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-   -   Best driver(s) for an N-profile Ripole? (http://www.diyaudio.com/forums/subwoofers/108623-best-driver-s-n-profile-ripole.html)

MJL21193 17th September 2007 03:27 AM

Best driver(s) for an N-profile Ripole?
 
2 Attachment(s)
Hello,
I'm looking for driver options for a pair of N-profile Ripoles. I'll use one or two drivers per box if needed.
My understanding is that they will need a fairly large Xmax. I'm also looking for high efficiency, so a pro driver is fine.
Fs need not be rock bottom, as this alignment will lower the resonant frequency a bit. Basically looking for an F3 (when done)of about 30Hz to 36Hz.
Not really a subwoofer, but a singular bass speaker

Also, if anyone knows of a good program to model these with, I'd appreciate it.

For anyone confused or doesn't know what a N-profile is, I've attached a sketch of the box shape:

MJL21193 19th September 2007 01:52 AM

Not much of a response. Not a popular alignment, I know, but one that can give exceptional results for music.

I'll start the ball rolling. I've looked at quite a few different drivers with an eye on a few key points: price - I won't spend more than $250.00 on any driver. Efficiency - needs to be high. Xmax - has to be enough excursion to provide high SPL at low freq. Vas - TBH, I'm not sure. Is a stiff suspension better or loose one perform better?

One driver that got my attention is the Basslite C2515 from Eminence. It is below $200.00 here, It has high sensitivity at 98db, Xmax is a decent 4.5mm (considering the expected freq range of the speaker and it's size, thats pretty good).
Full specs are here:
http://www.eminence.com/pdf/basslite-c2515.pdf

planet10 19th September 2007 03:29 AM

I believe there is a whole 'nuther thread here on this same subject.

dave

MJL21193 19th September 2007 04:35 AM

Hi Dave,
Similar subjects (W Ripole, dipole). Lots of good info on the moray james thread, but not specific to the N profile.
In particular, I'm looking for a simulation program. I've considered trying to use MJK's worksheets but I can't say that I'd trust the result, though it might be useful for excursion predictions.
Maybe a real world test is in order. What's your opinion on the speaker I mentioned above?

planet10 19th September 2007 02:47 PM

2 Attachment(s)
Quote:

Originally posted by MJL21193
Hi Dave,
Similar subjects (W Ripole, dipole). Lots of good info on the moray james thread, but not specific to the N profile.
In particular, I'm looking for a simulation program. I've considered trying to use MJK's worksheets but I can't say that I'd trust the result, though it might be useful for excursion predictions.
Maybe a real world test is in order. What's your opinion on the speaker I mentioned above?

Don't know. Omce i realized i was sitting on 14 12" suitable for a ripole i didn't pay much more attention. Going to pick the 8 best matched and move some air.

dave

MJL21193 19th September 2007 03:25 PM

Very nice Dave. How did you determine the dimensions of the box? These Fosters, what are the T/S specs, in particular the Qts?

Once again a W-profile (though there are big benefits of the opposing drivers canceling mechanical movement) I'm looking for a slimier, less cubical shape in the N-profile.

I may go to the extreme of buying a driver (the Basslite) and trial and error a box. I have a spare (yeah, not 14!) 12" here doing nothing that I could test, but I want to do this for keeps.

NO idea how this could be accurately simmed?

planet10 19th September 2007 07:49 PM

Quote:

Originally posted by MJL21193
How did you determine the dimensions of the box? These Fosters, what are the T/S specs, in particular the Qts?
I used the guidline of as small as possible. Driver Qt is ~0.5

The woofers owe me nothing (the boxes they come in yield up tweeters that by themselves generate a profit)

dave

MJL21193 20th September 2007 02:07 AM

2 Attachment(s)
Dave,
Consulting with Bjorno on this thread:
http://www.diyaudio.com/forums/showt...7&pagenumber=2
He ran some simulations with MJK's BLH Sections worksheet to get tentative results.

I have used the open end TL worksheet to get a rough idea of the output. Using the Basslite speaker specs and a line length of 18", I came up with these charts.
The section area (So - Sl) is Sd*1 for the top, Sd*.5 for the middle and Sd*.25 for the bottom.
Looks like a bigger section area give better higher freq response and also improves step response.
Downside, is larger section area, higher the Fs peak.

Once again, can these results be treated as accurate?

Calvin 22nd September 2007 06:35 AM

Hi,

to my taste these are inaccurate. At least the freq-range above the first resonance is not as I know from praxis. Im not familiar with those sheets and havent used them yet, but the folded dipoles definitely show other frequency responses....in my own simulation as well as in praxis.
Since from the range above 100Hz only the area around the first resonance is of importance the sheet might be usable if it models the range below 100Hz and the position and strength of the first resonance correctly. Assuming that the blue curve is the amplitude and red for the phase it could be ok. At least the tendency regarding the freq-response depending on the dimensions of the chambers is correct.

As for the driver-Q...please use the search function. Sorry to say, but there are enough and precise enough answers given in several threads already and Im just not in the mood to repeat myself each and every week again and again (I guess this holds true for anybody else)

jauu
Calvin

MJL21193 1st October 2007 03:42 AM

Quote:

Originally posted by Calvin

As for the driver-Q...please use the search function. Sorry to say, but there are enough and precise enough answers given in several threads already and Im just not in the mood to repeat myself each and every week again and again (I guess this holds true for anybody else)

Wow. It would have required a lot less effort for you to type either "high" or "low" as an answer regarding driver Q. You would rather see a member search (maybe for hours) to find this information.
Thanks for the high quality help you are offering but with all due respect, stuff it.


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