Your experience with and without wings has got me thinking. To get the ‘dipole’ effect my research suggests not having wings for the FR driver but wings could be beneficial for bass content/bass drivers. With this in mind I wonder how using an sb-acoustics-sb20pfcr30-8 to augment the bass would work for my design? The physical size, FS and sensitivity are all quite similar to the FR driver. This could be mounted low in the baffle (or midway up) and have wings partway up for it but not for the FR driver. I would run each side, wired in parallel with each other (4 ohms combined) and crossed at say 150 (a guess) from a single plate/subwoofer amplifier.Some tweaks... First I removed the wings, but it led to a very thin bass - but to more clear mids, more liveliness; sure, my woofer are mounted at about 70 cm, so no floor effect. Next I shorted the wings as shown in the picture and the bass came back, but I still missed some liveliness. So I reduced the serial resistor (level adjustment for the FR) from 5,1 ohms to 3,6 ohms. Now it sounds better than at the beginning. Small steps 🙂
I think I will make a measurement soon. But it means, I measure my ears, in fact
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I suggest the Pass ones .you have the slot and floor to add some precious db ,just add under
https://www.diyaudio.com/community/threads/pass-slob-build-discussion.300952/page-19
I like this design a lot, though I suspect (but don't know for sure) that the baffle size can be reduced in size quite a bit with little or no loss in sound quality - depending on the drivers of course. Those barrel shaped baffles used in the Betsy and Big-Betsy OB's are not that tall even with the Lii 15" drivers. The 8" betsy has a baffle much smaller than this and works well when pared with a good subwoofer. So logic tells me the SLOBs using two 15" bass drivers shouldn't really need such a huge baffle for an 8" driver. The shape of the baffle and driver placement on it will make a bigger difference than the size. YMMV, but might be worth experimenting with that.
for another good example of the counter-intuitive benefit of a smaller baffle w/driver closer to the floor and tilted up read his comments further down the page in this blog about modding his Lii 15" OB's in this way: http://www.glowinthedarkaudio.com/lii-audio-f15.html
did you read what he wrote? I guess not, or you didn't believe him - that they were "more refined", bass increased, image improved, "sound enormous"...
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Thanks for linking - his is a really interesting website to study.
Yeah i know you're smarter than everyone else 😂 ...the many experienced people who have actually heard them.
Just hearing them on the Decware YouTube page is enough for me to know you are wrong.
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Anyway, sorry don't wanna pull this thread further off track. It's supposed to be about the SB 8" FR driver, and apparently also now OB's 😉
I also dabbled with OB , and 15" FR.
The first thing I find wrong is the mention of a 15" OB in a small room. OB needs room to breathe, and so does 15" drivers. So, putting 15" FR drivers in a small room seems a bit odd to me.
Also, the beaming of a 15" driver in the upper Hz is quite intense. We're talking a cm or two above 10kHz. So, if one places his/her head just right, it might work... but for real world listening, a 15" FR will need help up high. Well... not so high in fact.
I love OB sound. The non-booming bass one can get is mesmerizing. The spatial environment from OB is also something I enjoy very much.
But I would never think of putting a 15" OB in a small room.
Currently building a TL for my SB20FRPC30-8 full range speakers. Inside dimensions are 9inches wide, 11 inches deep and 44 inches tall. Driver down 11inches from inside top, 3inch port 5.5 inches up from inside bottom approx 3inch long. Double 3/4 ply baffle and top. Will report back on their sound when complete.
Larry
Larry
Out of curiosity I mounted a GRS PT2522-4 tweeter in a waveguide on top and crossed it with a simple high pass.
The result - it gives the whole speaker "shine", opennes, liveliness. And the upper highs are crystal clear now. Wow.
The result - it gives the whole speaker "shine", opennes, liveliness. And the upper highs are crystal clear now. Wow.
Nice move using that dipole tweeter. What affect did it have on the soundstage/imaging?
Do you find the treble "shine" on the bright-ish and fatiguing side with it or still sufficiently smooth and non-fatiguing?
I had seen that same tweeter (btw, it's 4 ohm only?) and wondered the how it would sound as an FR OB add-on "super-tweeter".
What capacitor value did you use to cross it over? Just curious even if you're still experimenting with the crossover point.
Once you get your speakers sufficiently dialed in it'd be great if you can make and post a recording of the sound like @nandappe and some others do.
Dunno if you have a mic, and knowledge, sufficient for that. 🤔
That's actually a subject I've been interested in too - what is the minimum you need to make these recordings?
I assume a phone with a good mic is not sufficient, so what are some low cost mic's that an be connected to a phone or laptop that are sufficient?
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TBH that room doesn't look small to me, well small is subjective 😉
Logic tells me if putting 15" driver in a small room is bad, doing the same with a BIG OB is prob even worse.
Maybe that's why he reduced the size of the baffle and liked how it sounded.
Btw, I own a pair of Hawthorne Audio 15" coaxials (pro style tweeter mounted concentrically) in a small OB and they sound just fine in a small room (albeit at low volume levels).
WRT to treble, I have no doubt it could be improved by adding a "helper" tweeter, but we really need to know more about the driver design, the moving mass and response of that large whizzer cone, to understand why so many people seem happy with the overall sound of it even without a tweeter.
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Thanks. I'm very sensitive for harshness/brightness, but it's very fine what I hear, it's also non-fatiguing.
The highs are clearer, crisper, more refined and defined. And it gives the sound a more open character.
The whole thingie very homogeneous, with wide, deep and high stage. I'm very satisfied, really. The cap value is 9.4 uF (2×4.7).
Further tweaks may/will come. And further trials with different wings. In one of the next steps I will mount the driver into another, slightly narrower baffle and make some more tuning, and a measurement too.
I have a micro and will check regarding recording, but first things first.
It's nice that you're not hearing a lack of coherence even with the large distance the tweeter is from the FR driver.
I guess eventually you will mount it permanently closer.
That cap puts the tweeter high pass crossover around 4K 1st order 6db?
Thanks for posting the details of your project/experimenting.
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Yes, I will mount it closer to each other, I just didn't want to saw today 😀
The crossing is somewhere between 4 and 5 kHz, but I will increase the cap to 22 uF and use an attenuation on the tweeter.
Step by step.
The crossing is somewhere between 4 and 5 kHz, but I will increase the cap to 22 uF and use an attenuation on the tweeter.
Step by step.
that low ?? 9uf you in a range of 4.3k .... Ps post too later
you can cut the whizzer 🙂)
😉
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👍 Btw, I just bumped into this comment by a long time member of this forum with regards to some big 15" coaxial drivers he had in an OB and thought it was interesting, and so also if you feel the same or not with the SB8 when you experiment with wings...
"even small wings make them more claustrophobic sounding than a simple baffle"