Open backed boxes ? Anyone ?

[holdent]

U-frame sheet which doesn't account for the top

Unless I misunderstood MJK's Figure 2 (pg. 4) in his "Comparison of the Bass Performance of Passive Open Baffle, U Frame, and H Frame Speakers" paper (http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf) his U Frame MathCad model does account for the top. Yes?

[MJK]

Originally posted by holdent
Unless I misunderstood MJK's Figure 2 (pg. 4) in his "Comparison of the Bass Performance of Passive Open Baffle, U Frame, and H Frame Speakers" paper (http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf) his U Frame MathCad model does account for the top. Yes?

Yes. The U frame worksheet is just like a very short TL.

[Scottmoose]

Ah, I was wrong about that too. Luckily I don't like OBs, so I've never needed to use either the U or H frame sheets, so no harm done.

[skorpion]

Scottmoose,

You are somewhat unlucky, I think ! Do you like music and above all live music ? If so am I sure you would like OB.

With regard to 'Topless-U' as I have coined winged OBs with bottom and two sides and no top, MJK's models will give a good prediction if you calculate the corresponding flat OB baffle size.
With regard to the U- and H-baffle models they are very versatile. Both will allow for user determined terminus size and user determined stuffing of damping. The H-baffle besides also will allow for any placement of the main baffle in the H, thus at the extremes converging to traditional U or having all the H in front to an front U OB.

/Erling

[skorpion]

Sorry,
Corrected now for my underliner !

/Erling

[c2cthomas]

Norman -

Thanks for the link to auditorium23.de BTW - They do have an "English language option on their home page - interesting stuff! http://www.auditorium-23.de/Welcome/Contents.html

[Scottmoose]

Originally posted by skorpion
You are somewhat unlucky, I think ! Do you like music and above all live music ? If so am I sure you would like OB.

Not unlucky at all. I've heard plenty of OBs & designed a few as well. They all sound decent enough, but I just happen to prefer monopoles. As for using the regular flat fronted mathCAD worksheet to model an open topped U frame rather than an open backed cabinet, forgive me if I have reservations. It doesn't account for potential standing waves / resonances in the rear cavity for a start, or any other performance related departures from a purely flat baffle.

[skorpion]

Scottmoose,

I think in fact a bit unlucky because you miss some excitment. Otherwise I am glad you could stand the ironic undertone.
My stating 'From an Elks point of view' was also a paraphrase pointing to E.S.T's 'From Gagarings point of view'. I have heard E.S.T live on several occasions and I am glad to play their records over my OB speakers. Tragically Esbjörn Svensson died in a diver accident this summer. He was in fact one of this worlds really renewing jazz/rock personalties, producing all over enchanting jazz performances/records.

The argument about standing waves, resonances etc in 'Topless-U's has been covered by MJK (with argument) and myself (with measurement) in some threads over at the Audio Circle. The short story is: no problems.

/Erling

[Scottmoose]

Actually, that's one of the reasons I don't like baffles all that much: I've yet to hear one that gives me any real sense of excitement sonically, with the exception of my mate Ed's electrostatics. They just don't give me what I happen to value.

Re the other, I'll maintain my reservations if Martin will forgive me. That will likely be a design-dependant issue, particularly WRT the size shape & depth of the side pieces. Given that several such bent (hinged actually) baffles I've heard suffered from a variety of colourations / resonant issues which vanished the second they were straightened out (no preconceptions either as the subject of modelling them was not in question at the time), I regard the notion that you can simply treat all of them as flat baffles & expect no differences of any kind with deep suspicion.

Either way, my opinion, for what it's worth (nothing) is moot, because, as I say, I'm simply not very interested in OBs.

[skorpion]

Scottmoose,

Why don't you come tomorrow.

I'll treat you with the 'Volks-OB' MkII, simple and cheap but I don't think you would regret it.

/Erling