Dipole comparison: Orion/Phoenix vs Nao

[paulspencer]

Linkwitz Orion and Phoenix speakers have interested me for quite some time. I'm inclined to think they are hard to beat in terms of fidelity. They are quite expensive to construct, however, considering that they use a considerable number of expensive drivers and require and require at least 6 amp channels. More recently I have come across what appears to be a viable alternative.

The Nao



Some notable differences:

1. 6.5" drivers to allow a lower crossover point

2. rear tweeter

3. single open back woofer with a cardiod polar response

4. passive crossover for the top section to reduce the number of amp channels

I'd like to hear some views on the merits of the different aspects of this design when compared to Linkwitz Orion / Phoenix.

[Magnetar]

Looks to me like a goofey little pipe for the bass. Probably VERY one noteish!

[sfdoddsy]

It's difficult to say without hearing both speakers, but I suspect that they'd sound more similar than different. The main difference seems to be tht the Nao is a bit simpler to build and operate.

Fortunately, construction of eiither is pretty easy, so you could always do a test baffle for both and see.

Cheers

Steve

[paulspencer]

The Nao will still be quite expensive, but it seems to demonstrate that simplification and lower cost are possible.

I would perhaps make some more changes for a budget version:

Drivers - Seas 27TFF, 8" Peerless HDS, Peerless 12" XLS

Possibly a second woofer with a passive first order lowpass filter at 250 Hz to compensate for cancellation and use less active filters.

This design would only need to be biamped. The U frame woofer would probably do okay with some simple eq to extend the bass a little, down to say 40 Hz.

Driver cost approx $710 AUD
This is about a third of the cost of the drivers in the Orion!

Now, I don't expect it would sound as good as the Orion,
but at that cost, who would expect it to?

[diamdiam]

go over to the madisound discussion forum. there's some people who've heard it there. plus, john k frequently posts there.

i don't think there's been a side by side comparision w/SL's designs yet.

[MBK]

What to expect:

From my own experience, I have a 6.5" fullrange crossed to two cheap Vifa 10" woofers, active EQ, all run in dipole (with folded baffle probably closer to the Nao, i.e. slightly cardioid, but I have not measured them accurately enough to confirm). And I have heard the Orions.

The cheaper drivers give you less detail, and more distortion in the bass. Subjective slam and bass fullness is higher (due to higher distortion I guess). The smaller mid (or my fullrange) give you better imaging.

No free lunch

[PeteMcK]

It strikes me that a U dipole such as the NAO could be de-tuned with a Karlson type slot; of course it would change the rear radiation pattern, so some experimentation would be required....
Pete McK

[wingman]

what about

Arvo Part project

[john k...]

(JPK) I just joined this forum and was pleased to see that the NaO is being discussed here. FWIW, the NaO was designed to be a simpler system with similar capabilities as the Orion. The hybird approach of acitve eq and woofer/panel crossover combined with a passive mid/tweeter crossover allows the system to driver by only two amplifiers. The panel has similar max SPL capability as the Orion, but the U-frame woofer has significantly higher output capability than the dual 10" XLS woofer of the Orion, on the order of 10 dB greater max SPL. The woofer is not a perfect cardioid but does have reduced rear radiation to the tune of about 10 dB below the on axis response.

[Ian J]

John, as an admirer of your work in the field of audio design and measurement I'd like to wish you the warmest of welcomes here. You will find there is much interest in the open baffle/dipole concept generally. Regarding the U-frame section in the NaO, an idea I find particularly interesting, could you give some idea as to how the pseudo-cardiod radiation pattern interacts with the room in comparison to dipoles? This is often mentioned as a large advantage with dipoles as room modes are comparatively unexcited compared to monopole sources. Also, would there be any benefit in 'de-tuning' the U-frame with an exponential (Karlsson- type) slot, as somebody suggested in another thread?

Ian