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My RS180 MTM Design

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  • Re: My RS180 MTM Design

    Pvc

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    • 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

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      • 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.

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        • 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.

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          • 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?

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            • 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.

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              • 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.

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                • 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.

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                  • 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

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                    • 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.

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                      • 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

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                        • Re: My RS180 MTM Design

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

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                          • Re: My RS180 MTM Design

                            Here's one http://techtalk.parts-express.com/sh...M-Towers/page2 (see post#34) although this has been modified to suit a different tweeter (see post#1 of the thread).

                            Another in this thread (see post#12) http://techtalk.parts-express.com/sh...80-L-C-R-Build

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                            • Originally posted by Jeff B. View Post
                              If you build it, as always, let me know what you think.
                              Jeff B.
                              Hi Jeff, I'm planning to build these MTM's and use your cross-over. Dr. K mentions ""

                              I'm wondering if you'd advise using your crossover in this larger cabinet?

                              Comment


                              • Originally posted by bekim View Post

                                Hi Jeff, I'm planning to build these MTM's and use your cross-over. Dr. K mentions "A larger “extended bass” version of the tower would be approximately 1.7 cu. ft., tuned to 35 Hz via a 3" x 6-1/2" port. Again using 3/4" MDF, this cabinet would measure roughly 9" wide, 40" tall, and 12" deep. Note for these larger cabinets, a 3" diameter port is preferred, and a 4" port is an option if you are going to be running the speakers at high power. "

                                I'm wondering if you'd advise using your crossover in this larger cabinet?
                                it should work fine
                                Click here for Jeff Bagby's Loudspeaker Design Software

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