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Proposed super-budget mini subwoofer to complement desktop speakers

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  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Originally posted by thekorvers View Post
    So you like that driver in your application? I bought some of those, but have not used them in anything yet. They did seem to produce some fairly clear sound when I quickly tested them. I believe PE had in excess of 3000 of them and they are already sold out. The product page says they are a buyout, but PE expects more of them in on 4/10/2014!?
    yeah, i'm not sure quite what its limits are in this sub, but for what it's doing now - filling in from 30-something to 100hz for some 3" fullrange drivers, and taking up about a 10" cube... i can't complain one bit. i will get around to putting the $5 MCM poly woofer in there too at some point to compare, although i'd suspect it'd also keep up with a low-sensitivity mains too, but again, not sure to what SPL that'll hold true.

    i cannot recommend the kemo amp module. it's taking way more effort to filter out noise than it's worth. the SA25 is the only way to go.

    Leave a comment:


  • thekorvers
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Originally posted by patrickm View Post
    http://www.parts-express.com/6-1-2-p...4-ohm--299-609

    some folks were calling it that when it appeared, sorry i forgot a link
    Thanks for the clarification. I wondered if that was the driver you meant, but the term BR-1 threw me off. I thought that you may be referring to the Dayton DC160 which is used in the BR-1 kit or even one of the old Bravox drivers which you have used in some builds a few years ago.

    So you like that driver in your application? I bought some of those, but have not used them in anything yet. They did seem to produce some fairly clear sound when I quickly tested them. I believe PE had in excess of 3000 of them and they are already sold out. The product page says they are a buyout, but PE expects more of them in on 4/10/2014!?

    Leave a comment:


  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    http://www.parts-express.com/6-1-2-p...4-ohm--299-609

    some folks were calling it that when it appeared, sorry i forgot a link

    Leave a comment:


  • thekorvers
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Originally posted by patrickm View Post

    here's what actually got built:
    - 2x minions III (W3-1053) in a 4.5" (external) cube made of .25" baltic birch ply, stuffed with denim insulation.
    - one 9.5x10x11 semi-subwoofer, 4th order bandpass, made mostly out of 1/4" birch ply, with bracing, and a 1/2" ply internal baffle and removable "top" where the port/amp will go.. Currently the BR-1 buyout is in there and doing well, and running off an SA-25 amp.
    Which driver is the BR-1 buyout?

    Leave a comment:


  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Originally posted by [email protected]o.com View Post
    I'm not sure you'll be satisfied with the Kemo amp module for subwoofer use. Also, I've never liked the sound of a 'filterless' bandpass subwoofer - they really need a filter because otherwise there will be midrange leakage through the port. I would recommend using the SA25 plate amp and adjusting its crossover setting to whatever your setup requires.
    thanks Rory - i actually did make that switch, in part because of the hassles i had with the kemo and a feedback problem. (even as a mechanical engineer who's done a decent amount of electronics, this wasn't worth the $10 net price differece when i factored in the filter, at least for the time being. part of the plan was just to challenge myself with a really low cost constraint). on another project, i did use the kemo 18w as the integrated sub amp with a speaker powered by the DTA-2, but i just added a conventional 2nd order filter with components i had laying around, and that worked out ok. like this one, that system was not going to be pushed to loud volumes. so i'm not going to totally rule it out at this point, but the SA25 is the better choice.

    Leave a comment:


  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    ok, after more car-related delays saturday, i now have some speakers running. no measurements yet, I'll do a separate thread for the final outcome, and link it to Lee's build.

    here's what actually got built:
    - 2x minions III (W3-1053) in a 4.5" (external) cube made of .25" baltic birch ply, stuffed with denim insulation.
    - one 9.5x10x11 semi-subwoofer, 4th order bandpass, made mostly out of 1/4" birch ply, with bracing, and a 1/2" ply internal baffle and removable "top" where the port/amp will go.. Currently the BR-1 buyout is in there and doing well, and running off an SA-25 amp. the kemo had some ground loop issues resulting in ear-splitting humming, so since this is connected to my real stereo for testing & measuring, i pushed it aside in the interest of time. the sealed chamber is 5.25" tall, the vented is about 4.5", with a 1.5"d x 3" L buyout vent glued in. there's a lot of stuffing in the sealed chamber. like i almost needed a clamp to hold it in.

    first listening impressions:
    the minions have a nice, detailed sound out of the box. excellent imaging as long as you stay between them. the drivers t/s measured within expected tolerances. i'll experiment with the BSC filter next, which i think will only help their performance without a sub. using the winisd tone generator, i can get reasonable volume @ 80hz, and still hear something down to 66hz. but depending on the music, they sound a little thin, so i think that's the midrange overpowering what mid-bass is there.

    For $39, the sub has overachieved. the SA25 isn't even turned halfway up, and it clearly outpaces the minions, even with the sensitivity-for-lower-F3 tradeoff i made. after roughing in the SPL level to blend with the minions by ear, i can hear a 32hz tone. i didn't believe that the first time i tried it, i figured 40ish would be the absolute bottom if i was lucky. below 32 things go off the rails. we'll see what the measurements say in a week or two.

    other thoughts:
    it's also super-light - it weighs under 7lbs without the amp mounted, so it should be in the sub-10lb class overall. This is a good thing from my perspective, since it opens up a new option for gift projects i have to ship.

    i would imagine this could be further optimized, or shrunk down a bit and still maintain acceptable performance. as it stands, this is a pretty decent sounding project for one day's work and $80 plus a 2-channel amp.

    for another $15 or so plus materials, you could run 4 around a room in series-parallel. hehe...

    Leave a comment:


  • RoryB@daytonaudio.com
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    I'm not sure you'll be satisfied with the Kemo amp module for subwoofer use. Also, I've never liked the sound of a 'filterless' bandpass subwoofer - they really need a filter because otherwise there will be midrange leakage through the port. I would recommend using the SA25 plate amp and adjusting its crossover setting to whatever your setup requires.

    Leave a comment:


  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Originally posted by johnnyrichards View Post
    Yeah mine were closer to 0.7, but the Fs was also around 45 so they worked pretty nice in a sealed box. They are definitely not subwoofers, though.
    ha, i wish. i'm still above .90 and 64 hz free-air w/o the fleece wrapped around, even after beating on them during break-in. however, i dug through my shelves, and the $4.88 br-1 buyout may win the crappy woofer shootout. luckily both fit the same cutout, and it's not much extra work to knock out the internal baffle and put the ND105 in if both are terrible.

    and no, it's not a real sub by any means, but when your satellites have an F3 of 100-125 Hz and you're giving it to a 6-year old who's never had anything but computer speakers, it'll do the trick

    Leave a comment:


  • johnnyrichards
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Yeah mine were closer to 0.7, but the Fs was also around 45 so they worked pretty nice in a sealed box. They are definitely not subwoofers, though.

    Leave a comment:


  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    lame. after re-soldering several loose wires inside the WT3 i haven't used since the summer, the tang band full-ranges came out pretty close to spec (leading me to believe it's been repaired correctly), but the MCM woofer was way off.

    . spec measured
    Fs 40.0 67.1
    Qts .424 .91

    this is after break in by hand and a little music, but that's a full 65% over Fs and more than 110% higher Q.

    with 12 grams of sticky weatherstripping adhesive tacked on and a fleece blanked around the backside, it's down to 62hz and 0.68. that may work better in the end, although this project may wind up being a dud.

    Leave a comment:


  • patrickm
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    Originally posted by johnnyrichards View Post
    The MCM can easily handle more than 3.5mm of excursion, but be advised they will likely be a higher Q than advertised.
    fair point. i actually modeled it to 4.5 or more after seeing your 4-from-1 shootout, but when i typed too long, i lost the line about "if these work out on the WT3". we'll see tomorrow.

    Leave a comment:


  • johnnyrichards
    replied
    Re: Proposed super-budget mini subwoofer to complement desktop speakers

    The MCM can easily handle more than 3.5mm of excursion, but be advised they will likely be a higher Q than advertised.

    Leave a comment:


  • Proposed super-budget mini subwoofer to complement desktop speakers

    A few weeks ago, I agreed to do some measuring on the Minions III using the tang band W3-1053sc full range driver and testing to see if some BSC compensation was worth the cost in dollars and sensitivity. While the weather and the holidays have so far stalled any plans to pull tools out to cut the enclosures, I hope to knock them out this weekend. In the process of thinking about this project, and keeping with Lee's goals for the Minions III (good performance with simple, small enclosures and inexpensive, currently available drivers), i'm considering a super-budget "sub" as an alternative option for boosting the low end. here's the plan:

    Driver: 6.5" poly "4" ohm woofer from MCM, 55-3230. 3.5mm x-max, $5.43 with discount code.
    Amp: Kemo 18W module $16.
    Power supply: (any available 12V 2A-5A), roughly $10-15
    10k Audio pot, an RCA jack, and some misc connectors. ~$5
    Low pass will be handled by the 4th order bandpass enclosure.
    [yes, an SA25 would also work fine for a few more bucks, but I thought i'd try playing with the amp modules].

    The enclosure is .41 ft3 gross, divided into a sealed chamber of ~.21 net and a vented ~.17 net tuned to 80hz. After factoring in a 3-4 db sensitivity loss -- not a big deal in this application given the woofer is advertised with an 87-88db and this is for low level listening -- the -3db points from this new reference level are about 45-48hz and 165-170hz, although i can roll it off earlier with lower tuning in the vented chamber if that's needed to blend with the Minions. It hits x-max with about 8-10 watts, which is ok, because i doubt the Kemo really delivers 18 clean watts anyhow.



    I'm considering cutting the "sub" from the same 2x4 handy panel of 1/4" material the Minions will be made from, to economize on material. This is possible with a roughly 9.5" cube. from 1/2 stock, it's roughly 9.5"x9.5" x 11" tall. (maybe i'll do both and compare if i have enough 1/2" scraps around).

    and if all this crashes and burns, i'll go back to the ND105-4 + SA25, which will fit in essentially the same overall box, for about $30 more per sub, and get below 40hz. but i have the potential for 3-5 of these builds this year, so that factors in.
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