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8 Inch Woofer
I'm working on a design for a high end 3 way loudspeaker. I can't find a woofer with the specification I want. This will be an active/Passive crossover design. The woofer will have its own amplifier and I want to use a Class D board that I can enclose inside the speaker so I need an 4 Ohm woofer since most Class D amps output more power at 4 Ohms. I'm planning on a mass loaded transmission line for the woofer alignment. I would consider a 10 inch woofer but this usually requires a larger enclosure. I say usually because some 10 inch subwoofers will work in relatively small enclosure. I need a driver that is half woofer/half Subwoofer. I will use a 250Hz crossover frequency.
The Specs I'm looking for
• 4 Ohm (will work better with Class D amplification)
• 1-1/2 inch or larger voice coil.
• Die Cast frame with venting under the spider.
• Motor with distortion reduction devices, Shorting Ring(s)
• 6.5mm X-max or greater
• Qms >= 5; Fiberglass or Titanium Voice coil former
• Qts = 0.35 to 0.40
• Fs <=31 Hz
• Aluminum, Carbon fiber, Textreme or Carbon fiber reinforced paper Cone
Maybe there is something available but I haven't found it yet. I have even considered modifying an existing woofer but would like to avoid that. My whole design just falls apart without a woofer with these specs.
Shawn
Comments
Scan 22w/4851T is close but qts is low.
Depending on budget you could have something built spec
http://www.audiotechnology.dk
https://www.madisoundspeakerstore.com/approx-9-subwoofers/sb-acoustics-sb23mfcl45-4-8-polypropylene-cone-sub-woofer-4-ohm/
Darn close, but poly cone, unsure on motor treatments
https://www.madisoundspeakerstore.com/approx-8-woofers/sb-acoustics-sb23cacs45-4-8-ceramic-woofer-4-ohms/
Almost spot on but ceramic cone
The NE225W-04 comes very close.
https://parts-express.com/pedocs/specs/264-1138--tymphany-ne225w-08-spec-sheet.pdf
Parts Express no longer carries the 4 ohm version but Meniscus Audio shows them out of stock.
Ron
https://www.parts-express.com/Wavecor-WF223BD01-8-3-4-Balanced-Drive-Paper-Glass-Fiber-Cone-Mid-Woofer-4-Ohm-298-1212
Fs is just a touch high at 32.6
Does the Standard SB Acoustics have a shorting ring in the motor? - The distortion figures I have seen are not that great. Also I have seen some of the measurements for SB Acoustic drivers a HiFi compass and they rarely match datasheet TS parameters.
Thanks for the suggestions
Shawn
Looks like there is some sort of shorting ring in the specs
Their product page claims it has a shorting ring. Le is pretty low, but not crazy low.
Sehlin Sound Solutions
I have considered this driver but some of the early Klipple measurements done on this driver were horrible. But I read also online that some people got samples of this driver will defects and maybe one of those were measured during the Klipple analysis. I have the 8 ohm version of this woofer in another speaker I built and it's a very nice driver.
Shawn
I find is weird that the SB23 woofer have only a 60 Watt power rating considering they have a 45.5mm Voice coil.
Shawn
Wonder if they are considering mechanical limitations vs thermal?
What do you think of that wavecor?
I had contacted Wavecor a few weeks ago to see if they had burn in TS parameters for that driver. They responded back that they updated the spec sheet on their website. After burn in; FS = 31, Qts = 0.37. I wish this driver had a stiffer cone; paper/fiberglass combo is a good compromise if you want to use this driver higher in frequency aka 2 way. I was thinking maybe 1 could adhere some carbon fiber 3k tow strips to add stiffness.
Shawn
Be an expensive driver to experiment on but one could treat the back side of the cone with CA. Wouldn’t add much mass.
https://www.madisoundspeakerstore.com/approx-8-woofers/scanspeak-revelator-22w/8857t-00-8-woofer-aluminum-cone/
That's very close on all counts, slightly lower Q but otherwise fits the bill.
Sorry, it's also 8 ohms. The 4 ohm version is even lower Q. They should take some EQ, though. Probably more linear out of the gap than most contenders.
So, use a pair of them to get the 4 ohms... (cough)$$(cough)
InDIYana Event Website
If you are amplifying the woofer not sure why the parameters are so critical. Add DSP and tune any way you want.
Also thinking several of the class d amps are optimized for 8ohm?
Scan Speak unfortunately doesn’t offer a 4 ohm version of the 22W/8857T-00. I sent a massage to them to see if this was something they would offer in the future. They do offer the 10” Revelator aluminum cone in 4 and 8 ohms.
Shawn
https://meniscusaudio.com/product/scan-speak-22w4851t/
Why not just use a larger amp with an 8 ohm driver. We're only talking 3db difference 4 to 8 ohm
The picture is wrong at Menisus site for this item. The spec sheet says its paper
Shawn
I could use a larger amp, But I still want to have it inside the speaker enclosure and a Class D amp would produce less heat inside the box. I was thinking about using one of the mono ICE amp boards from PE because they have the amp and power supply all on one compact board, I haven't done a lot of looking around if there is an Class D amp with enough power with 8 ohm loads and with the power supply all on one PCB.
Shawn
How much power? IIRC, https://hifimediy.com/product-category/amplifiers/ has an offering with 150w@8∩. It would need a separate power supply. I've heard the 125w older design ice amps, only deliver about 80w at normal distortion levels. What about the irl designs? Class d audio has some offerings but maybe more expensive than what you were looking at? classdaudio.com/amplifier-modules/all-amplifier-modules.html
Hypex fusion amps should give you enough power.
What about the older hypex ucd (didn't someone on here have trouble with their ucd?), or newer ncore, or purifi.
And what's the word on the Gallium Nitride amps?
http://www.loudspeakerdatabase.com/search/7.9_size_in_10.0/3_z_5/9_fs_31/0.35_qts_0.40/6.4_xmax_42.5
Only half a dozen options…