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The Quarks - M.O.S.D. Computer Speaker

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  • Kootskid
    replied
    Thanks Chris. I am unwinding an inductor, so just checking. Would you suggest a 5.6uf or 4.0uf , 100V capacitor inseries with the 0.3mH inductor?

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  • Chris Roemer
    replied
    I don't SEE any ref. to a 0.35mH coil in my quote.
    Use #257-028 for a 0.30mH #20 coil.
    If you've GOT a 0.35, may as well try it. It'll change the shape of the rolloff shoulder though.

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  • Kootskid
    replied
    Hi Chris Roemer,
    Could you tell me if the 0.35mH inductor is the correct value for the Dayton #20 coil you reference in the following quote. Thanks for the help,
    Myles

    Originally posted by Chris Roemer View Post
    If you look at the Quark XO, here's how I'd mod it to use the DS90-8 woofer (same box, and same vent).
    The tweeter HP filter changes. Instead of a 2.7uF cap & 0.20mH coil, try a 5uF series cap (Dayton poly) and a 0.30mH shunt (to gnd) coil.
    Also, for attenuation, take out the series resistor, and try an L-pad instead: 6n (ohm) series resistor, and 4n parallel.
    Use a (Dayton) #20 coil, and 5w resistors would probably be OK w/a relatively low power system.
    Positive polarity is indicated, but try the tweeter both ways and go with whatever sounds best to you.

    The woofer needs a bit more than just the 1.0mH series coil (due to cone breakup around 8kHz).
    I'd add a Zobel across the woofer: 10n resistor and 3.3uF cap.
    Also run a "tiny" 0.22uF cap (027-402) across the 1mH coil. This acts like a notch (tank) filter.
    You could probably go w/the "buyout" bobbin coil here (269-2124).

    Fc around 3kHz, w/not much baffle-step (about +3dB).

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  • djg
    replied
    I glued all my components to the walls. The coil I screwed to a piece of underlayment then glued that. My Quarks (Pg 11) are sealed, never to be opened again. I have had speakers 15 years old that I disassembled to sell the components. Nothing had moved at all.

    You can put the crossover on a piece of thin ply small enough to go through the woofer hole and epoxy that down.

    I don't care if you use them upside down, I'm just telling you that you don't need to.

    It's DIY, have fun.

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  • robca
    replied
    Originally posted by djg View Post
    If you make the crossover small enough to fit through the woofer hole, you won't need any access besides that. There's not much going on inside these.
    Well, one of the inductors is pretty heavy and needs securing (screws, since any glue would not hold on the paper-like MDF), plus I like glueing everything down to avoid rattling crossover components or wires over time. Would be pretty messy to try and do it from the small midwoofer hole, so I prefer to have easier access.

    More than anything I'm trying to understand what would the problem be if I were to use the speakers upside down, since that would make my plan (open back) possible

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  • djg
    replied
    If you make the crossover small enough to fit through the woofer hole, you won't need any access besides that. There's not much going on inside these.

    Leave a comment:


  • a4eaudio
    replied
    Originally posted by robca View Post
    Can anyone think of any downside doing so? I have seen quite a few two ways speakers with the tweeter at the bottom, and aside from noting they should have the tweeter at ear level, no other consideration applies.
    From what I have read, the tweeter height is the main thing.
    The other theoretical issue would be the bounce/reinforcement of the woofer being down by the surface of the desk vs further away with the speaker inverted. But with this small woofer and speaker I doubt if that is going to make any difference, and it's not clear which would be better anyway.

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  • robca
    replied
    I'm building the Quarks using the DIYSoundgroup kit. I was hoping to be able to leave the back removable and with exposed MDF (possibly painted black), and veneer the rest of the speaker. But due to the way the kit is designed, the top panel is smaller, and the back panel is exposed at the top. If I were to assemble the cabinet so that the smaller piece is at the bottom, the port would interfere with the midwoofer. I could replace the back panel and drill a new hole for the port, but I don't have woodworking tools anymore, and would probably not be worth the effort anyway (and the cost of buying MDF just for 2 tiny panels)

    One possible alternative is to use the quarks "upside down", with the tweeter at the bottom and the midwoofer at the top. I do realize that I will have to "sit them higher" so that the tweeter is at ear level (btw: I use them as a desk speaker, near field). Can anyone think of any downside doing so? I have seen quite a few two ways speakers with the tweeter at the bottom, and aside from noting they should have the tweeter at ear level, no other consideration applies

    I found some reference to change in phase, depending on the type of crossover used, but I'm afraid it completely flew above my head, and could not follow that explanation

    And, yes, the other alternative is to build them the way they are supposed to, and not have the back removable, but why make life easy when you can make it hard on yourself?

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  • dkalsi
    replied
    Click image for larger version  Name:	Quarks actual vs measured.JPG Views:	1 Size:	215.0 KB ID:	1398969 Has anyone measured their Quarks build? I built mine earlier this year and am now just getting around to taking measurements.

    I've attached an image comparing my measurements with Jeff's measurements in the first post.

    Blue = Jeff
    Red = Mine

    Leave a comment:


  • jdhill
    replied
    I posted this in another thread but I figured it would belong here as well... The MTM version! The sound is great but I don't have much of a reference having never made the originals. It was a fun build in any case.

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  • warllo
    replied
    I do, I figured that one was pretty hard to screw up :-) Thanks for the response!

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  • Jeff F.
    replied
    Originally posted by warllo View Post
    Hello everyone, this is my first speaker build that uses x-over components. Does this layout look correct for the quarks?
    Looks correct, you have the inductor for the mid as well?

    Leave a comment:


  • warllo
    replied
    I forgot to notate that the positive terminal of the tweeter would get a wire connecting to the same solder joint as the inductors negative side. The forum wouldn't allow me to edit my post for some reason.

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  • warllo
    replied
    Hello everyone, this is my first speaker build that uses x-over components. Does this layout look correct for the quarks?

    Leave a comment:


  • Jeff F.
    replied
    Originally posted by corwin6654 View Post
    That is a nice little boom box build. I’m looking to do something similar for my wife for the kitchen. Do you have plans for the box and crossovers you can post? What amp is that on the top? Sent from my iPhone using Tapatalk
    Thanks! As for plans, it's just two Quark speakers on their sides and built into one enclosure. The crossover is the same as the original as well. The amp is a Nobsound and can be found on the Zon or the Bay and has built in Bluetooth. It sounds and works well.

    Leave a comment:

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