GR-research AV 1 enclosure questions.

Discussion in 'Archived Threads 2001-2004' started by Ryan T, Apr 5, 2002.

  1. Ryan T

    Ryan T Second Unit

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    Hi,

    I hope to start building some enclosures for the AV1 kits soon. I just have a few questions before I start cutting. I'm going with the 8" W, 12" h, 10.75" D enclosure for the 60 Hz tuning. since I need to make some stands for them I thought it would be cool to make stands that are boxes. They would be the same width and depth of the AV 1 enclosures. So when the speakers are on the stands they would look like tower speakers. The stands would be 8" w, 10.75" D and about 30" tall. I would put sand bags in the bottom of the stands for weight so they would not tip over. Will having the stands flush with the baffle of the speaker mess up the acoustics or anything? Thanks.

    Ryan
     
  2. jeff lam

    jeff lam Screenwriter

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    That sounds fine. You could even turn the AV1 into a tower with a false bottom. Still use the original dimentions of the enclosure, just use the bottom peice of the enclosure to divide the false bottom and the effective enclosure. You can fill the bottom with sand all you want but make sure you brace it or double the walls if you fill it with a lot of sand because it will be very heavy.

    Understand what I'm saying???
     
  3. Brian Bunge

    Brian Bunge Producer

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    Ryan,
    That sounds good to me too. I have my AV-1's on top of my subs, which are about 26" tall with spikes and they sound great. You may want to email Danny and ask him if he feels that 30" stands are too high. I guess if they put the tweeters close to the same plane as your ears it should work fine.
    Brian
    P.S. Jeff, my AV-1+ kits arrived yesterday! [​IMG]
     
  4. Ryan T

    Ryan T Second Unit

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    So your saying instead of making two separate boxes just make one big box. Then put a board 12" from the top to make a smaller enclosure inside the large tower. That sounds like a better idea. Would I have to brace the lower "stand" part of the box for any acoustic reasons? I guess the dimensions would be 42" H, 8" W, 10.75" deep. I think I will ad a base plate and spikes so it won't tip over. Thanks for the idea Jeff! Another question I've been meaning to ask is why do you have to flush mount the dome tweeter? It seems like a lot of work to get the .145" (I think thats the right depth) are around the tweeter cutout.

    Ryan
     
  5. Brian Bunge

    Brian Bunge Producer

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    Ryan,

    The purpose of flush mounting the tweeter is to help eliminate edge diffraction. Also, the woofer overlaps the tweeter flange so you really don't have much choice in the matter. Otherwise, you really won't be able to get a good seal around the woofer hole.

    I could cut you some 12" x 8" baffles for cheap if the recess is a huge issue for you.

    Brian
     
  6. Ryan T

    Ryan T Second Unit

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    Thanks for your offer Brian I appreciate it. I think with the design changes the baffle will be 8" by 42" so that might be hard to ship. I will give it a shot and if my Grandpa and I can't get it done then I might change the design back to separate boxes and take you up on your offer. How hard is it to make the tweeter recess? My Grandpa has a router but he does not have the guide plate. When I was up there for my sub box we had to make our own guide with some scrap wood. It took a few tries to get it right so this time I think I'm going to buy a real guide.

    Ryan
     
  7. Brian Bunge

    Brian Bunge Producer

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    Ryan,

    I would definitely get the Jasper Circle jig if you want to build more speakers in the future. It's not hard to use as long as you use the right bits and follow the instructions. If he doesn't have a plunge router it will be a problem.

    One other thing you can do: Get a 3 1/8" hole saw. Use it to cut the through hole for the tweeter, then use a 1/2" rabbetting bit to cut the recess. this will give you a diameter of 4 1/8" for the recess. The depth should be just over 1/8". The recess states a .145" depth, and 1/8" is .125, so you only need another .02".

    BTW, the plans call for a 3.1" through hole and a 4.1" rebate. Use 3.125 (3 1/8") for the through hole and 4.125 (4 1/8") for the recess diameters. Other than my cutting the depth of the recess a bit too deep, using these specific diameters worked perfectly.

    Also, you could still use the tower design and just have the 12"x8" top section butt up against the 30"x8" bottom section. The seam should be pretty easy to cover up. Just keep it in mind if you have any trouble with the driver holes/recesses.

    Let me know if you have any other questions!

    Brian
     
  8. Ryan T

    Ryan T Second Unit

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    Dang thats a lot more complicated than I thought. I like your idea about keeping the tower design and having you cut the baffles for me. Could you e-mail me how much you would charge for the baffles, my address is [email protected] again thanks for you help.
    Ryan
     
  9. Ryan T

    Ryan T Second Unit

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    I just thought of another question. What about internal bracing in the speaker enclosure? I was just thinking about reviews of the Titans that I have now. The reviewer said that the midbass was a bit boomy and it could be the lack of internal bracing that is causing it. I did not see any bracing in the designs I have for the AV 1's, does that mean they don't need it?

    Ryan
     
  10. jeff lam

    jeff lam Screenwriter

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    They don't need bracing if you use 3/4" MDF. The enclosure is fairly small so bracing is not really needed but you can if you want but you need to make tha cab bigger to compensate for the loss of volume.

    I suggested bracing the bottoms if you go the tower route and want to fill them with sand. It would be a real mess if sand got all over the place.
     
  11. Brian Bunge

    Brian Bunge Producer

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    Ryan,

    I disagree with Jeff about the AV-1's not needing bracing. As deep as the cabinets are I really think that they should have a simple shelf brace right in between the woofer and tweeter. If you made it so that the walls of the brace were only 1" thick then I think any changes in the internal volume would be irrelevant.

    Mind you, I don't hear any resonance that negatively affects them, but the knuckle test leads me to believe a small brace couldn't hurt. I do know that Danny recommends the Black Hole 5 and said that it is more effective than 3 layers of MDF, so I'm sure he designed the enclosures with that in mind.

    I'll email you shortly!

    Brian
     
  12. Kevin Deacon

    Kevin Deacon Second Unit

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    Brian, I'm building the AV1's as well, and planned on using about a 1/4" of bituminous felt damping (roofing felt) to line the inside. Do you have opinions on using this stuff?

    The reason I decided to use roofing felt is I'm also building the Proac Response 2.5 clones and this recipe calls for this type of damping. I figured if a design that mimics a $4500.00 speaker uses felt, it must work well. Any thoughts?
     
  13. Ryan T

    Ryan T Second Unit

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    I think the brace in the middle is a good idea so I'm going to try it. I'm using 3/4" MDF for all the walls. Jeff your saying to brace the lower part of the speakers so when I put sand in them the won't bust at the seems right? I'm still not sure if I need sand in them or not. Then MDF by itself should be fairly heavy. Does anyone see a real need to and wight to the bottom? I'm thinking about having 3 layers of MDF on the bottom about 2" wider and deeper than the speaker. That way I think it would look better. It would also allow me to put spikes further out to and to stability. I think I'm going to make lower the size a few inches I just want to make sure the tweeter does not go above ear level.
     
  14. Ryan T

    Ryan T Second Unit

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    Kevin,

    I don't know much about roofing felt but I heard the best damping material is Acusta-stuff poly fill. It's about $10 a pound and they say to use one pound per cubic foot. You can get it at Parts Express. Maybe someone with more experience will chime in here.

    Ryan
     
  15. Brian Bunge

    Brian Bunge Producer

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    Kevin,

    I haven't used it but think that it should work fine. ThomasW is probably a lot more knowledgeable about that kind of stuff than I am. I actually have no damping material whatsoever in mine right now and they sound pretty good, but I will add some in the future. I will probably put some acoustic foam on the side walls of the enclosure and maybe a little poly batting in there. I may just do like my Emeralds. They have a piece of poly batting folded into fourths on the back wall in between the bottom of the port and the bottom of the enclosure. Then two small pieces of acoustic foam are directly behind the 5.25" driver.

    I really think Danny should either include precut pieces of Black Hole 5 in with the kits (with a price increase of course) or make a specific recommendation (exact amount as well) of what to use if you aren't using the Black Hole 5.

    Brian
     
  16. Ryan T

    Ryan T Second Unit

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    Brian, what is Black Hole 5? I'm wanting to put one pound of acusta-stuff in each of my enclosures. I figured it's worth the extra cost. They claim it's better than regular poly fill, fiberglass and acoustic foam but who knows.

    Ryan
     
  17. Brian Bunge

    Brian Bunge Producer

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    Ryan,
    Here's a link to Black Hole 5. Before you look it ain't cheap, but Danny swears by it. I'm going to try some just to see if I can tell a difference.
    I think the acusta-stuff should work fine.
    Brian
     
  18. Bob Bartlett

    Bob Bartlett Stunt Coordinator

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    Brian, the enclosures you are building for the av1 are you putting a brace in there?
     
  19. Brian Bunge

    Brian Bunge Producer

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    Bob,

    I will not be adding any bracing to the cabinets. I will be building them per Danny's specs.

    Brian
     

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