Anyone use the Morel MDM-55 in a 3-way?

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  • Patrick Sun
    Super Senior Member
    • Aug 2000
    • 1380

    Anyone use the Morel MDM-55 in a 3-way?

    I'm thinking about retrofitting my existing center channel speaker with drivers from my mains and rear channel speakers:

    Tweeter: Morel MDT-30
    Midbass: Peerless HDS 850439

    (Or simply building another box for the center channel speaker, now that I think of it, I can reduce the height by 1" and width by 3" if I rebuilt the box).

    I wanted some opinions on the Morel MDM-55 midrange that I would use to fill in the mid's in a W(T/M)W configuration for the center channel (click on the link below for visualization of the speaker.

    Center Channel speaker

    My current drivers in the center channel are:

    Tweeter: Phillip AD11600/T8
    Midrange: Peerless 1385 (KO40MRF)
    Woofers: Vifa M18-WO-09

    (I built this center channel when I still had different speakers which used the same tweeter and midrange, but now I think I want to use the drivers in my current speaker setup).

    I'm aiming for a better timber matched front soundstage.

    I don't think I want to go with a sideways MTM configuration due to disperion characteristics, thus my desire to use the Morel MDM-55 for the midrange.

    Any thoughts?




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  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15214

    #2
    I'm probably not the right guy to respond to this, as I'm more of a hard dome fan than big soft domes- regarding the latter, been there, done that- in the 70's.

    That's not to say you can't get results that will please you out of the Morel MDM-55. It looks pretty usable from around 1000-1200 up to 6 kHz or so, allowing for the fact that you ideally would have some driver capability above and below the crossover points.

    I haven't been real fond of the work involved in optimizing smaller three way speakers- dealing with the interaction between upper and lower filters, etc. A reasonable guideline Dickason gives is that if you use a mid it should be able to cover 4 octaves- most domes can't do that. Of course, that's a somewhat arbitrary guideline, too.

    The last three way with a dome I built was an WMTMW system with Scanspeak kevlar 8's, MB 2" dome mids, and MB 1" dome tweeters. The crossover was a bit of a bear, went through two major iterations, but in the end sounded pretty good. Crossover frequencies were 800 and 4 kHz. The MB isn't sheilded, and so isn't suitable for HT applications around direct view CRT or RPTV. Since I don't use either of those, no consequence. I have threatened to design an WMTW mid for Thomas and some others using the MB mid and two HiVi 8's; that could work pretty well, re dispersion, with an MTM crossover at 800 Hz. The MB mids area available on sale at Madisound; when they're gone, they're gone.

    Trying to do a three way by ear could be a bit of a challenge- are you getting an inexpensive mic and some test software, Pat?

    -Jon




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    • Patrick Sun
      Super Senior Member
      • Aug 2000
      • 1380

      #3
      Jon, thanks for the thoughts. I went ahead and pulled the trigger on ordering the drivers I needed for the project, and in my mind, the enclosure is taking shape (I want the spacing between the drivers to be pretty tight as possible).

      As far as test gear/mic, I may still lean on one of my local buds who has a LEAP/LMS setup to do some measurements for me once I get the enclosure done. He sort of likes doing it because he gets more "free" exposure to different driver without having to pay for them (though he's always buying the on-sale drivers from PE or Madisound - last count, he was up to around 35 different pairs of misc. drivers)

      I think I will be shooting for similar crossover points (800Hz and 4KHz) and I think it's doable as the MDM-55 seems to be pretty well behaved.

      Plus, I have used my midwoofers and crossed them at 2.7KHz, and the tweeters also crossed at 2.7KHz, so I think those drivers are okay on their end, so the midrange has a bit of play either way in its operating region.

      And I've given it some throught as to how to go about doing it by "ear" and SPL meter, by attacking each driver at a time and then hope everything integrates well once the drivers are all playing at the same time. I've thought about setting up the enclosures so that I can make easy changes to the XO as needed.

      We shall see...and hear...




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      • Patrick Sun
        Super Senior Member
        • Aug 2000
        • 1380

        #4
        I was in speaking building nirvana yesterday as I embarked on creating the new center channel speaker enclosure. I was kicking up plenty of MDF sawdust, covered from head to toe in the stuff, just having a fun time. The front baffle is done, and the box is pretty much glued up, but I need to glue in the bracing and caulk the interior seams, and screw in the back panel.

        After that, it's just a matter of mucking with the crossover and tweaking.

        I'll try to post a pic or two later.




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        • JonMarsh
          Mad Max Moderator
          • Aug 2000
          • 15214

          #5
          Show us what you've been up to, Patrick! I'm guessing from what you describe you've finalized the front panel layout, too.

          I've been spread too thin on several projects, plus some stuff with my daughter, and helping my girlfriends younger son finish his overdue electronics project for school.

          I got a bit more work done on my latest bookshelfs (the enclosure back panels are now finished, except for the port holes (you know, so the squirrels can see out , and the front panel braces and tweeter subpanel were routed out), and a little bit more work on the diple test bed. Some weekends there's so much going on it's like wading through molasses to make any significant progress on projects. :roll:

          Regards,

          Jon




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          Comment

          • Patrick Sun
            Super Senior Member
            • Aug 2000
            • 1380

            #6
            Jon,

            Hopefully I'll be able to post some shots later tonight, or tomorrow. I'm definitely getting faster in building the cabinet and the front baffle (lots of planning, measuring, and marking for holes to be cut and recessed). I don't find myself thinking of being creative to make a certain cut or recess, I now know how to achieve what I want given the limited tools at my disposal.

            I'm beginning to think this cabinet making stuff is really just "arts and crafts for men".






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            • Brian Bunge
              Super Senior Member
              • Nov 2001
              • 1389

              #7
              Pat,

              Yeah, it's kind of scary hearing myself ask my wife if we can go to Michael's or JoAnn's so I can pick up some polyfill!

              Brian

              Comment

              • Patrick Sun
                Super Senior Member
                • Aug 2000
                • 1380

                #8
                I felt pretty out of place when I was in Wal-Mart looking for polyfill in their sewing department...




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                • Patrick Sun
                  Super Senior Member
                  • Aug 2000
                  • 1380

                  #9
                  Update - it was meant for a wider release, so some details have been reiterated below:

                  Here's a couple of photos of my DIY center channel speaker project, which I've dubbed: The SunCC.

                  This CC speaker uses the same tweeter (Morel MDT30) and midwoofers (Peerless HDS 850439's) as my other DIY speaker projects, a pair of 2.5-ways (SunOnes) for the front speakers, and a pair of 2-ways (SunTwos) for the rear speakers. I've incorporated the Morel MDM-55 midrange in an effort to help its dispersion pattern for a speaker that lies horizontally.

                  No crossover is done yet (you really need to measure the drivers installed in the front baffles to get something to work with in crossover design). My intention is to shoot for crossover points of 500Hz and 4000Hz, but that's subject to change, but stay tuned for updates.

                  Photo 1

                  Photo 2

                  The tweeter and midrange drivers are recessed, but not the midwoofers (supposedly it helps in getting their acoustic centers closer in line, plus recessing tweeters help in combatting diffraction effects.

                  When I get some more free time, I'll post all of the construction photos in a webpage (but it's pretty much the same as my other enclosure designs, with a few differences to regain some more volume I lost by going with a shorter and narrower front baffle. I do change some things around given the constraints of the project, like locating the port (not shown yet) on the backside of the enclosure.

                  The dimensions of the enclosure are 24"x9"x14.75" (WxHxD).




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                  • Patrick Sun
                    Super Senior Member
                    • Aug 2000
                    • 1380

                    #10
                    Okay, here's a shot of the work-in-progress known as the crossover (I got smarter, and made something that allowed me to swap out the crossover elements without the need for soldering them in place - I just need to find a local place that sells small alligator clips...):

                    Photo 3

                    And here's a rough look at the frequency response (this was all done with textbook filters, plus taking into account the acoustic roll-offs of the drivers themselves), and I won't certify how valid the graph is, but it got me into the ball park, and my ear tell me that it's relatively useful given that I am only using 1/3 octave test tones and a Radio Shack SPL meter, a notepad, and Excel to graph the results):

                    Photo 4

                    I need a little help in the 2000-5000Hz region with the low pass on the midrange (perhaps I need to go to a higher order filter to get a sharper knee in the corner frequency. But for a first pass at a crossover design with rudimentary tools, I don't think I did all that badly for now. Can't wait to get on a real measurement system one of these days...




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                    • JonMarsh
                      Mad Max Moderator
                      • Aug 2000
                      • 15214

                      #11
                      Looking pretty good, Pat. Even if you're using Excel, that's what I'd call a "hand crafted crossover".

                      It reminds me of days in the past when I hand entered measured data into a DOS program called CACD, (still got a copy of that somewhere around here), which is the first program I had with optimizer, though no where near the power or flexibility of something like LspCAD.

                      My "bargain of the year" recommendation for measurement mic is the Behringer ECM800; we've picked up a few to evaluate for friends on tight budgets, they're under $40, and it's hard to see how they can even build the mic body for that. They run on standard phatom power.





                      You can read about them, and snag the PDF here:

                      It even comes with a nice hard case. Of course, it's probably made in China, but designed in Germany.

                      I figure combine 'em with an MAudio/Midiman Mic/ADC unit; such as this:




                      This unit, besides phantom power, a direct output, and USB connection straight into your PC, supports up to 24bit/96 kHz sampling rates, so it's got a lot more headroom for growth than most relatively low buck mic preamps (it's dual channel, to, so you can get into recording natural sounds or live performances, to evaluate your speakers).

                      Acclaimed audio interfaces, studio monitors, and keyboard controllers


                      -Jon




                      Earth First!
                      _______________________________
                      We'll screw up the other planets later....
                      the AudioWorx
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                      Resistance is not futile, it is Volts divided by Amperes...
                      Just ask Mr. Ohm....

                      Comment

                      • Patrick Sun
                        Super Senior Member
                        • Aug 2000
                        • 1380

                        #12
                        Say I don't want to invest in the Duo (for the current time being), any easy way to create or buy a phantom power supply for the mic?




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                        Comment

                        • JonMarsh
                          Mad Max Moderator
                          • Aug 2000
                          • 15214

                          #13
                          There are less expensive mic preamps out there; most of them are pretty compromised in one way or another; such as the Behringers, which have such a hostile user interface, and so much DSP processing stuff that has to be turned off.

                          Paia has some interesting kits, including an inexpensive vacuum tube mic preamp for about $70, with phantom power; two channels can go in a rack chasis they sell for $30.






                          This is a kit and requires assembly, but isn't that what us DIY types thrive on?

                          The front end in the Midiman Duo has gotten some series kudo's by some pretty fussy reviewers for it's sound quality, using a special chip set for active balanced input, even compared with some mic preamps going for 5 to 10 times the money; so between that, and it's feature set, it's a "recommended buy".

                          BTW, it's not very feasible to add phantom power to a PC mic input, because you have to have a balanced mic connection for phantom powering connection to work, and PC mic inputs are pretty much all unbalanced, and rather lower grade.

                          Regards,

                          Jon




                          Earth First!
                          _______________________________
                          We'll screw up the other planets later....
                          the AudioWorx
                          Natalie P
                          M8ta
                          Modula Neo DCC
                          Modula MT XE
                          Modula Xtreme
                          Isiris
                          Wavecor Ardent

                          SMJ
                          Minerva Monitor
                          Calliope
                          Ardent D

                          In Development...
                          Isiris Mk II updates- in final test stage!
                          Obi-Wan
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                          Modula PWB
                          Calliope CC Supreme
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                          Natalie P Supreme
                          Janus BP1 Sub


                          Resistance is not futile, it is Volts divided by Amperes...
                          Just ask Mr. Ohm....

                          Comment

                          • Patrick Sun
                            Super Senior Member
                            • Aug 2000
                            • 1380

                            #14
                            Here's one last look before I go for the nitty gritty crossover design portion (though my make-shift crossover isn't doing all that badly). I was able to get the edges of the front baffle rounded over with a 3/4" roundover bit this past week. This was the only photo that shows what it now looks like from an angle.

                            Photo 5

                            The reason I waited to round over the edges after everything else was done was to have a good edge to work with when I was glueing and clamping the enclosure together.




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                            Comment

                            • JonMarsh
                              Mad Max Moderator
                              • Aug 2000
                              • 15214

                              #15
                              Hi Pat,

                              The enclosure looks very nice- do you think you'll do a veneer roundover on it someday?

                              Looking at your crossover, I have to wonder about the relative phase between the mid and tweeter; the relatively low summed levels suggest that the phase match isn't where you want it yet- you're probably getting some destructive interference. That's not unexpected combining a 1st order electrical low pass on the mid with the 2nd order HP on the tweeter.

                              The mid to woofer crossover looks in better shape. As you suggest, bumping up to a higher order network to get your phase behavior complementary may be just what you need.

                              BTW, I found there's an application note at the Jensen Transformer site on adding balanced inputs and phantom power to a Sony DAT machine with stereo single ended mic inputs- like on a PC sound card. But the cost would probably be more than an MAudio mic preamp.

                              I just got in an MAudio DMP3 to evaluate- it's straight analog, mic and direct inputs, phantom power, VU meters on the two channels, 100 kHz bandwidth- from places like Zzounds its only a little over $200. I'm going to try mating it with the Behringer mic, and see how well that works as a portable system- for example, with my laptop and True Audio software.

                              Let us know how the crossover work goes, Pat.

                              Best regards,

                              Jon




                              Earth First!
                              _______________________________
                              We'll screw up the other planets later....
                              the AudioWorx
                              Natalie P
                              M8ta
                              Modula Neo DCC
                              Modula MT XE
                              Modula Xtreme
                              Isiris
                              Wavecor Ardent

                              SMJ
                              Minerva Monitor
                              Calliope
                              Ardent D

                              In Development...
                              Isiris Mk II updates- in final test stage!
                              Obi-Wan
                              Saint-Saëns Symphonique/AKA SMJ-40
                              Modula PWB
                              Calliope CC Supreme
                              Natalie P Ultra
                              Natalie P Supreme
                              Janus BP1 Sub


                              Resistance is not futile, it is Volts divided by Amperes...
                              Just ask Mr. Ohm....

                              Comment

                              • Patrick Sun
                                Super Senior Member
                                • Aug 2000
                                • 1380

                                #16
                                Since I rounded all 4 edges of the front baffle, there's no good way to apply veneer and not look like caca. If I only rounded over the sides, I could get away with the veneer. But since now all of my speakers have the same roundover on 4 edges, I'll just paint the rounded over baffles, and veneer the rest of the box sides to make it easy on myself. The backsides will be painted black (I think).

                                I'm still debating on either metallic green or metallic blue for the front baffles. Any thoughts either way? The veneer will be red oak, been sitting in a closet for a year or so.




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                                • JonMarsh
                                  Mad Max Moderator
                                  • Aug 2000
                                  • 15214

                                  #17
                                  What kind of shade do you have in mind? Have you seen any of the pictures of the Wilson speakers in automotive finishes? What do you think of them?

                                  How do you like to finish the oak- a light honey oak, or something darker?

                                  -Jon




                                  Earth First!
                                  _______________________________
                                  We'll screw up the other planets later....
                                  the AudioWorx
                                  Natalie P
                                  M8ta
                                  Modula Neo DCC
                                  Modula MT XE
                                  Modula Xtreme
                                  Isiris
                                  Wavecor Ardent

                                  SMJ
                                  Minerva Monitor
                                  Calliope
                                  Ardent D

                                  In Development...
                                  Isiris Mk II updates- in final test stage!
                                  Obi-Wan
                                  Saint-Saëns Symphonique/AKA SMJ-40
                                  Modula PWB
                                  Calliope CC Supreme
                                  Natalie P Ultra
                                  Natalie P Supreme
                                  Janus BP1 Sub


                                  Resistance is not futile, it is Volts divided by Amperes...
                                  Just ask Mr. Ohm....

                                  Comment

                                  • Brian Bunge
                                    Super Senior Member
                                    • Nov 2001
                                    • 1389

                                    #18
                                    I've become quite partial to using red mahogany dye lately. I've finished some cabinets with cherry and then applied the dye and they look awesome! I think something like this with Pat's idea of the green baffles would look pretty good.

                                    Brian

                                    Comment

                                    • Patrick Sun
                                      Super Senior Member
                                      • Aug 2000
                                      • 1380

                                      #19
                                      The metallic green or blue appears to be a dark shade (Jack Gilvey did this with one of his small cube subs that looked pretty good).

                                      If you have links to the Wilson speakers, please post them! Would love to have a reference point or two.

                                      If I ever get around to veneering and finishing the veneer, I think going dark is also better than a light coat just because when the lights are off, I don't want the speakers to stand out if possible.

                                      I wonder if there's some betting pool on the over/under as to how many months/days it'll be before I finish the exteriors of my speakers...




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                                      • JonMarsh
                                        Mad Max Moderator
                                        • Aug 2000
                                        • 15214

                                        #20
                                        8O Pat, I thought we'd kept that pool really under wraps- how on earth did you hear about it?

                                        I'll see what I can come up with for Wilson links this evening.

                                        -Jon




                                        Earth First!
                                        _______________________________
                                        We'll screw up the other planets later....
                                        the AudioWorx
                                        Natalie P
                                        M8ta
                                        Modula Neo DCC
                                        Modula MT XE
                                        Modula Xtreme
                                        Isiris
                                        Wavecor Ardent

                                        SMJ
                                        Minerva Monitor
                                        Calliope
                                        Ardent D

                                        In Development...
                                        Isiris Mk II updates- in final test stage!
                                        Obi-Wan
                                        Saint-Saëns Symphonique/AKA SMJ-40
                                        Modula PWB
                                        Calliope CC Supreme
                                        Natalie P Ultra
                                        Natalie P Supreme
                                        Janus BP1 Sub


                                        Resistance is not futile, it is Volts divided by Amperes...
                                        Just ask Mr. Ohm....

                                        Comment

                                        • Patrick Sun
                                          Super Senior Member
                                          • Aug 2000
                                          • 1380

                                          #21
                                          Finally got to my friend's place to do some measurements. I have no graphs yet (hasn't emailed me the graphs), but we only had to do a bit of fine-tuning for an acceptable 1st pass of the XO. I bumped up to Rs to 4 ohms in the tweeter L-pad to pad the tweeter another couple of dB, and added a little more capacitance (2.6uF -> 4.1uF) on the tweeter cap to smooth out the slope. That flattened out most of the response, and there are slight dips in the XO regions, but nothing objectionable. My friend did say he'd play around with the measured driver responses and cook up something with his LEAP setup to see if he could flatten out the overall response. My lowest impedance was 4.3 ohms (in the midwoofer region, of course, but I did have a peaky impedance in the midrange region, so he was going to look at that as well).

                                          Using the 2 midwoofers and crossing it low totally removed the need for baffle step compensation.. I just about hit my Fb tuning point of 45Hz (it measured 46Hz - where the impedance was at a minimum), and the F3 was also around 45Hz.




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                                          • Patrick Sun
                                            Super Senior Member
                                            • Aug 2000
                                            • 1380

                                            #22
                                            Here's a link to the SunCC construction webpage.




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                                            Comment

                                            • Patrick Sun
                                              Super Senior Member
                                              • Aug 2000
                                              • 1380

                                              #23
                                              There are some FR graphs up now with my DIY XO.




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