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2-way MT: Dayton RS180S-8 and SEAS 27TDFC

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  • clyde47
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Never mind, missing xmax and pe in the Bassbox database. Edited, normal now.

    Originally posted by clyde47 View Post
    When I modeled that woofer in BassBox no matter what vented profile I tried there was a huge hump at cutoff. I wonder if the fs/qes of 85 is responsible, not really vented, not really sealed.


    Design Goals

    This design employs two cost-effective, low-distortion drive units, Dayton RS180S-8 and Seas 27TDFC (H1189), which have been popular and tested favorably by several well-known DIY'ers. The goal of this designing attempt was to develop a relatively simple crossover network that exploits the potential of the drivers in a 2-way.


    Crossover


    LR4 crossover at 1.6 kHz


    For this design, to suppress the high frequency breakup nodes of the metal cone driver, a bottomless LC notch filter, which is made of C2 and L3 in the above schematic, is used. This not only suppresses breakups but also contributes to low pass filtering of the woofer. In fact, a notch filter alone is not very effective in suppressing breakup nodes when applied to the RS180 since the woofer's breakup has two main peaks at 6 and 9 kHz. In this design, a low crossover frequency (1.6 kHz) through a large shunt capacitor (C2) and a notch filter centered in the middle of two breakups provide a good result.



    Predicted system response and individual driver rolloffs


    Plots of filter transfer functions and system impedance curve are attached below.


    Enclosure

    Net internal volume:
    For a vented option, 14 to 21 liters with 35 to 45 Hz port tuning.
    For example, Dayton 0.5 cu ft cabinet with PE 260-476 tube with no cutting;
    or Dayton 0.75 cu ft cabinet with 2" ID Precision Port cut to total 7".

    For a sealed option, 8 to 11 liters. Requires a subwoofer or two for full range reproduction.

    Baffle size:
    8" to 10" wide. Baffle height does not matter though it will somewhat affect midrange tonal balance.

    Driver layout on baffle:
    Tweeter's center is 3" from the baffle's top edge with 0.75" horizontal offset (L/R mirror image).
    Midwoofer's center is 5.75" below the horizontal line at which the tweeter's center is located.
    Drivers should be mounted flush with the baffle in recessed cutouts.


    Options

    Non-BSC, in-wall mount version is here (post yet to be added).


    Listening Impressions

    These are decent sounding speakers; way better than any commercial offerings under $500/pr I recently auditioned (mostly from Internet Direct loudspeaker companies). Voicing is near-perfect to my ear. The SEAS tweeter is really an excellent performer; it handles the design's low crossover requirement with aplomb. No wonder it's so popular. After trying various filter topologies, I really don't think this driver combination needs a more complex crossover.

    See another review here.

    [/QUOTE]

    Leave a comment:


  • clyde47
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    When I modeled that woofer in BassBox no matter what vented profile I tried there was a huge hump at cutoff. I wonder if the fs/qes of 85 is responsible, not really vented, not really sealed.


    Design Goals

    This design employs two cost-effective, low-distortion drive units, Dayton RS180S-8 and Seas 27TDFC (H1189), which have been popular and tested favorably by several well-known DIY'ers. The goal of this designing attempt was to develop a relatively simple crossover network that exploits the potential of the drivers in a 2-way.


    Crossover


    LR4 crossover at 1.6 kHz


    For this design, to suppress the high frequency breakup nodes of the metal cone driver, a bottomless LC notch filter, which is made of C2 and L3 in the above schematic, is used. This not only suppresses breakups but also contributes to low pass filtering of the woofer. In fact, a notch filter alone is not very effective in suppressing breakup nodes when applied to the RS180 since the woofer's breakup has two main peaks at 6 and 9 kHz. In this design, a low crossover frequency (1.6 kHz) through a large shunt capacitor (C2) and a notch filter centered in the middle of two breakups provide a good result.



    Predicted system response and individual driver rolloffs


    Plots of filter transfer functions and system impedance curve are attached below.


    Enclosure

    Net internal volume:
    For a vented option, 14 to 21 liters with 35 to 45 Hz port tuning.
    For example, Dayton 0.5 cu ft cabinet with PE 260-476 tube with no cutting;
    or Dayton 0.75 cu ft cabinet with 2" ID Precision Port cut to total 7".

    For a sealed option, 8 to 11 liters. Requires a subwoofer or two for full range reproduction.

    Baffle size:
    8" to 10" wide. Baffle height does not matter though it will somewhat affect midrange tonal balance.

    Driver layout on baffle:
    Tweeter's center is 3" from the baffle's top edge with 0.75" horizontal offset (L/R mirror image).
    Midwoofer's center is 5.75" below the horizontal line at which the tweeter's center is located.
    Drivers should be mounted flush with the baffle in recessed cutouts.


    Options

    Non-BSC, in-wall mount version is here (post yet to be added).


    Listening Impressions

    These are decent sounding speakers; way better than any commercial offerings under $500/pr I recently auditioned (mostly from Internet Direct loudspeaker companies). Voicing is near-perfect to my ear. The SEAS tweeter is really an excellent performer; it handles the design's low crossover requirement with aplomb. No wonder it's so popular. After trying various filter topologies, I really don't think this driver combination needs a more complex crossover.

    See another review here.

    [/QUOTE]

    Leave a comment:


  • cruzer
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    how would the dayton rs28f compare vs the seas tweeter since its specifically designed to compliment the dayton woofers?

    Leave a comment:


  • Applesauce
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Nice looking design! Anyone have any thoughts on a two-woofer variation on this? i.e., basically a Dr. K, but with the Seas tweeter... It almost looks like I could mix-and-match the tweeter portion of Jay's crossover with the woofer portion of the Dr. K, or with one of the 2.5-way topologies seen here?

    Leave a comment:


  • ReissM
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Careful... you're converting 250uH to .25mH, but the schematic doesn't show 250uH.

    It shows 25uH. My advice is simply use the values shown as mH on the schematic. In this case 0.025mH.

    (By the way, that value is really small compared to what you might use in a typical x-over filter. Looks like the implementation justifies it's value though.)

    Leave a comment:


  • greywarden
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    google will do the conversion for you if you type it out...

    http://www.google.com/#hl=en&safe=ac...f657eb4d8c6f0d

    Leave a comment:


  • CZ Eddie
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Ahhh, the "Internet" was telling me to use two decimal places and that wasn't making any sense. Thanks!

    Leave a comment:


  • mattk
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Originally posted by CZ Eddie View Post
    Is the conversion of 250 uH to mH going to be two decimal places or three? 2.5 mH or .25mH?
    micro to milli is 3 decimal places - so .25mH

    Leave a comment:


  • CZ Eddie
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Originally posted by [email protected] View Post
    cz read the vaules again. note they are listed in mh as well as uh. cambining caps if fine. wired in parralell the sum.
    Is the conversion of 250 uH to mH going to be two decimal places or three? 2.5 mH or .25mH?

    Leave a comment:


  • arlis_1957@yahoo.com
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    cz read the vaules again. note they are listed in mh as well as uh. cambining caps if fine. wired in parralell the sum.

    Leave a comment:


  • CZ Eddie
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    I'm having a little trouble figuring out components to purchase from parts express for this two-way's non-BSC crossover.

    Specifically:
    • L5 - 20 ga 250.00 uH (no such thing?)
    • C9 - 11uF (no such thing, unless I use 1uF with 10uF?)
    • L3 - Jantzen 18 ga 22.00 uF, can use .022 to .025 (out of stock)


    Any suggestions?

    Also, what is the max horizontal off-axis suggested for listening if mounted flush in-wall?

    Leave a comment:


  • Wolf
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    I assume that would be fine. It's to trap out unwanted resonances and bandwidth, and a strong way to do so. Value sounds about right.
    Later,
    Wolf

    Leave a comment:


  • Ryan_M
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Is the value of L3 right? 25uH? Just seems abnormally small. Also could you provide a tolerance for the component values? I know a rule of thumb is usually within 5% but I'm kind of wondering since you spec C9 to 4 significant digits, and a 2.5mH coil was unwound to 2.4mH for L0 - for a ~4% difference.

    Thanks for any help,
    Ryan

    Leave a comment:


  • marvin
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Glad to see it, too!

    Hope you can add the in wall modded version (for those who need that option) when you get a chance. It also helps us less experienced to see how BSC may be adjusted in a simple xover.


    Thanks, Jay.

    Marvin

    Leave a comment:


  • jclin4
    replied
    Re: 2-way MT: Dayton RS180S-8 and SEAS 27TDFC

    Nice project and write up Jay! Good to see your designs republished here on the PE board.

    Keep them coming!

    Leave a comment:

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