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monoprice 2way ribbon speaker

not sure if its even worth the price of the cabs 

Today only, Monoprice offers its Monoprice 6.5" 2-Way Bookshelf Speakers in Black for $44.99. Coupon code "BFNOW" cuts it to $35.99. With free shipping, that's $4 under our June mention and the lowest price we could find now by $14. (It's also a very low price for speakers with ribbon tweeters.) They each feature a 4" x 0.76" ribbon tweeter, 6.5" subwoofer, and 60Hz to 20kHz frequency response.

Comments

  • Got a set of these, I will do a tear down and measurements, hopefully this weekend
    cssaudio1S7910
  • edited October 2018


    I dont think the crossover will suprise anyone at this price point.

    No part numbers on either driver
  • edited October 2018
    Be interesting to see some as-is measurements and what a proper crossover can accomplish.

    For what they are, how do they sound?
  • For $35 speakes, I would reccomend saving money at this point.  The box seems decent for its size, hopefully the ribbon can be salvaged. 
  • Curiosity has the best of me - so a pair is on the way. Similar deal as before, shipped for around $38. 

    I am a glutton for punishment, I guess. Worst case, I can flip the individual components after playing around. 
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  • I'll be interested in your thoughts,  been a busy couple weeks so I havent got them mesured
  • Finally showed up - very nice looking at first blush, doesnt take long to understand the cabinets are pure junk, though. Full 3/8" construction from the looks of it - black and hollow, like my heart. 

    I'll get measurements today, my hope is on the ribbon being useful. 

    Seriously though, from an aesthetic perspective, it is right up my alley. Understated, very high driver:baffle ratio, and the cone on the woofer is simply a beautifully classic example of how nice poly can look. The drivers both stand a tad "proud" of the baffle - not a perfect mounting from a measurement standpoint, but I always liked how it looks. Just a millimeter or so really makes things pop for me. 

    Anywhoo, I'll start a new thread or tack onto this one, will take some time to get all the measurements done. 
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  • Impedance is fairly benign. I zoomed it in to a 2.5db scale, and as you can see it doesn't offer too significant swinging, and phase stays within +/-45 degrees. Not overly tube friendly (I bet a TON of these have been bought in tandem with Monoprice's tube amp, though). 

    Tuning appears to be upper 90's, and depending on the Qtc that could mean anemic or boomy - smooth is probably not a word that would be used to describe the bass out of these. Without pulling the woofer and measuring the T/S, I imagine it is the latter. This is likely a driver with a very high Qts (think around the 1.0 or even higher), and a high-ish Fs (my guess is around 65Hz). I'll pull the drivers after in-box measurements to confirm.

    The rather large resonance at `215Hz is somewhat troubling, but expected. That is a really shitty frequency to have problems with. The wrinkle at 1K is likely the woofer, a common issue in many drivers independent of cost. However, in this case it is probably not due to the surround such as what is found on Satori drivers, for example. Probably a poorly damped cone causing some linear distortion. We'll see.

    This was taken on pretty much an "out of the box" speaker - I flexed the woofer cone a bit, but no other break-in. 
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  • Some in-box measurements...

    Frequency response over impedance shows a large, likely very audible and annoying peak at ~3800. The tweeter is several db hotter than the woofer, and of course no baffle step compensation to be seen. The peak followed by the dip is probably destructive interference from the woofer running wide open. I will pull the woofer and disconnect it to be sure. The dip at ~1.1k coincides with the wrinkle in the impedance, and was predicted. Other than that wrinkle, the woofer is actually pretty flat and smooth through the midrange, a single coil plus a resistor on the tweeter would help these out tremendously. 



    Distortion in the midrange is quite acceptable, especially given the volume I took this at. This is SPL accurate at around 30", so it was quite loud. The horrible spike at ~3800 may be woofer related, tweeter related, or a combination of both. When I do individual in-box I will know more, but it appears if a real crossover were applied, this could easily be within +/-3db. 

    My educated guess on having fucked around with similar shitboxes in the past is the lack of a crossover is ruining an otherwise high-potential design. I *hope* the tweeter is not contributing significantly to the aberations around that 3800-8000 range. 

    Off I go to find some hex head bits to remove some drivers. 



    rjj45
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  • Woofer free air impedance:




    Loudspeaker parameters:

    Fs  = 59.75 Hz
    Re  = 4.83 ohms[dc]
    Le  = 393.33 uH
    L2  = 698.37 uH
    R2  = 24.31 ohms
    Qt  = 0.89
    Qes = 1.06
    Qms = 5.52
    Mms = 16.55 grams
    Rms = 1.125467 kg/s
    Cms = 0.000429 m/N
    Vas = 11.62 liters
    Sd= 138.93 cm^2
    Bl  = 5.319862 Tm
    ETA = 0.22 %
    Lp(2.83V/1m) = 87.81 dB

    Added Mass Method:
    Added mass = 25.00 grams
    Diameter= 13.30 cm

    The parameters are a smidge better than I predicted, little lower Fs and Qts. The compliance is also relatively low.



    This is a close approximation of the bottom end. 

    Here is what the driver would do in a small tower of 30L, heavily stuffed:



    In the theoretical tower, we could expect F3/6/10 of 59/49/40 so not completely useless if a guy wanted to build a 1 cubic foot tower around a $3 woofer. 

    Up next, tweeter in-box, woofer in-box. Maybe some ideas for a crossover mod. 


    D1PP1N
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  • So here is the tweeter with its single cap inbox distortion. I turned it down a few db from the system measurement just because.



    Essentially useless as anything but a super tweeter, in my opinion. At the very least, nothing good can happen using it under 4 or 5k. The only reason the distortion is no piercing at the relatively high crossover point is due to the shallow slope. Using 2nd or higher slopes at the same frequency would drive it way up there. Ugh. It appears to be very smooth response, otherwise - and lets face it, lots of people like the sound of higher distortion tweeters, so it might be fair to assume others may find a use for this. 

    Woofer in-box distortion:



    The woofer is definitely the better performer of the two. Even the spike in odd order at ~1300 would be a non-issue with a real crossover in place. Too bad the tweeter will not go low enough to do something like that. 

    Here are both in-box underlayed with the summed response:



    The good news is, with a notch and a single coil on the woofer, plus a resistor on the tweeter, this would measure very flat. The bad news is, not sure the tweeter would play nice. I think if we stuck with a 4th order crossover at 5K, and did nothing more than notch the small breakup on the woofer plus some type of BSC circuit, it would still suffer from the cabinet being too small, and built like shit. 

    I did some quick modeling, and... not sure this can be saved with this tweeter. At the very least, a guy could EQ it a little better, provided he does not try to EQ that null out - that will just put more strain on the tweeter. Notch it at 3800 or so, and shelve the whole thing about 6db above 400Hz and it would be adequate for many people. 

    I give these a rating of pure shit, I will be putting it back together and bundling them with that little Pioneer AIO thingy, maybe some of my non-audio friends will appreciate them. 

    PS - I do not do subjective reviews but maybe once every five years. I did not listen to them, I have spent enough time correlating measurements to sound quality to know these are at *least* as bad as the Bose 201 without the potential. 
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  • PPS - the woofer is influencing the tweeter well into the upper octaves. 
    GowaJasonP
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  • jr@mac said:
    In the theoretical tower, we could expect F3/6/10 of 59/49/40 so not completely useless if a guy wanted to build a 1 cubic foot tower around a $3 woofer. 


    I'm in the process of building 1 cubic foot towers right now with what I consider more cost effective drivers.  Building towers is so much work and I'm getting so tired of routering driver rebates I can't imagine using a $3 driver.
  • I like these reviews and dissection.  It's fun to think there might be something decent in that sale price.  Too bad we've not seen any gems in awhile.
    PWRRYDjr@macJasonP
     John H, btw forum has decided I don't get emails
  • I like these reviews and dissection.  It's fun to think there might be something decent in that sale price.  Too bad we've not seen any gems in awhile.

    Wasn't it you that was going to do something with the Linaeum tweeters?   
  • I did, I gave them to JR  :)
    MartyH
     John H, btw forum has decided I don't get emails
  • When I typed "more cost effective drivers" that was not directed towards these drivers.  What I was trying to say is I am using $30 Peerless woofers, not NanoNeo $12 woofers and $9 tweeters.
  • Screw it, I'm going to attempt some improvements. Why not?
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  • This can be done pretty inexpensively using the cheap Dayton coils, and the Xicon resistors. I have to experiment with the tweeter next, that will probably be tomorrow - have company coming over in a few minutes to listen to some speakers I have for sale. 

    I imagine just a small coil and an L-Pad will be needed. 

    Just for a reference, this is the cost at PE for the woofer parts. This should not be taken as gospel as yet - purely on paper at the moment:



    I expect another $15 in tweeter parts, which means a good crossover for these drivers will double the cost of the speaker, and we still have a shitty cabinet. I will see about gluing a few braces inside the cabinet, as well. I am remembering how much fun this can be, even if it is a useless piece of shit overall. 
    D1PP1NSilver1omoPWRRYDGowakonfyousedS7910JasonPBryan@MAC
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  • Scratch that, I actually burned a terminal off one woofer desoldering. Wow. So, pulled the ribbons (probably work well with a cheap 4" like the new Dayton poly stuff), and toss the rest. 
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  • Fudge....this was getting real fun, fast. Still.....will be interesting to see what you come up with for the replacement woofer.
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  • I can ship you a pair if you want them :P
  • brek81 said:
    I can ship you a pair if you want them :P
    Im good, thank you ;-)
    I have a signature.
  • But the cardboard box could be used for somthing else?
  • Currently there is a Bose 201 in it, getting ready to ship to Meniscus :-)
    ani_101
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