x15 Cabinet Build(What a stupid Idea!)

[BogeyBass]

Not really really stupid, just stupid.

Here is really basic speaker design theory for dummies.
1) too big of box makes speaker go, Fart Fart
2) too small of port makes speaker go, Chuff Chuff.

Well perfect....I'm gonna build a box...thats too big, and then im going to make the ports too small.
And then I am going to buy some really expensive speakers..and just stuff em right in there.

WHY? you ask. Well because im bored and i actually just wanted to build a ugly old cabinet to test some things i wanted to know.

1) how bad does round ports that are to small sound
2) how bad does a rear mounted port sound
3) how bad does a speaker sound when placed in its maximum recommended volume.
4) Can you use really really thin wood 1/4 inch or even 5mm panel board without vibrating, to build a light all wood cabinet.
5) Can 2x15 work with a 1/2 inch plywood baffle
6) Will some multi layer wool/rubber/plywood weird idea baffle thingy, improve baffle resonance (more later)
7) Even thou a Eminence 3015 looks better than a FaitalPro 15FX560 in simulation, which one sounds better.
8) will my dumb idea for port construction actually work
9) Is buying 2000 dollars worth of speakers a dumb idea

So lets bring on the stupidness.....and the bonus is, i'm not some guy trying to be the next amazing builder, and i stated how stupid i am...so we can all have fun watching me pretend to be stupid and building a 2x15. yah see?
you all can flame and bag on me for my horrible mistakes....or in this case stupid mistakes



Here is the basic idea, i wanted to create a "core" which is a set volume, and at anytime i can change the front and rear panels, for any port/speaker combination i might test in the future. With a simple bulkhead i can just screw the panels on and off, and use a stupid amount of visible ugly screws to do it.

The front and rear panels are gonna be only 1/2 inch thick, and the "core" is just gonna use a framework of pine, and then get covered in super thin panel wood 5mm....yes 5mm thick.

face palm city, too thin wood, too big of volume, and rear ports.
man this is stupid.

gonna test the following 3 drivers as pairs=

1)Eminence Kappalite 3015
2)Eminence Kappalite 3015LF
3)Faital Pro 15FX560

[Rick Auricchio]

Port location makes no difference, front or rear. So that's on experiment you can skip if you like. With a rear port, however, you have to place the cab several inches from the back wall to avoid blocking the ports.

If you put a lot of bracing to reduce panel vibration, that will subtract from interior volume. But you might be able to use 3/8" void-free plywood with bracing and save weight.

[grendle]

Subscribed. I'm interested in what you get. The math is great but you only actually really learn / understand when you experiment and see what the outcome is for yourself. We're surrounded by great mistakes.

Please start with a sealed version! Kinda logical no? Before holes/ after lol.

[grendle]

Originally Posted by Rick Auricchio

Port location makes no difference, front or rear. So that's on experiment you can skip if you like.

You sure?

[BogeyBass]

Originally Posted by Rick Auricchio

If you put a lot of bracing to reduce panel vibration, that will subtract from interior volume. But you might be able to use 3/8" void-free plywood with bracing and save weight.

Im using luan underlayment sheets for hardwood floors, all i know is its 3ply and 5mm thick, and actually has a really nice grain/color to it for being so cheap.

3/8 void free ply is a good idea, that would be about 9mm thick, i wanted to go stupid thin......so 5mm was the choice.

Forgot to mention the cab is 22 inches deep or 558mm so it barely fits in a standard door. so 24x40x22 inches for roughly
12 cubic feet or 339 Liters.

hopefully with alot, i mean alot of damping material and considering speaker,brace and port volume bring it to a realistic actual internal volume of 10 or so cubic feet or 283 Liters.

similar (sorta) to having a single 15" speaker in 5 cubic ft x 2

[brendanbassist]

Originally Posted by grendle

... The math is great but you only actually really learn / understand when you experiment and see what the outcome is for yourself. ....

I'd say the opposite is true; experience is great, but you only learn and understand when you do the math.

[BogeyBass]

Originally Posted by BogeyBass

6) Will some multi layer wool/rubber/plywood wierd idea baffle thingy improve baffle resonance (more later)

i think it weird when people quote themselves, but oh well
lets get this multi layer thingy out of the way.

Read a little about highend speaker manufactures using multiple materials like ceramic, felt, wool to line cabinet walls to improve cabinet damping.

Also heard about builders using roofing asphalt sandwiched between layers of plywood for good results.
The idea is their is no perfect cabinet damping material. so using layers of different material will maximize the ability to absorb sound and reduce resonance.

So i wanted to take a wack at this and use a very thin 1/2" baffle which is about 12 to 13mm.
And then somehow sandwich a few layers of wool and Rubber to see if this "multi material" thing actually worked.



here is a work in progress shot showing only 1 wool/rubber layer,
the final wool/rubber layer is just applied to the back of the baffle, which will sorta act as a "gasket" when i mount it to the "core'


and here is the back of the baffle with the final wool/rubber layer applied

[pie_man_25]

putting ports at the rear shouldn't change the sound - to my knowledge - unless of course you put the cab right up against a wall and choke the port, or you put the port precisely across from a magnet/speaker.

Originally Posted by BogeyBass

i think it weird when people quote themselves, but oh well
lets get this multi layer thingy out of the way.

Read a little about highend speaker manufactures using multiple materials like ceramic, felt, wool to line cabinet walls to improve cabinet damping.

Also heard about builders using roofing asphalt sandwiched between layers of plywood for good results.
The idea is their is no perfect cabinet damping material. so using layers of different material will maximize the ability to absorb sound and reduce resonance.

So i wanted to take a wack at this and use a very thin 1/2" baffle which is about 12 to 13mm.
And then somehow sandwich a few layers of wool and Rubber to see if this "multi material" thing actually worked.



here is a work in progress shot showing only 1 wool/rubber layer,
the final wool/rubber layer is just applied to the back of the baffle, which will sorta act as a "gasket" when i mount it to the "core'


and here is the back of the baffle with the final wool/rubber layer applied

that might actually be a good idea for helping to dampen the cabinet material and keep it from vibrating, particularly it might help to simplify bracing - making the process of designing a cabinet slightly easier. This might be a good idea. Of course, mind you, I'm a neophyte to building speaker enclosures, so my opinion should be taken with a grain of salt.

[grendle]

Originally Posted by brendanbassist

I'd say the opposite is true; experience is great, but you only learn and understand when you do the math.

Gotta have them both really. I was a little hasty there.

[BogeyBass]

Originally Posted by pie_man_25

putting ports at the rear shouldn't change the sound - to my knowledge - unless of course you put the cab right up against a wall and choke the port, or you put the port precisely across from a magnet/speaker.

Darn it you guys, where is all the trolls when you need em.

I seen all kinds of threads with rear port hate. And now everyone is being all positive about rear ports. Darn it cant i just build something you all hate and can argue about...man

well alrighty then lets get on to my Diy port construction.

I think for good port velocity we would be looking at 8 ports 3" round for a 2x15. So i decided to do the wrong thing and go with 4.



anyhoo started with a small board strip to hold 2x 3" black abs drain pipe the circle was cut very tight to the outside diameter of the pipe.

Using a Harbor Freight El Cheapo router with a wood top, i just marked my circle and drove a finish nail into the plywood and wood router top for the pivot point.



here is the strip with 2 holes cut




I forget what port, i was building for this photo since i have changed them already 3 times for 3 different drivers. but you get the idea, i think this is for the 3015. just black abs plastic.




here is the reverse side after i glued in the pipes and sanded the mounting side really smooth, this assembly would be glued to the baffle, so it needs to be nice and smooth.



to make a dual flare port i would need to repeat this wood strip, but i decided to just round of the ends, instead of leaving them straight you cant really tell in the photo. the forward one is rounded over the rear is still flat for comparison.



here is the inside of the core with the rear panel mounted, I have marked where this assembly will be glued. And drilled some pilot holes. this of course is only 2 ports. I will repeat this again for the other 2.

[JimmyM]

Rear port hate comes from people who think port location matters.

[BogeyBass]

Use glue and screws, here is where it gets piled on




Ok now it gets a little ugly, i have a thing with glue, and if i have alot of it, i tend to just pickup sawdust and throw it in the glue. So it looks ugly but here is the ports mounted to the rear baffle.
you can see the sawdust I tossed in the glue. yuck.



here is all 4 mounted.



ok now here is the reverse side of the rear baffle, with those ugly pilot holes i drilled. Now im going to slip in my large trimming bit with a follow bearing on the router and cut the port opening.



and now here is the first cut with a port which might actually work



now using a roundover bit to give it a little flare. this is just one port and had to do this 4 times.



maybe this drawing will help make sense if your confused.



Sneak peak at the core again with the finished ports.
not too bad...4 ports = To small high velocity krap, real stupid idea

[BogeyBass]

Ok few more pics then im hitting the hay, Figured I would show a few more of the rear baffle.

Decided since the 5mm wood i used for the core looked so nice i would stain it. Tell you the truth I dont really care for natural stain cabinets...but here i am doing a stain cabinet.

So had to at least paint the back black, to rebel against my own self. Because i hate painted cabinets too, but yet here i am painting a cabinet.

can only get so far with spray paint, the camera flash does a good job in showing why.



Well how do you get a nice spray can finish? well you let it dry real good, Do a wet sand with very light sandpaper to get rid of the spraying can hazing, and then clear coat the heck out of it.
I knew i would not get a "Piano Finish" like i imagined in my head.
But you can see the reflection of the shelfs so not to bad for spray paint.

[Bass Unique]

Unless you put some bracing in, it wont just sound bad, the 3015LF will blow the cabinet apart at 450W.... I predict around 63 Hz :-)

You could use some tie rods side to side to add stiffness to the sidewalls etc at minimum weight. Dowl rods glued in place (maybe with a small screw too) can do a great job. Try to make them so you have different unsupported panel sizes in different positions to minimise resonance.

Small ports work well at low volume. However, at high volume it will chuff but may not be that noticable if they are around the back. I did a small box with a 12 and a single 68mm pipe. Once flared and round the back, you wont notice. Once you achieve over aroudn 35m per second air velocity, you are loosing a significant amount of bass energy in turbulence so you will not achieve +3 dB for each doubling of power. (adds to power compression losses in the speaker limiting output).

Using a thin material will definately screw up the midrange even if you stiffen it. It would also be a problem if you drop it but as a test bed - sound like a bit of fun though and light!

[MuzikMan]

IMO it is easy to make a box that is too small for a driver but it is very difficult to make one that is too big. The only thing that comes to mind is that the driver might unload early but that should be easily offset by the additional sensitivity in the lower bass region. What is your reasoning for thinking that the box is too big?

[BogeyBass]

Originally Posted by Bass Unique

Unless you put some bracing in, it wont just sound bad, the 3015LF will blow the cabinet apart at 450W.... I predict around 63 Hz :-)

Thanks Bass Unique for stopping by with all your suggestion,
But oh yah...these paper thin walls have got to blow, thats what i'm talking about! no way in hell 5mm ply is gonna hold.....

Originally Posted by MuzikMan

What is your reasoning for thinking that the box is too big?

Good point MuzikMan, A good trade for powerhandling vs bass output for the Kappalite series and the Faital Pro, would be to keep the volume around 3.5 to 4 cubic feet. So a pair would do very well in 6 to 8 cubic feet. I decided to go with roughly 12 cubic feet, and with bracing,speaker and port volume, might bring it down to 10.5 to 11. Which is just a little to much for the 3015. But the 3015LF and FX560 can barely handle it, just the power handling goes down.....but the Max bass response goes all the way up......shhhh dont tell anyone.

Originally Posted by pie_man_25

unless of course you put the cab right up against a wall and choke the port, or you put the port precisely across from a magnet/speaker.

now your special Pie_Man_25, i quoted you twice now because i missed you ending statement.
So yes " no rear ports directly behind the speakers" so if you look real close, I put my too small ports, perfectly in line with those speakers...ooopsss. Its got to sound like poo.......Right!

Anyways moving on

Lets look at this stupid "core" i keep talking about.

I needed a basic skeleton frame to skin with the paper thin 5mm ply. With 2 mounting bulkheads for a flush mount front and rear baffles.

Keep in mind the pictures below Is Not the design i used.
And i will not be showing the actual design used.
To get 5mm ply to work the skeleton construction is the Key. Lucky for me i was smart enough to revise this before actual building. Obviously from the photos I show, you can see more how i did it. And to make things work i used my model airplane building experience to make a very strong, but light skeleton. And will only clue in that a large amount of joints must be used
and those lazy boring butt joints that most use, dont stand a chance.



Here is the skeleton wrapped with the 5mm ply, which im sure is getting annoying since i typed (5mm) a billion times now.
Oh! almost forgot, did i mention this was wraped in 5mm ply.
Anyhoo my top secret is out, oh know



like i mentioned before i hate natural stain, but yet this wood had nice grain and i decided to give it some stain.



so some steps are being skipped here, and some other top secret inside coatings are not being shown.
But...you can see i used the most highly non recommended very itchy pink stuff to fill it up. The secret is to use the pink brand which is covered in plastic to make it not itchy when you handle it. Then after i glued and stapled the stuff in place, i cut the plastic away.
I was extremly careful and made sure i left every loose staple as possible, hoping that one would find the speaker magnets when assembled.



I think i already mentioned this thing is 22 inches deep (558mm)
so it barely fits inside a standard door. Which i took into consideration so i think 22" is about max depth for most portable applications. otherwise you would need a special door to get in the place.



so if your familar with the Sunn 200S the front dimensions are a similar match 24x40 ......but the 200S is 15 deep for about 7.5 to 8 cubic feet.
But the much larger Sunn 2000S was about 10 cubic feet. So your looking at (not really) a Sunn 200S with the volume and sound of a 2000S.
But enough about those old dinosaurs, this looks nothing like a Sunn....Duh. But the Dimentions follow the Golden Ratio, used by many over the years to provide a aesthetically pleasing ratio...hence the Golden Ratio. Plus old school speaker design recommends using a Golden Ratio cabinet to reduce cabinet resonance. and i think ....i need all the help I can get

[s_mcsleazy]

i do beleve this thread is giving me a nerdy hardon

[kelleysdad]

I do see the humor in this. What a great idea.

[BogeyBass]

oh' tay...lets see covered the rear panel and core. Now the front baffle.

mock up before cutting speaker mounts.



with cutouts



using T bolts of course...then i covered the back with the last layer of rubber/wool for the multilayer baffle.



now add some stain, this is the first coat looks like poo in the flash, sanded and did about 2 coats of stain, then coated everything with 2/3 coats of polyurethane

[BogeyBass]

Thanks guys for stopping by

Originally Posted by s_mcsleazy

i do beleve this thread is giving me a nerdy hardon

Oh yes! you dirty man you....just be careful and don't bump that thing against the wall.

Originally Posted by kelleysdad

I do see the humor in this. What a great idea.

glad you like....not only humor, but hopefully a complete failure for the whole world to see.

no way in heck this thing sounds good.

Anyhoo

here is a reprint of my ground breaking multiply baffle



one more shot laying off centerd , on core with one more layer needing to be applied after the T bolts.

Look closely and you will see that i made sure to Not use void free plywood. The void free gremlins are going to haunt me now!
boy this is junk!