Open baffle horns?

[Magnetar]

I've run JBL 2420s and Altec 288s sans the caps but hearing no big difference (if any) I put them back on. There was some discussion of this on the Lansing Heritage site, evidently some early WE compression drivers had no back cap but an open protective screen.

If you turn them around and use them without a horn you end up with a Super Dome, I have used/ measured a few drivers this way. The sensitivity goes down like 10 db but they really get linear, extended and open - to me they still sound like a dome though. - compressed and fake

 

[critterxl]

This has turned into quite an interesting thread, I'm enjoying the discussion. I know now that while horns can be mounted on an open baffle, if used by themselves they probably aren't capable of the sonic characteristics I was looking for.
I've also been corresponding with Darrel Hawthorne and he's been excellent explaining the whole dipole/bipole concept(not that I completely understand it yet ). I'm going to eventually build a set of OBs using his Silver Iris drivers.
BTW, anyone interested in a set of Mageplanar SMGa's? They sound lovely and have the soundstage I'm looking for but not the punch I want-
Thanks for the great discussion!

 

[rcavictim]

Here's My Usher/Altec Horn Loaded Open Baffles...

There are probably counties where you`d have to bribe the planning commission by buying a building permit to build a set of speakers like that!

 

[AJinFLA]

I've run JBL 2420s and Altec 288s sans the caps but hearing no big difference (if any) I put them back on. There was some discussion of this on the Lansing Heritage site, evidently some early WE compression drivers had no back cap but an open protective screen.

Hi Tom,

What I was really asking was, were these part of an overall dipole design? An attempt to lessen the imbalance in the power response? Or basically just to see how it sounded in an existing design?
One of the issues that I looked at from my previous dipole/horn design was the power response shift between dipolar to directional monopole in the crossover region. Rear radiation from the tweeter helps to offset this, although there may be a penalty in the polar response. I need to do a ton of measuring with these yet (bottom pics)
http://www.diyaudio.com/forums/showthread.php?postid=1366614#post1366614
I will search the Lansing forum to see how they were being used.

cheers,

AJ

 

[ScottG]

They sound lovely and have the soundstage I'm looking for but not the punch I want-
Thanks for the great discussion!

You can get that easily enough by integrating a sealed "subwoofer" with the panels.

(Note that it isn't really a subwoofer, more like an active bass "augmenter").

Most open baffle solutions don't have a lot of punch either (though yes, better than the maggies).

 

[critterxl]

You can get that easily enough by integrating a sealed "subwoofer" with the panels.

(Note that it isn't really a subwoofer, more like an active bass "augmenter").

Most open baffle solutions don't have a lot of punch either (though yes, better than the maggies).

Well when I use them now I use them in conjunction with a Klipsch passive sub which balances out the sound nicely all off the way thru and gives the low end punch. What I'm missing is a little more "up front" sound and dynamic in the midrange- Thanks!
Lee

 

[Tom Brennan]

Hi Tom,

What I was really asking was, were these part of an overall dipole design? An attempt to lessen the imbalance in the power response? Or basically just to see how it sounded in an existing design?

I was just screwing around to see how it would sound.

 

[chops]

Most open baffle solutions don't have a lot of punch either.

Adding some EQ or building larger baffles can overcome that issue.

 

[critterxl]

My crude understanding is that there is a trade-off on efficiency and sound stage on the baffle design.The narrower the baffles, the better the sound stage but the response suffers some. Wider baffles in general provide more punch and response but narrow the sound stage somewhat. Is this off base?

 

[chops]

My crude understanding is that there is a trade-off on efficiency and sound stage on the baffle design.The narrower the baffles, the better the sound stage but the response suffers some. Wider baffles in general provide more punch and response but narrow the sound stage somewhat. Is this off base?

I'm not too sure really. My baffles are 24" wide and they image and soundstage like good bookshelf speakers.

 

[MaVo]

i think the good image comes from the fact that they will have a narrow coverage pattern, so less waves hit the walls and generate phantom images of the speakers. since horns are directional and your big drivers are directional at higher frequencies due to beaming and directional at low frequencies due to the dipole calcellation, its a good setup for image.

 

[Chestnutt]

I was actualy thinking of a horn with no back chamber, goint to ~100hz-500hz
Smallish, yeh....HORNish. I think you lose some of the bottom octave without the chamber.
Any horn specialist around?

 

[POOH]

I was actualy thinking of a horn with no back chamber, goint to ~100hz-500hz
Smallish, yeh....HORNish. I think you lose some of the bottom octave without the chamber.
Any horn specialist around?

I use an 80hz front horn with an 8" driver and no back chamber and I estimate the front wave to be up around 18-24db from the back when listening in front of the horn. The particular horn/driver combo sounds better without the back chambers I've used with them and there is little that the reactance annulling of the back chambers does to effect the bottom response of the horn.. A front horn that goes to 80hz with little ripple is not small. Mine are around 50" long.