DIY 15" cab build: calling the buildmeisters!

[Fine Cut]

EDIT: post edited to remove supurfluous mid-driver discussion.

simply put, i plan to build myself a 15" cab in the next couple of weeks. i've given myself a strict $200 budget, and i've chosen my building material, driver and basic hardware; jacks and such. the woofer will be an Eminence CA154, or Eminence Basslite Neo, and it will go into a 3.375 c.f.

this is my first venture(obviously) into cab building, but i feel pretty confident once i figure out my components. this thing doesn't need to sound amazing, just good enough to work through a 3-piece gig with decent volume. any and all help here is greatly appreciated

[rpsands]

Leland @ Speakerhardware is making prebuilt fEarful crossovers.

[MuzikMan]

You are interested in using a two way passive crossover. With this design the crossover receives the signal. It splits the signal. You now have two completely independent signal paths. The components of each path is chosen to work with a particular impedance (ohms). Be sure to chose your drivers with this in mind.

For example, if you buy a prebuilt two way passive crossover that states it is for an 8 ohm system, each driver (woofer, mid) needs to be an 8 ohm driver for the system to work properly. In the end you have an 8 ohm cab.

If you install drivers with the wrong impedance then the crossover will work at an unexpected frequency and the results will be very unsatisfying (bad sound, possible blown drivers).

[MuzikMan]

You should also be aware that the woofer and mid drivers should be in their own box. For you that means a box in a box for the mid driver. There are also sealed back mid drivers that drop right in without a separate box, but these setups usually have unwanted artifacts and are only recommended if your system is already built and you want a quick and dirty drop in.

[Passinwind]

Originally Posted by Fine Cut

simply put, i plan to build myself a 15/mid cab in the next couple of weeks. i've chosen my building material, driver and basic hardware; jacks and such. i originally planned to make the cab a basic 15" cab, but the more i'm feeling like i'd like to throw a mid-range into one of the corners, and i'd like to have the higher frequecies, but i don't care much for tweets.

what i'm unfamiliar with is what to consider as far as Ohm ratings for the mid-driver and crossover, to maintain atleast a stable 4 Ohm load.

It doesn't work that way. Neither driver is a stable load to begin with. You start your crossover design by at least looking at the manufacturer's impedance plots for the drivers, but to do it right you need to actually measure them yourself in the cab they are going into.

Start with the DIY speaker build FAQs stickied at the top of the Amps Forum. The fEarful threads and Bill Fitzmaurice's forum are good resources as well.

[billfitzmaurice]

what i'm unfamiliar with is what to consider as far as Ohm ratings for the mid-driver and crossover, to maintain atleast a stable 4 Ohm load. would the Ohm loads of the woofer and mid run seperate one-another via the crossover? would the 4ohm woofer and a 4 Ohm mid wired series result in an 8 Ohm load?

If you don't already have a very firm grasp on how impedance loads and crossovers work you're not in a position to design your own cab.

this is my first venture(obviously) into cab building, but i feel pretty confident once i figure out my components. this thing doesn't need to sound amazing

Your first build can sound amazing, if you don't try to reinvent the wheel. The fEarful, for one, has already done all the grunt work, you just have to put it together.

[BurningSkies]

Its not going to happen at $200 bucks though...

Whether its a fEarful, or any other home brew. Once you're in on the crossover parts, two speakers, any additional hardware and some wood....

[1n3]

I don't want to be overly critical, but it doesn't look like you've got this very well thought out. Wonder if you picked the woofer on the basis of it's low cost, and 4 ohm rating.

18 x 18 x 18 is a rather awkward size, IMO. Curious where you got those numbers. You don't say if that's interior or exterior, but either way, there won't be room for a mid in the corner of an 18 x 18 baffle.

Your comment about wiring the woofer and mid in series is another indicator that you are not ready for a project like this.

As others have suggested, your best chance of having a good result is to use a proven design. Otherwise, my suggestion would be to study a lot more before you start, lest you waste your money. Also, if you're on a tight budget, consider trying to find some good speakers on the used market (eBay, CL, TB classifieds...).

[Fine Cut]

Hmm. I see what you mean. I chose the driver on it's price, but the more I read, the more I'm thinking maybe I should just spend more on the proven neo and build a one way box lol. Atleast that would give me a better starting speaker if I decide to go two-way later.

I can't help but wonder though; is it that design intensive also for guys who build a tweeter into their cabs?

The 18x18x18 box design is based off the markbass 151 dimensions. I like the idea of a nice squarish cab (Eh, personal preference), and the resulting volume seemed like it would work well with the cheaper Legend, or the Eminence Neo, whichever I chose to go with. If I decide to shrink the internal volume, the depth will probably be shallower to accommodate.

I reckon a mod should change this title to reference a 15" one-way build...

[BurningSkies]

Eh.

Speaker 50 bucks. Mid ?$, Crossover $40. Grill? getting one cut will be about 25$. Depending upon the l-Pad resistors, you could be another 20$+ ...Feet, handles, Jack plate, jack components=?, screws & bolts, Decent wood 40$, glue, damping material etc. ?. Shipping for all this stuff, more than you think.

Result? I don't know you keep talking about tonal goals, but does the speaker you've chosen fit any particular goal? How have you tuned the cab? What about the porting?

[JMac4strngr]

I am in no way trying to discourage You from building Your own cab, but there is a lot more work to it than buying the parts, cutting the lumber and assembling. DIY cabs are cool and fun to build, but You'd need to be prepared to do a lot of homework if You are expecting decent results. I have built a couple and they can go from being a fun project to a huge dissapointment really quick if You haven't done the research to get optimum results.
I guess what I am trying to say is, "Homebrew cabs" (for the off the street guy/ hobbyist who try to design and build them themselves) are allways gonna be a mystery cab. You will have no idea how it's gonna sound until You finish it and plug it in. At that point if it sounds bad, You have already spent the cash on the drivers, lumber and goodies and have a cab that sounds like poop. On the other hand it may sound decent, but there is no way You will ever be able to sell it and return Your investment.

IMO, You be better off buying a used factory built 15 cab for the $200 You have and calling it a day.

[Fine Cut]

Originally Posted by BurningSkies

Eh.

Speaker 50 bucks. Mid ?$, Crossover $40. Grill? getting one cut will be about 25$. Depending upon the l-Pad resistors, you could be another 20$+ ...Feet, handles, Jack plate, jack components=?, screws & bolts, Decent wood 40$, glue, damping material etc. ?. Shipping for all this stuff, more than you think.

Result? I don't know you keep talking about tonal goals, but does the speaker you've chosen fit any particular goal? How have you tuned the cab? What about the porting?

It seems like working out the crossover and mid/woofer combination are out of my practical reach right now. I started this thread to feel that concept out and I got the answer on it. Specific tonal goal would be something approaching a smooth round mid-range with response down to D. I play 4 string, so low B extension isn't paramount.

I still haven't ran these dimensions through winISD, but I'll be looking at porting and tuning further tonight

[dhomer]

I've been modeling a few speakers on WinIsd lately to get some inspiration for a commercial venture... that CA154 needs a 9cu.ft box to run vented.. Tried modeling smaller boxes w/it, and the line ain't pretty... For your intended box size, the Delta 12LF would be a better choice..

[1n3]

Originally Posted by Fine Cut

Hmm. I see what you mean. I chose the driver on it's price, but the more I read, the more I'm thinking maybe I should just spend more on the proven neo and build a one way box lol. Atleast that would give me a better starting speaker if I decide to go two-way later.

Yeah... job gets simpler, cost comes down. I don't see a clear winner between these two speakers (CA154 and C2515). If you threw the 3015 into the mix, that'd be different.

I can't help but wonder though; is it that design intensive also for guys who build a tweeter into their cabs?

I don't know. Tweeter crossover design might be more forgiving because the frequency range is less critical to bass, there's less power there, and the components are smaller. I could be wrong.

The 18x18x18 box design is based off the markbass 151 dimensions. I like the idea of a nice squarish cab (Eh, personal preference), and the resulting volume seemed like it would work well with the cheaper Legend, or the Eminence Neo, whichever I chose to go with. If I decide to shrink the internal volume, the depth will probably be shallower to accommodate.

I find a cab that deep awkward to move. But if you've lugged one that size and like it, cool.

Originally Posted by dhomer

I've been modeling a few speakers on WinIsd lately to get some inspiration for a commercial venture... that CA154 needs a 9cu.ft box to run vented.. Tried modeling smaller boxes w/it, and the line ain't pretty... For your intended box size, the Delta 12LF would be a better choice..

Sounds like you don't want any mid-bass hump; something most users of these speakers probably accept. The cab sheet for the CA154 shows a "large vented" cab at 5.66cf; medium vented is 3.75cf. And the Basslite appears to like a larger volume than the CA154.