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Thread: Project M2 DIY Thread

  1. #46
    Senior Member ivica's Avatar
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    Quote Originally Posted by pos View Post
    It looks like it is too long though, and the inner part looks too large...
    Hi POS,

    If Vb=130 Lit, Fb=27Hz, with TWO vents Dia=76mm, then Lv=198mm, owing to BB6.

    regards
    ivica

  2. #47
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    Fig40 profile 'c' ?

  3. #48
    Senior Member srm51555's Avatar
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    So after searching for input control solutions to use with a Crown dci 4300 N for an hour, I decided to leave that for another day and work on the M2's. Over the past week or so I was able to mount the waveguides, ports and T-nuts of the woofers. I wanted to see how it looked with the woofers in so I mounted them in the second picture.

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    Still on the list:
    -Crossover
    -Mount Banana Plug Jacks
    -Figure out cabinet feet
    -Grills

    I was a little disappointed the crown doesn't have digital cards in it, I never even thought of it when I was looking it over. So any control solutions will be much appreciated. The only Preamp I have left is a Mcintosh C32 and it's 30+ years old so I really didn't want to turn it up to get the proper gain needed for the analog card. The best solution I came up with is to use a BSS EC-V and some sort of network switch to provide power and run the CD player directly into the Crown. Thanks, Scott

  4. #49
    Senior Member grumpy's Avatar
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    For somewhat less $, there are the options in the GPIO-VCA notes.
    (Similar function, and form factor) curious to see what you end up with.

  5. #50
    Senior Member pos's Avatar
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    Sweet!
    How did you mount the horn to the enclosure?

    Regarding the feet, I will use 4 of these per speaker on my clones: http://www.audiophonics.fr/fr/pointe...te-p-8954.html
    Based on the weight of the M2 the resonance frequency will be under the normal range and the isolation will be pretty high. This can all be calulated and work pretty well. The shape of those rubber pads also allows for some margin on the weight (the weight/resonance frequency curve is not a strait line because the thinner part will compress more).
    I need isolation because my I have an old style parquet with floorboards on joists...
    But of course depending on your floor you might want to couple the speaker to the floor (using spikes, the so called "decoupling" ones ) rather than isolate it if you have an hard and heavy floor.

  6. #51
    Senior Member srm51555's Avatar
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    Quote Originally Posted by pos View Post
    Sweet!
    How did you mount the horn to the enclosure?

    Regarding the feet, I will use 4 of these per speaker on my clones: http://www.audiophonics.fr/fr/pointe...te-p-8954.html
    Based on the weight of the M2 the resonance frequency will be under the normal range and the isolation will be pretty high. This can all be calulated and work pretty well. The shape of those rubber pads also allows for some margin on the weight (the weight/resonance frequency curve is not a strait line because the thinner part will compress more).
    I need isolation because my I have an old style parquet with floorboards on joists...
    But of course depending on your floor you might want to couple the speaker to the floor (using spikes, the so called "decoupling" ones ) rather than isolate it if you have an hard and heavy floor.
    I used the thread forming screws for plastic recommended by Donc found here http://www.mcmaster.com/#99512a465/=10lcxgv along with washers. I originally used a 1/2" spade bit for all of the holes, but the spacing was slightly off so I ended going over them with a 13.5mm bit to get the horn to fit. I used speaker gaskett material on the inside and outside of the screw holes. There was plenty of room to work with inside so screwing them wasn't too bad.

    The speakers will be sitting on concrete. The waveguide for me is already at ear level so I want to keep the height of the feet to a minimum. Thanks for posting a link to the rubber feet, that seems like a very reasonably priced option.

    Thanks,
    Scott

  7. #52
    Member sebackman's Avatar
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    Hey Scott,

    Excellent job, those will surely be enjoyable.

    I have some questions related to POS question above.

    I’m mounting my M2’s to some cabinets and found that they are not flat on the mounting side, they are warped ( all 5 of them) so when I lay them on top of the baffle the sides are not flush on both sides.

    When laid on the “nose” and using a ruler across on the rear side, there is a 3 mm difference on either side. The centre part is not in line with the sides but actually slightly higher that the outer sides.

    How did you solve that? Did you see it?

    One way would be to reduce/lower the baffle vertically in the centre or potentially use a thicker gasket on the sides.

    I also had the same problem with the mounting bosses not exactly aligned…

    I also found that they are not parallel on the sides, mine are 1,5 mm narrower at the top than the bottom. This poses a bit of a problem to me as I will mount them upside down and using the out sides of the waveguide as sides in the cabinet. The baffle is correct for the bottom but a few mill to narrow at the top….

    Maybe I will have to bring out the good old router again. A bit reluctant to do that as the waveguide material eats routers….

    Kind regards
    //RoB
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  8. #53
    Senior Member srm51555's Avatar
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    Quote Originally Posted by sebackman View Post
    Hey Scott,

    Excellent job, those will surely be enjoyable.

    I have some questions related to POS question above.

    I’m mounting my M2’s to some cabinets and found that they are not flat on the mounting side, they are warped ( all 5 of them) so when I lay them on top of the baffle the sides are not flush on both sides.

    When laid on the “nose” and using a ruler across on the rear side, there is a 3 mm difference on either side. The centre part is not in line with the sides but actually slightly higher that the outer sides.

    How did you solve that? Did you see it?

    One way would be to reduce/lower the baffle vertically in the centre or potentially use a thicker gasket on the sides.

    I also had the same problem with the mounting bosses not exactly aligned…

    I also found that they are not parallel on the sides, mine are 1,5 mm narrower at the top than the bottom. This poses a bit of a problem to me as I will mount them upside down and using the out sides of the waveguide as sides in the cabinet. The baffle is correct for the bottom but a few mill to narrow at the top….

    Maybe I will have to bring out the good old router again. A bit reluctant to do that as the waveguide material eats routers….

    Kind regards
    //RoB
    I did not see any difference when dry fitting them to the cabinets, but then I really wasn't looking for it either. Hopefully someone can chime in and provide some data too. I assume since mine are already mounted they wouldn't be a good test subject anymore since they may already have been "bent" into shape. If no one responds then I will pull them for information's sake

    Thanks,
    Scott

  9. #54
    Senior Member srm51555's Avatar
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    Quote Originally Posted by srm51555 View Post
    I was a little disappointed the crown doesn't have digital cards in it, I never even thought of it when I was looking it over. So any control solutions will be much appreciated. The only Preamp I have left is a Mcintosh C32 and it's 30+ years old so I really didn't want to turn it up to get the proper gain needed for the analog card. The best solution I came up with is to use a BSS EC-V and some sort of network switch to provide power and run the CD player directly into the Crown. Thanks, Scott
    Here is what I'm going to go with:

    http://www.audioheritage.org/vbullet...l=1#post385363

    I posted it into the main thread just in case someone wasn't watching this one.

  10. #55
    Senior Member srm51555's Avatar
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    I had some time so I removed the waveguides and they appear to have the same 3mm difference between the center and outsides Rob is talking about. Thanks, Scott

  11. #56
    Member sebackman's Avatar
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    Hi Scott,

    Thank you for confirming.

    I thought so. I need to add some gaskets to cover the difference and potentially take down the baffle a little in the middle. My WG will be the top and the sides of the cabinet so it better at least look flush...

    Kind regards
    //RoB
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  12. #57
    Senior Member srm51555's Avatar
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    Quote Originally Posted by sebackman View Post
    Hi Scott,

    Thank you for confirming.

    I thought so. I need to add some gaskets to cover the difference and potentially take down the baffle a little in the middle. My WG will be the top and the sides of the cabinet so it better at least look flush...

    Kind regards
    //RoB
    I'd be curious to see what JBL is doing when assembling the M2. I can't imagine them modifying every cabinet or waveguide when there banging out production. Can someone think of a way to measure if the waveguide even gets warped when the waveguide gets screwed down? I might try to make a curved cardboard template with the one that is out of the cabinet and compare it with the one that is still in it's cabinet.

    Thanks,
    Scott

  13. #58
    Member sebackman's Avatar
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    Hi Scott,

    I just stole your idea and bought 4pcs 3" reflex ports with only the inner flare to be used in both ends.

    This version has separate flares and a basic plastic pipe inbetween. Normally the have a smaller flare for in box use and a bigger for external mount. The thing is that the flates are the same but the external is much lager to look impressing....

    This will bring down baffle surface for the ports so they acctually fit. Thank you for the idea.

    kind regards
    //RoB
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  14. #59
    Senior Member srm51555's Avatar
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    Update

    Both crossovers and banana plugs have been installed. Even though the crossover is only 4"x6" I found it difficult to find a place that made sense for mounting the crossover. I ended up mounting it on the cross member of the top brace for now until I rip everything apart for paint. BTW any input on what color I should paint it other than black? My DCi is at my buddy's house awaiting an EC-V that should be here this week. If everything goes right I should be listening this weekend. Maybe the first album will be The Long Run by Eagles, because it sure feels like it.

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  15. #60
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    Regarding color, I would love to see M2 (including horn) painted in faux concrete.
    And then maybe some grafitti on it, to top it off

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