Open Invi8tions

[6thplanet]

http://s1151.photobucket.com/albums/o624/6thplanet/Open%20Invit8tions/?start=all

This is my latest build and was my entry in the MWAF 2012. It's an OB/H-frame inspired by the Linkwitz Orions, but done entirely with passive components. The tweeter is an LCY-110 which has its face plate removed, I milled the opening in the baffle, and mounted it directly to the baffle. This allowed me to get the mid and tweeter closer together and helped time align the two. The baffle is 10 guage 5052 aluminum plate with woven Carbon Fiber/Copper laminated on the front and Cascade VB-2 Damping on the back. The midrange is an Audax Areogel HM130Z0, and the woofers are Audax Aerogel HM210Z12's. The bases are made of 1" thick Walnut butcherblock countertop. The internal woofer baffles are 3/4" MDF. Crossover duties are 12dB @ 90Hz low pass on the woofers, 6dB @ 150Hz high pass to the mids, then a serial crossover based on the Acoustic Reality platform between the mid and tweeter (6dB @ 2500Hz). This design employs no capacitors in it yielding no phase shift at the crossover point.

[Brewski]

Re: Open Invi8tions

Looks very cool in the photos there's an NPE is that in place to protect the tweeter or was that only there in the preliminary design? Since your not running any caps I take it every pass is first order electrical and natural roll off makes them second order acoustical slopes? I think last years 2 way is still my favorite from an ascetics stand point that speaker was simply stunning in it's appearance and sounded great too. Also did your friend's (Adam?) Fountek project make it's way to MWAF or is that on slate for a future trip?

Take it easy
Jay

[6thplanet]

Re: Open Invi8tions

The NPE is under the two poly caps as part of the high pass to the mid/tweeter combo. Adam brought his MTM for the under 200 class ( won 2nd place). The Fountek project isn't quite finished yet.

[charlielaub]

Re: Open Invi8tions

This design employs no capacitors in it yielding no phase shift at the crossover point.

I assume that you used some reactive component... only inductors maybe? If so, why does this not result in a phase shift at the crossover point? Even a raw driver has phase shift... so I am not really following this. Can you elaborate on this a bit or show some modeling of the phase?

Also, how did you create a highpass filter on the tweeter not using capacitors. Was this a series crossover?

-Charlie

[Wolf]

Re: Open Invi8tions

I assume that you used some reactive component... only inductors maybe? If so, why does this not result in a phase shift at the crossover point? Even a raw driver has phase shift... so I am not really following this. Can you elaborate on this a bit or show some modeling of the phase?

Also, how did you create a highpass filter on the tweeter not using capacitors. Was this a series crossover?

-Charlie

Yes- it's likely an AR-SXO capless version. Oh- and I agree that inductors still yield a phase shift.
Later,
Wolf

[honfatboy]

Re: Open Invi8tions

Why did you pick the Audax 8s? The specs don't look right for OB. Obviously, they work for you, but I'm just curious.

[6thplanet]

Re: Open Invi8tions

Search "Acoustic Reality serial crossover". Uses two inductors, no caps. A cap induces a 90* phase shift one way, an inductor the opposite. By using two inductors the phase remains basically constant, i.e. "flat" through the xover region.
As for the use of the 8's, I had 4 of them on hand so with a Qts of .61 and Fs of 40Hz they worked out in my favor in the H-frame set-up. And quite nicely I might add, but they do have they're limitations as the xmax is only 9mm. You get 4 of them going and they produce some really nice bass. The PE staff member running the sound (Mike?) said these towers produced the most bass of anything in the room that day being flat to 30Hz. Must have been in the right location to load to the room where they were at. He jokingly asked what kind of "magic" was I doing to make this happen!!

[greywarden]

Re: Open Invi8tions

Those are crazy looking, good job!

[ReissM]

Re: Open Invi8tions

I've tried lots of design over the years, but never something like this. Hmmmm... you've got me thinking.

They look great. Nice job.

[honfatboy]

Re: Open Invi8tions

As for the use of the 8's, I had 4 of them on hand so with a Qts of .61 and Fs of 40Hz they worked out in my favor in the H-frame set-up.

Sorry, I must have looked at the wrong specs!

[DjDisturbed]

Re: Open Invi8tions

Those turned out really nice and apparently sound really nice too. Congrats on your win at MWAF :applause:

[LouC]

Re: Open Invi8tions

Definitely one of the best looking OB speakers I've seen. Nicely done. I always thought those Audax Aerogels were sexy looking. If you are getting that kind of response out of OB w/passive, you have earned your pointy wizard hat!

[6thplanet]

Re: Open Invi8tions

I always thought those Audax Aerogels were sexy looking.

No doubt, I always had a thing for the HM-Z series, but couldn't afford them back when they were all available. Now I can and try to get my grubby hands on them whenever possible. Nice to see a couple (4's and 6's?) are being reissued, wish the 8's would come back! Also, thanks for all the complements people!!

[ReissM]

Re: Open Invi8tions

PM sent... regarding four 8" HT210Z Aerogels. (Sorry they're not HM-Z's but they're still decent)