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My RS180 MTM Design

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  • mastercraft1990
    replied
    Re: My RS180 MTM Design

    Does anyone have a picture of a completed Bagby MTM crossover?

    Leave a comment:


  • djg
    replied
    Re: My RS180 MTM Design

    Somewhat dated info, I would do Jeff Bagby version as it is the latest, designed with newer software and some talent.

    http://www.rjbaudio.com/RS180MTM/rs180-rs28-mtm.html

    Leave a comment:


  • mastercraft1990
    replied
    Re: My RS180 MTM Design

    The number of different crossovers and different price points to do the same thing is kind of mind boggling. I'm brand new to the DIY and had a Bragi kit coming from Madisound with all Seas drivers and then found that they back ordered from Denmark. I had the PE cabinets sitting there and my old Klipsch stuff had all flew out the door via Ebay, so I was soundless. That's where the 722 kits come in. After putting them together they sound good but not great. I need to wade through all the different options for the best second attempt at crossovers, money is not really a factor, want best sound.

    Leave a comment:


  • fbov
    replied
    Re: My RS180 MTM Design

    Originally posted by mastercraft1990 View Post
    ... they seem a little bright. ...
    I think the tweeter's sensitivity has changed a bit over the years. I've bought 7 RS28's, and I see about a 1dB shift in sensitivity. The RS722 is PE's design, so you'd think it was done early in product availability, while Jeff's is quite recent. I was building a Bagby design when I noticed the difference between a new and old tweeter... he suggested a padding resistor to even them out.

    You wouldn't be the only one...
    http://techtalk.parts-express.com/sh...60#post2101860

    Frank

    Leave a comment:


  • mastercraft1990
    replied
    Re: My RS180 MTM Design

    I can't believe this thread has been going strong from back in 2011, pretty cool. I just finished the RS722 in black and they seem a little bright. Is that the reason that Jeff and others have taken the time to rework the crossover or were there different reasons? I'm pushing them with a Outlaw amp with a Yamaha AVR controlling things. Thanks in advance for your feedback.

    Leave a comment:


  • Mobin
    replied
    Re: My RS180 MTM Design

    Thanks for your input Chris, I was able to order the unshielded RS180 wile they are still on sale.
    Now I'm trying to decide what kind of box I want to do as I just found out there are a few configurations.

    Leave a comment:


  • Chris Roemer
    replied
    Re: My RS180 MTM Design

    Here's my suggestion for using the 27tbfcg: 3rd order HP filter (but w/value changes) PLUS an initial series resistor for level adj. :
    1.5 ohm series resistor and 8uF series cap, 0.20mH shunt coil (to gnd), lastly a 15uF series cap next to Seas tweeter.

    Most here on TT say that the shielded/unshielded RS180-8 woofer FR curves are so close as to be interchangeable.
    The shielded woofer CAN play a bit lower (due to slight diffs. in T/S parms), however.

    I'd line the vented box interior w/acoustic ("egg-carton") foam.

    Leave a comment:


  • Mobin
    replied
    Re: My RS180 MTM Design

    I would like to build these, I have some seas 27tbfcg/byeasf tweeters on hand that I would like to use. My main question is could I use the unshielded version of the rs180 woofer?
    Also what kind of bracing should I do?
    Would it help to use any acoustic foam in the cabinets?

    Leave a comment:


  • coniacvsop
    replied
    Re: My RS180 MTM Design

    Originally posted by kraigo View Post
    OK, one more rookie question: Someone in some thread or another posted that this (http://www.parts-express.com/speaker...lared--260-480) is an appropriate port for this cab, but my modelling in WinISD show that as not even being close to right to getting a 1ft^3 box tuned to 40 Hz. A single 3" port somewhere between 9.5" and 9.75" looks to work ("9.66" according to WinISD), but now I'm second guessing my school-of-hard-knocks speaker skills. If anyone can give me a confirmation, I'd appreciate it. That port gives (by my work) about a 53.5 Hz tuning.

    Added: Or someone could just tell me what the appropriate dimensions are (bonus points for why)! :-)

    If it helps, enter the following text into Notepad, save it as a .WSD file and load that into WinISD.

    >>
    [Driver]
    Brand=Dayton
    Model=RS180-8
    Manufacturer=Dayton
    ProvidedBy=kraigo
    DateAdded=20150807
    DateModified=20150807
    Qts=0.31154861916003
    Znom=8
    Fs=35.54549813519
    Pe=0
    SPL=86.268920766928
    Re=6.4
    Le=0
    fLe=0
    KLe=0
    BL=7.82
    Xmax=0.006
    Cms=0.00112
    Qms=1.22
    Qes=0.41839257817385
    Rms=3.27685838851422
    Mms=0.0179
    Sd=0.01247
    Vas=0.02470560978984
    Dia=0
    Vd=0.00007482
    no=0.0025789727626
    Dd=0.12600514720775
    EBP=84.9572865043019
    numVC=1
    Hc=0
    Hg=0
    SPLmax=0
    SPLmaxLF=78.0447656770847
    USPL=87.2428497375749
    alfaVC=0
    Rt=0
    Ct=0
    gamma=436.871508379888
    Rme=9.5550625
    Mpow=3.09112641281459
    Mcost=0
    Gloss=0.03276728653333
    VCCon=1
    c=343.684120962152
    roo=1.20095217714683
    Thick=0
    Depth=0
    MagDepth=0
    Magnet=0
    Basket=0
    Outer=0
    Vcd=0
    DVol=0
    ParState=ECNCENNNEENEECCCEECCNCCENNNCCNNNCCCCNCNNN NNNNNNCC
    <<

    I used that port with the tower design. It works like a champ for the larger volume, but probably not for the smaller cab. I have a build thread over in the other forum if you want to take a look.

    Leave a comment:


  • speedle
    replied
    Re: My RS180 MTM Design

    Just to add to the fun, remember that the Natalie P uses the unshielded version of this tweeter, and seems to keep up just fine.

    Leave a comment:


  • fbov
    replied
    Re: My RS180 MTM Design

    Originally posted by Jeff B. View Post
    Actually, it was a test that Paul Carmody did that showed the two identical except in the are of Fs where the difference in their Q's showed up.
    Jeff, you may not recall, but I had about a 1dB difference in sensitivity from RS28's purchased over a period of several years, and so several production runs. It showed up when I first did my Continuum build, as I used a new and old driver. You suggested padding one of them down, but that also changed the slope, so I used a contemporaneous pair, with silk domes to boot. Difference was gone.

    So, the issue isn't getting mismatched pairs from PE, but rather mixing new/old, or using new with an older XO design. Jeff's is one of the later RS MTM designs, so I doubt you'd see an issue in this build.

    Have fun,
    Frank

    Leave a comment:


  • ROTECH
    replied
    Re: My RS180 MTM Design

    Pvc

    Leave a comment:


  • kraigo
    replied
    Re: My RS180 MTM Design

    I am at 25 m/s at excursion limit for the woofer (~120 watts) at 35 Hz. I'm not worried about that because I won't have 120 watts and this is mostly for music where there is not much content at 35 Hz. Thanks for the confirmation.

    Leave a comment:


  • fastbike1
    replied
    Re: My RS180 MTM Design

    It depends on the velocity through the port. If you're in the 20m/s or less area with your max power you should be fine. Rear mounted ports also help.

    Leave a comment:


  • kraigo
    replied
    Re: My RS180 MTM Design

    The drivers and boxes arrived yesterday. It should be good. I'll probably order the rest of the parts tomorrow.

    One more sill question: I bought the curved 1 ft^3 boxes. They are 4.5" wide in the back. Everything I'm seeing in WinISD suggests I want a 3" port - it gives me good air flow and is still short enough to fit nicely in the cabinet. In my bass cabs I've always just used a PCB tube and it's been fine for my needs. Looking at the flared tubes, the flares are bigger than my 4.5". Two 2" tubes would also work, but the placement gets more sketchy and the flares are still too big for the 4.5".

    So it looks like 3" PCB is my only realistic choice.

    So the question: Given not extreme volume levels, how much does one really get out of flared ports?

    KO

    Leave a comment:

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