Avaclone driver hole chamfering?

[superapplekid]

I'm a first time builder looking to join the ranks of the many other DIYers who have made Avalon cabinet clones with accuton/eton drivers. The cabinets look as follows:
http://homepage.mac.com/marc.heijlig...t/cabinet.html

I've rounded over the driver holes as described in the drawings, and am ready to glue the front baffle onto the speaker. Then I read this :
chamfering driver holes
Now I'm concerned about driver airflow
Because there are already braces so close to the drivers, my only chamfering option is #3. I haven't seen this configuration recommended anywhere else, however.

Other Avaclones seem to simply round over the holes as I've already done, and even pictures I've seen of Avalon Acoustic speakers indicate they probably only round over. My question is - should I chamfer? Should I just leave it rounded over for fear of changing the frequency response of the drivers since I'm using an already designed crossover? How big of a difference would this really make?

[planet10]

C is the best... and strongly recommended.



dave

[superapplekid]

Originally Posted by planet10

C is the best... and strongly recommended.

dave

Thanks for the input. I would imagine C would be the best, and in future projects I'm planning on making a point to accommodate such a chamfer. Currently that's not so much an option, since the mid and woofer driver holes are only about an inch or so above cabinet bracings (too late to change this now). If I were to chamfer the double baffle at a 45 degree angle it would 'scoop out' where the bracing meets the baffle (can't think of a good way to describe it, so I'll draw a picture later if its not clear). D seems to be my best bet for chamfering, or doing E at a smaller angle. You seem to feel chamfering is worth the effort, any idea which of those options might be best?

Also, I've been reading about chamfering in regards to mids and woofers, but haven't been able to read anything in regards to tweeters. I would imagine the benefits would be the same, but I would think this would bring up all sorts of issues with thinning out the baffle, especially when you have the tweeter and mids as close together as they are on the Avaclones. Thoughts?

[buggsson]

Originally Posted by planet10

C is the best... and strongly recommended.



dave

What about D or E?

[superapplekid]

Originally Posted by buggsson

What about D or E?

Thanks for the reply

D is possible, and what I am strongly leaning towards. I have about 3/8" from the midrange cutout to braces, and about 13/16" from the woofer to braces. This makes E a little troublesome given a 2" baffle, but it might be possible if I were to use a 12 degree chamfer bit as opposed to the traditional 45 degree.

I could see reasoning behind either. Doing D would leave parallel walls around the driver, which might promote more reflections back towards the membrane than E with a slighter angle. At the same time, E with a slighter angle would also leave less room for air to flow away from the driver closer to where the driver mounts. I'm sure either will be an improvement from what I have, though.

Also, how important is to do the same for the tweeter?

[buggsson]

Originally Posted by superapplekid

Thanks for the reply

D is possible, and what I am strongly leaning towards. I have about 3/8" from the midrange cutout to braces, and about 13/16" from the woofer to braces. This makes E a little troublesome given a 2" baffle, but it might be possible if I were to use a 12 degree chamfer bit as opposed to the traditional 45 degree.

What do you think of just going with the 45 degree where it works, and just not chamfer where it is not possible, as close to your bracing etc.? I'm thinking this way, but I'll check just how much less chamfer there will be in comparison.

[superapplekid]

Originally Posted by buggsson

What do you think of just going with the 45 degree where it works, and just not chamfer where it is not possible, as close to your bracing etc.? I'm thinking this way, but I'll check just how much less chamfer there will be in comparison.

If I'm reading you correct, that would be like D (expect specific to have much room I have to work with). I think that is that route I'm leaning towards, both for airflow and for ease of building.

[buggsson]

Originally Posted by superapplekid

If I'm reading you correct, that would be like D (expect specific to have much room I have to work with)

I'll try to be more precise. Think of the full circle, and where the baffle edges will meet the sides for example. If, for example, you strive for a very narrow baffle, where the baffle is not much wider than your driver, you route the circle, but where the sides will meet the baffle, you do not route, so your circle will be truncated where the baffle meet the sides. You must then of course, decide if the truncation is usable, or intrudes too much on the "breathing requirements". Quite a few do the same for where their T-nuts will be on the backside of the baffle. Clearer? My explaining has huge room for improvements.