Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

[fjhuerta]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

So.. yeah. A pair of RS225s down to 80 Hz is doable. 120 Hz seems easy (according to SL and his Phoenix). I'm still leaning towards a U-frame with the 225s and an MTM with the ZA14's crossed over at 250 Hz, 4th order.

My plan is to cross them to the tweeter at 2KHz, 4th order again.

Here's something I'm unsure about. I could probably do this by trial and error, but an error would be somewhat costly.

1) SL uses an 8" midrange and according to him, an OB doesn't have many issues getting to 1.4KHz, 4th order. So, I'd assume a pair of 5"s at 2 KHz would be OK?

2) I'm assuming that the extra midrange output will not allow me to use the Vifa DQ25s at 1.8 KHz.

3) Would a 4th order 2 KHz filter make sense for my dipole? Since my mids are far smaller than SL's I'd expect so. I'm also thinking it'll be a pretty high output speaker, even with the ZA14's, since I'll be crossing them quite a bit higher, so the Vifa DQ25 will not be able to go much lower than 2KHz, if not higher. If I need a lower x-over point I'd need to switch to the RS28 or the DXT tweeter. Which I don't want to, because I'm planning to use front / back firing tweeters (SL's site is a goldmine of information!) and I already have 4 DQ25s.

Opinions? I'm assuming the baffle will be narrower, too.

(I've pretty much abandoned the idea of a Neo8 based dipole, BTW. I'm convinced the way to go would be with Neo10's, and I hadn't noticed how expensive they are now!).

[jonasz]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

In the latest iteration of Orion the W22 is crossed at 92Hz.

[natehansen66]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

I say stay the course! With 2 of the RS' per side on a baffle you ought to be able to get to 80-100 without extreme eq. You have a sub, right? Look at the Nao Note, and the Orion. I think Linkwitz crosses that Excel at 120hz........

And the RS would be ok to cross at 800-1000 to the Neo8, would it not? I'd also vote to stick with the Neo3 in dipole mode.

FWIW, I got my Neo8's today and they're super easy to work with sans baffle.......+8db 850ish for a 900hz lr4. A good bit of boost for the planar but for sane apartment levels it sounds fine. Be interesting to see what happens with some real volume. Measurements taken 4' off the ground from about 30" away in 15 degree steps, 3ms gate.

[JasonP]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Hahaha, it seems great minds think alike, or something! I too am working on a sim with the ZA14W08 on my OB dipole design and possibly the DXT. It'll be interesting to later compare and contrast our designs ;)

[fjhuerta]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

After playing around with MathCad and A,B,C, Dipole I don't see my speaker happening as I planned it.

I need a big U or H frame because of my smallish woofers. I have to build a smallish U or H frame for my very high crossover point. As it has been pointed out, I can build a small U frame and EQ the living cr*p out of it.

Case in point: if my x-over between mid and woofer is at 200 Hz, I need +2 dB EQ to reach a flat FR at 80 Hz. If my x-over point is 800 Hz, I need +11 dB. :eek: Not going to happen. That's not going to make for a nicely balanced speaker. I don't want to stress the Neo8, either.

So, I'm now leaning towards something quite a bit different. The 225s are still on my plans, but I'm mating them to something that can play lower - a pair of ZA14s, crossed over at 200 Hz.

I'm still undecided about the upper end. I can use an RS28f, RS28A, the Seas DXT, or a pair of Vifa DQ25s.

Pros and cons, the way I see it, are.

RS28f - nice tweeter, nothing fancy. Big frame, so x-over point needs to be low.
RS28A - can play lower than the RS28f
DXT - more uniform power response, can play pretty low.
DQ25 - Although x-over point would need to be closer to 2 KHz, since I have 4 of them I can use 2 in front and two in the back. Besides, the ZA14s are small enough that they could get to 2 KHz with nice power response.

Any ideas about my new plan?

[6thplanet]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

U frames definatly need some damping and what not to perform correctly, an H frame is balanced so it dosen't need it. Yeah they are usually used below the hump (2-300 Hz), hence my cut off of 200 and rolling that into the 500 HP of the neo8. And yeah the 8" is pretty much all it needed to balance out what the neo8 needed to fill out its lower end, at least to my ear....

[cjd]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Yeah, I just double-checked the mathcad sim and you are right. Off axis is worse. Hmm.

Maybe a U / H frame is something to be considered only if the system has a midrange that can go as low as 250 Hz or so. At least that's what I've been able to understand.

Well, it's simply working within the limits of the system you assemble. Deward covered this re: Orion. I think the parts you have can make a super dipole, they'll just have certain constraints. The more you push to get low-end extension, the more you run into woofer-mid integration fun.

For my own slow project, there's a reason I've flipped over to the Neo10, and one of them is how low they'll go. I'm also probably going to end up with a 5-way all said and done, probably a 12" (possibly 15") on baffle below the Neo10 and then a pair of 15's in a W baffle below that, and then for the real bottom end some monopole sub (I'd like to see f3 at 8Hz in room... we'll see if I can do that) - most people won't feel the need for the sub. I also need to find a room to put these in, so my project has plenty of runway left before it really takes off. If it does.

My Neo8's are going to find their way into a monopole paired to a nice ribbon (well, folded diaphragm really) and a quad of 165mm mid-woofers. Love the sound.

At some level, the pursuit and learning and experimentation is the game. For me, definitely. So give in, make some sawdust, and "fail" a bunch till you achieve the success you had in mind. You can always put everything back to where it is today, no?

[Deward Hastings]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Does anyone know if an U frame can work up to, say, 1 KHz or so?

ORION is "U frame" (on the mid), and crossed at 1.4kHz. The U frame cavity resonance is a function of its depth . . . otherwise it's not much different from a flat baffle (just folded to make it narrower). There are few "hard" transitions in these designs (which is why I said baffle width doesn't matter much, give or take a few inches). You can push anything too far, but there is almost always some "wiggle room" . . .

[fjhuerta]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Active EQ may give you more range more easily to try to tame this, but in the end you're still best off avoiding it. I believe the problem is that off-axis is uneven, especially in a U-frame.

Yeah, I just double-checked the mathcad sim and you are right. Off axis is worse. Hmm.

Maybe a U / H frame is something to be considered only if the system has a midrange that can go as low as 250 Hz or so. At least that's what I've been able to understand.

[cjd]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

* U and H frames should only be used when the crossover point is below their hump (I suppose this shouldn't apply when using active EQ).

Active EQ may give you more range more easily to try to tame this, but in the end you're still best off avoiding it. I believe the problem is that off-axis is uneven, especially in a U-frame.

[fjhuerta]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

http://techtalk.parts-express.com/sh...d.php?t=229698
I don't feel the neo8 sounds strained at all. I will say they sound...how should I say, smooth. They don't have the impact that a normal cone speaker has playing lower midrange, but they play it kinda subdued in a sense. BG recommends this driver to 200 Hz in a low wattage, nearfield application...

That's a really interesting application. It's surprising how a single 8" mounted on an H or U frame was all you really needed, bass-wise.

I've been trying to read as much as I can about dipole woofer operation, and this is what I've been able to understand.. please correct me if I'm wrong.

* A U-frame is a bit more efficient than an H frame, provided measurements are on-axis, and the line is damped.

* U and H frames should only be used when the crossover point is below their hump (I suppose this shouldn't apply when using active EQ).

* U and H frames have a defined upper frequency limit, and it's not that high.

I've been playing around the Mathcad FRD tool, and I don't see an upper limit that can't be fixed with proper EQ. But, from the NaO II measurements, I see that even a properly damped U frame woofer can't get to 600 Hz.

I don't know if this is because of the driver used or a limitation on the U frame. I suspect it's the latter.

I'm starting to worry about this. Is a U / H frame only usable when crossing over at, say, 200 Hz or so to a suitable mid / woofer?

Because, in that case, there's no way I'm going to be able to make this work by crossing it over to a Neo8. I'd need to make it a 4 way.

I gave it a quick thought, and in that case, I'd rather make a 2 way with 2 RS225s and a the SEAS Waveguide tweeter, crossing them over at 1.1 KHz or so with a very sharp filter (8th order L-R), going fully active, and avoiding the use of a dedicated midrange. Just like the original NaO. But that would go against my idea of doing a full dipole / open back speaker.

Does anyone know if an U frame can work up to, say, 1 KHz or so?

[6thplanet]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

http://techtalk.parts-express.com/showthread.php?t=229698

I don't feel the neo8 sounds strained at all. I will say they sound...how should I say, smooth. They don't have the impact that a normal cone speaker has playing lower midrange, but they play it kinda subdued in a sense. BG recommends this driver to 200 Hz in a low wattage, nearfield application...

[fjhuerta]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

BTW, fjhuerta, your speakers and posting about them are what got me interested in the Neo8's. Just go for it man!

Thanks! I do like the Neo8s, although they are pretty complex to work with, IMHO. I'm reading The A,B,C Dipole guide. I'll need all the help I can get...

But I already suppose I'll be building a narrow tower with a U-frame, from what I've been able to understand.

[Deward Hastings]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

Just go for it man!

+1 . . . :D

But I agree . . . 800-1000 seems to me more reasonable for the neo8 as a dipole.

[natehansen66]

Re: Instead of hijacking the OB thread... how does a 2xRS225, Neo8, Neo3 OB sound?

I already noted the Neo8 can go 'low' just fine. 500Hz LR4 would be easy.

Without a baffle? I don't have my Neo8's in hand yet so I can't measure them myself, but I think 500 would be pushing it. B&G's FR shows them down 16db at 500 hz (and the graph looks like that of a 'naked' driver). A quick Edge sim with a driver of similar dimensions show -8db @ 500hz. Not only that, but the driver is rolling off 6db/octave below 2000hz........

Depending on how you do the dipole compensation, 500 might be doable, but not very loud. I'd be wary of boosting the bottom end more than 8db or so, and I don't like knocking down the response to match the low end. That's just how I work, to each his own.

I know 6th planet is doing it this way, but I can't help but thinking it sounds strained in the midrange. To me the Neo3 sounds strained below 2000hz.

I guess I'll know next week when I get 'em in my greasy paws! :D

BTW, fjhuerta, your speakers and posting about them are what got me interested in the Neo8's. Just go for it man!