What do you think of this project?

Discussion in 'Archived Threads 2001-2004' started by Dustin B, Jun 26, 2002.

  1. Dustin B

    Dustin B Producer

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    http://home.hetnet.nl/~geenius/index.html
    I posted a pick of these in another thread after I ran across them hoping some of those here with experience designing their own speakers would chime in with some opinions. Since that didn't happen I guess I'll start my own thread about them and see what the experts think.
    The efficiency of just one of those 6.5" drivers is higher than the tweeter. Is that a bad thing, or does it look like the crossover network has looked after it?
    The drivers are available from Madisound and would run you about $340 for a pair. Can someone give a guestimate as to how much the parts for the crossover designs provided would cost?
    This link has some better quality copies of the pictures in the other article:
    http://www.speakerbuilding.com/content/1105/
    The crossover schematics are images 11 and 12.
    Any other random thoughts (beavers and ducks)?
     
  2. Patrick Sun

    Patrick Sun Moderator
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    Are you referring to the Proteus? If so...

    I don't think the midwoofer's efficiency/sensitivity is more than the tweeters. The guy padded down the tweeter (that tells you the midwoofers are lower in efficiency/sensitivity right off the bat).

    Series XO diagrams give me a headache.

    The D'appolito MTM gives you almost a 6dB boost for the midwoofers when paralleled as one midwoofer unit, which would require less padding on the tweeter. But's a basic 2-way XO design, which usually requires that you design for 3rd order acoustic slopes between the tweeter and the combined midwoofer outputs to get the lobing issues corrected. The guy just played around until the drivers sync'd up, but they seem to have some flavor to their sound, which you may or may not like.

    The 2.5 way MTM will follow one midwoofer's sensitivity (maybe a little boost, though the guy claims he's only losing 1dB - hmm...) and require more padding on the tweeter. This seems like the better XO for these drivers in this configuration. The 0.5 midwoofer filter consists of an inductor to roll off the output down low (anywhere from 200Hz-400Hz), and there's a Zobel (cap and resistor series combo that's parallelled to the 0.5 midwoofer to stabilize the impedance of the midwoofer (and make it look more like a resistive load vs. a reactive load). The rest of the series XO for the tweeter and 1.0 midwoofer is to sum their outputs nicely within their respective optimal operating regions.

    Cost for crossover? Hmm....$20-$80 (depending on how much or how little you want to spend on the components).
     
  3. Dustin B

    Dustin B Producer

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    Thanks Pat, yes I am. I don't know what's going on. The link I posted is identical to the one in my bookmarks, except my bookmark takes you to the Proteus while the link here doesn't.

    Madisound lists the sensitivity of the 6.5" as 91dB/W/m and the tweeter at 90dB/W/m. Does the real world sensitivity just have something to do with the enclosure/baffel?

    From what he writes about the sound, I'd probably go with the 2.5way crossover. Mind you this is just idol curiosity and exploring other possible options for when I build a full set of 6 or 7 speakers right now. Mind you I should really be more worried about finding a job right now rather than what speakers I'm going to build when I find a job. Ah the sickness :p)
     
  4. Patrick Sun

    Patrick Sun Moderator
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    The only thing I can think of is that the guy introduced some baffle step compensation within the series XO in some manner which shelves the midwoofer output over 500Hz (anywhere from 3dB to 6dB, depending on where the speakers will be placed in the room, i.e. near/away a wall), so, that would explain the sensitivity loss on the midwoofer side, which then would require the tweeter to be padded down.
     
  5. Dan Wesnor

    Dan Wesnor Second Unit

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    The woofer will lose as much as 6dB efficiency due to baffle step.
     
  6. AjayM

    AjayM Screenwriter

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    Well I'm certainly not a designer or anything of that nature, I've looked at some of this guys designs a couple of time, and I've spoken to a few people who have built some of his other designs (the Andromeda and Eve), and they have all been very enthusiastic about the results. So I would say that the guy does know how to design something fairly well.

    As to the costs involved, just watch out for the inductors he uses on the woofers, he likes to use ultra-low DCR inductors (like 3.5-4mH with .0xxx dcr) which are a little pricey (I believe E-speakers will start stocking those inductors though), you may get close with a low gauge iron core though (which would be a bit cheaper).

    Andrew
     

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