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Get familiar with the reaction system: Introducing the Reaction System
Weird but cool SB driver
Check this out:
If the published off-axis is to be believed, the overall power response of this 8" should be absolutely ok as an actual 8" full range driver. $60 isn't a bad price for any 8" driver, plus you get a whizzer cone and phase plug out of the deal. Full range drivers are not my bag - I like designing crossovers - but this seems almost too good to be true, at least in the 8" size class. Well done, Sinar Baja.
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Comments
Pretty impressive value for a 8" incher. Maybe a 1.5Khz tweeter, and a 15 inch woofer.
Why is it that every speaker I look at with a whizzer cone I wonder how well it will work with the whizzer cut off?
Not much on full rangers either, but very interesting.
It kinda reminds me of the midrange in Nick's Mnemosyne build, but without the connection at the whizzer edge.
InDIYana Event Website
Wolfy's Photobucket
Might be a good good choice for 2023 InDIYana theme woofer...
InDIYana Event Website
Wolfy's Photobucket
That looks very interesting and only A$70 - unusually, it's cheaper here in real terms than in the States.
https://www.wagneronline.com.au/sb-acoustics-8-full-range-frpc/sba-drivers/sb-acoustics/speaker-drivers/audio-speakers-pa/sb20frpc30-8-97808/1005860/pd/
Given its treble response, you would need a tweeter or full range anyway so the SB20pfc woofer at A$55 would be an even better buy. The SB16pfc sounds really nice so I would expect similar quality from this one.
I haven't used a speaker with a whizzer cone since my first pair of "Interdyn" 210s many years ago: they were an 8" full range and sounded OK, the driver was a SEAS.
At least on paper, the SB20 has very similar specs and FR to the much loved Dayton RS225. Someone on stereo net has matched it with a Vifa TC9 in a sealed cabinet crossed at 600Hz and is very happy with the sound.
Geoff
The 30° off axis is superb, all things considered. If you are worried about "smooth", don't be. Not really.
Wow that is quite decent in many aspects. I like it.
Wouldn't a high shelf from 1KHz to 20KHz make them just about right as a full-ranger?
I thought these old OEM versions looked pretty good on paper so I put away a pair a couple of years ago --> https://meniscusaudio.com/wp-content/uploads/2018/07/SB20PFC30-04.pdf
Stupid question, what's a 'high shelf' please - perhaps a resistor and cap to tilt the response?
Thanks
Geoff
Here Geoff --> https://rebootrecording.com/high-and-low-shelf/
Thanks Steve, but how would you put a 'shelf' in a passive crossover - or is that only do-able in an active one?
After baffle step you may not need a shelf. You can make a shelf with a notch plus a inductor or use this filter.
I doubt that shelving the top end would have the effect you think it will. The off-axis measurements show that at 30 degrees off-axis the top-end is shelved considerably above 3K already, but it then recovers nicely during the transition to 60 degrees off-axis. A shelf would dull that thing down considerably, to the point you may as well buy a true $60 woofer. There is enough top-end energy being radiated into the listening space.
Look at the on and off-axis and try to imagine a point source power response. These are likely very balance just slightly off-axis from the listening point.
Part of the way they achieved this HF response is the use of a full copper sleeve. On a $60 driver. Any way you slice it, this is (on paper) an incredibly high performance old school looking full range 8" driver.
I'm not an advocate of point source large diameter drivers in general principle, but these are something different. Compare it to this (which is a more traditionally built large diameter full range):
https://www.madisoundspeakerstore.com/approx-8-fullrange/fostex-fe208ns-8-full-range/
That one is nearly $300 with an inferior motor, shitty cone, and less controlled top end. If 8" full range are your thing, you can't beat the SB (apparently at any price if the Fostex is a reference).
^^^^This.
Dammit! I don't NEED any more drivers!!
(I keep telling myself to no avail . . .)
Thinking back to my copious driver acquisitions of my youth from Radio Shack I recall that I really liked full range drivers for listening too for background music and non-critical listening - they just seemed so smooth and well balanced . . .
Wow, another Rat Shack driver aficionado....
InDIYana Event Website
Wolfy's Photobucket
Obsessions . . . Addictions . . . Expenses . . . .
I wish I had pictures to share of some of my past creations.
At 18 YO, I had built a pair of 6' tall towers made of 2x4's and filled them with every driver Radio Shack made and they sounded fantastic.
Imaging in the sweet spot was superb but lacked bass - but I didn't care . . .
22 watts per channel Radio Shack Receivers sounded great back then.
Still have a Realistic STA-110 receiver here in my basement I listen too all the time because it still works and has the best balanced sound of any analogue amp I have ever heard - maybe that is just because it is what I got used too.
I did the same thing - then after I got them I realized that they need 1.5cf to hit an F3 of 50hz. Maybe one day I will use them when I have some more space (wife doesn't like big speakers in the front room)
"I realized that they need 1.5cf to hit an F3 of 50hz"
WinISD says F3=47 Hz in a 1.0 cu ft box tuned to 42 Hz with a pair of 2" x 8.1" ports.
WinISD also says F3=40Hz in a 1.5 cu ft box tuned to 42 Hz with a pair of 2" x 4.9" ports
Maybe you can get a pass from the boss on the 1 cu ft boxes? (Worth a try . . .)
The more I consider this baffle-step comp and JR's comments I think you are on the money jhollander.
I guess one could substitute a series calculated resistor with a potentiometer for adjustability, yes?
I resemble that remark...
I see that shelf and I'm a kid again.
I picked up a pair for my shelf.. The phase plugs seem to be plastic, which I'm not surprised based on the price point. But one seems slightly loose if I wiggle it with a bit of force. A little concerning, but hopefully it won't make a difference to the sound.
Anyone else try them yet?
I got em to potentially use for inDIYana if I do try to build something and come out. Instead of risk destroying the w8-2145s in-transit and handling.
In case anyone was interested. Here is response/distortion in a 1.15cf box with a single 2" precision port (2 flares butted up for ~4" length) 13.25"x18" baffle. The mic was a little off axis, say ~5-10deg. The dip at around 2.8k is extremely deep. Wonder if that is where it hands off to the whizzer.
Black = THD
Red = 2nd order
Orange = 3rd order
Any comments on the sound? Looks pretty good considering what it is.
I'm using it as a woofer in my indiyana build. I did listen to one direct wired for a few minutes. That bump above 3k makes itself known by making the upper end of vocals pretty in your face. Though I didn't have both wired up to get any stereo magic. I've got a two pair binding post cup on the box. Thinking of maybe wiring up one set of binding posts for the two way and the other set linking into a baffle step circuit straight to the woofer to be able to hook em up either way.
Notch 3-8k with some baffle step added might be magic.