It feels good to be back!

[lemans23]

Woo hoo!

After a long break from DIY audio in favor of the more lucrative field of car audio sub enclosure building (sufficiently pleased with my 871s towers), I have decided that it's that time in every young man's life to do the thing. In my case, that thing is attempting to replicate my favorite speaker to date: The Definitive BP7001SC. It's their 2nd to highest end dipole design with their typical built in subwoofer. However, I have no desire to incorporate a sub into the tower as when I auditioned the speakers some time ago, I just turned the gain all the way down anyway. Now, it's time. First off, the things that I need 100% help on:

Drivers:

What sort of cones would be suitable for this speaker? I happen to have four HiVi D6Gs laying around from a previous project that I'd like to use. Unfortunately, they are absolutely hideous, and don't go well with any decor. Is there something that I should look for in the t/s that should give me a clue as to whether or not it will be a good candidate? I've also had bounds of luck with the Dayton 6.5" classic woofer, and buying for or even 8 of them would be cheaper than buying four more HiVi's.


Cabinet:

I'm fully aware as to what a dipole is, however, I'm unsure as to how to design one. Could I use two regular bass reflex enclosures opposed to eachother within the same cabinet, or would that just be counter productive? This is the part I need the most help with.


Arrangement:

Hamlet once said, "To D'Appolito, or not to D'Appolito, that is the question." Would a MTM for this design be superior to a TMM, or even a TM, or would it not be noticeable in my case?

Again, any help would be greatly appreciated. I expect this project to take at least until my birthday (finishing included, turn 18 on 2/11), if I can start over thanksgiving break. Glad to be back on the site!

-Dave

[lemans23]

Bump.

[SY]

Re your last question, a properly done MTM will tend to have a narrower vertical dispersion than an MT or TM. That will definitely sound different; whether or not you like that sound (I do) is a matter of personal preference. I don't know what the Definitive is, but if it's got the sound you like, configure it the same way.

[Rudolf]

Originally posted by lemans23
I'm fully aware as to what a dipole is, however, I'm unsure as to how to design one.

The Definitive BP7001SC is advertised as a Bipole, not a Dipole.
Just a typo??

Rudolf

[ShinOBIWAN]

Originally posted by Rudolf


The Definitive BP7001SC is advertised as a Bipole, not a Dipole.
Just a typo??

Rudolf

No they are indeed a bipole design, they don't do anything dipole.

I've got a pair of the huge BPX surrounds and they're well good for the money I paid. I'm sure the larger floorstanders are equally as impressive.

[thylantyr]

Originally posted by lemans23
Bump.

LOL @ bump

You expected a response?

You might get more entertaining discussion
on the car audio forum

[lemans23]

Originally posted by Rudolf


The Definitive BP7001SC is advertised as a Bipole, not a Dipole.
Just a typo??

Rudolf

Pardon my typing, yes indeed.

[lemans23]

Originally posted by thylantyr



LOL @ bump

You expected a response?

You might get more entertaining discussion
on the car audio forum

Entertaining, yes, but you know caraudio.com. I need real answers for this

[lemans23]

And it appears those real answers aren't flowing too well

[lemans23]

Okay, I said "F it" to the D6G's for a few reasons:

1. They're hideous
2. They're incredibly expensive to have to buy ANOTHER four
3. They're hideous

Now, I'm looking at these drivers and I made a design using both:

http://www.partsexpress.com/pe/pshow...75-070&scqty=4

http://www.partsexpress.com/pe/pshow...95-305&scqty=8

The drivers are cheap, sound good, and they fit the criteria for this endeavor: to replicate the sound of the speakers for a fraction of the cost.

It doesn't tell you much, but here's the design I made up. Circles are full diameter. The rolloff is decent with the design as sealed, but when I tune it to 50hz with a round port, the extension is lower, but the rolloff is like a cliff. I WOULD be worried, but my subwoofer should be stretching and waking up to do its job right around 50-60hz anyway. Okay, enough talk, onto the pics:













I want them to be black anyway, so here's what I was wanting it to look like in the end:



Here's some rough dimensions:






What I still need help with the most is the size of each chamber. As it stands right now, each side is around 1 cubic foot for each set of mids and tweets. I do not plan to put the tweeter in its own chamber like I have done before because it would separate the mids and would give each a different amount of Vb. Anyway, help me out!

-Dave