I'm planning to build some OB speakers using two Alpha 15s per side. Approximate baffle dimensions will be 25x50. Is their any consensus as to the best 8 inch FR driver to use with the Eminence? I've looked at Betsys, A.N. Super Cast 8, Fostex FE206 EN and a few others. I think I'm leaning towards the Audio Nirvana but I'm wide open to other suggestions in this price range.
I have never build any speakers and I'm, unfortunately, pretty ignorant to the mechanical working of speakers and their design. Sorry if this has been touched on before. I've read a lot of the OB threads which has both enlightened and confused. I just haven't seen if there is a clear cut favorite 8 in driver and why. Thanks.
cubdog
I have never build any speakers and I'm, unfortunately, pretty ignorant to the mechanical working of speakers and their design. Sorry if this has been touched on before. I've read a lot of the OB threads which has both enlightened and confused. I just haven't seen if there is a clear cut favorite 8 in driver and why. Thanks.
cubdog
I think you are on the right track and will end up with an great sounding system. Currently, I am listening to the TB 1808 on top of a single Alpha 15 and it sounds terrific. The TB has a sonic character (a bit forward and very detailed) but can sound very realistic with good recordings. The Betsy and any Fostex should also be great. I never heard any of the AN drivers but I'd imagine they are very good too.
I would go with a smaller full range on top to reduce beaming that 8 in drivers may have. A 4 inch or smaller full range will have much better uniform polar response.
The Tang Band 8 inch fullrangers have very good dispersion! Excellent drivers, one of the best I've heard!
Larry
Larry
I'm with xrk on driver size. The biggest i'd go would be Alpair 10p.
I've heard all the 8" mentioned except the Cast 8" (which i would like to), the stamped basket ones were quite dissapointing.
dave
I've heard all the 8" mentioned except the Cast 8" (which i would like to), the stamped basket ones were quite dissapointing.
dave
+1
For value with a single driver I'd select the 4 ohm version (TC9FD-18-04) of the Vifa/Peerless TC9FD18-08 in the more recent version of the "Manzanita".
For something with greater efficiency I'd go with 4 of the 16 ohm version (TC9FD15-16) wired in parallel.
+1 on the TC9FD as a full range top for an OB. Here is a measurement of the Vifa in an OB with XO at about 300 Hz. It has very nice response and HD is about -50dB.
More info in the "Cheap and FAST OB" thread.
More info in the "Cheap and FAST OB" thread.
I had not thought about using anything smaller than an 8 inch driver. I know a couple of guys who use 8 in drivers with great success. Plus there are quite a few examples of this configuration online.
Does anyone know size driver was used on the Jamo OB? Or for that matter what does Emerald Physics use. I believe they use 15in Eminence drivers.
I'll definitely look into using a smaller full range. I want to do this right the first time if possible.
cubdog
Does anyone know size driver was used on the Jamo OB? Or for that matter what does Emerald Physics use. I believe they use 15in Eminence drivers.
I'll definitely look into using a smaller full range. I want to do this right the first time if possible.
cubdog
I think the Jamo (909 & 907) was using a 4.5" driver with a tweeter (..and no rear tweeter for a dipolar effect).
It also had problems relating to the baffle and the midrange because they didn't off-set the driver on the baffle:
Jamo Reference R 907 loudspeaker Measurements | Stereophile.com
(..it's the 1 kHz "dip" from the baffle).
Emerald has used both coaxial drivers and just horns/waveguides for higher freq.s.
BOTH designs are not at all simple as far as crossovers go. 😉
The Edge can show you baffle modeling effects with an open baffle (and it's easy to use):
Tolvan Data
Note that there are problems if you don't "chamfer" the rear of the driver's "opening" as I've mentioned here (with a technique to avoid complex router-work/chamfering):
http://www.diyaudio.com/forums/multi-way/123512-ultimate-ob-gallery-103.html#post3603412
Below are some good off-set driver examples with (IMO) good aesthetics:
Attachments
Thanks for the information. Regarding the chamfering, I planning to use 1 inch oak planks for my baffle. I have no tools, or skills for that matter. Hopefully whoever I hire will understand this chamfering technique. I'm sure I'll be asking more questions.
cubdog
You could do like me and go with two 15a,s per side and 4 of these per side.Tang Band W4-1337SDF 4" Titanium Full Range Speaker | 264-916
I was a die hard fan of larger FR drivers until I heard these. They are amazingly detailed drivers.You may not want to use 4 per side like me though...he he
They are not FR though and you most def need tweets with them.
I was a die hard fan of larger FR drivers until I heard these. They are amazingly detailed drivers.You may not want to use 4 per side like me though...he he
They are not FR though and you most def need tweets with them.
I think I'm going to keep things as simple as possible. I'm in over my head as it is. 😉
cubdog
-with only a single 1" thick board you'll need to use a router (or have someone use a router).
Here is a visual representation of not good:
http://www.diyaudio.com/forums/multi-way/123512-ultimate-ob-gallery-103.html#post3603218
Even though there is routing (shown in dark brown), there is still a significant cavity close to the driver's diaphragm.
Here is a decent example with very little cavity around the driver's diaphragm:
Attachments
So I gather a more shallow and extended chamfer starting at the forward edge of the basket, and baffle, is desired?
cubdog
cubdog
Can you clarify "uniform polar response"? I'm guessing it means an coherent frequency response from top to bottom. Not sure though.
cubdog
Before i decided to go with the TB,s I was using a fe166en for the top end. it took some moddifying to get the driver sounding right but it worked very well with the two 15a.s. I bet the dayton 8" fr could be a great choice with some eq.
I am referring to uniform SPL vs angle off axis for any particular frequency, especially highs above 2khz. This is the polar response (polar plot of SPL vs angle). At higher frequencies, small driver will have a more uniform response over a wider cone angle than a larger driver - this is why tweeters are around 1 inch dia domes and no one makes an 8 inch tweeter.
+1 for the Tang Band W8-1808. The T/S parameters of Qts=0.44, Fs=45 and Xmax=5mm provide flexibility to uses in a dipole, sealed midbass, simple ported bass reflex, or MLTL. A lifetime of possibilities.
I own 4. Two run full range in a 4 cuft MLTL bedroom speaker. I removed the whizzer cone from two and use them as a vocal range(80-1400) midbass in a 2cuft heavily stuffed sealed F3=75Hz box. When I cut off the whizzer, I left about 3/16 inch for mechanical support of the cone/voice_coil interface. Without the whizzer, you could mimic a Linkwitz LX521 or NaNo Note II minimal baffle dipole, which have proven excellent polar response.
Read over JohnK's musicanddesign NanoNote II white papers on using baffles small to enough stay under the dipole Fb(baffle width is < wavelength at Xover).
I own 4. Two run full range in a 4 cuft MLTL bedroom speaker. I removed the whizzer cone from two and use them as a vocal range(80-1400) midbass in a 2cuft heavily stuffed sealed F3=75Hz box. When I cut off the whizzer, I left about 3/16 inch for mechanical support of the cone/voice_coil interface. Without the whizzer, you could mimic a Linkwitz LX521 or NaNo Note II minimal baffle dipole, which have proven excellent polar response.
Read over JohnK's musicanddesign NanoNote II white papers on using baffles small to enough stay under the dipole Fb(baffle width is < wavelength at Xover).
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That's a LOT more complex.
I think the idea here is something as simple as only a simple inductor on the low-end as a low-pass for the 2 Alpha 15's, and the "full-range" driver used without any filter - a basic FAST design.
Keep in mind the thread poster's skill level. 😉
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