The SunCC: a center channel project

Discussion in 'Archived Threads 2001-2004' started by Patrick Sun, Jun 10, 2002.

  1. Patrick Sun

    Patrick Sun Moderator
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    Here's a couple of photos of my DIY center channel speaker project, which I've dubbed: The SunCC.
    This CC speaker uses the same tweeter (Morel MDT30) and midwoofers (Peerless HDS 850439's) as my other DIY speaker projects, a pair of 2.5-ways (SunOnes) for the front speakers, and a pair of 2-ways (SunTwos) for the rear speakers. I've incorporated the Morel MDM-55 midrange in an effort to help its dispersion pattern for a speaker that lies horizontally.
    No crossover is done yet (you really need to measure the drivers installed in the front baffles to get something to work with in crossover design). My intention is to shoot for crossover points of 500Hz and 4000Hz, but that's subject to change, but stay tuned for updates.
    Photo 1
    Photo 2
    The tweeter and midrange drivers are recessed, but not the midwoofers (supposedly it helps in getting their acoustic centers closer in line, plus recessing tweeters help in combatting diffraction effects.
    When I get some more free time, I'll post all of the construction photos in a webpage (but it's pretty much the same as my other enclosure designs, with a few differences to regain some more volume I lost by going with a shorter and narrower front baffle. I do change some things around given the constraints of the project, like locating the port (not shown yet) on the backside of the enclosure.
    The dimensions of the enclosure are 24"x9"x14.75" (WxHxD).
     
  2. Michael_UK

    Michael_UK Stunt Coordinator

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    I like it a lot, it looks like a real killer centre channel.
    Whats the F3 point of the speaker?

    My home cinema is on the back burner at the moment due to starting a new job (Wireless networking and Computer teaching asstance) and with a AV company messing me about for two weeks so now I need to find new denon receiver in stock.

    I am building a DIY subwoofer kit in the next few months, it should be fun!!!!!!
     
  3. Cam S

    Cam S Screenwriter

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    Nice looking center pat, pretty big too!

    BTW, how hard is it to design and build your own crossover? It seems hard, and that's what keeping me from building DIY mains.
     
  4. Patrick Sun

    Patrick Sun Moderator
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    The F3 will probably be in the neighborhood of 50Hz (the Fb will be around 45Hz-50Hz).

    The crossover design process is a pain if you don't have access to measurement gear and crossover design software. You can try to do it the "trial-n-error" way (1/3 octave test tones, a SPL meter, Excel spreadsheet and lots of patience and detemination), and you'll get sort of close if you educate yourself on crossover design, and understand the variables (attenuation, filters, zobels, resonance traps, etc) that affect the sound quality of the drivers, and their integration.

    Luckily for me, I've done it the hard way, and I've done it the easy way, and I much prefer the easy way (I have a local friend with a speaker testing setup and LEAP crossover design software). I will try some "trial-n-error" just to do some initial listening and testing until I get a chance to take this CC to my friend's place for some measurements.
     
  5. Cam S

    Cam S Screenwriter

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    Geez, that sounds WAY too complicated for me. Guess I could always go the pre-built crossover way.
     
  6. Patrick Sun

    Patrick Sun Moderator
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    If you selected drivers that Madisound sells, you could pay them $60 for a LEAP crossover design that would get you around 90% "there" in terms of maximizing the sound quality of the speakers (you would specify front baffle dimensions and they could suggest optimal enclosure size, etc).
     
  7. Patrick Sun

    Patrick Sun Moderator
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    I've been cobbling together a crossover for the speaker the past couple of nights. I've got the low end pretty much in sync (went for a crossover point around 800Hz). The high end crossover needs a little work getting to cross over around 4000Hz-5000Hz. The padding for the tweeter and/or midrange is also a work in progress, but surprisingly enough the CC was functional last night, and it didn't sound all that bad for a first effort attempt. I listened to it while watching TV late last night, and it sounded okay. It's nowhere near optimized, but it's operational.

    I'll try to post a photo of the crossover network in progress later tonight (it's ugly!)
     
  8. Patrick Sun

    Patrick Sun Moderator
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    Okay, here's a shot of the work-in-progress known as the crossover (I got smarter, and made something that allowed me to swap out the crossover elements without the need for soldering them in place - I just need to find a local place that sells small alligator clips...):
    Photo 3
    And here's a rough look at the frequency response (this was all done with textbook filters, plus taking into account the acoustic roll-offs of the drivers themselves), and I won't certify how valid the graph is, but it got me into the ball park, and my ear tell me that it's relatively useful given that I am only using 1/3 octave test tones and a Radio Shack SPL meter, a notepad, and Excel to graph the results):
    Photo 4
    I need a little help in the 2000-5000Hz region with the low pass on the midrange (perhaps I need to go to a higher order filter to get a sharper knee in the corner frequency. But for a first pass at a crossover design with rudimentary tools, I don't think I did all that badly for now. Can't wait to get on a real measurement system one of these days...
     
  9. Patrick Sun

    Patrick Sun Moderator
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    Here's one last look before I go for the nitty gritty crossover design portion (though my make-shift crossover isn't doing all that badly). I was able to get the edges of the front baffle rounded over with a 3/4" roundover bit this past week. This was the only photo that shows what it now looks like from an angle.
    Photo 5
    The reason I waited to round over the edges after everything else was done was to have a good edge to work with when I was glueing and clamping the enclosure together.
     
  10. Brian Bunge

    Brian Bunge Producer

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    Pat,
    Looking good! Are you going to design the crossover the hard way or are you going to get that buddy of yours to take some measurements and go from there?
    BTW, I just won the Adire LCC center channel kit from HTT! [​IMG]
    Brian
     
  11. Patrick Sun

    Patrick Sun Moderator
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    I've already designed the XO the hard way (though it didn't take me too long (I'm learned a few things along the way in the year or two of mucking around with filters), but it's no substitute for real measurements and XO software and your ears. So hopefully I'll be able to take the CC in for the measurements one of these days... (my friend with the XO gear travels a lot for his job).

    Congrats on the Adire CC, next thing you know you'll be building the HT281 to mate them to the CC...
     
  12. Patrick Sun

    Patrick Sun Moderator
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    Finally got to my friend's place to do some measurements. I have no graphs yet (hasn't emailed me the graphs), but we only had to do a bit of fine-tuning for an acceptable 1st pass of the XO. I bumped up to Rs to 4 ohms in the tweeter L-pad to pad the tweeter another couple of dB, and added a little more capacitance (2.6uF -> 4.1uF) on the tweeter cap to smooth out the slope. That flattened out most of the response, and there are slight dips in the XO regions, but nothing objectionable. My friend did say he'd play around with the measured driver responses and cook up something with his LEAP setup to see if he could flatten out the overall response. My lowest impedance was 4.3 ohms (in the midwoofer region, of course, but I did have a peaky impedance in the midrange region, so he was going to look at that as well).

    Using the 2 midwoofers and crossing it low totally removed the need for baffle step compensation. I just about hit my Fb tuning point of 45Hz (it measured 46Hz - where the impedance was at a minimum), and the F3 was also around 45Hz.
     
  13. Brian Bunge

    Brian Bunge Producer

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    Pat,
    Sounds like your crossover design skills are getting pretty good! Can't wait for you to finalize a design and then finish the cabinets! [​IMG] (I'm not going to give up on this!)
    How about a deep red, similar to my pics I posted yesterday, for the veneer and then do a faux green marble finish on the baffles?
    Brian
     
  14. Brian, Brian ,Brian.....when will you ever learn....Pat will NEVER finish a cabinet he builds...
    ....you want to know WHY.....because the last time he tried to veneer, he accidently glued his face to the cabinet while he was sniffing the glue!!!
    [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG] [​IMG] [​IMG] :p) [​IMG]
     
  15. Patrick Sun

    Patrick Sun Moderator
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    Hurt like hell too!
     
  16. Brian Bunge

    Brian Bunge Producer

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    Tony,
    Sounds like that final covering your finals has gone straight to your head! [​IMG]
    I've actually become quite fond of the smell of contact cement! [​IMG]
    Brian
     
  17. ya...well....it starts in less than 1hr, there is no point in worrying about it anymore=)
     
  18. Patrick Sun

    Patrick Sun Moderator
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    Here's a link to the SunCC construction webpage.
     
  19. Patrick Sun

    Patrick Sun Moderator
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    There are some FR graphs up now on the webpage with my DIY XO. [​IMG]
     
  20. Griff

    Griff Stunt Coordinator

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    How will you be finishing them?
     

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