DIY Kappalite 3015LF 'sub' - good idea?

jimcroisdale · #1 09-19-2011, 03:24 AM

Hi all,

I'm currently running a Trace Elliot RAH600SMX head into a new Schroeder 15PL (the tiny one!)

The rig is great and almost replaces what my Warwick 6x10 could do, yet all fits in the boot of my little car. I recently cured a buzzing grille problem on the Schro, and all is well.

However, at some gigs I feel the need for a little more low end, and as most of you know, the Shro's don't really have any.

So I thought about building an additional cabinet using a single Eminence Kappalite 3015LF, and then using the Trace's crossover/stereo output option to bi-amp the two cabs.

Would this work? Any thoughts?

Cheers,

Jim

Mr. Foxen · #2 09-19-2011, 03:39 AM

Probably need a seperate power amp for it, and once you have a 3015LF on the go, you only need a 6" mid driver to keep up with the rest of the audio spectrum (maybe a tweeter).

jimcroisdale · #3 09-19-2011, 03:42 AM

Well, the way I figure it, I may as well buy a 3015LF before the prices go through the roof.

I can always make a fEarful-esque down the line.

I also know the the Trace's 300w into 8ohm isn't ideal.

BUT - I just need a little more low end, and surely this setup would provide that?

oerk · #4 09-19-2011, 03:43 AM

With a proper crossover, I don't see why not. Your Schroeder cab will be reduced to a dedicated mid, though.

OzzyGreg · #5 09-19-2011, 03:48 AM

.
I'm no speaker design expert, but I'd imagine if the new cabinet was designed around the 3015LF then your proposal would definately work.

Assuming you don't know this already......

There's a bunch of info on 3015LF cabinet design here: http://www.eminence.com/pdf/Kappalite_3015LF_cab.pdf

Then there's always Greenboy's fEARful designs:
greenboy's fEARful downloads

.... and Bill Fitzmaurice's stuff:
http://www.billfitzmaurice.com/

Good luck!
Greg

Mr. Foxen · #6 09-19-2011, 04:04 AM

Might be best selling the Schro to fund a whole Fearful build. Only problem is the no cab gap while you make it.

jimcroisdale · #7 09-19-2011, 04:09 AM

I see on the eminence website, the last plan seems to be what I would need (the others are for PA applications).

They all mention a steep hi-pass filter set to 30-40hz. Would I definitely have to have this built into the cab? The Trace has a selectable crossover frequency, but no hi-pass for the woofer output.

Oobly · #8 09-19-2011, 04:23 AM

I'd say build a fEARful 15sub. Has a passive lowpass filter, so you can send a full range signal to it and you can later add a separate headcase if you want to turn it into a "full" 15/6.

Since it's a fEARful, you know it will work well, and you can get support over at the fEARful forum or here if you need it, since others have got experience building these.

jimcroisdale · #9 09-19-2011, 05:04 AM

Would it definitely need a passive hi-pass filter though? That's something I've not read of on here, although It sure sounds like the Schroeder has one (set to about 200hz....)

Oobly · #10 09-19-2011, 05:19 AM

No need for a hi-pass filter when running the fEARful. It can take all the lows you can give.

I asked about this on the fEARful forums: fEARful

jimcroisdale · #11 09-19-2011, 05:44 AM

I think even the fearful sub is too much for my woodworking facilities at this time.

I was looking at something much more rudimentary unfortunately.

Just a simple vented ply box with handles, corners, and a grill of some type.

I know it won't perform 100%, but then I don't really need it to at the moment. I just need a little extra oomph to add in what the Schro is missing.

Part of the problem is that the Trace cost me a lot of money as it is a mint example so I'm loathe to sell it because i fear I'd lose money on the deal overall. So I'm kinda attracted to a 2x cab setup for a) portability and b) flexibility.

At this point, £150 for a 3015LF, plus the cost of materials and time to build a basic cab is probably the cheapest solution to my problem without buying a junk speaker or second-hand item.

Oh, I dunno!

Oobly · #12 09-19-2011, 06:07 AM

Well, I built my 15/6/1 with a handsaw (and electric jigsaw for the round driver holes), glue and nails, no clamps or fancy equipment.

I don't see how it could get much simpler (I mean, even I was able to do it), except by leaving out the bracing. It's all basic butt jounts. The glue that is recommended can make up for slight inaccuracies (filling gaps up to 1/4" if needed), too.

JdoubleH over on the fEARful thread mentioned a great technique to use if you use nails. Cut the head off one and use it as a drill bit to make the holes where you will whack the nails in later to hold the panels together. It goes deep enough to give a straight guide for the nails and gets the pieces aligned how they were when you drilled. A great help when get to that stage. Would be good to have someone to help hold the panels in place when you do the drilling.

Anyway, it's worth the effort IMHO.

parapentep70 · #13 09-19-2011, 06:12 AM

Quote:

Originally Posted by jimcroisdale

I think even the fearful sub is too much for my woodworking facilities at this time.

I was looking at something much more rudimentary unfortunately.

Just a simple vented ply box with handles, corners, and a grill of some type.

I know it won't perform 100%, but then I don't really need it to at the moment. I just need a little extra oomph to add in what the Schro is missing.

Part of the problem is that the Trace cost me a lot of money as it is a mint example so I'm loathe to sell it because i fear I'd lose money on the deal overall. So I'm kinda attracted to a 2x cab setup for a) portability and b) flexibility.

At this point, £150 for a 3015LF, plus the cost of materials and time to build a basic cab is probably the cheapest solution to my problem without buying a junk speaker or second-hand item.

Oh, I dunno!

I think a fEarful Sub is very close to your idea of minimalistic cab. One of the best things about Greenboy designs is that they are "simple, as simple as possible, but not simpler". What I call a true piece of engineering.

I designed and I am building something slightly different for a number of reasons. Just a different optimization. I had a look at fEarful designs and I was overwhelmed about details, I thought the original design could be complex. But when I started working on my design and dealt with details I began to understand fEarful designs are simpler than the simplest effective solution I considered.

parapentep70 · #14 09-19-2011, 06:14 AM

Oobly, you wrote it faster!

billfitzmaurice · #15 09-19-2011, 06:15 AM

Quote:

Originally Posted by oerk

With a proper crossover, I don't see why not. Your Schroeder cab will be reduced to a dedicated mid, though.

+1, and in that role it's at least four times the size required.

Quote:

I was looking at something much more rudimentary unfortunately.

Just a simple vented ply box with handles, corners, and a grill of some type.

You only get one chance to do it right the first time.

IMO you only add to a system to get more volume, not to get a different sound. If you don't like the sound of your cab get one that you do like the sound of, then use two if one isn't enough. The only exception is if you run a smaller top along with a true woofer, using a crossover, with the physical size of the bottom being at least twice that of the top.

chokeslam512 · #16 09-19-2011, 06:27 AM

Quote:

Originally Posted by jimcroisdale

I think even the fearful sub is too much for my woodworking facilities at this time.

I was looking at something much more rudimentary unfortunately.

Just a simple vented ply box with handles, corners, and a grill of some type.

I know it won't perform 100%, but then I don't really need it to at the moment. I just need a little extra oomph to add in what the Schro is missing.

Part of the problem is that the Trace cost me a lot of money as it is a mint example so I'm loathe to sell it because i fear I'd lose money on the deal overall. So I'm kinda attracted to a 2x cab setup for a) portability and b) flexibility.

At this point, £150 for a 3015LF, plus the cost of materials and time to build a basic cab is probably the cheapest solution to my problem without buying a junk speaker or second-hand item.

Oh, I dunno!

Why not order a fEarful Cut kit? Kinda like an Ikea piece of furniture; shipped flat and ready to assemble. Warning, the fEarful kit will actually difer from the Ikea stuff in that it will contain all pieces necessary to complete the build.

jimcroisdale · #17 09-19-2011, 06:46 AM

Quote:

Originally Posted by billfitzmaurice

+1, and in that role it's at least four times the size required.
You only get one chance to do it right the first time.

IMO you only add to a system to get more volume, not to get a different sound. If you don't like the sound of your cab get one that you do like the sound of, then use two if one isn't enough. The only exception is if you run a smaller top along with a true woofer, using a crossover, with the physical size of the bottom being at least twice that of the top.

Well, I'm kinda stuck with the Trace Elliot head, and seeing as it can biamp 2x 300w into 4ohms, I may as well go with a woofer/top cab setup. The individual cabs can be smaller too, so I can get one in the boot and one on the back seat of my little car. This is very important as I have no other means of getting it around!

So again, I understand what you are all saying. I know that for a biamp setup the Schro is overkill for the mid/top application, but my point is that this cab works well by itself 80% of the time, so it will be nice to have the choice between the two....

Oobly · #18 09-19-2011, 07:15 AM

I say run them both full range, letting the 3015LF fill the missing bottom end. No need to cripple the output of the Schroeder.

Just balance the levels til it sounds good to your ear.

Is your Schroeder a 4 or 8 ohm cab? The 3015LF is 8 ohm only.

jimcroisdale · #19 09-19-2011, 07:18 AM

The Schroeder is 4ohm - I had the speaker out yesterday while I was trying to fix the vibrating grille. It's one of the Celestion Neo's.

Yes, I could run them both full range I guess. That's the beauty of the Trace in many ways - 2 independent amps each with their own volume knob. I can get the Schro sounding good and then just bring up the low bass to taste.

will33 · #20 09-19-2011, 08:24 AM

I wouldn't run them both fullrange, defeats the whole purpose. The 3015lf likely wouldn't sound too good that way either. I'd make use of your heads biamping features and do it properly. You can run your schroeder fullrange by itself when that's all you need, bring the sub and biamp when you need it.

The sub isn't a complicated build, it's a box with some bracing. Having an active biamp system you can just load the speaker in the box and be done with it, no need for passive crossover parts, etc. You could add that stuff later if you ever get a different amp. There are flat pack kits that are already cut you assemble yourself or if the build seems too much for you, show the plans to a local carpenter and see what they'd charge. Just building it really isn't that involved, all the designing has been done for you.