opening up a minimus-7

Discussion in 'Archived Threads 2001-2004' started by DaleR, Jan 17, 2002.

  1. DaleR

    DaleR Stunt Coordinator

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    i hope i can get some help here... i have a couple of minimus-7s that i would like to modify but can't find a way to get at the crossovers! these boxes are hermetically sealed or something. has anyone successfully opened these things up without destroying the grille. these are the metal enclosure type. also does anyone have any experience tweaking the crossovers in these otherwise underrated speakers. thanks in advance.
     
  2. Greg Monfort

    Greg Monfort Supporting Actor

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    Mine are first generation, and they have a small super gooey black caulk strip ~1/4" long near the corners on the sides that the grill is pressed into, and over time mine has gotten a bit hard. I haven't had mine off in probably 20yrs, but I just removed one with a putty knife and a hair dryer without damaging it, so give it a try.

    As for mods, it depends on the version you have as there's several different ones.

    This was given to me when it was published, and is good for any made up to the time of the article, but I've never upgraded since I use mine out in the workshop:

    "Modifying Radio Shack's Minimus-7" William Hoffman, "Speaker Builder", V.9, N.1, January 1988:

    L1 = 3.5mHy 10% 1.2 ohm DCR

    C1 = 3.9uF 10% 100W/V

    C2 = 2uF 10% 100W/V

    R1 = 82 ohm 1W carbon

    Years later on the basslist someone posted that the later versions that have a ~5.8ohms DCR (mine are 6.2ohms) and/or concentric rings around the tweeter will have a huge suckout with these values.

    If you have a late version with a vent, the only info I have, again from the basslist, is to stop it up and reverse the tweeter leads.

    HTH,

    GM
     
  3. DaleR

    DaleR Stunt Coordinator

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    thanks greg,

    oddly enough i have both versions. i was going to modify the older ones first. they are my surround speakers. i was then going to open the newer pro x44. for now it is my center channel.

    i will try the values suggested for the crossover mod. but iam curious as to the value of blocking the port and reversing the tweeter polarity in the pro x44. perhaps if you read this you can enlighten me.

    thanks dale
     
  4. Greg Monfort

    Greg Monfort Supporting Actor

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    I don't have any first hand experience with this version. The advice was posted by someone who I know was extremely knowledgeable about all things audio and had his own audio/TV repair shop. Unfortunately he passed away the other year so can't query him in detail.

    Normally you plug a port to flatten out an underdamped (boomy) alignment, and reverse a tweeter when its output is too far out of phase with the other driver. They're easy tweaks, so please try them and let me know what you think. I'd appreciate you letting me know about any other useful mods you do so I can add them to my database.

    TIA,

    GM
     

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