Enhancing 'cheap' speakers?

Discussion in 'Archived Threads 2001-2004' started by JohnnyG, Jun 15, 2001.

  1. JohnnyG

    JohnnyG Screenwriter

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    A customer of mine (I own an A/V store) imports a bunch of different things from China and he recently brought by a set of of home theater speakers for me to try out. The fronts are 3-way towers with side firing 8" woofers, a 6.5" midrange and a 1" silk dome tweeter. The center channel has 2 5.25" woofers and the same 1" tweeter, and the rears are dipoles with 2 5.25" and 2 3/4" mylar dome tweeters each. Surprisingly, they actually sound pretty darn good! The bass is quite decent and the tweeter on the mains and center really blew me away (based on what the speakers cost).
    I took them all apart and noticed a few 'thing':
    1. One of the woofers on the front speakers was wired out-of-phase. Is this normal for side firing woofers or an obvious mistake?
    2. The main speakers have one 'sheet' of sound absorbing material in them - hardly anything. The other speakers are hollow.
    3. The '3-way' front speakers only have a cheap 2-way crossover
    4. The center and rear speakers have no crossover, only a cap for the tweeter
    5. On the surrounds, the woofers are wired out-of-phase, but the tweeters aren't. Is this normal or another obvious error?
    Now, for some strange reason [​IMG] I have an overwhelming desire to use these speakers for a little project. I believe that the drivers themselves are actually half decent and the front towers are quite heavy with well constructed cabinets. I think I can make them sound much better.
    What I'd like to do is to put some half-decent crossovers in all the speakers (I was looking at the Dayton's from Parts Express), fix the wiring problems, and stuff them all with polyfil (or whatever). The total cost of these additional items is actually about equal to the cost of the entire system to begin with.
    Am I nuts here, or does this sound like a reasonable thing to try?
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    John Golitsis
    Next Big Thing Electronics
     
  2. Dustin Haug

    Dustin Haug Agent

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    Do you have access to another set of them? If so check if those are wired the same way. It's possible that it's intentional, but my guess is that it's a mistake.
    As far as whether it's worth it to try and fix them, that's a judgement call if you can get the crossovers cheap it may be worth trying just for fun.
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    My DIY sub page
     
  3. Stephen Dodds

    Stephen Dodds Second Unit

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    Some very good speakers have pretty cheap parts, but assembled with care. Check the reviews of the Radio Shack Optimus LX(?) at Audio Review for an example.
    This was your typical cheap RS speaker that just happened to have a superb tweeter. There were all manner of tweaks.
    I'd look at the build/assembly problems first, and then work your way up. Same stuffing, bracing, damping etc.
    Changing crossovers would seem to require more knowledge of the drivers, enclosures etc.
    But what the hey, give it a bash.
    I'm currently researching ways to modify my main speakers which were very expensive when new, but pretty cheap used, because I'm sure there is improvement there.
    Go for it.
    Steve
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    Steve's Toys
     
  4. Allan Jayne

    Allan Jayne Cinematographer

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    Just a guess, cheap speakers have a less uniform frequency response. You can optimize the cabinet for them to get rid of obvious resonances but small peaks and valleys in the response will still be there.
    I haven't studied speakers for several years but the last time I did (over 10 years ago) even good speakers had frequency response at least plus or minus five dB as you did a frequency sweep test.
    Video hints:http://members.aol.com/ajaynejr/video.htm
     
  5. Jin E

    Jin E Second Unit

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    I use modified Son MB215's all around. They are really cheap ($100/pair) 3 way bookshelf speakers. They use a accoustic suspension design... and out of the box they seen to be lacking. An A-B compairison with some B&W 602's the high's vere VERY lacking with very little detail. I took the drivers out and had a gander at the capactors they use. The tweeter was cut off at 20khz and the mid was cut off at something like 15khz (If memory serves, it's been a long time since I've done this). So... basically the tweeter was reproducing sounds I could not hear and the mid was being used as a tweeter. I bought some capacitors at radio shack and just soldered them in parallel with the current capacitors. The difference was night and day! This change really brought the speaker to life. Enya had never sounded so rich and clear through those speakers! I beleive the accoustic suspension design really helps this speaker out... keeping what bass it can produce nice and tight. With the 8" woofer it easily goes down the the 80hz I have them crossed over at. I've been so happy with the speakers since then I have continually put off buying my B&W 602's for over 2.5 years. Instead I have upgraded my DD only receiver to DD/DTS, found a Laserdisc PLayer (two of them), bought tons of Laserdiscs and DVD, new Dreamcast, new bed, new car, new motorcycle leathers, new washer dryer... the list goes on and on.
    It took me lots of experimenting finding a good combination of capacitors. I had a blast the whole time though. Fixing the cheap speakers was a really fun and rewarding experience. Give it a try!
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    -Jin
    My Theater
     

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