[PDR]

Any reason an H frame can't be done with a tube? Like converting a small kick drum by mounting a baffle in the middle? Any weird resonances ya think compaired to a square/rectangle?

Was wondering that myself, or if double (stacked) does the top have to be the same shape as the lower?  Can the lower be a normal "H" and the upper have a curve on top?

[MJK]

A tube would work fine, other people have done it. If you look in the gallery on my site there is an example of a cylindrical tube H frame.

[6thplanet]

Back to the pure H frame, still has plenty of low end. It blends better this way (to the neo8) as I've seen that the N frame was an inbetween kinda deal and had a bit of the inherant midbass peak that a U frame exhibits.
Not sure if I want to lower it any and do the tilt back deal as it kinda locks you into a specific listening location with the directiveness of the planar...right now the c-c distance between the woofer and planar are working well with each other.
I think the next step will be to shorten up the depth. I still feel there's some midbass gain thats kinda "muddying" up the lower midbass/midrange area. Certain male and deeper female voices sound a bit heavy, maybe chesty so to say, might be from some of the dipole peak happening around the x-over point. Fun times!!

[Rudolf]

I think the next step will be to shorten up the depth. I still feel there's some midbass gain thats kinda "muddying" up the lower midbass/midrange area. Certain male and deeper female voices sound a bit heavy, maybe chesty so to say ...

Shortening the depth is exactly the wrong way.
How about the "eq to compensate for dipole rolloff", as already suggested by JohnR?

Rudolf

[6thplanet]

Really? I thought the depth dictated the upper 1/4 wavelength resonance, therefor shortening it pushed it up higher. I'm trying not to EQ, honestly right now its very listenable I'm just getting a bit picky and figured this modification would help the transition between drivers. What am I misunderstanding about the depth of an H frame?

[Rudolf]

What am I misunderstanding about the depth of an H frame?

This is a H frame without EQ. It starts with red and is cut down in depth until only the plain baffle is left (dark blue):

This is the same H frame as above (red). Then with the right passive EQ applied (blue):


It should be self-explaining ...

[6thplanet]

Ahhh hahhh... So I'm sorta right in thinking that trimming depth smooths the midbass hump, but I see it also loses efficiency on the low end as well. So I should prolly try maybe lowering the LP part of the x-over a bit to maintain the low end, but tame the upper hump? What your calling "passive EQ" looks like a crossover topology to me, am I right? Or should I be thinking a series notch/ parallel contour filter? Thanks again Rudolf, MJK, and others the graphs and your help are awesome!!

[Rudolf]

So I should prolly try maybe lowering the LP part of the x-over a bit to maintain the low end, but tame the upper hump? What your calling "passive EQ" looks like a crossover topology to me, am I right?

Yes, it is a crossover. In this case a passive 2nd order low pass at 100 Hz. You may have noticed how the passive filter helps to raise SPL around the Fs "knee" of the driver (30 Hz). Simply lowering the LP of your existing crossover will always lead to an exposed upper bass.

I don't understand why people refrain from "doing it right" when it could be as easy as adding a coil between amp and driver. 

[6thplanet]

So I've tweeked the crossover a bit and spent some $ to install MP caps in the series spots on the planars (swapped from NPE's) Not sure if I can tell a sonic difference yet, but makes me feel better knowing they're there.    I'm happy with the overall sound now so I went ahead and built the second unit this weekend and now finally get to hear them in STEREO!! All I can say is WOW, still,...the bass is so clean and these planars just sing. I know it sounds a bit cheesy, but its true. I also know some people consider the BG neo8 to more of a mid oriented driver, though the top end shines enough for me. Granted they are just a bit shy compaired to my HIVI RT2C-A's, but I like them in the fact that they play down to 500Hz and still have the amount of topend they have.
 
Now I have to finalise what I want to do as finish...decisions...decisions!!