BigmouthinDC Messages: 41 Registered: February 2010 Location: No VA
Baron
Time for less talk and more building as I need to first get some speakers made. Then I can give them a listen and maybe convince a friend to come over with his calibrated mic and software to test them in place.
If you have any interest in furthering the "Science" of making Pi speakers more AT screen friendly I could drop some fabric remnants in the mail.
Wayne Parham Messages: 18789 Registered: January 2001
Illuminati (33rd Degree)
Well, sure, if you have some of the screen material and the open cell foam, I'll measure the speakers with and without the screen in front (at various positions and angles) and with and without the open cell foam sandwiched between screen and speaker. I'd like to also try it with a piece cut to fill the horn like Geddes does, because if the foam is just put in front of the speaker, then we have an abrupt transition at the mouth. Kinda trying to make a "medium" for sound to pass through that is relatively constant from phase plug to screen face.
BigmouthinDC Messages: 41 Registered: February 2010 Location: No VA
Baron
Progress has been slow, not for complexity only a time allocation issue.
So I decided to go with a two layer front baffle consisting of 3/4 MDF and 1/2 MDF. Using the 1/2 inch MDF as an easy method of flush mounting the woofer and horn. I also decided to use Green Glue dampening goo between the layers. The baffle turned out to be remarkably quiet once assembled.
I originally planned to use the leftover 1/2 scraps to make the ports but once I had them glued up I didn't like how they responded to a knuckle test so I glued up some 3/4 versions and they sounded better.
Here is the front baffles and ports glued up. When the sides are all glued up I will be removing those screws and washers you see in the picture. I used the washers to keep the 1 1/4 inch screws from going through the front.
Next, item is the horn isn't quite 1/2 so I cut some gaskets out of some rubber foam I had sitting around.
Then test fitted everything. When I screw the horn in it will flatten the gaskets a bit and sit flush.
I will probably cut a little more out of the woofer recess.
Couple of questions. I'm planning on rounding over the cabinet edges but what about that port opening? can I take a little off?
On mounting the woofer I've used putty caulk in the past to seal woofers yet make them removable for service and did note that you mentioned shower liner in another thread, any other thoughts? Guess I could cut some more gaskets out of the foam rubber. I've got some 10-24 T- nuts and bolts for the mechanical attachment.
Wayne Parham Messages: 18789 Registered: January 2001
Illuminati (33rd Degree)
I definitely emphasize with you on the time crunch and having a hard time scheduling projects. But it looks like you're making good progress. Getting close now!
Wayne Parham Messages: 18789 Registered: January 2001
Illuminati (33rd Degree)
Sure, no problem. They're large enough port velocity is real low even at full power. But radiusing the edge won't change tuning by any appreciable amount so it can't hurt.
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