I removed these & put the 5.5 M drivers in the PAWA horn (had to enlarge the hole to do it of course.
I then fired them up with a 2a3 SET amp & a modded NOS TDA154a chip Phillips Cd player.

Initial Impressions:
The 5.5M drivers are a very significant improvement over teh 4"ers. I think Dave has really made a lot of changes that were needed. Let's see, much less IM distortion of course, and they sound noticeably fatter than the 4"ers in the midbass. The plug seems to help the midbass, midrange & treble considerably.
I am listneing to them full range without a sub, and frakly, for music the bass is very adequate!
I measured them with a rat schak meter, and they seem to go down to about 70 Hz, and then drop, but honestly, they sound more like 45Hz drivers to me with music. maybe becuase it is a horn, the bass response was not measured accurately by the rat schack meter at my lsitening distance of about 15 feet.

The amazing thing is the 100 Hz to 5,000 Hz response...very very flat within +/_ 2 db in my listening position! Very nice.
The one drawback I can see is that in the 6000-10000 Hz range they seem to go up by about 10 db, which may just be that they need break in. Anyway, ther eis not much program material over 5,000 Hz, so the subjective effect is that of added air with a slight treble sheen to higher voices & instruments (exagerrated 2-3rd order harmonics maybe?). Very subtle, and really not too bad at all.

I am listening to them with the drivers almost facing straight ahead (almost no toe in), and the imaging, etc are dead on. Very clear and nice with very goodbass for music. They ar about 3 feet from the side wall and about 5 feet from the back wall in a largish room.

I'm going to keep these in the PAWA horns, and have ordered another pair from DAve as a spare.

Will keep you all posted as I listen more!
-akhilesh

Poinz

In many ways these drivers in the PAWO horn do things at a level I have not heard before in any system. Transparency, coherence, imaging, depth, instrument placemnt, focus are all amongst the best I have heard in ANY speaker system. Tone is acceptably good. Dynamic range is on the low side (compared to the usual horns I am used ot listening to) so they are best in a small room, heard at about 8 feet.

And for the first time the lack of frequency extension in a signle driver system is not bothersome to me...while most single driver systems I have heard are suitable for acoustic & jazz, and after a while the lack of low end or high end starts bothering me, these are suitable for acoustic, jazz, as well as pop & classical....only deep rap tends to not sound great (the bottom octave is kinda low on these).
Highs are great. I am listening to them about 10-15 degrees off axis.

Overall, highly highly recommended, IN THE PAWO HORN of course. I can't speak for them in any other enclosure.
-akhilesh

I myself own and have listened to a lot of these single drivers, and usually they need bass augmentation, and in some cases a supertweeter.
OFten, they have objectionable frequnecy aberrations as well.
But the DCA 5.5 in a PAWO horn is the first setup I hav eever heard that does NOT need ANY twewakng, no passive components, no notch filter, no BFC circuit; NOTHHING in the path between the amp & the driver, and STILL sounds great without serious compromise.

AS mentioned before, I recommend this setup strongly.

Here is the catch: Dave was selling these for $90-$100 a pair (a very very reasonable price if you ask me), but he had very few initial drivers. THe PAWO horn BTW is an excellent design, available on the web, and shoould not cost more than $300 to build if you get a carpenter to build it for you. If you build it yourself, should be even less, like a $100-$150.
NO curves in this horn! GREAT WAF! Very elegant design.

I thinkd Dave's initial set of drivers is gone (fortunately I bought a spare pair!)
For example, Mark M, an audiophile buddy & owner of a mega buck audio note system, decided to buy one or two pairs of these drivers on the spot after listening to them in my house. This should reassure you that I have not lost my mind, these are indeed good!

In order for Dave Merrill to get another batch, i thnk he needs to order a few hundred from his source at least. So if you are interested, and for the money, frankly, you;d have to be crazy NOT to be intereted, I recommend you email Dave and tell him of your interest. If he gets enough emails of interest, he may be motivated to get another batch made.

Otherwise, I fear this driver will fade into legend. And we don't want that.
-akhilesh

i just got mine two days ago, will be trying them this weekend, i am happy to learn that the 5.5 sound better tha the dca 4"

zeno