It feels good to be back!

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Woo hoo! :wave:

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
 
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.
 
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/pshowdetl.cfm?&DID=7&Partnumber=275-070&scqty=4

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-305&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:

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

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Here's some rough dimensions:

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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
 
Okay guys, what other information do you need from me to decide whether or not this design will be suitable? Am I missing something here, or not? I know I'm young, but I want to take Definitive sound all the way to the bank! Any pointers, and I mean ANYTHING whatsoever is helpful!
 
Okay, I think that it's time to reconsider my goals. I want to have sound that can rival the Definitives. As it turns out, I am unsure as to whether or not I have the funding required. So, here's the new question: is it reasonable to say that a normal MTM speaker would give me greater performance than the bipolar design I originally wanted to work on since I am unsure on how to design it? Remember, I am after the sound moreso than the look. Also remember that I am working on a teenager's budget from building car audio systems, aka, not much at all. So be honest, but help me make the right decision.
 
Hmm I'm a teen too. How much is your budget. I built three way bookshelfs in this thread that are still taking shape. http://www.diyaudio.com/forums/showthread.php?s=&threadid=85710&highlight=

they were approximately $750.

I've never heard definitives but i've had mirage omnipolar's and i've loved them. I'm actually working on a small bipolar design just for fun with 2 hi-vi 3 b3n on both sides and two B1S tweeters. It shoud be an iinteresting project. I really want to see what a cheap bipole sounds llike and also how to tailor the sound. The fact is you have to take room reflections into account so you might need to reduce the midrange or treble a bit because the dispersion is so wide. That really seems to be the tricky part of designing a Bipolar speaker. Just go for it and have fun just be sure to be able to measure the response at the end and make changes to the crossover. What have you built in the past?
 
angsuman said:
Hmm I'm a teen too. How much is your budget. I built three way bookshelfs in this thread that are still taking shape. http://www.diyaudio.com/forums/showthread.php?s=&threadid=85710&highlight=

they were approximately $750.

I've never heard definitives but i've had mirage omnipolar's and i've loved them. I'm actually working on a small bipolar design just for fun with 2 hi-vi 3 b3n on both sides and two B1S tweeters. It shoud be an iinteresting project. I really want to see what a cheap bipole sounds llike and also how to tailor the sound. The fact is you have to take room reflections into account so you might need to reduce the midrange or treble a bit because the dispersion is so wide. That really seems to be the tricky part of designing a Bipolar speaker. Just go for it and have fun just be sure to be able to measure the response at the end and make changes to the crossover. What have you built in the past?
I think that I'll do what you've done actually. I'll make these a traditional D'Appolito, and then tool around with various small bipolar designs to get a feel for what they sound like. Good suggestion.

What have I built? What haven't I built is a better question. When I first started around 3 years ago, I would literally build a pair of cabinets in two days and just throw in cheapie cones and tool around with the cabinets and see how the sound would change when I made various mods to the Vb and Fb. I've got too many pairs of speakers to even begin to count, 85% of which are completely unfinished MDF.

:D
 
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