Need Help Building a Cab...

pzaxtl

pzaxtl

Gibletsologist
I'm building a 2x12 cab. I don't need any help with the actual construction/woodworking but the design details. I'd like to build a smaller sized 2x12 ala Dr. Z ZBest. I want a closed back cab and am thinking of a ported design to reduced standing waves and provide a bigger bottom end.

So, if you have any ideas on porting, (size, length and materials) dampening, interior volume requirements, etc. please let me know.

Most likely I'll build it out of Baltic birch ply, dovetailed joinery and maybe veneered with some crazy looking hardwood.

I just need help with the actual design parameters/requirements. Any suggestions or links to pertinent information is much appreciated. Thanks!
 
Re: Need Help Building a Cab...

No one? huh?! I guess I shouldn't be too surprised. From what I've discovered searching the net, most cabs werent designed, just built. Looks like I'll have to head to the local library... unfortunately, that means I'll probably have to decipher overly technical sources full of equations like this:

b4fefe1ddd56023d2fd87e7fbed8f048.png
 
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Re: Need Help Building a Cab...

I was going to build a "super" 2X12 and found alot of resources online, a great sounding cabinet is definately designed and not just built ..openbacks are no brainers but closedback and especially ported need to be designed.

You can copy a proven design or build it ground up, I ended up re-tuning a ported bass 2X12 for guitar and it kicks @$$ ,because its almost the size of a 4X12 with the speakers diagonal and its 16"deep.

anyway heres one link to get you started, but I will have to find some of the more basic hows and whys, because my build was 2 hard drives ago.


http://www.webervst.com/spkrcalc/cabmenu.htm
another
http://www.ajdesigner.com/speaker/bcv.php

you can get speaker parameters from speaker manufacturers websites\
Peace!
 
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Re: Need Help Building a Cab...

Karmadog777 said:
I was going to build a "super" 2X12 and found alot of resources online, a great sounding cabinet is definately designed and not just built ..openbacks are no brainers but closedback and especially ported need to be designed.

You can copy a proven design or build it ground up, I ended up re-tuning a ported bass 2X12 for guitar and it kicks @$$ ,because its almost the size of a 4X12 with the speakers diagonal and its 16"deep.

anyway heres one link to get you started, but I will have to find some of the more basic hows and whys, because my build was 2 hard drives ago.


http://www.webervst.com/spkrcalc/cabmenu.htm
another
http://www.ajdesigner.com/speaker/bcv.php

you can get speaker parameters from speaker manufacturers websites\


Peace!
Click to expand...


Thanks, man! :D I appreciate the info. I'm definitely not wanting to just jump into it. I'd much rather think this through since I'm wanting to build a ported, closed back cab and I'd be really annoyed if I invested all that time and effort and it sounded like crap. :laugh:
 
Re: Need Help Building a Cab...

Are you sure you want to dovetail plywood? I donno how that'll work out...

Anyways, yeah there are formulas for vent dimensions based on the speaker and box as Karmadog777 linked for you. Usually ported enclosures are used to extend and flatten the frequency response down low, so I'm not sure that would be so great for guitars... There's probably a reason why there aren't many ported guitar cabs.
 
Re: Need Help Building a Cab...

I meant to mention that I build custom cabinets for a living(kitchen and bath not speaker) dovetailing plywood is not a good idea. Rabet or simple butt joints are the way to go with ply. If you wanted to veneer like you mentioned, then you veneer after its built for a seamless look.

As far as ported 2X12 for guitar YES ! Its a great idea, listen to the ones that ARE ported and you will be a believer, yes it does extend the bass response so you end up with a 2X12 that sounds like a 4X12 Check out a BuzzBomb cab by EarCandy or the G-Flex 2X12 by Genz Benz

I am speaking from a perspective that I love low end power from guitars, it came from being a King's X fan in the 80s and feeling Ty Tabors guitar heart punch me everytime he hit a chord at a small club in Orlando. At that time buzzy and tinny was the guitar sound of the day, and that tone and power was something different, something I have chased after ever since.
 
Re: Need Help Building a Cab...

In general the outside dimesnsions will end up about 30-inches wide by about 12 to 13-inches deep, by about 24-inches tall.
 
Re: Need Help Building a Cab...

Lake Placid Blues said:
In general the outside dimesnsions will end up about 30-inches wide by about 12 to 13-inches deep, by about 24-inches tall.
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mine is 26W X 25H X 16D ...then again a bunch of morons play their basses thru these

You can build it pretty much any size you want, its the porting that will need to be calculated so it dont fart and weeze
 
Re: Need Help Building a Cab...

Several years ago I built a ported 2x12 for the other guitarist in the band I was in at the time. Mic'ing up wasn't always an option. As I recall it was 29" wide and 14" deep and about 22" tall (I'm not too sure about the height, but the depth was 14" for sure). I just experimented with the port tube by trial and error and it ended up sounding huge.
 
Re: Need Help Building a Cab...

supernosher said:
Are you sure you want to dovetail plywood? I donno how that'll work out...
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If I was using veneer core plywood, you're right, I wouldn't want to join it with dovetails because there's too much chip out of the veneer. I would use box joints (finger joint) instead. The alternative is to cut them by hand, which I wasn't planning to do since chisel work in plywood is just plain stupid. However, baltic birch is composed of 1/16" plys and veneer vs. 1/40" veneer you get with veneer core plywood. In fact, dovetails look very nice with baltic birch ply.
 
Re: Need Help Building a Cab...

Karmadog777 said:
I meant to mention that I build custom cabinets for a living(kitchen and bath not speaker) dovetailing plywood is not a good idea. Rabet or simple butt joints are the way to go with ply. If you wanted to veneer like you mentioned, then you veneer after its built for a seamless look.
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Actually, I've been a semi-serious (meaning I have more machinery than time) woodworker for 20 years. I would agree with you that rabbets would be much simpler and probably strong enough, and were I to use standard veneer core ply that might be the approach I would take. With Baltic birch ply, there is much less concern with chip out because every ply (including the face) is 1/16". I've done it numerous times with good results. Box joints would also work and be nearly as strong. However, after thinking about it, I may just go with a splined miter, especially if I decide to veneer the case.
 
Re: Need Help Building a Cab...

Karmadog777 said:
mine is 26W X 25H X 16D ...then again a bunch of morons play their basses thru these

You can build it pretty much any size you want, its the porting that will need to be calculated so it dont fart and weeze
Click to expand...

Yeah, that's the issue I want to be certain about. With a closed back cab, if the interior volume isn't sufficient, all those standing waves will kill the sound, which is why I want to build a ported cab. So far, everything I've read states that the ports need to be optimized for ideal sound characteristics. Funny, most of the info I've come across heretofore has been for loudspeakers or subs, which are a little different design -- I think.
 
Re: Need Help Building a Cab...

My custom 2x12 bass cabinet = 30"x25"x15" www.emperorcabs.com I believe this is the same as their oversized guitar 2x12s, just a deeper + ported.

My 4x12 guitar cab = 28"x28"x14"

It is baltic birch ply that is dovetailed....looks amazing.
 
Re: Need Help Building a Cab...

pzaxtl said:
Yeah, that's the issue I want to be certain about. With a closed back cab, if the interior volume isn't sufficient, all those standing waves will kill the sound, which is why I want to build a ported cab. So far, everything I've read states that the ports need to be optimized for ideal sound characteristics. Funny, most of the info I've come across heretofore has been for loudspeakers or subs, which are a little different design -- I think.
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How a port tube works: The negative or backward signal from the speaker comes out of the hole with a slight delay. Lower frequencies move more air so this is predominantly what you will hear from the tube. The speakers do receive an increase in sensitivity because the extra low end + there is no compression inside the box to worry about. This is why a correctly made 2x12 port can sound as loud as a sealed 4x12.

Tuning the cab is important. You will get a 3db increase at the frequency of the port with a steep roll off below that. I would research the speakers you are using and the f0 value will work great for the tuning frequency.

Let me know if you need any more help from the tuning aspect. I used to work with speakers + have tons of info on box design.
 
Re: Need Help Building a Cab...

ksmith63 said:
How a port tube works: The negative or backward signal from the speaker comes out of the hole with a slight delay. Lower frequencies move more air so this is predominantly what you will hear from the tube. The speakers do receive an increase in sensitivity because the extra low end + there is no compression inside the box to worry about. This is why a correctly made 2x12 port can sound as loud as a sealed 4x12.

Tuning the cab is important. You will get a 3db increase at the frequency of the port with a steep roll off below that. I would research the speakers you are using and the f0 value will work great for the tuning frequency.

Let me know if you need any more help from the tuning aspect. I used to work with speakers + have tons of info on box design.
Click to expand...

Thanks, I just may take you up on that offer. Truth be told, I'm less concerned with the box dimensions than I am with getting the porting correct. Of course, I'm sure there is a strong correlation between the two, and I'd rather get that right from the outset than doing hit or miss, trial and error.
 
Re: Need Help Building a Cab...

supernosher said:
I'm not sure that would be so great for guitars... There's probably a reason why there aren't many ported guitar cabs.
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I'm certainly glad there are some. My two go-to cabs are a Buzz Bomb and a ported no-name 2x12 that I picked up used a long time ago.
 
Re: Need Help Building a Cab...

pzaxtl said:
Thanks, I just may take you up on that offer. Truth be told, I'm less concerned with the box dimensions than I am with getting the porting correct. Of course, I'm sure there is a strong correlation between the two, and I'd rather get that right from the outset than doing hit or miss, trial and error.
Click to expand...

Everything is connected....speakers, box size, ports. It can all seem intimidating at first.

PM me with speakers you are using and the size of the box you want. 28 ¼” H, 19 ¼” W, 13 ¾” D are the dimensions of the Dr. Z so that may be a good starting place.
 
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