Just Another Line Array :)

[MattM]

All done and working well! Photos and story here: http://www.marulla.com/audio/line-source-speakers/

[planet10]

All those concave cones have a certain appeal.

dave

[TroelsM]

Looks nice, but there seems to be very little space between tha baffle and the back of the speaker-units.. That would restrict airflow a lot? - any thoughts on this?

Regards TroelsM

[jormajj]

According to John "Zaph" Krutke for B3S

"The absolute most important thing to do when building the enclosure is to angle the back side of the driver cutout to promote airflow. Angle as in a chamfer, not a roundover. If you don't do that, Fs will go way up, and the sound will be compressed and colored"

See http://www.zaphaudio.com/audio-speaker18.html

Jorma

[TroelsM]

As seen here:

http://www.zaphaudio.com/audio-speaker18-B3Nchamfer.jpg

Regards TroelsM

[tinitus]

Sorry to say that its very true, but those mids have very little space to breathe, you have created very small ventilated midrange chambers, it might not be a OB/dipole anymore ... but if it works it works

[MattM]

Yes, the spacing around the woofers is fairly tight and is probably responsible for a lot of the response bumps that were equalized out. Another factor to consider is that with the open back, there is less total resistance to air movement, even with the tight spacing around the woofers. In other words, it should probably be chamfered, but I think it might have less total effect here than in a sealed cabinet.

Thanks for the link to the other design using the same driver - now I have another project: modifying these.

Hey, nothing is ever truly done in this hobby, is it?

[Cal Weldon]

Originally posted by MattM
Yes, the spacing around the woofers is fairly tight <snip> Another factor to consider is that with the open back, there is less total resistance to air movement,<snip> In other words, it should probably be chamfered, but I think it might have less total effect here than in a sealed cabinet.

Hi Matt, first off, congrats an such a good looking and labour intensive project. Your sense of patience is to be admired.

Second, I think what the others have mentioned concerning the chamfering should be given more thought. Your ideas about the back being open having less effect is opposite of the way I see it. Because the air is freer to move, the effect is almost venturi like and the open back cabinet only accentuates the concern. I am wondering if the nasal sound you had to EQ out was a result of the lack of air flow. Definitely something to consider.

Planet10 was the first to demonstrate to me how big an effect the chamfering has. In fact, I now prefer to back mount the OB mids and flare the baffle the way you have done with the tweeters.

And you're right, nothing ever seems finished in this hobby.