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  1. #1

    Default Minimus 7 crossover help

    Hey all... I picked up a pair of the old Minimus 7 speakers in walnut. Got em for basically nothing and they look absolutely brand new. Not a mark or scratch on them but the only problem is that they are missing the speaker terminal block which of course means the crossover (if you could call it that) is missing as well. I have another pair of these speakers that I use at my desk for the computer and love them so pretty happy to get them.
    I know the drivers are fine in the new ones as I switched them out using my other pair and they sound great. Soooo, simple enough to get an adequate terminal cup for them but what could I use for a crossover? I was looking at these......

    https://www.parts-express.com/pe/sho...number=260-174

    Would this work for me? Any other recommendations? Would like to get these up and running asap so my click to add to cart finger is itching pretty good...haha. Thanks in advance!

    Steve

  2. #2

    Default Re: Minimus 7 crossover help

    I recommend you post a picture of the terminal cup with the crossover attached of the working one. Be sure to have the values shown in the picture. Nevermind, I found this thread here: http://techtalk.parts-express.com/sh...s-7-rebuilding

    So you need 2 inductors, a 1.0mh and a .2mh as well as two capacitors, 8uf and 15 uf. I'm not positive on the wiring of the crossover, but I'm sure someone here can tell you how to wire those up, or you can just copy the wiring on the good crossovers you already have.

  3. #3

    Default Re: Minimus 7 crossover help

    Taran... I looked over that thread you linked to (maybe not enough?). I looked at the crossover out the "good" speakers and it doesn't mean a thing to me. I can solder like nobody's business but I don't know the first thing about caps, inductors and so on and how to actually put together a crossover for a speaker. I'm really hoping to find something that's just plug and play. Glue it to the inside of the housing, solder on leads and hook 'em up to my little T amp I bought just for them.

    Steve

  4. #4
    Join Date
    Oct 2011
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    Tulsa, OK
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    Default Re: Minimus 7 crossover help

    Could you post a picture of the crossover on your "good" speakers? Make them very well lighted and close-up as possible. If you can measure the size (diameter) of the missing speaker terminal, I can order all the parts needed and build the crossovers for you and send you the crossovers to solder to the terminal cups, or I can get some more help and build a better than stock crossover that will cost more money, but make your speakers sound much better. We're here to help. We can also tell you exactly how to lay the parts on a small piece of hardboard and solder them up. Pictures and everything! Welcome!

  5. #5

    Default Re: Minimus 7 crossover help

    You might like this design. Zilch based his final selection on my design - he
    tweaked it a bit:
    http://www.audiokarma.org/forums/sho...d.php?t=199790

  6. #6
    Join Date
    Oct 2011
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    Tulsa, OK
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    Default Re: Minimus 7 crossover help

    Pete, you should tell him, he has to be an Audiokarma member to see things. I printed off the late Zilch's mod. Looks pretty good, and shouldn't break the bank. I re-simmed it with a 20 gauge ERSE 1mH air core inductor with a DCR of ~.7 ohms which gives a lift from around 120Hz down of a couple of dB. Lot's cheaper and may not be audible in some cases, will be in others. Either way, this mod should sound a mile better than stock, and better than the 7 other mods I found (including the two shown on the Audiokarma site).

  7. #7

    Default Re: Minimus 7 crossover help

    Yes, good point. I think that inductor should work fine. I thought a small 20 ga iron core would make the most sense but they are hard to find.

  8. #8
    Join Date
    Aug 2009
    Location
    Ohio
    Posts
    1,210

    Default Re: Minimus 7 crossover help

    You can also add a small value resistor to raise the DCR of the 1 mh inductor to 0.7 ohm.

  9. #9

    Default Re: Minimus 7 crossover help

    Got a couple pics that I hope will help and that you can actually see what there is to this so called crossover. Excuse my laziness, I tried taking some pics with my phone but it doesn't have a macro mode and they turned out pretty horrible. Put the speaker back together but then the wife pulled out a digital camera that I didn't even know we had.. haha. Didn't feel like taking the speaker all apart again so just popped the terminal cap off and shot these. As you can see there really isn't anything to them... just a cap, I guess you call it and the coil thing.
    The only markings I can see/read on the cap say "Polar-Bipolar" and it has a 4.7 on it. The coil thing is marked 0.4mH. That's it, no other marking or parts.
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    So anyway, I tried looking at the thread you linked me to at audio karma but couldn't see any of the pictures. I need pictures, when you start talking about caps, coils, resistors and so on... I got nothing. If a list of parts was given to me with a drawing or picture of how they need to be soldered up I am sure I could do it but I'm wondering how complicated a circuit does it really need to be? Those crossovers I linked to in my opening post seemed they would do the trick because they didn't involve anything more than what the original crossovers are composed of. If you all think something a little more "complicated" would give me an absolute noticeable difference in sound quality I'm game. Otherwise I'm perfectly fine with how the speakers sound with no more than is involved with the original crossovers.

    Steve

  10. #10

    Default Re: Minimus 7 crossover help

    Quote Originally Posted by CHIguy View Post
    Got a couple pics that I hope will help and that you can actually see what there is to this so called crossover. Excuse my laziness, I tried taking some pics with my phone but it doesn't have a macro mode and they turned out pretty horrible. Put the speaker back together but then the wife pulled out a digital camera that I didn't even know we had.. haha. Didn't feel like taking the speaker all apart again so just popped the terminal cap off and shot these. As you can see there really isn't anything to them... just a cap, I guess you call it and the coil thing.
    The only markings I can see/read on the cap say "Polar-Bipolar" and it has a 4.7 on it. The coil thing is marked 0.4mH. That's it, no other marking or parts.
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    The only way you are going to get a ready made, plug and play crossover is to (maybe) purchase one from Radio Shack. Unless you can exactly duplicate the existing one with not only the same values but also the same grades of components, the results might not be to your liking, unless of course you absolutely don't care either way.

    If it were me, I'd duplicate, replicate the original old crossover two times for two new replacements. Actually I'd "voice" the existing working unit first and then make changes as I felt necessary.

  11. #11

    Default Re: Minimus 7 crossover help

    Quote Originally Posted by View Post
    If it were me, I'd duplicate, replicate the original old crossover two times for two new replacements. Actually I'd "voice" the existing working unit first and then make changes as I felt necessary.

    Hmmm, well see that's kind of what I thought I was doing by looking at these.....

    https://www.parts-express.com/pe/sho...number=260-174

    They consist of that cap and it's marked 4.7 and then they have the coil thing. I really have little, okay, no knowledge of how these parts work together to do what they do. And as far as how they sound, I wouldn't say I don't care. If they sound like crap well that's not gonna work. If a simple little cap and coil set up makes them sound as good as the other pair then I'm happy. If there is something a little more elaborate that makes them sound even better than I'm am more than willing to go that route as long as somebody is kind enough to "hold my hand" through the process and tell me what I need in parts and exactly how they have to go together.

    Steve

  12. #12

    Default Re: Minimus 7 crossover help

    Quote Originally Posted by Pete Basel View Post
    You might like this design. Zilch based his final selection on my design - he
    tweaked it a bit:
    http://www.audiokarma.org/forums/sho...d.php?t=199790
    I modified my Minimus 7s with the PZ2.1 crossover mod in that thread. MAJOR difference. Highly recommended. Go to post #421 for complete info.

  13. #13
    Join Date
    Oct 2011
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    Tulsa, OK
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    Default Re: Minimus 7 crossover help

    Pete Basel's/Zilch's mod I'd be more than happy to build for you for cost and mail to you. I'll need to run prices this evening on parts, and get back to you later. You may want the mod for your other pair; it should make that much difference.

  14. #14

    Default Re: Minimus 7 crossover help

    Quote Originally Posted by Whitneyville1 View Post
    Pete Basel's/Zilch's mod I'd be more than happy to build for you for cost and mail to you. I'll need to run prices this evening on parts, and get back to you later. You may want the mod for your other pair; it should make that much difference.
    Cool beans! Yes indeed, I'd be interested in that if you could give me an idea on what it would cost. Would the crossovers be something that would be mounted to a small piece of masonite or cardboard that I could just hot glue on to say the inner side of the cabinet? I need to get terminal cups for the newer speakers that are missing them and then I want to replace the terminal cups on the older pair because they are cheesy little spring loaded things that have lost most of their spring so to speak. I would just solder some leads from the crossover to the terminals on the cups then, yes?

    I can't see any of the pics on the A karma threads but reading through them it appears there is a pretty decent crossover that was made and the sound improvement was very noticeable. I think the speakers sound great as they are so I am really looking forward to hearing what an improved version sounds like. I have my current pair in use as computer speakers and play either Pandora or mp3s through them constantly and everyone that has ever heard them has to comment on what great sounding little speakers these are.

    Steve

  15. #15
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    May 2012
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    Bessemer City, NC
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    Default Re: Minimus 7 crossover help

    Steve, I agree, you should definitely go the route of Zilch's crossover. From the looks of your pics, the current one's just have a first order crossover on both components, A 4.7uF cap that wires in the the positive side of the tweeter, and a .4mH (?) inductor that wires in the positive side of the woofer. I imagine Zilch's will have much improvement over that.
    HAGD,
    Marc

    Even though I try to tell everyone upfront, understand that I am still a Newb. I wish the status of Seasoned Veteran/Senior Member, etc. was earned with time not posts...

    TMWW thread

    Maurbacs DCR Tower

  16. #16

    Default Re: Minimus 7 crossover help

    Quote Originally Posted by WernerM View Post
    Steve, I agree, you should definitely go the route of Zilch's crossover. From the looks of your pics, the current one's just have a first order crossover on both components, A 4.7uF cap that wires in the the positive side of the tweeter, and a .4mH (?) inductor that wires in the positive side of the woofer. I imagine Zilch's will have much improvement over that.
    Just for the record, the Minimus 7 had a second order electrical crossover on the tweeter, and no crossover on the woofer. It ran free. The little coil is the second leg of the tweeter circuit. You can see the resulting response here: http://murphyblaster.com/content.php?f=minimus.html
    If you place them on a flat surface like a desk instead of on a stand, The midbass comes up and the overall sound is quite good without modification. I tried some mods, and they flatten out the response, but the volume taken up with the extra components was a downside in terms of the already modest bass extension.

  17. #17

    Default Re: Minimus 7 crossover help

    Quote Originally Posted by framus View Post
    Just for the record, the Minimus 7 had a second order electrical crossover on the tweeter, and no crossover on the woofer. It ran free. The little coil is the second leg of the tweeter circuit. You can see the resulting response here: http://murphyblaster.com/content.php?f=minimus.html
    If you place them on a flat surface like a desk instead of on a stand, The midbass comes up and the overall sound is quite good without modification. I tried some mods, and they flatten out the response, but the volume taken up with the extra components was a downside in terms of the already modest bass extension.

    I was wondering about space inside the cabinet when looking at this diagram I found....
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    And then I found the crossover upgrade on the auction site at was looking at the size of that. Definitely seems like a lot of stuff to cram in there. Would more stuffing help in that regards? I know on the working pair the stuffing that was in there was just a small sheet of fiberglass kind of loosely poked in there. Quite a while back we had a wicked storm come through the area when we weren't at home and my dog went ape-nuts and shredded a large bed pillow. I had a hefty bag of polyfil after the clean up. I ended up pulling the fiberglass out of the speakers and stuffing them quite full with all the polyfill I had. Maybe just me but it seemed to make a difference in the sound, for the better.

    Steve

  18. #18

    Default Re: Minimus 7 crossover help

    You could stuff the enclosure and run the crossover externally if you want.

  19. #19
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    Default Re: Minimus 7 crossover help

    The Minimus 7's ran the woofer unfiltered, so the components are for the tweeter. So that pre-made XO at the link will not work...the Zilch one would be what I'd go with. Whitneyville1's offer would be great, too! If you have a challenge with the layout and the diagram, you can confidently accept Whitneyville1's skills and get something that will definitely work. I had a difficult time of it when I was first doing my own XOs, mainly with deciphering the schematic and translating that into a soldered and working XO. With practice and a small amount of teeth-gnashing, I got to where I can do it with the best...not as good as some and Wolf, as his are genuine art, but they take up a minimum of space and my solder joints are nice. I've soldered up quite a few XO's for forum members, also. All we usually need are any size requirements (for the little "board"), since they'll probably need to be placed through the woofer hole. Good luck and let us know how it turns out, especially if you go with the upgraded XO design. Dennis Murphy has some information at his site:

    http://murphyblaster.com/content.php?f=main.html


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