[Rudolf]

OK, thanks Rudolf, I see your point. But I would think that since the outer edges of the baffles will be closer to the side walls (mine are only 25cm away), the radiation patterns will be different anyway?

That is a whole different story indeed. If the side wall distance is less than the baffle width (just as a rough rule of thumb) your OB practically is "wall-mounted" and you would have to consider the mirror sources and other effects IMHO. Just as you have to consider floor bounce and floor gain for the "floor-mounted" baffle.

[mcgsxr]

Thanks for the help and clarification so far.

I am a little lost about the Xover using the Reckhorn, AND a passive network - I would have thought that if the Reckhorn was used, there would not be a need for any passive network.

The Xover for the MAW is 70Hz, and the Xover for the b200 is at 400Hz?

The prices I referenced are around the price for a quality cap of 150 uf - they appear to run around $25 a piece, plus the 18g air coils about the same, thus my throwing $100 around.

I can certainly see now the complexities of speaker design - did I stumble accidentally onto something decent the first time around (using only the Reckhorn) or do I just put up with bad sound???

I appreciate that folks are chiming in here, I really am interested to learn more about this!

[jonners]

I appreciate that folks are chiming in here, I really am interested to learn more about this!

Glad to hear that you didn't mind me butting in. I'm learning too. My OBs (B200 + 15" Celestions) ended up close to the side walls simply as a result of moving them apart until they sounded best, but I'm always glad to know a bit more theory in the hope of making things even better. 

[Rudolf]

I am a little lost about the Xover using the Reckhorn, AND a passive network - I would have thought that if the Reckhorn was used, there would not be a need for any passive network.

You would be right if we were dealing with some conventional two-way box. But dipoles are a little bit different.

The Xover for the MAW is 70Hz, and the Xover for the b200 is at 400Hz?

Look how the unEQed response (green) of the U frame is bent into shape by "folding" it down at 70 Hz:


I have added the first dipole peak and dip of a point source driver as a dashed line. What you might have considered the woofer roll-off at 300 Hz is not done by a Xover filter, but by the baffle roll-off into the first dipole dip.

The prices I referenced are around the price for a quality cap of 150 uf - they appear to run around $25 a piece, plus the 18g air coils about the same, thus my throwing $100 around.

I could open a can of worms and discuss the quality needs for Xover components below 300 Hz. Certainly I won't do.

I can certainly see now the complexities of speaker design - did I stumble accidentally onto something decent the first time around (using only the Reckhorn) or do I just put up with bad sound???

By sending a simulated response diagram, made from some odd data across the big pond I don't know how your system actually performs. I believe some lower mids have been quite attenuated, but the ear is a VERY adaptable instrument. Loudspeakers have to be really bad to not get acquainted to.

PS: I'm off to Berlin over the weekend - so no answers from my side before monday.
(This does NOT say that there is no internet available in Berlin - but there are a lot of other things more tempting.)

[mcgsxr]

I hope that Berlin is awesome, and that you have a great time!

I wonder what would happen, in terms of leveraging my existing Xover, if the woofer was sealed, instead of OB - could I then use the Reckhorn to trim the b200, and feed the sub without resorting to passive components?

[Rudolf]

Some results for the MAW in a closed box of 40 liter - compared to the same driver in OB:



It does not make much difference, if the CB is 30, 40 or 50 l. Active crossover is 150 Hz with 12 dB/oct, both for the MAW and the B 200. Note how the B 200 has to reach lower than with the OB solution.
The lower black line in the diagrams is the energy response. You can see how it changes from dipole to monopole in the bass region. Another visualisation is the directivity index (DI):



DI changes less along the frequency range with the OB solution (red) than with the CB. I'd say that the CB version can be done without much sweat. Just find out if it is to your liking.

[mcgsxr]

Thanks for the insights into how a closed box bass implementation will change the dynamics of the speaker - I appreciate your continued (free!) support!

I will likely build up a set of mules to test how sealed bass makes me feel - I have been listening to OB bass in that room for over 5 years now!

[Rudolf]

mcgsxr,
I forgot to mention that the MAW has to be connected with reverse phase compared to the B 200. This is due to the distance of both drivers in the baffle.



Black line is for one driver with reversed leads, red for both drivers in phase. The difference should be very well audible.

[mcgsxr]

Thanks Rudolf, I figure flipping the phase switch on the sub amp should highlight THAT in a hurry!

[mcgsxr]

I picked up a new sub amp today, one with a parametric EQ that might prove useful, and can act as a bass boost capability too.  Should be a fun toy to add to the mix on this project.

One of Dayton's 500w units.

http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=300-806&ctab=5#Tabs