OB Project Design Started, Help Requested.

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DQ828

DQ828

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Joined 2010
#1
My previous OB was a direct copy of Lukasz Frikas P17, which are the best sounding speakers I have ever heard, (not that I have a lot of experience) but they are NOT the best speakers I have ever seen, that’s an understatement.

My goals for the next design are:
1. Aesthetically pleasing, at least to me anyway.
2. Less bulky than the P17’s
3. Highly efficient.
4. Flat as possible 20Hz to 20KHz
5. Passive in the first instance, then possible converted to Active, should I ever figure out how to do that.
6. 3 way.

Proposed Speakers:

· Tweeter: Raal 140-15d, I know this is a Tweeter-Mid, but I have faith in Lukasz speaker recommendations after the P17.

· Mid: Either Saba 8” Green cone or Isophon Oval as in Lukasz P24, if I can find any that is, the Saba’s sound great, IMO

· Bass: Well this is where it gets tricky, I don’t want to use the 15” bass drives, because of my design & to reduce bulk, but I am having little luck finding smaller drivers (10” if necessary 12”) that are efficient, (95-98dB) & have a usable range to get me down to the 20Hz. The following are what I have found so far.

o BMS 12N630 - 12"- 600 W - 4.1Kg - 96 dB 1W/1M-25-300Hz
Neodymium, these pretty much meet the bill but as you will see, in
the design I MUCH prefer, the side pieces, obscures the speakers, which
I assume will have a very bad effect on the sound?
What do you think?

o Eminence DELTA LITE II 2510 - 10" WOOFER, the sensitivity is
good, 97.3dB but the frequency range is way off, 60Hz-4kHz, I have
read that by having the dual speakers in a U/H frame, can increase the
dB & lower the Hz, but getting to 20Hz I think I would need a miracle,
what do you think? And of course they are still slightly obscured by the
sidepieces.

oAny ideas on suitable speaker’s guys?

o Has anyone used the BMS speakers?

Baffle: As you will see my baffle isn’t flat, what do you think?

Crossover Frequencies:
o Bass: Probably somewhere between, 150 & 200 Hz
o Mid: Probably somewhere between, 4 & 5 kHz

The pictures may be decieving, as they are all the same height. the least preffered is wider, the only difference between the other two is bass drivers size, 10" & 12"
 

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#6
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#8
This one is great I want it my self 😎

xmax motor 1mm 😱 mechanical 18mm This is a shame it is use full with restrickted low end or low power 95dB.

simultation openbaffle 2phi.
 

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#10
Hi Helmut

Thanks for all of your input, much appreciated

I have read conflicting information on the Qts side of things, yes I have read lots where they highly recommend a high Qts, but Lukasz recommends a 0.35, which is what I believe the altec 15" 416 8B I'm using at the moment is & it sounds great. I had one eye on the Qts but couldmn't get all of the ducks to line up so to speak. dB, SPL & qts.

I will have a look at the drivers you recommend.

What do you think about the baffle shape & the obscuring of the speaker?
 
#13
DQ828 said:
Hi Helmut


What do you think about the baffle shape & the obscuring of the speaker?
Click to expand...
191254d1286632171t-ob-project-design-started-help-requested-wide-top.jpg

I have the experience that a flat baffle isn't perfect.

It shout have sloping side's( like you did) so the reflections on the baffle go side ways and not go cross the front radiated sound. Your design is nice to see but I would not make it deep is you did in this drawing. I think it has to be flat with sloping side's. To control the reflections on the baffle.
 
#14
DQ828 said:
I just had a look at the drivers Linkwitz uses & his bass drivers for the Orion have a Qts of 0.17?
Click to expand...

Then I have to simulate that one. With that Q it shout have very low Fs and big x-max and equaliser.

I know linkwitz uses a formula that calculates a driver as a piston.

Surface X extrusion= Spl and this spl decreases with lower frequencies.

So the driver has to make more extrusion and have a lot of surface in a OB and often a equaliser.
 
#15
Here the simulation of the orion woofer. peerless xls10.

xmax 12,5mm sd=352 moved air max=440 cubic cm


http://www.selenium.com.br/site/assets/produtosfinal/248_pdfManual.pdf
The selenium xmax 3mm sd=860 moved air max=258 cubic cm

So it performs poorer to the xls 10 what maximum spl concerns within x-max of the motor.
But it perform better what low end cut off concerns due higher Q.

-3dB cut off xls10 = 60Hz

-3dB cut off selenium = 30Hz!!

The selenium is great but you shout use 3 drivers to compensate the limited xmax.
 

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