[Brad]

(I know - I should try it both ways and EXPERIMENT)

Just wondering what people's experience with this is:

When you mounted the drivers in the baflle, did you route out a countersink for the speaker to be flush with the panel?

[mcgsxr]

I have not, with either the Visaton b200's, nor the 12 inch subs that now share the main panel.

When I do my final baffles, I will rebate them to be flush, if only for the looks...

I believe such commercial products do flush mount.

[Bemopti123]

I do not know if this might apply to OB sound quality, but when I oversaw the plans for North Creek Audio's Rhythm loudspeakers, the designer had specifically advocated at change of tonal quality that is attain by doing 2 things:
1-Flush mounting the driver to the cabinet.
2-Smoothing/routing the edges of the baffle plane. 

Maybe the physics is different for OB design, but maybe the above two will also apply?

PS:  BTW, which is the easiest way of routing cuts for flush mounting?  I have a regular Bosch router and the Woodhaven circle jig to make such cuts ready did not cut it for me.

[SET Man]

Hey!

  Woooow! OB circle! Seems like everyone is getting on this OB speaker thing now a days.

  Hmmmm..... maybe I build myself a pair

  Hey! Bemopti123... now you have a place to hangout and talk about your OB project How its the project coming along anyway?

Congratulation guys and have fun guys! Keep us posted on your project and if anyone here in NYC I want to hear your OB speaker!

Take care,
Buddy

PS
Okay, now I want.... "SET circle" and "Horn Speaker Circle" Just kidding guys

[mcgsxr]

I cut circles with a cutout tool, basically a spiral saw/dremel, with a relevant bit, and circle jig.  Then the router to add the appropriate depth and width channel to flush mount.

My OB speakers have a roundover on all the edges, though since adding wings, I did not route the main panels, which I might choose to in the future.

Having added subs to the panels, vibration is more of an issue though, so I am now reviewing much thicker panels, to address this.

Pics in my gallery, once I sort out how to post friggin pics again, I will add them!

[JoshK]

My thoughts, coming more from an objectivists perspective (although not wholly so)...

Diffraction affects OB just the same as a boxed speaker.  Actually it has been shown that baffle edge diffraction is the worse case diffraction when it is OB.  Lots of work on Linkwitz's site that demostrates the theory in this and there is numerous empirical studies and evidence that show how this works and the affect it has on FR with OB speakers.

Similar physics are at play with bass reinforcement from the baffle and baffle edge diffraction.  The reason why you guys have been getting audibly different results with the size & shape of baffle and location of driver on that baffle is evidence to this truth. 

Flush mounting the drivers in a baffle minimizes some diffraction.  It is wavelength (and hence) frequency dependent.  Since the edge of the driver is relatively near to the acoustic center, the frequency is rather high up...which is worse IMO that diffraction lower in freq because it affects imaging and presence frequencies. 

This is one of the few topics where the physics does a really good job of explaining reality and is quite predictable.  There are a number of free software programs that will help you calculate optimal baffle size, shape and position based on the diffraction created.

[JohninCR]

JoshK,

You're quite correct that OB's and edge diffraction is important enough to warrant discussion its own thread, not get buried in this one, because the effects are much greater than with boxes.  Flush mounting drivers has pretty much the same benefit as with boxes, except that with some drivers flush mounting can significantly change how open the rear is to radiate its sound.

Also, I believe it should be separated into 2 different topics.  One related to baffle size, shape, and driver placement similar to the baffle step issue with box speakers and how that affects bass response with OBs.  The other issue is actual edge diffraction due to the shape and dimensions of the edges of your baffle, because these effects are far greater with OBs since the velocity of movement is greater than with boxes.  This last part is where I believe the vast majority of OB designs are flawed, including SL's Orion.

[JoshK]

The other issue is actual edge diffraction due to the shape and dimensions of the edges of your baffle, because these effects are far greater with OBs since the velocity of movement is greater than with boxes.  This last part is where I believe the vast majority of OB designs are flawed, including SL's Orion.

I agree.  I also agree with not sidetracking this thread.  I meant my tangent more to explain that diffraction IS and diffraction DOES, so yes flush mounting with OB is just as important as otherwise. 

Re: your comment on velocity of movement.  Do you have anything to point to that supports this idea?  Thread, empirical, study, etc?

[renfrow]

Another option, which I am considering, is to mount the drivers from the rear of the baffle, and round over the opening. Does/Has anyone do/done that? And, what did you think of it?

Tom.

[Acudoc]

Tom,

I know bastanis does this on the prometheus OB and stresses its importance but I can't remember why? 

maybe you can find more info on his website

www.Bastanis.com

John

[renfrow]

I know bastanis does this on the prometheus OB and stresses its importance but I can't remember why? 

maybe you can find more info on his website

www.Bastanis.com

John

Well, I looked for about 45 minutes all over their site and forums, found brief mention, but, nothing substantive. They do look lovely, though! I think I will try it .

Tom.