Dipoles like Avro / Orion / Statements, passive XO

[ThomasW]

40+ years of DIY audio, and the SS 9800 is the finest sounding metal dome I've heard.

[Jonasz]

The seas tweeter I have is alu dome with a waveguide - see picture earlier. Are they bringing out another one?

Yes they sure are, the 27TBFC/G-DXT, where DXT stands for Diffraction Expansion Technology. If you want I can email you the preliminary pdf for it.

Some info about DXT:

http://mikethomas.dk/product.asp?articleGuid=29573&menuGuid=6057&subMenuguid=12075&groupid=3181

http://www.masterpiece.dk/UploadetFiles/177/25/SOUNDBAR_speakers.pdf

[Kevin Haskins]

Interesting - you mentioned using them, but also not liking them. Is that following from using them? I'd interested to know what you don't like. I have certain issues with them, but it could be more related to what they're paired with.

re dispersion 20 degrees down on vertical and there is a huge audible change in response. I've not spend ages measuring either. If you take one, no baffle, and tip it just away from you (vetically, not horizontally) - compare pink noise / mms signals, and it is as if all the very high frequencies aren't even there. Quite astounding. Horizonatl dispersion simlar to dome, yes (well, by ear).

When I say ribbons... I mean true ribbons. I don't like their fragile nature and the ease with which you can damage them nor do I like their measured performance. The BG Neo3 has neither of those problems as it is very robust crossed over low and the distortion levels are low. The fact that it can be used easily as a true dipole is icing on the cake.

The vertical dispersion is to be expected and it may be more of a blessing than a curse. Limiting your vert. dispersion may help with floor reflections just like the tighter dipole radiation pattern to the sides helps to limit the early wall reflections. Both are typically issues in the midrange and by limiting both you theoretically end up with better results than wider dispersion.

[Dennis H]

The Neo3PDR gets my vote. I just built one yesterday and its a fairly simple solution to work with. Its handles a low crossover point with ease, has a true dipole dispersion with the rear cup removed, and for $50 its hard to get that type of performance.

Its only difficulty was the need for a notch filter up around 12K on my baffle with the rear cup removed. Other than that it was an easy solution at 1.8K 4th order acoustic.

Hey Kevin,

If you don't mind my asking, what did you end up with for baffle dimensions and where did you locate the Neo3 on the baffle? The Edge makes it look pretty sensitive to location but maybe it's overly pessimistic?

[Kevin Haskins]

My test baffle is 12" x 48" with the goal being that someone can walk into any Home Depot and pick up a 24" x 48" x 0.75" piece of wood, cut it in half and cut the holes for drivers and your done with the cabinet building. ;-) This one took me about a half hour to make including cutting the flush mount holes for the drivers.

It looks like this...

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I'm going to take another swing at it with the Neo3 removed from its round faceplate and squish the two 6.5" drivers closer to the Neo3.

My first results where promising though. Sounds great and the crossover is a manageable 16 components, which includes the impedance compensation network.

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[Dennis H]

Thanks Kevin. It looks like your results with the Neo3 are better than the Edge predicts, which is a good thing. I think SL found the same thing, that the real world peaks and nulls weren't as bad as pure dipole theory would suggest. Here's what the Edge says about your baffle with the tweeter position just eyeballed in.

[Kevin Haskins]

Thanks Kevin. It looks like your results with the Neo3 are better than the Edge predicts, which is a good thing. I think SL found the same thing, that the real world peaks and nulls weren't as bad as pure dipole theory would suggest. Here's what the Edge says about your baffle with the tweeter position just eyeballed in.

I'd have to look at the measured response again but yeah... the theory is one thing the measured results another. There are too many factors that are not in the model. The notch isn't there in the measurement but you see some of the hump.

[Davey]

I fiddled with it for awhile, but I think the "Edge" yields results which are essentially useless for dipole setups.

There's no substitute for actually constructing a baffle and taking actual measurements...preferably outdoors.

Cheers,

Davey.

[littlesaint]

I'm going to take another swing at it with the Neo3 removed from its round faceplate and squish the two 6.5" drivers closer to the Neo3.

Does the faceplate play into the response at all?

How would you mount the Neo3 sans faceplate?

[Kevin Haskins]

Does the faceplate play into the response at all?

How would you mount the Neo3 sans faceplate?

I'll tell you after I get some measurements without it. ;-)

It has four screws that mount it to the faceplate. I'd cut a rectangular hole for the driver, route out the rear of the baffle with a chamfer and a flat area to drive four screws holding it in place. It will be more complex to cut. The circular faceplate would certainly ease matters for people who are not Norm Abrahms (me included).

[BobEllis]

I fiddled with it for awhile, but I think the "Edge" yields results which are essentially useless for dipole setups.

There's no substitute for actually constructing a baffle and taking actual measurements...preferably outdoors.

I've found that increasing the speaker and edge source density often eliminates the deep nulls The Edge predicts, making it closer to reality. Of course the penalty is slower recalculation times.

Of course we're still better off measuring.