Slow work takes time....

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  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15209

    Slow work takes time....

    Well, it takes even more time when you're working a lot, and also when the development effort takes some unexpected twists and turns.


    Two weeks ago a second test box was finished, using an old Woodstyle W123 standard enclosure- not very heavily braced, compared with the M8 (see earlier post).

    After business travel and various activities with my daughter last weekend, I finally got back to the project this weekend, and tested the new crossovers with the text box, revised and tweaked them, about four cycles through on evaluating measurements and listening, before "freezing" the design for now. Then, since the first M8 enclosures were finished over a month ago, I loaded one with a set of crossover and zobel boards and drivers (MB MBTTR1 tweeter, Focal 8V4412 woofer.)




    I've been listening and cleaning up the disaster area a little- so far, I'm quite pleased on a variety of material. I haven't finished "final" measurments because I don't have the diffraction control materials in place, and I haven't set them up for room measurements- sill, out in the center of the room, they're behaving as well as I would expect.





    The crossover is the biggest hoodoo-voodoo here- besides the heavily braced and dampened enclosure. It accomplishes some of the same things that Joseph Audio does in their RMsi series speakers, but in a very different way. Net result is ability to run a relatively low crossover frequency (1.5 kHz), having more uniform than average frequency response even 30 degrees and 45 degrees off axis, and having a wider vertical window for good power response than you'd expect. What's weird about these is how good they sound even 70-80 degrees off axis. Or in the next room. That requires strong correlation between on axis reponse and total room power response.

    They "blow away" the ScanSpeak based two ways I built in the mid nineties on Sarah MacLachlan, one of the artists I really liked on those older speakers.

    Sax and female voice seem to be particularly soulful on these. I've been listening to "Yellowjackts", and now the SACD of Grover Washington Jr. "Prime Cuts" is on, with "Strawberry Moon" spinning right now, and bringing a big grin to me, even in glorious living "mono". I can't wait to here what a pair of these sound like; the way the midrange and sound field works from just one, [/understatement on] I think they're going to image reasonably well [/understatement off].

    Regards,

    Jon




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    Last edited by ThomasW; 09 October 2004, 21:58 Saturday.
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  • ThomasW
    Moderator Emeritus
    • Aug 2000
    • 10934

    #2
    Hey nice looking box

    If you're going to all the time and effort to make a world class 2-way, don't be so cheap. Lets pop for some felt for that front baffle :B




    theAudioWorx
    Klone-Audio

    IB subwoofer FAQ page


    "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

    Comment

    • JonMarsh
      Mad Max Moderator
      • Aug 2000
      • 15209

      #3
      You're right, Bro!

      In fact, there was felt on the tweeter panel, nicely hot glued in place, before I went to bed. The final felt checks will be double taped in place for testing, then hot glued when we have full engineering sign off. :B

      Internal damping, besides the heavy felt lining, is polyester batting in the blanket forms, which according to most reports, is good at absorbing midrange, but doesn't dampen the bass much. Just what we want.

      Still need to take impedance sweeps, and look those over to see if the bass dampening needs to be adjusted. Right now it's on the tight and slightly over damped side, so possibly I should let them run in a bit before making any changes. However, I like them like they are- very good definition on drums, stand up bass, and bass guitar, while still having some good fundamental puch.

      And a real hoot on the second cut on the Sarah MacLachlan album "Solace". The Focal 8V4412 is a very nice 8 in the upper mids- better than most seven's. Between that and the 48 dB/octave cutoff, they sing nicely. It keeps the grunge from the upper end of the bass driver out of her voice. Joni is pretty cool, too- gave the HDCD version of "Overture/Cotton Avenue" from Don Juan's Reckless Daughter. Man, wouldn't I like to have all of her albums on SACD.

      Best regards,

      Jon

      Rumors have it the 123 test boxes will be re-cut tonight for testing Eton 8-800 woofer and Focaaalll Td120dx2 tweeter.




      Earth First!
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      the AudioWorx
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      Resistance is not futile, it is Volts divided by Amperes...
      Just ask Mr. Ohm....

      Comment

      • Brian Bunge
        Super Senior Member
        • Nov 2001
        • 1389

        #4
        Jon,

        I was wondering where the MB Quart tweeters can be purchased. I've always liked the tweeters in their car audio speakers and I might want to try these in the future.

        Can you or Thomas provide us with some suppliers?

        Thanks,

        Brian

        Comment

        • JonMarsh
          Mad Max Moderator
          • Aug 2000
          • 15209

          #5
          Hello Brian,

          I've bought MB drivers from Madisound, but I understand that source may be drying up, because MB Quart has been bought by Fosgate, and they may not OEM drivers anymore. There is a similar 1" MB tweeter still available from Madisound; I've used it also, but I remove the diffusor grill, replace it with an Audax removable tweeter screen grill, and put a felt or cork hemisphere on the pole piece behind the dome.

          Regards,

          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

            #6
            Jon, I also use Sarah McLachlan for testing vocals. When I was having problems cleaning up the midrange on the 2.5-ways, the problems would manifest itself on Sarah's vocals immediately. When you can feel her (gutteral) vocals by the seat of your pant while sitting on the couch, you've got way too much bottom end.

            I recently discovered "Solace", love the intro to "The Path of Thorns".

            I'm now thinking of just placing felt for the entire baffle (all edges with 3/4" roundover).
            Good idea or bad?




            PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
            PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

            Comment

            • JonMarsh
              Mad Max Moderator
              • Aug 2000
              • 15209

              #7
              Hi Pat,

              No reason not to try that- I've never found it to hurt the sound, since usually it diffues the tweeter output so that there isn't a well defined edge refraction. Another problem with edge difraction/refraction is that the sound wave then travels back the other direction across the baffle. The felt helps kill that to a degree also, at higher frequencies. It's just a shame that it's contradictory to doing a nice recessed mounting job on a venerred front baffle, which looks pretty kool (aka Aria 5, for example), but may have issues still at the top and bottom edges.

              Yes, female vocals *are* a pretty good test in general, given the wide range of frequencies they cover. Any mid range honkiness, or shrillness, or driver grunge, or chestiness will show up the first listen- you don't even need to touch the measuring gear. :E Until you want to figure out how to solve the problem.

              For the "M8" above, there are two pads surrounding the tweeter, in a stepped configuration to the grill edge (which is beveled to reduce diffraction effects as well) and another pad on the woofer panel.

              What's fun about these is that they look so ordinary on the outside. But with all the bracing and the relatively heavy crossovers, they weigh a ton, even though the Focal woofer isn't any massive kind of unit.

              I've got some Lovan Jazz speaker stands on order for these; I hope the height works out well, else I'll have to go DIY for the stands as well!

              Regards,

              Jon




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

              SMJ
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              In Development...
              Isiris Mk II updates- in final test stage!
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              Resistance is not futile, it is Volts divided by Amperes...
              Just ask Mr. Ohm....

              Comment

              • JonMarsh
                Mad Max Moderator
                • Aug 2000
                • 15209

                #8
                More measurements and adjustments-

                As I suspected from listening tests, the bass is a little overdamped (too much damping material- stuffing). I measured the nearfield woofer and port output, and also measured the impedance curve.

                Surprise, surprise, the box is tuned lower than I expected based on port length and allowance for flare- it's Fb is 28 Hz. But the null for cone motion wasn't as deep as I expected, and the output was gently rolling from 50. So, some of the extra stuffing was removed, but there's still a polyester batting "U" behind the woofer, and a few more bits in addition to all the felt lining. Port output rose about 6 dB, so there's certainly more authority in the open C on a five string bass!

                Did a few more measurements, including off axis with the RTA. This is the only thing that in my mind can explain why they sound open and transparent with an on axis voicing that's actually "warm"; down a few dB in the highs above 2 kHz. The latter is so this pair will hopefully be fairly musical with the solid state electronics they wind up paired with.

                Below is the 60 degree off axis response....




                For a two way speaker, this is fairly remarkable. For a two way 8" speaker, this is definitely unusual. I think the crossover innovation is paying off.

                More work to do; back to the salt mines.

                Regards,

                Jon




                Earth First!
                _______________________________
                We'll screw up the other planets later....
                Last edited by ThomasW; 09 October 2004, 21:59 Saturday.
                the AudioWorx
                Natalie P
                M8ta
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                In Development...
                Isiris Mk II updates- in final test stage!
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                Resistance is not futile, it is Volts divided by Amperes...
                Just ask Mr. Ohm....

                Comment

                • Huskerduck
                  Moderator Emeritus
                  • Oct 2000
                  • 129

                  #9
                  I bet a person could learm a thing or 2 stopping in San Fran for a couple hours when your not busy




                  Mark


                  Ducks Meager Theater
                  Mark


                  Ducks Meager Theater

                  Comment

                  • JonMarsh
                    Mad Max Moderator
                    • Aug 2000
                    • 15209

                    #10
                    When I'm not busy.... gee, when is that? Though if you're ever coming to the SF Bay area (East Bay where I live), give me a holler, Mark.

                    Finsihed assembling second set of crossovers, and measuring them against the reference plots. Measured the crossovers and and second set of drivers in test box. Second finished box loaded with crossovers and drivers this afternoon. Probably overdamped a little, will tweak the LF damping this week.

                    Imaging. From two feet left of the left cabinet to a similar amount right of the right.

                    Uncanny percussion and piano timbre on Jacque Loussier "Play Bach".

                    James Taylor's vocals and the backing singers on "Gaia"'s are delicately clear, and the tenor sax hangs in space in front of me, the way they do with a Quad ESL or an Acoustat, but the drums thunder when they're supposed to.

                    Holly Cole "Take me Home" sends chills up my back- literally. Now I remember why I do all this hard, tedious work.

                    A satisfying way to spend a Sunday afternoon.

                    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

                    • Lex
                      Moderator Emeritus
                      • Apr 2001
                      • 27461

                      #11
                      Nice work Jon, so who built the cabinets? Thomas or you or both?

                      Lex
                      Doug
                      "I'm out there Jerry, and I'm loving every minute of it!" - Kramer

                      Comment

                      • JonMarsh
                        Mad Max Moderator
                        • Aug 2000
                        • 15209

                        #12
                        Hi Lex,

                        The cabinets are a gutted and highly modified Woodstyle W123REV, as described in the first posts in early October. ThomasW won't take any blame for these; they're purely a product of AudioWorx West Engineering and Prototyping Center.



                        Originally, this was just going to be something assembled pretty quickly so that a colleague of mine who was the victim of some strange politics at work (my former boss, actually) and was being forced into a relocation to Detroit, would have some speakers to use however long he was there. It was more psycho therapy for myself and how p*ssed off I was at the organization, as much as anything else.

                        In the process of solving the basic engineering problems, I came up with a new high slope crossover technique (results are similar to Joseph Audio's Infinite slope crossovers, but doesn't use Modaferri's patented technique/circuit, and now there's one pair of these completed for my friend, a second pair that should be completed by Thursday, two more in the pipeline, and a magazine article about 50% complete.

                        Because of changing driver availability, the first set used Focal woofers and MB tweeters (more reasonable cost, very good performance), while the subsequent sets are using Eton woofers and either Focal or Accuton tweeters (two different experiments in progress).

                        The first pair are being delivered today to my old friend- fortunately, he got a new position back in San Jose, starting last week, so the move to Detroit has become a none issue. So he and his finance` will have many things to celebrate this Thanksgiving.

                        Regards,

                        Jon




                        Earth First!
                        _______________________________
                        We'll screw up the other planets later....
                        Last edited by ThomasW; 09 October 2004, 21:59 Saturday.
                        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

                        • JonMarsh
                          Mad Max Moderator
                          • Aug 2000
                          • 15209

                          #13
                          Mk III version undergoing significant enclosure mods- same W123 REV starting point, but revised driver layout, revised bracing, and moving the port output to the rear.

                          I'll post a revised drawing for fun by this weekend.

                          -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

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