backline 22" T39 + OT12

[lalexb]

Following advises here about "the best home for a pair of Kappa Pro 12" last year, I've made some progress. It's been a busy year, got a shoulder reconstruction in the way, and the spring and summer have been blessed with great kitesurfing conditions... Not much time left for my speaker builds, but finally, the T39 has now joined its Otop 12.
It is now close to completion, not 100% there, but fully usable. Had first practice tonight, and I was stoked by the headroom I have on my old 200W Holden amp and the real ability to boost the bass if I see fit. The only limit being the things starting to rattle in the room around.

Here are a few pics:

The access cover, v1.0:


Casters for Tilt 'n go. Indispensable! Need to practice my skills in stairs though...


In the workshop / showroom / practice room


I kept the crossover outside in its own box. That's my deviation from the plans. This allows me more flexibility and modularity in the wiring, and an easy wiring too. The Speakon 2 and Speakon 4 prevent any possible mistake even if tired and drunk.


In situ, I wish I could have tried some boundaries loading but the closest wall is way too far! Not that I had a lack of volume, but just to try...



Plenty of clean bass, as written on the tin. Stoked! Thank you so much Bill, and also everyone who shared knowledge and experience.

Special thanks to Ju @ Tangent Designs for letting me use his workshop and upstairs space. Many beer packs to come

[jcmbowman]

Looks awesome! Glad to hear you love the sound.

Casters for Tilt 'n go. Indispensable! Need to practice my skills in stairs though...

one minor tip - if you expect to do the stairs routine with the T39 fairly often, look into getting metal extrusions to protect the two side edges on the rear of the cabinet. You only really need to go about 12-18" up, but it looks better to some people if you go top to bottom. here's a link to some examples:
http://www.penn-elcom.com/Default.asp?MC=1106010&GC=200

If you put those puppies on the back side edges you have a smooth, durable surface (that can be relatively easily replaced if damaged) to help slide the box up stairs.

Just a thought. and Nice Work on the speakers!

[Tim A]

Nice work!

A while back someone posted some nylon stair glides, a little more durable and less expensive than the Penn Elcom. I wish I had that link. Anyone?

[Haysus]

I think they were the plastic rails for skate boards.I did a quick google search and found them a skate board suppliers. I'm probably goin to order some myself.

[bgavin]

Leland is going to stock them, IIRC. He used to deal skateboard parts, and is familiar with them. Very durable.

Look at the typical Ampeg box, i.e. 610, if you want to see the evolution of useful handles, casters, kick plates, etc.

[wallywally]

Nice work!

A while back someone posted some nylon stair glides, a little more durable and less expensive than the Penn Elcom. I wish I had that link. Anyone?

Try this

http://www.mcmaster.com/#2638t22/=ddhnw

This is Delrin black in color 5/16" thick in 2 " wide strips. Delrin machines very well and is very durable.

[Tim A]

That'd work Wally. @ 2" wide you could rip in in half and end up with a couple of 1" nom. strips, and at $1.09/ft you'd only need $2 worth for a cab. I didn't check shipping costs. Hopefully Leland will get some in.

[wallywally]

That'd work Wally. @ 2" wide you could rip in in half and end up with a couple of 1" nom. strips, and at $1.09/ft you'd only need $2 worth for a cab. I didn't check shipping costs. Hopefully Leland will get some in.

http://www.mcmaster.com/#2638t21/=ddpzw

[LelandCrooks]

Forgot all about this. I'll try to get it done in the next few days. Too much to do, too little me.

[novasak]

That McMaster stuff can be pretty slick too. So no resistance when sliding on some surfaces. and yes, very durable stuff that is.

good job on the t39!

[lalexb]

I remember those skateboard rails! Not sure it's that easy to find nowadays, but two strips of machined 15mm MDF would do the job too if I can't find nylon or ABS. Just screwed in, and replaced when they get too trashed. That would help also when sliding the cab in the van.
Good ideas, guys!

As for the sound, I heard some people saying that with horns, the sound mosly appears a few metres away from the cab, but I didn't really notice any of that and I had a pretty good clean loud sound even when standing just in front of the cabs, (a very pleasant experience!). I guess it's related to room modes and all of that.
And with the OTop thumping straight at my chest it would have been hard not to hear/feel myself playing (poorly).

A great cab that can very well overpower the other band members if used without consideration.
"With great powers comes great responsibility" ((C) Spiderman)

Next step, install a melded array in the OTop, for use as party/PA stuff. I don't think I need that for bass, but I might change my mind once I have it.

[Harley]

I remember those skateboard rails! Not sure it's that easy to find nowadays, but two strips of machined 15mm MDF would do the job too if I can't find nylon or ABS. .

Try a couple of your local engineering plastics stockists - Ludowici, Dotmar and Mulford are three companies that come to mind and have office in ChCh. They always have an offcut scrap bins in their sales office with strips of nylon etc that would be just the ticket...plus cheap.

[lalexb]

Next step, install a melded array in the OTop, for use as party/PA stuff. I don't think I need that for bass, but I might change my mind once I have it.

OK, it's been done and I love it!!!

(Bigger Pic)

The plans call for a 4 piezo array for bass guitar use, I thought it wouldn't hurt to put 8 of them instead, if I could still come up with a clever wiring to only use half of them. The cleverness is yet to come but I really enjoyed the sound of it. Now, when just running the iPod through the rig, the songs really come to live with the tweeters for something really clear and natural sounding, yet very loud. To the point I can't imagine yet pushing the master past 70% on the old 200W amp. That's stupidly loud! Maybe outside it'll be different. I guess the P.A. guys can crank the volume while staying well away from the speakers, but in my case, that's those SPL straight in the face! So it'll definitely a very good option for parties or events, even if it's plain mono.

As for what it's been built for, bass guitar, wow, I got quite impressed by the effect of the tweeters, there's still plenty of zing coming out of those strings and it just opens another dimension of sounds. Even just a bit of that dialed in makes the bass sing nicely. I just have to control it through the EQ and remove quite a bit of treble on the amp to be in some kind of flat position tone wise. By that I mean that from the bass EQ set flat I can boost or cut low, mids or highs and it is very responsive and very noticeable change in every direction. On my previous cabs, a ported JBL 15", then a sealed 2x12" containing those Kappa Pro, I had to be really extreme with my on board EQ. When I wanted treble I had to turn them fully on the bass. When I wanted noticeably more bass, I had to be bold with my EQ. Now, I can have a lot more variation because the cabs respond so well to small changes. I have to learn the great art of subtlety! Subtlety in the playing also takes a complete new meaning. Let the fingers do the sound, they say!!!

I was just not initially thrilled with the sound produced by the tweeters when I stomped on the old MetalZone, but once I removed quite a bit of the highs at the pedal, it sounded all sweet (as I wanted it to sound, I mean. No sweetness in that thing!)

Overall I'm super stoked with all of that, there's some work required to control my tone a bit more, and find the sweet spot within the vast possible sounds, but I have a really nice performing piece of kit on which the StingRay will feel at home! Time to improve my playing now, but it's really rewarding to really hear every nuance of what you play. Sounds stupid but that was where I was before this whole BFM cab buiding experience.
!

One advice: Follow the plans! When Bill suggests to use some wax paper on the melded array gig, don't replace it with a sheet of cardboard... Or if you do at least take a black one, not a red one...

[BillyG]

Congrats on getting the job done. When you gig with this setup you will be totally stoked. Mine is the OT1-12 with a 22" dual loaded BP102. Powered by a Crown XTI2000 with a BMAXT BBE preamp. For me it's the mostest wampum-stompum bass rig. When we have full PA support I just leave the sub in the van and go with the OT1-12 as a backline monitor so I don't interfear with the PA subs.

[Nordskov]

It's a long time since I've been active here, but I have being reading the forum almost every day.
I have finished my O10.5 and a Wedgehorn and my drummer and I are almost done with two T39's. Just waiting for the 3012LF's to arrive at Sabbelbacke (who is a great guy and very helpful).
So now I'm finaly a part of the family

On my O10.5 I have wired my 4 x melded piezo array like David Carter suggest in this thread:
http://billfitzmaurice.net/phpBB3/viewt ... 84&start=0
Thanks David!
But instead of turning off half of the array (the piezos sounds better in multiple so that should be avoided) I used the woofer diagram and substituted the woofers with two banks of 4 piezos wired in series.
With a DPDT switch I can switch between; series/parallel, all series or off.
This works like a charm giving just the right amount of high end in "all series", and a little extra bite in "serie/parallel". I never turn them off as I lose too much definiton and string sound.