Soon the build of my first T48s starts!

[Robin_Larsson]

Hi everyone

So we decided to go for the DR 280 and Titan 48, got the plans from Bill last week, like one hour after I ordered, so that was quick:) Planning to start with Titans, most likely buying material tomorrow. Looks like where gonna go with Auruco (or how ever its spelled) They sell so damn cheap at Hornbach, a bit less including tax, then what I could get the same plywood at the grosser excluding tax for! So, atleast the first to T48s will be in pine. The material looks really good, and not warped at all so should work fine. I can get interior grade glued russian birch for maybe 40% more, in 1525x1525mm sheets, but not so sure about the glue, specially when I want to watercut it.

I´ve said before that I was planning to get the Behringer EP 4000 amp, and the DCX 2496 DSP, but now I´ve seen their new iNuke series, the 6000 model, 2x3000W in 4 ohm (must be peak, it doesnt say), with DSP onboard, fully digital, 6kg! Seems to cost about 430 euros, thats atleat 100 euros cheaper than getting one EP 4000 and a DCX 2496, for like 12-13kg less weight! Doesent that seem like a good deal?
It should be something like 1700-2000W rms per channel in 4ohms, half that in 8? maybe it unnecesarry much? or will the kappalites be able to use most of it?
Plan is to build 2 T48s and 2 Dr 280s, all Kappalite loaded and the melded array. First one amp, run a few gigs in mono, then one more amp, then 2 more subs and later more tops:P

What do you guys think? Is the iNuke NU6000DSP to much? just right to get plenty of headroom and really not push the them? The 3000 modell feels a bit to small..
http://www.behringer.com/EN/Products/NU6000DSP.aspx

//Robin

[Radian]

What do you guys think? Is the iNuke NU6000DSP to much?

If you feel like being a beta tester for Behringer, have at it. Odds for a single point failure are too high for my taste until they get all the kinks worked out....and I can assure you, there will be kinks for the first few generations of product.

[Robin_Larsson]

Hmm, Radian, you do make a very good point! It sucks having to send shit back even if its covered by the warranty..

[jjohnson]

You might want to consider the iNuke 3000 series since it should deliver 550 to 600 Watts per channel at 8 ohms. I am running two T48's on a single channel on the Peavey GPS2600 with 620 Watts at 8 ohms per channel. I can run at least 4 of the T48's with that single amp - pretty sure I could push 8 of them..

If you plan on using the built-in DSP on the amp make sure the specs on the limiter will allow you to limit the output. I have had problems setting the Behringer DCX2496 limiter because the amp is supplying so much power and the limiter only has about 3db of adjustment left - it's set at about -21db. On the 6000 series I would thinkthe fully limited voltage would be over 75V. A little too much power for the T48.

[Robin_Larsson]

jjohnson, the iNuke 3000 is rated at 2x1500W in 2 ohm, 2x880 in 4, atleast according to Behringers site, but it could of course be that it should be 4 resp 8 ohm instead. But if it is like their site say, it should be something like 500W in 8 ohm, and I do believe that is peak, not rms? The rate their Europower amps by peak, not rms, had to read the manual to find the rms rating on those. They havent published the manual for the iNukes yet..

Okey, that is definitly worth to check, about the limiters. Looks like the iNukes will have more or less exactly the same DSP functionality as the DCX 2496, only that its 2 way mono instead of up to 3 way stereo. Saw a youtube clip from some show we´re the Behringer guy said it was more or less the same DSP. And you can hook it up with USB and control it with a laptop, thats nice! We always have atleast 1 laptop for the DMX-control and a couple more with us on our own events so.

Would there be any real good reason to buy a DCX 2496 and the iNukes without the DSP? A bit cheaper after 2 amps, and the ability to do a active 3 way system with bi-amped tops ofcourse.

[jjohnson]

Would there be any real good reason to buy a DCX 2496 and the iNukes without the DSP? A bit cheaper after 2 amps, and the ability to do a active 3 way system with bi-amped tops ofcourse.

I've found that the DEQ 2496 to DCX 2496 combo for EQ & Crossover is very versatile and allows you to run a digital audio cable from the FOH (DEQ) to the Amp Rack (DCX). The DCX also includes delay options and a parametric EQ that can be applied per input or output.

[Robin_Larsson]

Hi everyone!

So, I started a bit, bought some plywood atleast, and checked for the glue. The PL-premium is not available in Sweden according to the Loctite Distributor, and the closest alternative was so expensive that they actually recommended my to buy Sika or such:P I´m gonna try the Sika Bond 520, we´ll see how it goes. Allways possible to seal the joins with some sealing compound or so, we´ll make a try and see. Since I cant find any reference at all to PL Premium expanding during cure in Loctites literature it feels like it cant expand all that much, but I may of course be wrong. Not all polyurethane products expands after all.

And the plywood, we went for 12mm Auruco, but it wasnt until I came home back to the drawings that I realised that some panels are 1219.2x609.6mm, while the plywood is 1200x2400... I really thought all plywood in that size here in Sweden was 1220x2440mm, apparently not so.
But I´ve found an easy fix, just need to make the top, bottom and back panel wider, to be able to shift the joint 90 degrees and make the sidepanels smaller.

But, one question, I´ve drawn the sidepanel in autocad, with all the lines for the horn panels laid out, and offsetted those 12mm, instead of 1/2 inch.
Is there enough tolerance in the design to simply draw the way the drawings says, but simply use 12mm instead of 12.7mm(1/2")?
Or should I balance it so i get 0.35mm mm difference each side?
Or, is the 1/2" ply you guys use in the states actually 15/32", which is much closer to 12mm? I know I´ve seen a photo here on a plywoodstack on a shelf, with a sign that said 1/2" (15/32). Since I´m gonna watercut some parts, atleast the braces and the driverbafle and such, I can get down to 0.1mm precision on those parts.
I´m also looking att cutting the sidepanels, with square holes that fits taps cutted in the horn parts, to keep them in exact place. Might get a bit more difficult to get it airtight then.. But would probably make it possible to assemble more or less everything in one go.

And some good news for me now that the drivers are getting expensive, I´ve managed to get a set price of 660euros for 2pc 3012Ho and 2pc 3015Lf, from two sources, Thomann, and one in Sweden, so just need to find the money and order next week.

And one more thing, is it a complete no go on putting recessed handles in the sides of the T48? Like you see in commercial subwoofers. I suppose it would be a noticable difference? Since we´re planning to build them at the full 36" width, we´re most likely gonna build some dollys with wheels, and lift them on to those in the same position as when playing. Should get us through doors and so. Might also build a dolly to hold two DR 280s stacked front to back on each other, locked togehter with the fly-hardware we´re gonna have.

Thanks in advance guys!

[netwerks]

Hi everyone!

So, I started a bit, bought some plywood atleast, and checked for the glue. The PL-premium is not available in Sweden according to the Loctite Distributor, and the closest alternative was so expensive that they actually recommended my to buy Sika or such:P I´m gonna try the Sika Bond 520, we´ll see how it goes. Allways possible to seal the joins with some sealing compound or so, we´ll make a try and see. Since I cant find any reference at all to PL Premium expanding during cure in Loctites literature it feels like it cant expand all that much, but I may of course be wrong. Not all polyurethane products expands after all.

Use only PL premium as per the recommended plans. If you cant get it there locally look online.

And the plywood, we went for 12mm Auruco, but it wasnt until I came home back to the drawings that I realised that some panels are 1219.2x609.6mm, while the plywood is 1200x2400... I really thought all plywood in that size here in Sweden was 1220x2440mm, apparently not so.
But I´ve found an easy fix, just need to make the top, bottom and back panel wider, to be able to shift the joint 90 degrees and make the sidepanels smaller.

I think you need to rethink how your panels are laid out. You should not alter the measurements of the plans. Use the cutlist program many here use to maximize your use of the plywood you have.
http://www.delphiforfun.org/programs/cutlist.htm

And one more thing, is it a complete no go on putting recessed handles in the sides of the T48? Like you see in commercial subwoofers. I suppose it would be a noticable difference? Since we´re planning to build them at the full 36" width, we´re most likely gonna build some dollys with wheels, and lift them on to those in the same position as when playing. Should get us through doors and so. Might also build a dolly to hold two DR 280s stacked front to back on each other, locked togehter with the fly-hardware we´re gonna have.

Thanks in advance guys!

You can do this but it will add weight but on a 36" cab it will be insignificant. The natural wood handles built into the cab and laid out in the plans work awesome, why spend the money. If you do decide to make sure they are airtight.

[Robin_Larsson]

Hmm, will have to think about the glue, but I´m rahter sure I can get airtight joins eihter way, and then it really doesnt matter as long as the glue is as strong or stronger, and as far as I can see, the PL Premium isnt really stronger then any other quality glue of that type, the plywood will fail before the glue anyway.
Does the PL really expand a significant amount when its curing, or is that just assumed since it ouzes out of the joint when pressed together and that its based on polyurethane? Cause I cant find any remarks on expanding in their techsheets? Maybe I missed it?

Regarding the sidepanels, I´m of course not changing the size of the cab, internally or externally and then it can not possible matter.
I spend most of my workday on planning metalsheets for cutting, and been doing so for years, I´ve got a good eye when it comes to fitting things on sheets, and got an good software to do it with in my office, but thanks any way for the link, will check it out!:)
The only way to cut the sidepanels in the exact dimensions as per the plans, is to cut only one on one sheet, which would waste much more material I feel.

I´m not trying to be ungrateful for the answers or anything, but I feel that I´ve got enough experience with design and woodworking to be able to build the cab to the exact dimensions even if making some joins in a different direction, if you see what I mean?

Regarding handles. Yeah, I belive that in most situations the recommended woodhandles work perfectly, and I´m planning to build those, was just thinking about when stacking 2 high it would be nice to have recessed handles in the top and bottom, or the sides sometimes. Wouldnt it take away to much volume from the horn if it comes in to the path or in the driver chamber? Most likely not gonna put in handles like that, just curious if and how much it would affect the sound:)

What say you about the difference in thickness of 12mm ply and 1/2" ply? Or is your 1/2" normally 15/32"?
I´ve measured with a caliper on ~10 different places on the ply I have, less than 0.1mm difference between them:)

[netwerks]

Does the PL really expand a significant amount when its curing, or is that just assumed since it ouzes out of the joint when pressed together and that its based on polyurethane? Cause I cant find any remarks on expanding in their techsheets? Maybe I missed it?

YES!

Regarding handles. Yeah, I belive that in most situations the recommended woodhandles work perfectly, and I´m planning to build those, was just thinking about when stacking 2 high it would be nice to have recessed handles in the top and bottom, or the sides sometimes. Wouldnt it take away to much volume from the horn if it comes in to the path or in the driver chamber? Most likely not gonna put in handles like that, just curious if and how much it would affect the sound:)

You can put handles on the front sides and bottom of the cab in the mouth or you can also use the mouth bracing to lift it.

p.s. I feel sorry for your back. Also figure in the cost of this.
http://bit.ly/gMcyv5

[Robin_Larsson]

Okey, I give in Still think its funny that they dont mention it on the specs:P Only say: use mechanical support for 24 hours:P I´ll see if I can get a good price somewhere, but still think it should be possible to make the joint airtight with one of the construction adhesives we use at my work, we glue glass to stainless steel, waterproof under pressure, so should manage to make a airthight plywood joint, will have to try simply:)
Any good tips of an online source that ships PL internationally?

Okey, so in the bottom of the cab, the horn mouth, a handle doesent completly f*ck up the sound? But if i cant have handles in the top, which would be in the driver chamber, thus making it a bit smaller, then theres no point in putting them in the bottom either:P Everyone agrees that handles like this :http://www.speakerhardware.com/deep_d_h ... 262821.php in the bottom wont be noticed for in sound quality? The reduction in mouth area maybe isnt large enough to matter? Would it be possible to put them in the top somehow?
Or could use handles like these http://www.speakerhardware.com/penn_spr ... h7154k.php
I dont really like the look on the last ones:P
Or i design/build something removable or so I have some ideas:P First the cabs of course.

Dont need to worry about my back, these will be a dream come true compared to stacking 2 high 2x18inch subs and a a 2x15 top on them:P But yeah, still needs to take care when lifting even if the cabs will be light:D Nice link:P

Btw, when you guys stack 2 or even 3-4 high BFM subs, do you just use locking corners, or put straps over also? I tired of putting strabs through handles and shit, and it doesnt look very good, but we cant have subs vibrating loose! So I was thinking, maybe some pins or latches or something that easily secures them? How do you do it?
I´ve used a very sweet fly system on a line array before, not unlike the system Bill suggests in a thread in the DR section, but in steel and with ball realese pins. I want to do something like that in my 280s, with steelstraps spanning the top and bottom loadpoints.
Maybe something similar on the subs.. But that can wait till we build more cabs

[netwerks]

Okey, I give in Still think its funny that they dont mention it on the specs:P Only say: use mechanical support for 24 hours:P I´ll see if I can get a good price somewhere, but still think it should be possible to make the joint airtight with one of the construction adhesives we use at my work, we glue glass to stainless steel, waterproof under pressure, so should manage to make a airthight plywood joint, will have to try simply:)
Any good tips of an online source that ships PL internationally?

Leland will ship internationally from speakerhardware.

Okey, so in the bottom of the cab, the horn mouth, a handle doesent completly f*ck up the sound? But if i cant have handles in the top, which would be in the driver chamber, thus making it a bit smaller, then theres no point in putting them in the bottom either:P Everyone agrees that handles like this :http://www.speakerhardware.com/deep_d_h ... 262821.php in the bottom wont be noticed for in sound quality? The reduction in mouth area maybe isnt large enough to matter? Would it be possible to put them in the top somehow?
Or could use handles like these http://www.speakerhardware.com/penn_spr ... h7154k.php
I dont really like the look on the last ones:P
Or i design/build something removable or so I have some ideas:P First the cabs of course.

You can cut a handle hole anywhere on the cab you want so long as it doesn't allow air out oft the cab. There are more than enough options in the plans and using as such on the top, bottom and mouth bracing should be plenty.

I personally used those spring loaded handles you provided the link to on my first set of cabs on the back and under the bottom front, they are very strong and work awesome but really not necessary if you strategically cut nice holes in the cab in the right places as per bills layout so i omitted them on future builds. If you do want to add those on the sides its fine just make sure no air leaks out around them.

Another thing you may want to look at is how you do your mouth bracing. Many people have replaced the flat horizontal connector piece in the mouth bracing with a 1" or larger dowel rod and use that as a handle grab spot as well when lifting the mouth. I can tell you that I have personally helped someone move 4x 24" T48 made of baltic birch and they were heavier than i would want to move so make sure you get a dowel that is very strong. (Everyone here knows i'm a self-proclaimed whimp.)

Btw, when you guys stack 2 or even 3-4 high BFM subs, do you just use locking corners, or put straps over also? I tired of putting strabs through handles and shit, and it doesnt look very good, but we cant have subs vibrating loose! So I was thinking, maybe some pins or latches or something that easily secures them? How do you do it?
I´ve used a very sweet fly system on a line array before, not unlike the system Bill suggests in a thread in the DR section, but in steel and with ball realese pins. I want to do something like that in my 280s, with steelstraps spanning the top and bottom loadpoints.
Maybe something similar on the subs.. But that can wait till we build more cabs

I personally don't use them but ratchet straps will work fine for this and they are cheap. You will be surprised that if you brace the horn mouths on the subs you will actually get very little vibration. In fact I find that the only reason mine tend to walk was when i didn't have the bracing installed, the duratex made the tops slip off. I have since added in the mouth bracing and put rubber feet on the bottom and they no longer walk anywhere. Keep in mind that when you say "stacking" I am assuming that you are having your stacks 56' apart from each other, this is why you don't hear of this problem too often here as most people center or wall cluster their subs with the tops on stands or placed elsewhere not on top of the subs.

[Rune Bivrin]

I've used a number of different types of glue - including PL Premium which I got from Leland - for building BFM cabs, and almost all of them work well, provided that:

• It's strong
• It's filling
• It's thick, not runny
• You apply it liberally
• You clamp meticulously or use brads/screws
• You don't futz around with the parts, spreading the glue in the process

Since you're having your parts water cut the expansion isn't of much value; there shouldn't be any gaps to fill.

The explansion of PL is nice for the last side of a horn when there's no way of caulking after the fact.

Personally I am a little bit too restless to wait the required 24 hours, so I tend to use glue that sets more quickly. To help I have just invested in a cheap compressor and brad nailer. That will come in handy for the upcoming T39 build.

[Chris_Allen]

Every glue I have used (polyurethane) has worked well, except for the 5 minute stuff. I wouldn't worry too much about sourcing PL premium, clean joints and bracing are far more important. Build yourself a small box to test, get used to the glue and how it behaves, it can be a nightmare when it starts sticking to the wrong things!

[netwerks]

To help I have just invested in a cheap compressor and brad nailer. That will come in handy for the upcoming T39 build.

+1 you can buy a used brad nailer and a cheap compressor it will be the best <100 you will spend its like having a second pair of hands.