My turn to build JC's DBB

[DrWho]

PM sent

Btw, I was just reminiscning on some of my posts when JC built these the first time...it's cool to see measurements showing what I would have expected from way back when:

http://forums.klipsch.com/forums/p/58314/568034.aspx#568034

I just wanted to add that the bass bloom would get more pronounced as you move the cabinet into the corner.

I also think one of the harder parts about voicing this speaker would be mating the wide vertical polars of your small tweeter to the narrow vertical polars of the dual 15's. Now I'm even more curious to mess around with a 2.5way xover this thing since you could probably maintain constant vertical polars down to around 200Hz or so if you do it right.

I wish there was more hours in a day, or that we all lived forever (stupid Adam and Eve), cuz then I would eventually get around to building a (cheap) rig for measuring polar response quickly, and then this stuff would just be a matter of time to dial it in.

But just looking at your data, I would suggest running the top woofer with the normal xover to the tweeter and then lowpass the bottom woofer at 6dB/octave butterworth at ~480Hz (sadly you'd need a third amplifier for this). The goal would be to get a flat passband from 350Hz to 700Hz. And then I would do a wide PEQ centered at about 110Hz with about -2dB of cut to help flatten that range out. It should be done in a room corner though because it'll bring that whole region up quite a bit more, so maybe you'll need more cut.

When it's all said and done, you'll need to raise the gain for the LF by about 3-6dB or so and the sonic improvement would be the perception of more solid low end (40Hz stuff) and a fuller lower midrange. It'll probably sound a bit less punch, but you could tweak the PEQ to taste after you've got the Q matched to the natural system behavior. You don't want to make the LF totally flat though, which is a complicated topic, but basically you want a slow ~3dB/octave rise as you go lower across the entire spectrum.

Btw, keep in mind that your plot is essentially showing a +/-3dB window across the passband which is typical marketing mumbo jumbo....so most of what I'm talking about here are really where the voicing of the speaker comes into play...shifting nuances around and all that. So must of what I'm suggesting is just pure guesses based on previous experiments messing around with stuff.

Would you happen to have any spare fluffy pillows laying around? I'd be real curious to see how the response changes before and after adding more stuffing in the box. I have two predictions, but if you don't have the time to mess with it then don't worry about it. I'll probably get around to it sometime this summer...

[Rudy81]

Dr. Who, I sent you the files already. Please keep the information coming. I will digest as much as I can.

I am going strictly 2 way with this so no tweeter will be involved.

I also have an RSW-15 that will be handling everything below 40 Hz.

[Rudy81]

One top hat done, one to go plus the DBB grilles.

[jwc]

Lookin awesome

[Rudy81]

JC, I wish you could hear these things. I beleive I made the right choice. So far the family approves. My son plays the guitar, piano and drums. He likes the bass of the DBB better than the Khorn bass bin. Says the bass is more immediate and has more punch.

These things can move air!

[Pete H]

Hey Rudy, your finished product is looking great and based on what you're posting, sounding great too. Congrats!

[Rudy81]

Hey Rudy, your finished product is looking great and based on what you're posting, sounding great too. Congrats!

Pete, thanks. I finished putting things together late last night. This is actually the fun part of the build. For my HT room, the all black enclosure is going to work very well. Not something I would do for a living room or something more formal. I really wish I had researched the lacquer issue before putting primer on the cabinet.

After taking apart my Khorns and those huge false corners I had, it 'created' a whole bunch of space I didn't realize I had in the room. I am now in the process of cleaning up my Khorns before they go up for sale.

The top hats turned out really good and look very good in person. The whole cabinet came together rather well and looks good for as big as it is.

The bass performance is still very impressive although I have not even started the voicing process yet. All I did after removing the Khorns was to reset the driver alignment to zero, which is closer to what these drivers will need vs. the Khorn settings. I also moved the crossover point to 600Hz just to take the stress off the HF driver.

Now that I can move the speaker all over the room, I realize that it is imaging sensitive if you don't set each speaker correctly. It is going to take some time to discover the best placement for the cabinets. Now, toe-in and wall to cabinet distance are going to be issues.

I think my next step is going to be some measurements to see where I should set the crossover as well as some quick timing measurements. Just a basic setup so I can get going on cleaning up my Khorns so I can get them ready for sale. I won't be able to really get good reading with the Khorn bass bins sitting up front near the DBB bins.

I sure have missed the immediate sensation of a bass bin firing at you vs. an enveloping bass such as the Khorn produces. I am looking forward to the many possibilities in setup this bass bin will offer.

[Rudy81]

BTW, one of the characteristics I noted last night while listening, was that being able to move the cabinets away from the side walls opened up my soundstage considerably. I am really pleased with the P. Audio driver/horn combination. Those horns seem to image really well and have a much larger soundstage in this cabinets than when up against the wall whith my Khorn setup. The placement flexibility of these cabinets is relaly making a positive difference in areas I had not considered before.

All this, of course, has been made possible by my dabbling with an active crossover.

[Rudy81]

One of the issues I am tackling now is that each corner has a subwoofer in it, so it does limit the ability to fully seat the DBB in the corner to get a feel for what that would do. Although, I'm not sure that would be the ideal setup since I suspect putting the DBB in the corner would limit the HF horn effectiveness being so close to the walls.

[Rudy81]

Dr. Who, one more question. You mentioned adding a pillow to the woofer enclosures to see what the difference is. As I understand, adding more stuffing 'virtually' enlarges the cabinet volume. What would be the expected effect of adding more stuffing?

[Marvel]

being able to move the cabinets away from the side walls opened up my soundstage considerably.

My LS open up more when the cabinets are away from the side walls as well.

Glad these are worth the effort for you.

Bruce

[Rudy81]

Thanks Bruce. I am looking forward to voicing the speaker. Right now it is pretty much using the settings I had for the 2 way Khorns. Once that is done, I will then concentrate on ideal room placement. Then I'll run the Audyseey calibration for the HT side of the equation.

I am very pleased with the results of the bass bin. I am even more impressed with the performance of the P. Audio horn and driver. This has turned out to be a very good combination.

I just need more hours in the day to do all the stuff I need to do. Spent all day cleaning and oiling the Khorns. Also rewired the AK3 crossovers since the cables were all nasty. Weird stuff inside the cable sleeve. I've seen it before in other Monster cable.

This was a lot of work and a little money. However, the more I listen to them, the more I like them.

[Rudy81]

One of the great benefits of going to the Pilgrimage was meeting the membership. In particular, I got to pick a few guys' brain concerning voicing a speaker. Thank you guys....your knowledge has greatly helped. It took me very little time to basically set the DBBs to where they sound very good. I currently have the DBB crossover set to 607Hz in two way configuration. The K69 (P. Audio) driver has two shelf filters at 3.7 kHz and 11.9 kHz. FR is looking pretty good. My room has a null at my seating position at 80Hz. I had to boost that frequency by 5dB with a Q of 10.

I wanted to work on that while I had the sound of the Jubilee's, 60th Anniversary Khorns and Palladiums fresh in my mind. These are sounding very good and are giving me the punch I was after.

Tomorrow I hope to run Audyssey to see what it does to the FR, but the more I delve into this stuff the more I am getting away from the idea of allowing Audyssey to make system changes without me knowing what they are.

Right now my HT is a mess, but as soon as I get everything nice and neat I'll post some pictures.

One issue I am fighting now is that by also going active with the center La Scala, is that when I started using 'C' channel in the DCX2496 has a very noticeable hiss. I definitely need to fix that issue, or get another crossover.

Again, thanks to all the guys that gave me great ideas and suggestions on how to set this up.

[Rudy81]

While I run Audyssey, I figured I'd add an interesting experience to the notes on this thread. While starting my listening tests yesterday, I realized something was not right. I could not get a good central image. Singers were diffuse and not easy to locate in the soundstage. I know that is not right since i had great imaging with my Khorns and the 1" drivers I had used.

I knew from setting up the crossover point that my left speaker, which I used to run the crossover setup, was good. Just for grins I decided to reverse the polarity of the right speaker HF driver. The image immediately centered and locked in. My initial guess was that somewhere in the right channel hookup, I had messed up the wiring. I also ran a pink noise comparison between right and left and the right registered lower, confirming that one of the drivers on the right speaker was out of phase.

After checking and double checking the wiring and even trying a different wire, I came to the conclusion that my right P. Audio BM-D750 driver diaphragm is wired incorrectly. The issue was fixed by reversing the wire terminals, but still bugs me that the factory lets a driver go out that way.

Just one more small headache in the setup of the system. At least now I have learned enough to know how to test for that type of mismatch instead of wondering which driver is messed up.

Now, if I could only get the DCX C channel to quiet down, I'll be in business.

[Rudy81]

Well, I am having to eat my words on that Audyssey statement I made previously. The Audyssey measurement results were about as good as I have ever gotten. Meaning, distances were exact or near exact, levels between speakers were very well matched and most importantly, it sounds better in stereo with Audyssey, than without. So, Audyssey seems to have done a really nice job. It actually seems that I boosted the highs a little much in the DCX because Audyssey lowered them just a bit. Hard to tell since there is no way to really tell what Audyssey is doing.

Things are coming together fast. Now to work on the DCX hiss in the C channel.

[bigrfish]

Thanks Bruce. I am looking forward to voicing the speaker. Right now it is pretty much using the settings I had for the 2 way Khorns. Once that is done, I will then concentrate on ideal room placement. Then I'll run the Audyseey calibration for the HT side of the equation.

I am very pleased with the results of the bass bin. I am even more impressed with the performance of the P. Audio horn and driver. This has turned out to be a very good combination.

I just need more hours in the day to do all the stuff I need to do. Spent all day cleaning and oiling the Khorns. Also rewired the AK3 crossovers since the cables were all nasty. Weird stuff inside the cable sleeve. I've seen it before in other Monster cable.

This was a lot of work and a little money. However, the more I listen to them, the more I like them.

Rudy,

I wound up using that same P. Audio horn for the midrange in the CB's first-build Cornscala cabs I inherited...mated with a Selenium phenolic-domed driver. I got the adapters and worked an inordinate amount of time to precisely, exactly match the apertures, and used the adapter holes to pilot the holes I needed to drill in the horn mounting flange....came out pretty good, and I am loving the midrange sounds. Those big wooden horns may be great, but this piece is not too shabby...I found my horns on e-bay for considerably under $50.00 each. If/when(more a matter of when than if) I do something like this again, I am sorely temped to use that same driver and horn combination....musical instruments sound like they are really supposed to sound...It's a good thing, and I did not need Martha Stewart to tell me that!!!

Chuck

[Rudy81]

Chuck, thus far I like the sound of the plastic horns just fine. Although I recently had wooden horns, my focus in the change has been the drivers. I have not lived with them long enough to make a detailed impression, but thus far, they are very nice and I have not missed the tweeter. This should be expected really, since I am basically using the K69 driver with a different horn, a horn designed by P. Audio to mate to this driver.

So far so good.

[seti]

A horn is just a rigid boundry. I doubt materials sound different. Certainly look different. I prefer the look of a beautifully crafted wood horn.

[Rudy81]

A horn is just a rigid boundry. I doubt materials sound different. Certainly look different. I prefer the look of a beautifully crafted wood horn.

Absolutely, a beautiful wood horn is preferred. Howevver, in these lean times, bang for the buck seems to be taking precedence. I am not sure if materials matter that I could tell the difference.

[seti]

A horn is just a rigid boundry. I doubt materials sound different. Certainly look different. I prefer the look of a beautifully crafted wood horn.

Absolutely, a beautiful wood horn is preferred. Howevver, in these lean times, bang for the buck seems to be taking precedence. I am not sure if materials matter that I could tell the difference.

We could always resort to airbrushed horns : )