[Polarbear]

Hi all

I'm in the process of building a new baffle/design for my ob. It's a combination of bastani prometheus and hawthorne augie. It's all magnetmounted. But I started to wander if the back "stern" would cause any unwanted diffractions to the sides, and thereby smear the sound in any way. I'm thinking of the large area between the magnets Any thougths?







The "stern"  has to be  at least 3 times as thick to minimize vibrations. But I do not want to carry it trough if the diffractions (or any other issues) would cause trouble.

Cheers
Bjorn

[Wind Chaser]

I doubt diffraction will be an issue from behind unless you have a lot of energy radiating from there happening at about 1.8 KHz and on up.

What you want to do is deal with the area around the tweeter.  Read THIS LINK to learn more about diffraction and how to deal with it.  Jim's product really works.  The difference is truly outstanding.

[Rudolf]

But I started to wander if the back "stern" would cause any unwanted diffractions to the sides, and thereby smear the sound in any way. I'm thinking of the large area between the magnets Any thougths?

Look at it this way:
Without that "stern" sound from the left half of the driver would reach over to the right half and vice versa. Now you are blocking this off. But the reflected sound is identical in frequency, phase and direction with the blocked off sound. This is only perfectly true for a stern of minimal thickness. If the stern becames thicker there will be reflections from there. But reflections/diffraction from the side of the stern would still be of no concern.

Rudolf

[Polarbear]

Thanks Rudolf

I also just realized that my trail of tougth was initially wrong. I had the sidereflections from the baffle edges in mind (different pressures front to back). This will not be the case with this issue. Same pressure on  both sides
Thanks.

Bjorn

[-Richard-]

Hi Bjorn ~

You could try a simple test of listening to your baffles with the stern and without it... especially since you are considering building a new pair of OB's... the ones you are now using could be used for investigating this issue.

I did quite a bit of critical listening to my simple flat OB's with and without "wings" of various sizes and lengths... I heard a definite smearing in all configurations... the result... no wings.

I think we sometimes lose sight of the simplicity of direct observation... favoring instead computer modeling and number crunching. I am Paleolithic man to be sure. But without their keen observations we would not be here now.

Warmest Regards ~ Richard

[panomaniac]

nice looking rig!
funny, but i would have called it the "keel" rather than the stern. =)

[hurdy_gurdyman]

Bjorn,

You might try gluing some thick felt to the edge facing the magnets, or even rounding them off. The sides should have no effect, being centered. If they were wings on the edges you'd definitely hear them.

Dave

[Mr Content]

The way the rear wave is radiated means that you will not have much of a problem with it Bjorn. I agree with some felt will improve things, and a generous round over.

The Augies will be a lot better than the bastanis drivers at bass duty.

Mr C

[dewar]

If you've got some felt, try the front of the baffle as well and see if you like it. I've also felted the inside of the driver basket. Here's my Bastanis/Hawthorne marriage

[Polarbear]

Richard. I agree in with you regarding wings. I will not have any wings. But this "keel" (thanks pano ) will not deal with the same issues as a wing on the side would have. The pressuration will be even on both sides.

I will round of the edges facing the driver yes. And try with some felt also. Both back and front of the baffle will be coverd in felt.

Dewar: I can't see any pictures of your bastani/hawthorn creation?

Cheers
Bjorn

[dewar]

strange, shows up in my browser. you can check them here http://www.stereo.net.au/forums/showthread.php?t=11112

[Polarbear]

strange, shows up in my browser. you can check them here http://www.stereo.net.au/forums/showthread.php?t=11112

I had to be a member on stereo.net.au to see the pictures. I just signed up for an account and do now see yor picture It's nice. How are you running the augie (xo, freq etc?) Are the bastanis  fullrange or xo'ed?

Cheers
Bjørn

[dewar]

Bastanis fullrange from 2W set, Augie from NAD amp. XO and room correction on the Augie via Behringer DEQ2496. Sounds damn good.

[panomaniac]

Both back and front of the baffle will be coverd in felt.

good idea!  it really helps imaging and overall smoothness.