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Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#1
As a budget-conscious musician, I realized that a Marshall full-stack was out of my price range, and that everyone and their Sheep dog has one anyway.

So I went speaker-hunting.

Choosing Speakers

When choosing speakers, figure out what you want to do.

12"s work very well for guitar, and Celestion is the most talked-about speaker of this type. It's the Coca-Cola of speakers. You know it's good, everyone likes it, etc.

Consider others, though. Sometimes the most common solution is also the most ordinary.

I settled on the Peavey Black Widow 15". Why? Because it can double as a bass speaker when it needs to.

So my cabinet, dubbed the "Bass Monster," has one BW 15" and a pair of 10" Scorpions (also Peavey) that I can opt for if I want more attack. When mixing, you often want to leave out some parts of your tone to make room for other instruments. If I plug a bass and a guitar into this cabinet together, I achieve a nice tone for both which is easy to mix.

Cabinet Design

When you buy a set of speakers from the stereo store - particularly high-end speakers for audiophiles, there is often some fancy wood used. This wood selectivity is not that important for guitar or bass. Pine and plywood work just fine.

The next consideration is size. Don't over-size your cabinet for two reasons; first, you want to be able to move it. Second, consider the acoustics. How can you make your cabinet work right acoustically? Odd-numbered dimensions!

Go for 13" by 17" by 23", or 25" by 17" by 49", something like that. Common sense says "design the cabinet to be 2 feet by 3 feet by 4 feet," but you may introduce modes, which are big, honking, unwanted bass noise that you don't want.

It's not that hard to overcome modes. Just pick ODD numbers that suit the size of you want the thing to be. Instead of making it 2.5 feet tall (30 inches), how about 2.3 feet? 2.7? Not a lot of difference, but it can go a long way.

Now think about speaker placement. Where to put the 15"? For most efficiency, I suggest putting the 15" at the bottom. This will cause the power of the speaker to nearly DOUBLE because the sound will reflect off of the hard floor and compliment itself (hard to explain, but it works.) That means more power, less electricity.

As for guitar, it doesn't matter a whole heck of a lot. Guitar cabs are easier to build than bass cabs because they don't put out all that low sound. Just make sure to build it solid.

STRUCTURE - The best thing to do is to build it like a house, out of "studs" or 2 x 4's. Build a frame out of 2 x 4's first, then add plywood second. I suggest putting the 2" side of the studs around the front and back of the cabinet, and using the 4" sides around the sides of the cabinet. This saves space, makes the cabinet smaller, and allows room for your speakers.

Run a 2x4 along the top and bottom of where you intend to put each speaker. Don't worry about the sides. If your cabinet is taller than 2 feet, use an extra stud to support the middle of the cabinet, about halfway up on each side.

Finally, plywood. 1/2" ply is fine for the front, and should work all the way around. If weight is a concern, use 1/4" ply for the back and top.

Venting/Breathing

As the speakers move, they will "ask" for air on the way out and will "push" on the air on the way in. You need to allow air to move freely in and out of the cabinet. If it's a guitar cab, just cut a slit in the back of the cabinet, or drill a large hole.

For bass, it's a bit tougher, because a hole in the wrong place will KILL your bass response. You can use a passive radiator or a port or both. For a radiator, you just need a speaker - preferably a blown one - that will move in the opposite direction of the others. To save weight, cut off the magnet and most of the metal behind the cone. You only need the cone itself.

Porting can get pretty complicated, but it doesn't need to be. Cut a hole in the FRONT of the cab, and put in some kind of cylinder that is AIR TIGHT, that extends all the way to the back of the cabinet. Just leave room back there for air to move (a cm or two.)

With mine, I used both methods.

Wiring

Last, but certainly not least, is wiring. Again, you can pay $10 a foot for special wire that is solid 24K gold or cryogenically treated. Don't. While this cable does improve the flow of electricity to your speakers, it DOES NOT work any better than plain old thick cable.

Thick cable is the best way to go for two reasons; you get extra energy flow, the exact same that fancy cable will give you, and you get the added benefit of greater power handling. Amps put out a lot of juice, and thin wire can get so hot that it will melt and break. Thick wire is also safer.

Wheels

Wheels, otherwise known as casters, will provide you with two advantages - mobility and acoustic isolation. If your cab sits directly on a wooden floor, the vibrations can travel through the floor, and rattle something else in the room. I've hunted around for hours trying to find what's buzzing in my jam space, only to discover it's Sharpie I set on the desk, or a picture hanging from the wall. Wheels will help out a lot with this.
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dave_c2k2
Still Laughing At You
Join date: Dec 2002
383 IQ
#2
Very interesting. You should submit this as a proper article or get it put in the archives or something....or a sticky!!!
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The1963Riffer
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Join date: May 2004
157 IQ
#3
Im motivated to build my own now.....:P I think it would be great to have a 2 x 12 extension cab for my fender princetions....
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Bubonic Chronic
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Join date: Aug 2002
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#5
I'll work on pics, for now I'd suggest just looking at a set of speakers you've got as a model. Some people have used plain poster board to port the speakers, and this just requires about a 3 or 4-inch diameter hole cut in the speaker, usually at the bottom corner(s). Roll the poster board up into a cylinder (cutting off excess you don't need) and taping it so it stays the right size. Once its the right size, a few cm shorter than the front-to-back length of the cabinet, feed it into the hole and secure it with staples or small tacks/nails. Hot glue around it and you're set.
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p00n
UG Newbie
Join date: Oct 2003
10 IQ
#6
this may sound like an ignorant question, but i don't find your rationale for the odd lengths.. how would the odd sides alter this 'modes' etc? acoustics do not really conform to that regular a pattern..
Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#7
Originally posted by p00n
this may sound like an ignorant question, but i don't find your rationale for the odd lengths.. how would the odd sides alter this 'modes' etc? acoustics do not really conform to that regular a pattern..
An excellent question, but one I'm afraid may be a bit too technical for general "I want to build my own cab" info...here goes:

Modes result from sound waves building on each other. Think of waves in the ocean, not crashing waves for surfing, but the ones farther out, the nice round ones. Well, if you put a concrete wall out the, the "up" part of the wave will bounce off the wall and move in the opposite direction. Sometimes, if the waves bounce between two walls lets say, the "up" can exactly counter the "down" as it arrives, so the two waves - the original wave and its reflection, will cancel and you get nothing.

The opposite happens with modes. If a wave (a sound wave now) is 2 feet long, that's one up and one down, each one foot apart. So a cabinet designed with a dimension of exactly two feet will cause the wave to encounter the "up" of its reflection while the wave is also "up," so the resulting wave is twice the size of the original. This keeps happening, so that the "up" parts of the waves keep building, and you get higher and higher waves that don't move - a standing wave. A mode, and I'm sure you've heard on at some point, is a standing wave in a room (and a cabinet is basically a small room.)

..told you this was complicated.

Anyway, by choosing odd numbered dimensions, you cut down on - not eliminate - standing waves. It's an easy and cheap solution for cabinet (and room) design. In reality, professionals use computer modeling, sophisticated gear, etc. to specifically "tune" a cabinet, but we don't have that. The best we can do is make it, say, 3.1 feet by 2.7 feet by 1.3 feet. Just good practice in general. If a wave bounces off the top, then bounces off the sides, there is less likelyhood of mode formation when you've got uneven numbers - especially prime numbers like 11, 13, 29, etc. It saves us from spending all the time to build this then and then have, let's say Bb, obnoxiously honking out of your box.

...phew. Haven't even thought about this since college.
"Virtually no one who is taught Relativity continues to read the Bible."

Last edited by Bubonic Chronic at Oct 14, 2004,
Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#8
Notice in the picture how the wide side of the studs face the top, bottom and sides. The narrow sides (the 2" sides) face the front and back. This makes the cabinet smaller and allows more room for speakers.

Also note the use of butt joints in the construction - how I've got 2x4's just nailed directly to one another. Since we are using 1/2" plywood, and adding extra studs to support the speakers this is not a problem. It will be plenty sturdy when we are finished.
Attachments:
stud frame.jpg
"Virtually no one who is taught Relativity continues to read the Bible."

wahappen
UG NMA Member #1
Join date: Sep 2003
411 IQ
#9
Originally posted by Bubonic Chronic
For bass, it's a bit tougher, because a hole in the wrong place will KILL your bass response. You can use a passive radiator or a port or both. For a radiator, you just need a speaker - preferably a blown one - that will move in the opposite direction of the others. To save weight, cut off the magnet and most of the metal behind the cone. You only need the cone itself.

Porting can get pretty complicated, but it doesn't need to be. Cut a hole in the FRONT of the cab, and put in some kind of cylinder that is AIR TIGHT, that extends all the way to the back of the cabinet. Just leave room back there for air to move (a cm or two.)



Great thread IMO, port diameter and length can be critical depending on the size of the cabinet. I'll see if I can pull up some charts showing related frequency responses that reflect the box size/ port size.

Anyone ever hear of compound loaded drivers in bass cabs ? I know the ergonomics aren't the best when considering space, but the frequency response is real tight in a sealed chamber. I just don't know if this has ever been tried in bass cabinets.
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Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#10
You've probably noticed that speakers have Ohms as well as Watts. Generally, guitar and bass speakers come in either 4 or 8 ohm varieties, and are designed to be used alone, in pairs, or in fours (multiple of two.)

Here goes:

Usually, you want the cabinet itself to be 8 Ohms. It's the safest way to go. 4 Ohms is louder, but you can blow up your amp more easily this way, so I recommend going for 8.

Single speaker design -

One 8 Ohm speaker wired like so...

+___X___-


..simple.


A speaker pair -

in this case you have two 4 Ohm speakers...

+___X___X___-

..this is an example of series wiring. Think of taking two AA batteries and putting them end to end. If they are Duracells, the gold top will touch the black end of the other battery. This is series wiring at its simplest: a flashlight.

A guitar jack has two leads, a positive and a negative. Start by connecting the negative lead of the guitar jack (the tip) to the negative lead of one speaker. Now run a wire from the positive lead of that speaker to the negative lead of the next. Now run a wire from the remaining lead, the positive lead of speaker #2, to the positive lead of the guitar jack. Done.


A quadruple speaker set-up (like a 4 cone Marshall or similar cabinet) -

In this case, we will use a series/parallel wiring scheme. We'll start with the parallel, since that's new.

In this case, we will be using 4 8-Ohm speaker cones!! - very important.

Since there are 4 speakers (cones), we will have 2 PAIRS of cones, each wired in parallel. Start by wiring each PAIR of speakes as follows...

+
/
X=X
/
-

..not the greatest diagram, I know. Here it is in steps:

Step 1) Run a wire connecting the negative leads of each speaker together. Now run a wire connecting the positive leads together. This should look like a loop, or an "=" sign, as in the diagram.

When we do this, the system of speakers we have connected becomes a single 4 Ohm circuit.

..do step one for each PAIR of speakers, which will result in 2 4-Ohm circuits (essentially 2 4-Ohm speakers made up of two cones apiece.)

Step 2) This is the easy part. Just as with the 2-speaker system above, connect the two circuits together in series. This will double the resistance, giving us a single 8-Ohm circuit.

-___X=X___+|-____X=X____+

..again, think of a simple flashlight with two Duracell's in it. Gold top to black butt.

This leaves us with a single negative lead and a single positive lead. Connect the negative lead to the tip of the guitar jack, the positive to the sleeve.

Done.


...other configurations are possible, but a higher level of expertise is required. My cabinet contains 2 jacks, each representing a 4-Ohm system. The 15" is a 4-Ohm single-speaker circuit, and the pair of 10's, each 8-Ohm's, is a double-speaker, 4-Ohm circuit. A bit riskier, but then I've done this before.

If you are nervous about this, or want to deviate from these plans, I strongly suggest experimenting with a small electronics kit, available for a few dollars from Radio Shack or similar. Try different circuits out with resistors, etc. Does it blow up? No big deal, that's what the kit is for. Find out if it will blow up first, THEN apply it to your expensive speakers once you know it works.
"Virtually no one who is taught Relativity continues to read the Bible."

Cmogi10
Team Slut
Join date: Mar 2003
840 IQ
#11
Congrats!

Awsome thread, it earns a sticky

cant wait to see pics
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pooch0072
Mr. November
Join date: Oct 2003
510 IQ
#12
What about covering? Waht did you use, did you use any? And did you put some kind of grill or mesh in front of the cab to protect the cones? And in the end, how much does your cab weigh?
ebashnitzil
UG's F[i]u[/i]ck Up
Join date: Jun 2004
128 IQ
#13
i am thinking of making a cabinet - but i would use carvin speakers ( www.carvin.com ), maybe 4x12
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Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#14
Originally posted by pooch0072
What about covering? Waht did you use, did you use any? And did you put some kind of grill or mesh in front of the cab to protect the cones? And in the end, how much does your cab weigh?
I actually made a lot of mistakes in mine, lol.

There is no mesh most of the time, because I use it in the studio, and sometimes I'll stick a mic like .01 cm away from the cones. Depends, though. Generally I don't really move that one around, so no, no mesh. I did build a cheap protection thing out of screen for, like, a screen door, but that's when I was hauling that thing to gigs, which I don't do anymore because I just bring my acoustic/electric for gigs. Plug right into the board with that.



In all, it weighs probably 80 or 90 lbs. Too heavy in my opinion, but it's nostalgic, you know? My cab has been with me for the better part of a decade now, but when I built it I wasn't thinking too much about it being too heavy or, like, the size of a fridge or anything.



I covered the sides with basically astro-turf, but not the green stuff you're thinking. It's like outdoor or industrial type black nylon carpet (rubberized on the bottom) they sell for $2-$3 a yard at Menard's. I swear by that stuff now. More recent work, like my studio rack, has really turned out sharp. You'd think I spent a thousand bucks, but it only cost me about $10.

The cab itself is all black around the sides, but the face is bright orange. That blown twelve I used as a passive radiator I painted as an eyeball, all bloodshot with a blue Iris.

Like I said, I would do it completely differently today because I know a lot more of what I'm doing, but I always liked the looks of that thing - big and orange, just staring at you from the corner like "I'm a fucking big amp, motherfucker!!" Like I said, nostalgia.

If those fairies from H&G TV came to redecorate my house, they'd try to toss that out in a heartbeat. I'd just stand and watch them try to pick it up, drink a beer and laugh at them.

Pansies.
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TGM
Transistor Tubes
Join date: Sep 2003
238 IQ
#15
What about the baffle construction? It's a pretty important part of your cab.
"You can practice to attain knowledge, but you can't practice to attain wisdom." - Herbie Hancock
Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#16
http://dictionary.reference.com/search?q=baffle

Baffle: "A partition that prevents interference between sound waves in a loudspeaker."

Depending on how you design it, you should be able to avoid interference. I've never actually used baffles before, perhaps you can enlighten us.
"Virtually no one who is taught Relativity continues to read the Bible."

TGM
Transistor Tubes
Join date: Sep 2003
238 IQ
#17
The baffle is the board that you mount the speakers onto, I was wondering how you made yours, and why.

The baffle does spot you from losing low end through phase cancellation, but depending on how thick it is and how you mount it it can change your tone for the better. (IMHO)

http://www.tone-lizard.com/lesson4.htm

Towards the bottom that article has information on baffles.

I guess that you used something solid, you wouldn't wan't it to flap out with a bass. I just found it kind of wierd that you didn't say anything about it,
"You can practice to attain knowledge, but you can't practice to attain wisdom." - Herbie Hancock
Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#18
^^ I guess I never knew the official name for it, but sort of inadvertently designed one anyway in that I support the speakers essentially with 2x4's on the top and bottom, so they are not held in place with the plywood at all. This also provides added rigidity, preventing almost any (except high frequency) vibration in the studs, and by default the ply, which is fastened tightly to the studs.

I also use 1/2" ply for the "face" of the cabinet, plenty sturdy to resist most vibration.

Edit: Some background on frequency and wavelength.

Frequency is short for "cycles per second", or #of waves/time elapsed.

Western music (yes, rock 'n roll and metal and punk and funk and pretty much everything else) is based around the "A" note, which is 440 Hertz, 440 cycles per second.

Octaves are multiples of the notes: 220, 110, 55 are all octaves of "A".

A guitar puts out a 160 Hertz "E," and a standard rock bass puts out an octave below this, 80 Hertz.

A wavelength is how far a wave will travel in a given amount of time. If you clap your hands in a large room, you can measure its size.

Say you stand in front of a distant wall and clap. If the clap takes 2 seconds to return to you...

CLAP..........clap

..then the "clap" has gone to the wall and back, and thus took one second to get to the wall. Sound travels 344 meters per second, so the wall is 344 meters away.


More important would be wave cancellation through the air by way of energy traveling around the cabinet, into the back, and impinging upon the back of the speaker. Cancellation will occur where a half-wavelength travels to the back of the speaker, resulting in a rarefaction that meets the compression caused by the speaker. Desnser air + less dense air = something in between, in this case something very close to average air pressure, or what we might call "silence."

In other words, you don't hear sh*t.

The wavelength has to be calculated as follows: (in metric)

(lambda) = v/f = (344 m/s)/160 = 2.15m

(in English - feet)

(lambda) = v/f = (344 m/s)*(3.281 ft)/160 = 7.05 ft.

...but you're not concerned about lambda, you are concerned with lambda/2, that's where you get cancellation.

7.05/2 = 3.503 feet

If the distance from the front of your cone, around your cabinet and into the back of your cabinet is > 3.5 feet, you're ok to just put a big-assed hole in the back of your guitar cab.

In general, though, you'll find that cabinets are usually enclosed. That means a sealed box, but if you think about it, a sealed box will resist changes in pressure, "wanting" to be the same pressure as the outside air. Thus you will "rob" your speakers of efficiency - a lot of power will go into fighting the air pressure differential, which doesn't give you any sound.

So you have to port. A simple porting method is to create a series of holes in the back of the cabinet, and then place another "box" in front of the back panel of the cab, then a third "box" in front of the previous one.

What I mean is, allow air to come in at two or three points in the back:

|
|

|
|

|
|

..something like that. Remember, this is the ghetto "I don't want to bother with math or anything" method. It does work, though. I chose this method because I wanted the cabinet to serve multiple purposes, even keyboards occasionally, so I wasn't sure about which frequencies I wanted to "tune" the cabinet for. If it's specifically for bass guitar, 40 Hz is a good ballpark, but keyboards can go lower, and guitars start much higher, so for a multipurpose cab like this, go for a semi-random porting technique that is not really "friendly" to any frequency by using a series (three is good) panels, each having holes of different diameters cut different distances apart. Keep in mind, though, that the total area of the holes in each successive panel should be about equal, and most importantly sufficient enough to allow enough air for the speakers to work efficiently.

Once holes are cut in the back, make a small frame out of cheap wood, 1/2" to 3/4" thick around the area where the holes are cut. This should be a square or rectangle that looks somewhat like a backyard garden frame. Solid base, rectangular surround, open top.

Now make holes in the second panel, this time using a different extreme of dimensions - either cut tiny holes at random locations throughout the panel, or place two or three very large (but not too large) holes in it. Whatever you did for the holes in the back (a lot of small holes is good for the back), do the opposite with this panel. So in my case, smale holes | large holes.

The reason for poking small holes in the back is just structural, you want the back to be strong. Big holes would mean you could reach inside the cabinet, or that you might wind up with a weak spot in the back. Not good.

Also important: space the holes so that they are far away from the holes in the previous panel. This way, air (and sound) must travel the greatest distance before entering the next stage of the port. This lowers the interference frequency, and gives the sound more material to travel through, which attenuates the sound and makes any interference less severe.

Slap the panel onto the frame and repeat.

I did Small | Large | Small, and by large, I mean about an inch diameter, not 5 inches. Small is like a pencil-width.

In all, three panels should do it: the back of the cab having several pencil-sized holes drilled in it, the next panel having three or four inch-or-so sized holes, then the third panel having pencil-sized holes again.

Any given hole will let in certain frequencies, and by using different sized holes, you reduce the number of frequencies that can get through. Ideally, only air will come through.

Another factor to consider is sound coming in from the sides. This is why I again use 1/2" ply attached to studs. Low frequencies do NOT like this construction, so only very high frequencies (which don't matter anyway) will easily rattle that cage.
"Virtually no one who is taught Relativity continues to read the Bible."

Last edited by Bubonic Chronic at Oct 20, 2004,
Shoestick
Wannabeatle
Join date: Feb 2004
239 IQ
#19


Maybe its the sleep deprivation talking, but could you possibly upload some photos/diagrams to go with these things? My head is spinning. Plus I just want to see a huge orange homemade cabinet.

EDIT: Forgot to applaud you on your knowledge and willingness to share it with the UG community.
Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#20
^^ Of course.

The photo will take a bit of time, though, as I'm working with a disposable camera and a scanner. Usually turns out better than digi anyway, though.
"Virtually no one who is taught Relativity continues to read the Bible."

Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#21
Here is the basic port design. I'm neglecting a lot in doing it this way, but it's the easiest and cheapest way to go. If you line these panels up, back to back, the cabinet can breathe, but less sound will get through.

Basically, you are building two small chambers, each about one and a half feet on side, and seperated by 1/2" or 3/4" of wood. Think of it as a sandwich:

Wood|Air|Wood|Air|Wood

It's crucial, though, that these chambers be otherwise airtight, meaning no air (sound) can escape except through the holes you've made. Also, use relatively small holes (between Sharpie-width and pencil lead width) so that sound really can't get through. You shouldn't need more than about ten Sharpie sized holes in a 2 foot by 2 foot panel for air to get through.

You're playing a balance game here. Too few holes will not allow enough air through, and too many will make the panels "acoustically transparent," meaning you've wasted your time, and basically opened up a big acoustic hole in the back, which defeats the purpose of building a cabinet.

I added a passive radiator (the blown 12" detached from its magnet) so I would have to put less holes in the cab. Each approach has its inherent weaknesses, but by using a bit of both, I compromise less of my sound overall.

Adding a passive radiator is easy, just put in a dead speaker that moves freely. If you don't have one laying around, check a resale store for a cheap set of stereo speakers. Anything over 10" will do.
Attachments:
port construction 1.jpg
"Virtually no one who is taught Relativity continues to read the Bible."

Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#22
Here is a diagram of the most complex wiring scheme for a guitar cabinet, the series-parallel scheme. All others can be derived from this.
Attachments:
4 by 12 wiring.jpg
"Virtually no one who is taught Relativity continues to read the Bible."

John Swift
Registered User
Join date: May 2004
899 IQ
#23
When designing a bass enclosure whether it is for Bass guitar or the bottom of a PA rig you have many options to consider. The first option is which type and make of loudspeaker to use. Budget loudspeakers offer the best value for money and with todays developement in technology you can get a very good loudspeaker at a very reasonable price, for my money Eminence speakers take a lot of beating, Once you have chosen your configeration ie 10s 12s 15s + horn (my favourite being 15" + 10" + Horn) you must then design your enclosure. A cab with one particular brand of speaker will sound totaly different with another brand in it, this where the Thiele Small parameters play a vital part. Next you must choose the materials, for a bass enclosure 18mm (3/4") plywood all round is best, it is lighter and stronger than MDF or chipboard, Finnish Birch Ply is the ultimate followed by Marine Ply. Finnish Birch has a very tough exterior and therefore can be painted the others need some form of covering. The tuning ports in a Bass Reflex cab require precise tuning for the required resonance frequency of the cab, 4" plastic drain pipe is the handiest material. To tune a cab properly you need a frequency counter and a signal generator as well as being a mathematical genius (the easiest way is to purchase one of the design programmes available), but you will still need a counter & generator. If your cab is tall (15+10+Horn) a front to rear brace near the centre of the cab is essenrial. If you design your cab and work out a cutting list any decent timber merchant will be able to cut a sheet to you measurements you will have to pay for each cut but it saves a lot of time. a hole cutter will cut out your tuning port holes I make a simple compass using two woodscrews through a scrap piece of wood to mark out the speaker holes most manufacturers supply dimensions. if a 10" speaker is in the same cab then unless it is of the enclosed chassis type it will need its own airtight section otherwise the 15" will affect it, you will also need a three way crossover if using this configeration a two way if you are using a 15" + horn.
When constructing the cab all joints must be screwed and glued, handles and socket panels must be secure and airtight. The two most popular ways of protecting the speaker cone is either a round grille held in with clamps or one of the various pattern metal messhes, I prefer to fasten in the speakers using 'T' nuts and bolts. For covering the cab I use Flight case type edging and corners with Vynil covering on the panels>
My own personal rig consists of an Ashdown preamp, a 5 band parametric EQ, a 400watt 4 ohm 15" sub bass cab with its own 450 watt amplifier module bult in and a 400 watt 4 ohm 15" + Horn full range cab once again with a 450 watt built in amplifier.
module.
My guitars are a Musicman Stingray 5 and an G&L L2500 tribute Bass.
I live in England, I have built my own many other musicians/artistes enclosures for a good number years now, I object to paying the very high prices that most manufacturers charge.

All The Best Bassman
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
Bubonic Chronic
Your bucket 'o love
Join date: Aug 2002
1,115 IQ
#24
^^ Thanks, I'm glad that there are other contributors to this thread with some know-how and experience behind them.

I just approached mine from the standpoint of killing all modes (resonance) thus the cabinet doesn't resonate at all. I kind of started with just a box, then made modifications as I went, like a front-to-back brace (just a pair of studs) and the kind of port I described.

Yours is certainly more conventional, I wouldn't mind knowing how to pick a resonant frequency and tune a cab, etc. on my next projects.

Got any photos/diagrams?
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chrisharrison
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#25
i do believe they are nodes ot modes
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Bubonic Chronic
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#26
No, they are modes. Nodes are the zero crossings of a wave, the point at which the air pressure is equal to the average pressure.

Modes are resonant frequencies within an enclosed chamber. Nodes are related, though. Your primary mode frequency between two rigid surfaces will be the distance between a node and an antinode, the point at which the pressure differential between your sampling point and the surrounding air is a maximum.
Attachments:
node vs mode.jpg
"Virtually no one who is taught Relativity continues to read the Bible."

John Swift
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#27
Hi Bibonic Chronic its nice to see someone prepared to spend a great deal of time as you have helping others.
If people had helped me as much when I was less experienced I would have saved a lot of time and money.

I hope you don't mind me adding a few tips.

Things to remember :- replacing a loudspeaker with a much more expensive one can just as easily make the cabinet sound worse and not better, cabinets if properly designed are tailored for the intended speaker.

Resonance can be reduced by using adhesive panels (the type used in automobiles for deadning sound)

A Bass loudspeaker likes to receive a good quality signal, therefore the amplifier must be up to the job, very often when people think that their speaker is flapping (farting) it is actualy reproducing the results of a clipped signal. Clipped signals on bass damage a speaker more than overloading it. I always use more amplifier watts than the rating of the speaker, as speaker technology has advanced so much in recent years it is within reason ok to do this.

More so on bass than any other band instrument will you find different venues effect your sound that is why I also us a 5 band parametric EQ this lets you fine tune your sound better than a 31 band graphic EQ. A parametric EQ lets you control the level and bandwidth of a frequency without filtering it out as in a graphic EQ

Hope that this is of help

Keep up the good work Bubonic

Regards Bassman
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
Bubonic Chronic
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#28
^^ absolutely.

Glad to have you on board.
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xifr
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#29
Bubonic, you are the next powerfreak, but for cabinets. Why? I don't understand a single thing you're saying, good job!

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Kirk_Krobain
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#30
Cool thread can't wait to see the pictures.

For the modes if anyone is wondering how you see if your going to get modes with your cab the way you calculate it is. In metres you do the Length times 2 then 340 divided by your answer and do the same for the Width and Height. Then on some paper draw three coloums and write your answer for the Length in one , Width in another and Height in the last. You should then have something thats like:example 30Hz -Width, 50Hz - Length, 20Hz- Height to work out the resonant frequencies for the say the Width add your original answer to your answer you just got so it will be something like this: 30Hz, 60Hz, 90Hz, 120Hz, 150Hz, 180Hz, 210Hz, 240Hz,270Hz,300Hz. The gap inbetween the numbers is 30 which was the original answer so the Length would be 50Hz,150Hz, 200Hz, 250Hz, 300Hz. The modes are when you have the same resonant frequencie in another coloum so in my example I have modes at 60Hz, 120Hz, 150Hz, 180Hz, 200Hz, 240Hz, 300Hz I actually picked a really bad shape for my cab. You don't want these modes so you have to design your cab shape around them to avoid getting any. You don't measure modes over 300hz as it's only the bass and some of the low mids you have to worry about.

Hz = Hertz

I hope this helps as I didn't see it explained anywhere and I hope the thread starter dosen't mind either, as I know working out modes can be confusing.
If my post didn't make any sense it's because it wasn't suppose to.
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Last edited by Kirk_Krobain at Nov 20, 2004,
John Swift
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#31
Reply to :- Kirk_Krobain

Hi Kirk
One of the problems with cab manufacturers is that often their main concern is getting the optimum number of cuts out of an sheet 8 Foot by 4 Foot (2440mm x 1220mm) sheet of wood. this often compromises the effidiency of the cabinets.

Unfortunately most musicians who try to construct their own cabs possess very little knowledge regarding woodworking requirements (tools methods etc), also, very few posses the equipment required to set up and tune a bass enclosure properly.

As each individual loudspeaker has its own characteristics it will always be a compromise when building your own cab if you don?t posses this knowledge and equipment.

As I said in an earlier reply there is cabinet design software available if anyone is serious about designing their own bass cabs.

Bassman
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
Bubonic Chronic
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#32
Using prime dimensions goes a long way towards fighting modes. 17cm long, 31 cm tall, 63cm wide...something like that. Also, shy away from square shapes. Tilt the face a bit, at a small angle upwards. Angled surfaces are less prone to modes.

And bassman is right, building bass enclosures is really involved. Guitar cabs are relatively easy as most of the energy is > 300 Hz. At that point, you're just dealing with building a rigid enclosure, something that won't fall apart. Also, attaching the speakers to a face constructed of studs facing width-wise (the short side to the speaker) will reduce vibrations (which suck up energy) considerably.
"Virtually no one who is taught Relativity continues to read the Bible."

power freak
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#33
Originally posted by Bubonic Chronic
And bassman is right, building bass enclosures is really involved. Guitar cabs are relatively easy as most of the energy is > 300 Hz. At that point, you're just dealing with building a rigid enclosure, something that won't fall apart. Also, attaching the speakers to a face constructed of studs facing width-wise (the short side to the speaker) will reduce vibrations (which suck up energy) considerably.

To carry on the point the most famous guitar cabinet in history (the Marshall 4 x 12) was to designed to be the smallest possible size that the 4 speakers can fit in!

This is a really interesting thread, I have never really got into speaker cabinet design before I am normally more concerned about the amplifier! Which I guess is best considering my wood working skills aren't great!

With the next Hifi collective order I might pickup a cabinet design book, it sounds like fun.

I can't wait until I can get back to making my amp and writing some more articles and stuff but I have been so busy lately, why does school always prevent me from doing anything.

Congrats on the cab man

For sale: Early 1985 Ibanez AH10 (Allan Holdsworth signature model) PM for details
Last edited by power freak at Nov 23, 2004,
John Swift
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#34
Hi power freak
In the 60s when Jim Marshall began building amps and cabs for people like the "Who" etc he first built an 8 x 12" but it was to big hence 2 x 4 x 12"s.
The main reason for the mutiple speaker loading was that in the sixties very few 12" speakers were rated ar anything over 25 Watts. I believe that the blue speakers in the Vox AC30 were only rated at 15 watts each, on bass it was terrible, I know, I had an AC30 for bass.
Anybody could build a high wattage amplifier, but nobody, in those days, had the technology to produce a speaker to handle the power hence 4 x 12"s and 2 x 15"s 18"s etc.
With speakers now being more effecient and able to handle more power you don't see the massive rigs at concerts these days that you used to do, where banks of massive JBL 4560 & 4520 bass bins were stacked up.

You can buy the best bass amp in the world, but, without a first rate cab you'r wasting your money.

Regards Bassman
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
Bubonic Chronic
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#35
You only get a 3dB increase for a doubling of the power. That means 2X12 is only barely louder than 1X12. 2X4X12 is just a touch louder than 4X12...

That's why it's a good idea to buy good speakers in the first place.
"Virtually no one who is taught Relativity continues to read the Bible."

John Swift
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#36
Good reply Bubonic
I don?t think that many people realise that to double your acoustic power you have to have ten times the wattage i.e.: - a 300 watt amplifier will be needed to deliver twice the acoustic power (twice as loud) of a 30 watt amplifier.
The real benefit of the multi speaker cabs is the actual volume of sound that they provide.
It is much easier on the ears to hear the same Dbs from a 4 x 12? than a 1 x 12?; this is called volume of sound and should not be used in the same context as loudness, which basically means more Dbs not fullness of sound as provided by volume.


Bassman
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
acdc101
pft
Join date: Jun 2004
295 IQ
#37
How much did the cabinet cost all together?
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Bubonic Chronic
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#38
^^ About $300, but that's because the single 15" cost me about $150 from the factory. I spent a lot on speakers.

Actually, the cabinet I built has a lot of flaws, and I've considered rebuilding it. Instead, though, I'm thinking of just keeping it around and building a new one now that I know more. I learned a bunch from building that first one, and the rest I picked up from books and stuff.

It does have a great sound for my fretless Jazz bass. The two have always gone well together.

Your cab will cost about as much as the speakers, because wood is cheap. Also, industrial carpeting is, like, $2 a yard and the paint is dirt cheap, too, because you don't have to buy much (if you paint it.) A can of spray paint will do fine, that's about $1.50 to $5.00, depending.
"Virtually no one who is taught Relativity continues to read the Bible."

metallicaman80
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Join date: Sep 2003
10 IQ
#39
so if i were to buy 4 celestions and make a cab outta that...then i bought an ADA MP-1....would that be it....because that would be only like 400 some odd dollars...thats nuts.....would it be good quality?
Bubonic Chronic
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#40
As mentioned above, a 4X12 Marshall cab was originally designed to be as small as possible (thereby saving money on wood.)

So yes, it would be (roughly) the same quality as a Marshall cab. The thing is, guitar cabs are much simpler to design than bass cabs because wattages are much lower and frequencies are much higher, so you are only concerned with the structure and the wiring. As long as the face and sides are air-tight, you can even leave the back open.
"Virtually no one who is taught Relativity continues to read the Bible."