My turn to build JC's DBB

[Rudy81]

Just after this was taken I cut the port holes and called it a day. Darn, that perfectly sealed cabinet has four big holes! LOL, that's for you Pete.

[mikebse2a3]

Hey Rudy just....awesome! [Y][][Y]

mike tn

[Rudy81]

Hey Rudy just....awesome!

mike tn

Thanks Mike. Should be fun to hook up to the active system in a two way setup. I should be ready to test them tomorrow afternoon.

[Pete H]

Just after this was taken I cut the port holes and called it a day. Darn, that perfectly sealed cabinet has four big holes! LOL, that's for you Pete.

LOL, the work is looking fantastic! Any damping material in the box?

[Rudy81]

Pete, I have never heard of any damping material in the box. JC, any comments on that idea? My feeling is that with the angled sides, standing wave resonances shouldn't be a big issue....but then again, my speaker building knowledge is limited.

[Pete H]

I would like to know the answer to that one myself. My Cornwall 2's didn't have any in them either and that's how they came from the factory.

[IB Slammin]

........."the originals have thin compressed foam damping on every other side"...........

tc

Pete, I have never heard of any damping material in the box. JC, any comments on that idea? My feeling is that with the angled sides, standing wave resonances shouldn't be a big issue....but then again, my speaker building knowledge is limited.

[Rudy81]

TC, can you be more specific? What kind of foam exactly? Good thing you chimed in before I glued the baffles on. When you say every other side, do you mean alternating sides? Here come some good pictures.....some just for you Pete.

[Rudy81]

OK, here we go for today's results. Port construction was a minor pain due to the angled sides, but the corners shure did strengthen the box. It seemed to really stiffen the entire structure. I made then a total of 12" as per JC's instructions.

[Rudy81]

Complete ports.

[Rudy81]

Decided to try something I read on some forum for attaching the woofers. I used EZ anchors from the local Lowe's. These work really well and can easily be changed if you strip one out at a later date. Price is right too.

[Rudy81]

After a little light lifting and some help from my son, one cabinet was upstairs next to a Khorn for quick testing. These are just a bit shorter than the Khorn, which I like since it brings the top hat section closer to my ear height from my chair.

[Rudy81]

For grins I layed the cabinet on it's side to see if it sounded any different. Didn't seem like it. Reason is I need to figure out a way to make an nearly identical cabinet for my center channel to have perfect timbre matching. I rather like the look actually. I'll have to give this some thought. If anyone has any ideas, fire away. I need the cabinet to be about this height in order to not block my screen. I may just go with all three cabs on their side. If I make the top hats moveable, no big deal.

[Rudy81]

OK, so how does it sound? Well, these things can move some air! If you get close to the cabinet it is a totally different experience then getting close to a Khorn. The air is slamming you in the chest. NICE! Much more like my La Scala when cranked up. BTW, the woofers barely move...that's amazing.

One thing I did was to turn off my top hats and just play music through the bass bins, one DBB and one Khorn so I could compare. Very different sound. The DBB is louder and I suppose due to the added boost from the second woofer. I can't imagine the DBB being as efficient as the Khorn. BTW, these drivers are each 8 Ohms in parallel. My crown K1 ran them effortlessly.

One thing that jumped out at me while I had the top hats off was how much clearer the male vocals coming from the DBB were vs. the Khorn. I then realized the DBB must be going higher than the Khorn....so, out came the measuring gear. WOW, this bass bin gets on up there.

The measurements were 2 foot from the baffles, in my room, centered on the bass bins. Nothing too scientific, but it gives you an idea of the capabilities of each. No EQ on the crossover. Ran the test 20Hz to 20kHz on the bass bin only. This is what I got. Comments?

The blue line, of course is the DBB.

Edit: Let me add that when I ran these tests I did not move my Khorn and place the DBB in the corner. So, it is not as corner loaded as the Khorn. So, I imagine the low response will only improve if moved into or closer to the corner.

[IB Slammin]

TC, can you be more specific? What kind of foam exactly? Good thing you chimed in before I glued the baffles on. When you say every other side, do you mean alternating sides? Here come some good pictures.....some just for you Pete.

Yes alternating sides. Sorry to not be more specific. Been years since I looked at it. It was gray and smooth as I remember.

I will look on PE to see if anything rings a bell.

tc

[IB Slammin]

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-318

It looks something like this, but I can't be sure. (jc must be working this weekend)

tc

[Rudy81]

TC, thanks. I also e-mailed JC. I'm going to take a weekend break anyway so will hold off on gluing the baffle. Thanks for the heads up. BTW, the DBB is an air moving machine!

[sootshe]

Rudy,

You could try some insulation & see how that sounds.....for sure you are going to need something in the cabinet to dampen things down. I've tried white polyester insulation & also fibreglass insulation in my LS bass reflex enclosures & I preferred the sound with the fibreglass insulation. Your cabinets look awesome .....you've done a great job!!

[Pete H]

TC, thanks. I also e-mailed JC. I'm going to take a weekend break anyway so will hold off on gluing the baffle. Thanks for the heads up. BTW, the DBB is an air moving machine!

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-516

This is what I used and put it on the rear, one side and the top of the box. Pictures look great, anxious to hear what you think with the tops running. I know you're going to take measurements on it, but I'm more interested in how it sounds to you, heads up against your K Horn. Have a great weekend.

[Rudy81]

Rudy, You could try some insulation & see how that sounds.....for sure you are going to need something in the cabinet to dampen things down. I've tried white polyester insulation & also fibreglass insulation in my LS bass reflex enclosures & I preferred the sound with the fibreglass insulation. Your cabinets look awesome .....you've done a great job!!

I have some 1" acoustic foam I can add to the interior. From what I have read, adding fill can tighten up the higher frequencies. My research shows that bracing is the best way to reduce problems with the lower frequencies. I plan on bracing the mid shelf and tops and bottoms to the sides. Tapping on the sides of the cabinet before the corner ports were added and then after was a huge sound difference. I compared the tapping 'test' with my La Scala (center channel) and my cabinets sound much tighter.

I expect to make a simple top hat with the 2" horn exposed as your is. I think there are several advantages to having the horn exposed like that. My horn is plastic, so I won't be able to make it as elegant as yours.I still have not decided on the finish.