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Open Baffle Epiphany!

How important is the thickness of the baffle? If thicker is better does it matter if it's one board or can two be sandwiched together?

cubdog
 
cubdog said:
How important is the thickness of the baffle? If thicker is better does it matter if it's one board or can two be sandwiched together?

cubdog
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The thought here is to reduce resonance and thick is better than thin. I've never used anything thicker than 3/4 inch plywood or MDF and so far haven't experienced resonance issues. Maybe that's due to the fact that I don't crank them to insane levels. Jazz at low to moderate levels is 90% of what I listen to.
 
Poultrygeist said:
The thought here is to reduce resonance and thick is better than thin. I've never used anything thicker than 3/4 inch plywood or MDF and so far haven't experienced resonance issues. Maybe that's due to the fact that I don't crank them to insane levels. Jazz at low to moderate levels is 90% of what I listen to.
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That's good to hear as our listening habits seem to be similar. What about the offset? I know you did this and many other designs offset the FR driver. What is gained by doing so?

cubdog
 
Poultrygeist said:
I offset because I try to follow MJK's proven designs. And if you ever decide to add a tweeter there's room.
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That make a lot of sense to me. One last question Paul. [yeah right] And I apologize if I've asked this before. What are the dimensions of your baffle?

cubdog
 
The woofers are commonly offset so you don't have the same cancellation frequency on both sides. The offset typically makes the response smoother. This idea will probably apply to mids and tweeters also.

As far as baffle size and width, it is a tradeoff between bass response and dipole imaging. There is not one correct answer, as far as I know. As always, I recommend starting with a big sheet of cardboard and experimenting with your drivers until you get the right sound. A wide baffle equals more bass typically.

I don't think the thickness of the baffle is critical, but a better damped baffle will help the sound somewhat.
 
My Lowther/double Alphas are 18.5" wide X 49" tall ( 48" is standard for a sheet of plywood/MDF but mine measured 49" so I went with that ).

I might would have gone 1 to 1.5" wider but I used the size MDF I had on hand. An inch here or there shouldn't be audible but I kinda like 18" or 19" as it's not at all intrusive.

If you go with double Alphas 48"/49" is a good height to house both woofers plus the 8 inch driver. The Alpha edge is 1.5" from the bottom of the baffle and the Alphas are spaced 1.5 inches from each other ( measured from outside edge not from cut out ). You want to build these so the two baffles are mirror image of each other. I laid all the speakers face down on the MDF, drew around them and then found the center. I made the speaker cuts outs using a Jasper circle jig attached to the router. Before I bought a router and the Jasper I cut my holes with a jig saw and if you take your time they can come out ok.

The 8 inch driver's center is located 11" over on the long side and 9" down from the top. The baffle have a slight back tilt. I'm 6' 1" and seated my head is still higher than the 8" driver.
 
Great information Paul! I really appreciate all your information and guidance. Thanks to everyone else as well. I'm going to start ordering my drivers this week. I'll start a build thread when I get them in the DIY forum.

cubdog
 
cubdog said:
Great information Paul! I really appreciate all your information and guidance. Thanks to everyone else as well. I'm going to start ordering my drivers this week. I'll start a build thread when I get them in the DIY forum.

cubdog
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Oh, you'll be having some fun for sure. If I lived near by I'd put them together for you.

The only negative about starting a thread in the DIY forum is that it's so all encompassing builds get buried. Wish we had an OB forum which IMO makes more sense than a tuner forum.
 
Poultrygeist said:
Oh, you'll be having some fun for sure. If I lived near by I'd put them together for you.

The only negative about starting a thread in the DIY forum is that it's so all encompassing builds get buried. Wish we had an OB forum which IMO makes more sense than a tuner forum.
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Believe me if you lived closer I'd probably just kidnap you for a week or so.
I too am concerned about the DIY forum. I hope those who can help me the most will find it there.

cubdog
 
An open baffle forum would have a total of 514 posts in it as of this post. There is certainly no where near enough traffic to even give it a moments thought.
 
dnewma04 said:
An open baffle forum would have a total of 514 posts in it as of this post. There is certainly no where near enough traffic to even give it a moments thought.
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Impressive considering there is no open baffle forum.

No highway = no traffic

Build it and they will come
 
As of this response, it would be 516. What I'm getting at is your thread is one of a small handful. We have far too many forums as is, adding another fringe element as it's own forum would just add more forums without increasing any traffic.
 
Would a subforum in DIY for speakers only be a possibility? I'm thinking it's probably been discussed, considered and decided upon, but just wondering. I'd probably spend a good deal of my time on AK there if it existed.

But, then again, if you started to subdivide you'd likely have to do one for amps, TT's, etc. as well. I'm sure the mods have plenty on their plates as it is.
 
I think there should be a new forum, the sole purpose of which, would be the discussion of possible new forums and sub forums. Yeah, that's it. That's the ticket. :thmbsp:

cubdog
 
Now that is a forum that would have more than 1 thread. "Where is the Polk SDA-SRS forum?" "No no, we need a Lepai forum!" "Clearly, we need a Manger forum!"
 
Well, I finally decided to mess around with "open baffles" today. I'll go ahead and admit that I've only read about 1/2 of this thread, but that was enough to intrigue me. So, with no idea what I was doing (and definitely no measurements or planning of any sort) I went to Lowes to buy some boxes to cut up.

The drivers I had were left over from a Magnavox console (the one that the amp in my signature came from). I got all 4 drivers and attached them to my baffles, paralleled just like they were in the console. The first bit of listening I did was nothing impressive, they basically sounded like junk drivers hanging on cardboard, something wasn't gelling.

So, I decided to disconnect the larger driver and run only the small one. This is where I started noticing something. Hard to describe, but I liked what I was hearing. The best part was with piano, you could just hear the "piano" resonating, it was pretty amazing to me that I was getting a pleasing sound out of this tiny driver attached to a moving box! The bass wasn't bad at all, my largest complaint was a bit of shrillness on some vocals.

More experimentation is definitely in order....I might even attempt to look up the proper way to set this stuff up.

On another note, I was talking with a friend on the phone and mentioned what I was trying, he said he had a pair of full range drivers if I wanted to try them out, so I went over and picked them up. They are Universitys, I couldn't find much about them, but I'll give them a try.
 
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