I'm getting there!

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  • PMazz
    Senior Member
    • May 2001
    • 861

    I'm getting there!

    I've been working on the Marchand XM-9 xover and I have new respect for all those that have gone before me. Between my large hands and not-so-great-anymore eyesight, I'll be amazed if this thing works. Soldering those small parts is right up there with having root canal. Thank God for the soldering station I got. Makes things bearable, at least. Power supply is done, and 1, of 4, xover boards is underway. Phil needs to somehow mark what all the parts are. I had to resort to a picture to figure some of them out.

    The kit and my new amp (B&K 7250) got here the same day. I felt like a kid at xmas! After I opened the kit and saw all the parts, the feeling faded and the saying "some assembly required" took on new meaning.

    Well, just thought I'd keep you all up to date on the speaker project. This is a speaker project, after all is said and done.

    Pete
    Birth of a Media Center
  • Dennis H
    Ultra Senior Member
    • Aug 2002
    • 3791

    #2
    After I opened the kit and saw all the parts, the feeling faded and the saying "some assembly required" took on new meaning.
    Aw, that's nothin'...... recalling fond memories of pulling all-nighters building a Heathkit color TV for my college apartment in the late 60's. Heck it even worked although I was a little shaky on the home theater concept with a 19" TV nestled between 7 ft. high DIY folded horns painted battleship gray.

    Comment

    • Lex
      Moderator Emeritus
      • Apr 2001
      • 27461

      #3
      Go Pete Go!

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

      Comment

      • Bruce
        Senior Member
        • Aug 2000
        • 156

        #4
        Pete,

        I sympathize! When I went to build Eric Wallin's microphone preamp for my calibrated measurement system, I thought I was all thumbs.

        Putting components on that tiny 2" by 3" board was a real exercise in finger gymnastics.

        Keep at it and good luck.




        Bruce
        ____________________________________________
        Bruce

        Comment

        • ThomasW
          Moderator Emeritus
          • Aug 2000
          • 10934

          #5
          Pete

          If your XO is like Pats (see pic below), the RCA's are attached to the PCB's with wires that screw into the blue terminal blocks. IF they are something different shoot a pic of it so I can see them






          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

          • Hank
            Super Senior Member
            • Jul 2002
            • 1345

            #6
            WILL SOLDER FOR BEER MONEY.

            Pete, if you need soldering done, I'm a solder-slinger from way back. Point-to-point wiring of an H.H. Scott integrated tube amp kit I bought as a teenager, then the DeVry Institute tech course that included a Heathkit breadboard/power supply, an oscilloscope and that best-picture-of-its-time 25" TV, Hafler amp and pre-amp kits, mods, etc. Ah, I love the smell of solder in the morning!

            Stick to it - you'll do good. Tip: you might consider one of those bench lights that's a large magnifying lens encircled by a fluourscent bulb. Good for last check before soldering a bunch of components you've placed and also for checking for solder bridges, etc.

            Comment

            • PMazz
              Senior Member
              • May 2001
              • 861

              #7
              Thanks guys!

              Well, while the board was down, I finished most of the soldering. Of all times to not have access to the board. The other 3 xover boards went a lot faster having a finished one on the bench to use as reference. How do you guys keep the straight pinned parts on the boards before you solder. Every time I went to flip it over, they fell back out. :evil: I finally wound up using a dab of super glue.

              Hank, if it were not for the magnified light that I already had, this project would've been impossible. Hell, I had to resort to a hand held magnifying glass on occasion.

              Tom,
              My boards are exactly the same except for the terminal blocks. I only have the holes in the boards to, I assume, solder the wires directly onto. I'll have to check. It said specifically if they came with RCAs, not to install them. Mine did not.

              Here is the instructions to connect the wires to the boards: "Be sure to solder the red wire to the small
              hole in the center of the group, and the brown
              ground wire to one of the 3 larger holes in the group."

              What I'm thinking of doing is to wire two DPDT switches between the respective connections to change the xover from a 2-way to a 3-way. Would this have any negative effect on the SQ tho? If so, how about some Molex M/F connectors?

              I cut the DPL12s into the bottom of the baffle of the RD50s today. Just a single 12 on each side just to try some dipole woofs . Once the xover is done I'll cross these over at 450 Hz to the ribbons. Can't wait. The 50s are sounding better every day. I can't believe how well they reproduce horns! I've been listening to a lot of jazz lately and have been amazed by their sound. I plugged one of my Kit281s in just to reaquaint myself to their sound and am floored by the difference.

              Pete
              Birth of a Media Center

              Comment

              • ThomasW
                Moderator Emeritus
                • Aug 2000
                • 10934

                #8
                Pete

                If you want to have the PCB's modular order some of the terminal blocks and solder them in place. Then the wires from the RCA jacks can easily installed/removed.

                For the money the 281's are a very good deal. But comparing them to any of the larger planars isn't fair......




                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

                • PMazz
                  Senior Member
                  • May 2001
                  • 861

                  #9
                  Well, I went ahead and wired in the switches. I'll give it a try and see how it works....if at all.

                  Next up, make some interconnects up to tie all this together. Maybe tomorrow. I'm out of room in the rack I have now, so the xover and amp will have to sit on the floor for a while.

                  I should probably run another 20 amp line to power all this. For now I'll plug it in with the dedicated line I have for my sub amp. I should've just pulled 4 runs of Romex instead of 2. Another project for another day. :?

                  Pete
                  Birth of a Media Center

                  Comment

                  • Jack Gilvey
                    Senior Member
                    • Aug 2001
                    • 510

                    #10
                    I cut the DPL12s into the bottom of the baffle of the RD50s today. Just a single 12 on each side just to try some dipole woofs . Once the xover is done I'll cross these over at 450 Hz to the ribbons.
                    Really looking forward to how that works out crossed over that high, Pete. Did you sample any dipole bass yet...your impressions?

                    Comment

                    • PMazz
                      Senior Member
                      • May 2001
                      • 861

                      #11
                      Not yet, Jack. I may get a chance tonight, if I get some cables made up and the xover actually works. :roll: I'm wondering myself how they're going to handle freqs that high. I may have to add extra wings on the back of the frame to extend the reach down low. I'll give it a whirl, as is, and do some measurements. Hell, I've been running my Tempests up at a 200 Hz xover with these, so how bad could it be?

                      If this bass box sounds like it integrates well with the ribbons I'll probably go to 2 8" drivers/side for the final prototype. I'd like to not have to do a line of drivers next to the ribbons if this winds up sounding homogenous, although that's what I'll do next if it doesn't.

                      Pete
                      Birth of a Media Center

                      Comment

                      • PMazz
                        Senior Member
                        • May 2001
                        • 861

                        #12
                        Well, I'm embarrassed to say it, but I installed a couple of the big caps backwards and popped them. I took the caps from the other two boards and replaced them, but to no avail. I get nothing form the xover. It's getting power but I don't know how to check anything else. I probably fried something else. It's not the Opamps, I switched them from another board. AARGH! I'll call Marchand in the morning and grovel....

                        Really bummed!

                        Pete
                        Birth of a Media Center

                        Comment

                        • Hank
                          Super Senior Member
                          • Jul 2002
                          • 1345

                          #13
                          Pete, don't take it too hard - we've all soldered parts in backwards.
                          Tequila on the rocks is good for your current condition.
                          You'll get through this and post results for us to see and learn from.
                          Feel better? If so, you'll receive my bill shortly.

                          Comment

                          • PMazz
                            Senior Member
                            • May 2001
                            • 861

                            #14
                            Hell, keep the bill and send the Tequila!

                            After some sleep and a handful of aspirin, it turned out OK.....for being F'ed up......

                            Got the XM9 working. It's definitely only a 2-way now! The last little Gotcha was some shorted speaker wire to one of the DPL12s.

                            I took some quick measurements to level things out. The only thing odd about the adjustments are that the left channel damping is set at +4 and the right is -2. Is that normal?

                            Initial listening has them sounding pretty good. So far, asking the DPL12s to cover up to a 450 xover is definitely stretching things. I'll wait for some break in, but I have my doubts. As Tom and Jon expected, the RD50s sound much more at ease relieved of the lower freq load.

                            The speakers have become more transparent in the room. While listening today I realized I could no longer pinpoint the speakers in space.

                            Feeling better, still need to order some "extra" parts, but at least it's working.

                            Pete
                            Birth of a Media Center

                            Comment

                            • Pat
                              Super Senior Member
                              • Aug 2000
                              • 1637

                              #15
                              Pete, don't feel too bad, my XM9 didn't work the first time either.
                              I flip-flopped the SCR's on the power supply.
                              Luckily I didn't blow anything up.

                              Glad you got it working now.




                              Pat's Page
                              Pat's Page

                              Comment

                              • ThomasW
                                Moderator Emeritus
                                • Aug 2000
                                • 10934

                                #16
                                Pete

                                The damping level can be fairly subtle depending on the situation. But a 6dB difference is a little much. Double check to see that the knob pointers match up when turned fully clockwise and counterclockwise.




                                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

                                • PMazz
                                  Senior Member
                                  • May 2001
                                  • 861

                                  #17
                                  The knobs are centered. Maybe it's simply a fact of different speaker position when doing the measurement. I was so excited that it actually worked I kind of rushed.

                                  Pete
                                  Birth of a Media Center

                                  Comment

                                  • PMazz
                                    Senior Member
                                    • May 2001
                                    • 861

                                    #18
                                    Here's some pics of where I'm at.



                                    Marchand xover with B&K 7250 amp.





                                    The RD50 with a DPL12 crossed over at 450 Hz.





                                    The current front setup.

                                    I think the DPL12s need more side baffle area. The lower bass is pretty thin and choppy. They also put some fairly strong vibrations in the whole panel at higher SPLs. Can't be good. Maybe adding a sealed enclosure around them with the added mass will take care of it. Maybe even adding extra wings will do it.

                                    They sound pretty damned good tho. I'm starting to appreciate this dipole thing. Very effortless and transparent. The buzzing I was hearing on a couple of new CDs is definitely present on the recording. I've gotten the same sound on 3 different sets of speakers.

                                    Pete
                                    Birth of a Media Center

                                    Comment

                                    • ThomasW
                                      Moderator Emeritus
                                      • Aug 2000
                                      • 10934

                                      #19
                                      Pete

                                      You might give the Linkwitz dipole woofer design a try. Remember that one needs 4 times the radiating area for a dipole cone set up to have the some output as a standard 'box' driver.

                                      I'm not sure how the Linkwitz design will sound with a 450Hz XO point...




                                      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

                                      • Dennis H
                                        Ultra Senior Member
                                        • Aug 2002
                                        • 3791

                                        #20
                                        Lookin' good, Pete. I'd try some front to back wings to boost the bass. They could be cardboard or scrap wood for a test, just taped to the baffle. Maybe something like 1' or 2' at the bottom tapering to nothing at the top. For sure, you're going to need to EQ it as well. Take a look at Linkwitz' crossover curves for the Orion.

                                        Comment

                                        • JonMarsh
                                          Mad Max Moderator
                                          • Aug 2000
                                          • 15214

                                          #21
                                          You're definitely making progress, but I have to chime in with the other guys, for the DPL12's youre going to need a bigger baffle.

                                          Look at it this way: for a given size baffle, there's a frequency at which the front to rear distance is long enough that there isn't too much attenuation of the front or rear sound. As you go down in frequency from this point, it rolls off at about 6 dB per octave. The higher that starting frequency is, the more it will be rolled off near the bottom end of the range you want to use. Even if you're triamping these 12's and getting off them by 75 Hz or so, that will leave a lot of cancellation to make up for with that small a baffle.

                                          The 4:1 guide is a rule of thumb- assuming a reasonable size baffle and output at the top of the driver range which is close to the closed box level, due to baffle size. With a really narrow baffle, it can be closer to 8:1, which really isn't very practical.

                                          For the range above 150Hz, an H frame woofer requires too much EQ compensation for the additional squirrels in the upper bass/lower mid response to be practical. But from 150 Hz on down, it's the way to go.

                                          -Jon




                                          Earth First!
                                          _______________________________
                                          We'll screw up the other planets later....
                                          the AudioWorx
                                          Natalie P
                                          M8ta
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                                          Resistance is not futile, it is Volts divided by Amperes...
                                          Just ask Mr. Ohm....

                                          Comment

                                          • PMazz
                                            Senior Member
                                            • May 2001
                                            • 861

                                            #22
                                            Well, this was really just an excuse to try the DPL12s. Also to see if the bass box concept would integrate well with the ribbons, which so far it has. Time to order up some 8" drivers, I think. I'm tempted to get 4 M8as, just to get my hands on some, but it's probably way overkill for this application. Any suggestion for decent 8" drivers that will work well in a smallish sealed enclosure? I was even thinking to try an aperiodic box if I couldn't get it down to the size I would like. I've never tried one, but now may be as good a time as any. I'll probably re-do the frame for the ribbons so they can attach to whatever I wind up trying. I almost hate to tear them apart at this point, tho.

                                            Pete
                                            Birth of a Media Center

                                            Comment

                                            • JonMarsh
                                              Mad Max Moderator
                                              • Aug 2000
                                              • 15214

                                              #23
                                              How many are you going to use, and where do you plan to cross them over? M8a's are a pretty good way to go; they're very well behaved up to about 1.8 - 2 kHz, but practially speaking, with normal crossover roll offs, you'd want to be getting out of them by 600 Hz (4th order L-R, as per Marchand crossovers). These keeps the upper cone peak at 2.6 kHz pretty well attenuated.

                                              Another possibility is the Seas L21RNX\P, about $65.00 each, an aluminum cone model pretty well behaved up to 1 kHz. It's a bit lower Xmax, 4 mm versus 5.8 mm, but somewhat higher sensitivity. It's hard to think of something I could recommend in an 8 which is less expensive. 6.5" drivers, that's another thing!

                                              -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!
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                                              Modula PWB
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                                              Natalie P Ultra
                                              Natalie P Supreme
                                              Janus BP1 Sub


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

                                              Comment

                                              • sfdoddsy
                                                Senior Member
                                                • Sep 2000
                                                • 496

                                                #24
                                                I'm using the Seas L21s for my temprary Orion baffle, and will use them for surrounds. They sound pretty good and go deep. The L21RNX4p goes even deeper, and is optimized for a very small box, but not as high.

                                                If you can go to a ten inch, I can highly recommend the Focal 10L6411s I am using. I got four of them for $42 each as a Hales Speakers sell off, but there is a guy on eBay selling them for about $45 each. You might need a bigger enclosure than the L21s though.

                                                There are pics on a link at the end of my post in the other thread.

                                                Steve




                                                Steve's DIY Dipoles
                                                Steve's OB Journey

                                                Comment

                                                • Hank
                                                  Super Senior Member
                                                  • Jul 2002
                                                  • 1345

                                                  #25
                                                  Well, I can see the necessity of a stack of mid-woofs with the ribbon, but the base implementation - I don't know - H-frame sounds right, but how much driver for sufficient SPL's...hmmm.
                                                  Jon, are you going to recommend those MCM drivers to Pete?

                                                  Comment

                                                  • JonMarsh
                                                    Mad Max Moderator
                                                    • Aug 2000
                                                    • 15214

                                                    #26
                                                    I'm getting the impression that Pete only wants to use a couple of drivers on each side- I wouldn't recommend just using two 6-1/2" per side to match up with RD50's! But I probably wouldn't use just 2 eights, either- more like 4, for comparable dynamics with the RD. That's the formula- 8 -6.5", or 4 8" per side.

                                                    But everyone knows I'm a bit of a wretched excess kind of guy, so maybe that's to be excused.

                                                    BTW, 8 MCM 6.5's per side (16 total) would set one back a total of about $320. They have raised the price since I last bought a few months ago, and the picture shown on the web site is not the correct one. 4 L21's total (2 per side) is about $260 plus shipping, so you can see the cost effectiveness of the MCM carbon fiber driver...

                                                    BTW, I've sent my friendly CO PE wholesaler a check towards a pair of RD50s....



                                                    -Jon

                                                    MCM Carbon Fiber 6-1/2" midwoofer 55-2321




                                                    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

                                                    • Hank
                                                      Super Senior Member
                                                      • Jul 2002
                                                      • 1345

                                                      #27
                                                      Oh, I didn't catch that Pete only wants a couple of drivers per side. Yeah, that would not do - level matching involved. It's enough to level match a ribbon, a stack of pistons and a couple of woofs below, all in dipole (or all in monopole enclosures for that matter). I mean adding resistors to the chain of xovers and drivers just leaves a bad taste to me. Maybe I'm too concerned, but I believe the fewer added components, the better.

                                                      A mistake on the MCM website???!! You've got to be kidding!! A first! :LOL:

                                                      So, you've taken the RD50 plunge, eh?

                                                      BTW I received an e-mail from NewForm Research regarding a long-standing internet mole posting false defamatory remarks/reviews along with an apology by a main perpetrator. Big investigation with apparent results. Anyone else see that?

                                                      Comment

                                                      • PMazz
                                                        Senior Member
                                                        • May 2001
                                                        • 861

                                                        #28
                                                        Hey Hank....Where've you been?

                                                        Since Jon is doing a traditional LA, I thought I'd try another approach. My goal is to build a small sealed enclosure for 2 8" drivers to handle the low end and sit the RD50s on top of these. Whether the RD50s stay dipole or go monopole is still undecided.

                                                        Hey, worst that can happen is I Klone whatever Jon finalizes.

                                                        Pete
                                                        Birth of a Media Center

                                                        Comment

                                                        • Hank
                                                          Super Senior Member
                                                          • Jul 2002
                                                          • 1345

                                                          #29
                                                          Pete: been busy with band rehearsal (concert this Saturday), and local HT group Austin movie nights:
                                                          We discuss and review all genre of movies, all types of home theater hardware, and maintain one of the longest running active forums on the web!

                                                          We did a series of horror films, now have started a sci-fi series, beginning with my DVD of "Forbidden Planet". It's sure nice to watch 'em on the big screens of the guys with front projectors!

                                                          So, you're doing an RD50 a bit like the NewForm Research thing: ribbon on top of a cabinet that contains two woofs. From all of the Grand Poobahs' posts, I got the message that one or two woofs in a traditional cabinet won't integrate well with the line source ribbon. They're saying the LS ribbon and traditional woofs will only be SPL level matched at one specific distance from the speaker, and at all other distances, they will be imbalanced. Are you planning your design such that the level matching will occur at your "sweet spot" and you aren't concerned about other locations?

                                                          Jon, what do you think about SCH's 8" woof?:

                                                          Comment

                                                          • Jack Gilvey
                                                            Senior Member
                                                            • Aug 2001
                                                            • 510

                                                            #30
                                                            Looks very cool, Pete! h: As has been stated, a bigger baffle will help a lot should you choose to pursue that route. Mine's quite large, and my DPL12's get very low with no eq at all. If you go with a box, though, that DPL12 also makes an outstanding sealed box woofer. I've got one in a 5ft^3 box (~Qtc of .5 or so, f3 ~29Hz) and it sounds great (as you might imagine) with strong in-room response to 20Hz.

                                                            Comment

                                                            • PMazz
                                                              Senior Member
                                                              • May 2001
                                                              • 861

                                                              #31
                                                              Originally posted by Hank
                                                              Are you planning your design such that the level matching will occur at your "sweet spot" and you aren't concerned about other locations?
                                                              After hearing them in my room and trying to find fault with the concept, it occurred to me. The difference in decay rate is 3 dB. The closest seated listening position is ~2 meters, the farthest ~3.5. That only translates, theoretically, into a difference of ~2-3 dB between levels at those distances. With the xover at 450 Hz, it's not something that is noticeable, IMO. Besides, the RD50s theoretically aren't behaving like a true LA thru the entire passband that they're handling. A 4' array should start to transition from NF to FF at ~1KHz at my listening distance. If you now factor in baffle step, it's a wonder they sound good at all. But they do!

                                                              Of course this is prefaced with a big "so far". They're a long way from done.

                                                              Pete
                                                              Birth of a Media Center

                                                              Comment

                                                              • JonMarsh
                                                                Mad Max Moderator
                                                                • Aug 2000
                                                                • 15214

                                                                #32
                                                                Jon, what do you think about SCH's 8" woof?:
                                                                http://www.speakerpage.com/S08911.htm

                                                                Hmmm, interesting "budget" part. Qts is a bit high for a reflex system, almost too high for a sealed system, though should be OK in a large sealed box (don't raise Fs or Qt very much).

                                                                Cone modes are well damped (typical of polypropylene), and they start at about 800 Hz (look at the amplitude transfer function as well as the impedance curve). For a conventional crossover, 2 kHz would seem to be OK, except that it will be beaming by then due to cone diameter.

                                                                For a 4 ohm driver, the sensitivity is a little on the low side. Given the senstivity number and impedance, I'd expect a bit higher Xmax, but then it's probably all related to the motor perforamce, particularly the magnet and gap- BL product is somewhat low at 5.7; a HiVi M8a, for example, is 9.6.

                                                                It's a pretty decent overall driver for the money, . But for $65, I'd probably go with the L21 Seas. Again, it's all about trade-offs, and what's acceptable. Then too, for almost $40, two of the MCM 6-1/2" drivers are attractive, but they're not sheilded, like this driver is. For a 450 - 600 Hz crossover to RD50's, there's nothing to complain about here except it's sensitivity and low BL product. Once you've done baffle step compensation, you've got a 4 ohm speaker that's about 81-82 dB efficient (for one driver), assuming a very low insertion loss crossover.

                                                                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

                                                                • Hank
                                                                  Super Senior Member
                                                                  • Jul 2002
                                                                  • 1345

                                                                  #33
                                                                  Pete - hang in there. Interesting comments - sounding very good so far and you haven't entered the tweaking phase yet. Promising.

                                                                  Jon, I've been listening to that SCH 8" in my SCH-designed 2-way towers for a couple of years and it sure sound great relative to its cost.

                                                                  Comment

                                                                  • PMazz
                                                                    Senior Member
                                                                    • May 2001
                                                                    • 861

                                                                    #34
                                                                    Called Marchand today for *ahem* spare parts. They're sending them at no charge. Nice folks! Asked about setting them up as 2 ways and the suggestions were switches or M/F disconnects or terminal blocks. They didn't seem to think any way was better than another.

                                                                    Pete
                                                                    Birth of a Media Center

                                                                    Comment

                                                                    • PMazz
                                                                      Senior Member
                                                                      • May 2001
                                                                      • 861

                                                                      #35
                                                                      Changed my mind again. After laying out the box for the twin 8" drivers I realized it would increase the height of the RD50 a little more than I wanted. It was either drop to 2 6.5"ers or a single 10". Worried about the lack of low end for using 6.5"ers I decided to go with a ten. Since I was always interested in Peerless's CSX line, I ordered 2 of the 10" from PE. They look good on paper, and hopefully they can perform better than the DPL12s for this application. I think a 450 Hz xover is just asking too much from them. I'm also going to try a sealed enclosure, since I have to tear apart the RD50s from the dipole frame anyway.

                                                                      Pete
                                                                      Birth of a Media Center

                                                                      Comment

                                                                      • PMazz
                                                                        Senior Member
                                                                        • May 2001
                                                                        • 861

                                                                        #36
                                                                        Here's an update:





                                                                        As you can see, I built sealed enclosures for the RD50s and a seperate sealed enclosure for the Peerless CSX10"ers.

                                                                        Bass is better but the overall transparency is not there as before. Some positioning helped but I can't reproduce the openness of the dipole setup. I've been listening to them this way for about a week now.

                                                                        I'm going to put the RDs back into a dipole frame and put those on top of the sealed CSXs and have a listen.

                                                                        The parts came in from Marchand and Digikey, so I'll also be working on the xover again. Hopefully this time I'll get it right.

                                                                        Pete
                                                                        Birth of a Media Center

                                                                        Comment

                                                                        • JohnR
                                                                          Junior Member
                                                                          • Oct 2002
                                                                          • 7

                                                                          #37
                                                                          Nice work Pete! So you think the lack of openness is due to the ribbon being in a sealed box? I ask because I have been thinking that for my project I will build the ribbons (Neo8s) and an array of mids into a sealed box, and use dipole woofers from 300 Hz down. Sort of like the Legacy I guess, except that the mids will be in a line and therefore have more limited vertical dispersion.

                                                                          JohnR

                                                                          Comment

                                                                          • PMazz
                                                                            Senior Member
                                                                            • May 2001
                                                                            • 861

                                                                            #38
                                                                            John, I've never been good at describing what I'm hearing.

                                                                            I can't say that it's the dipoles that are transparent or the sealed enclosures that are adding some "color" to the sound. All I can say is the soundstage has very noticebly changed....for the worse. The dipoles had a very wide soundstage and were crystal clear. The sealed enclosures have a smaller sweetspot and just don't achieve that level of transparency. I really don't know how else to describe it. Maybe Tom or Jon have technical reasons for this that'll make more sense.

                                                                            Pete
                                                                            Birth of a Media Center

                                                                            Comment

                                                                            • Hank
                                                                              Super Senior Member
                                                                              • Jul 2002
                                                                              • 1345

                                                                              #39
                                                                              Pete, you are very descriptive - don't worry - much better than the flowery, unrelated adjective-laden, paragraph-filling bile that the professional "reviewers" spew forth. Down-to-earth, simple description of what you hear - exactly what I want to read.
                                                                              Keep us posted on how the sound changes when you go back to dipole and play with placement. I'm expecially interested in your opinion of the integration of dipole ribbon and sealed sub.

                                                                              Question: Why did you build the ribbon cabinets so large? Did you use any fiber stuffing?

                                                                              Comment

                                                                              • ThomasW
                                                                                Moderator Emeritus
                                                                                • Aug 2000
                                                                                • 10934

                                                                                #40
                                                                                I don't have a big time technical explaination for the soundfield differences with dipoles. But I was certainly seduced by it in 1983 when I got the Acoustats.

                                                                                Part of it is the interaction of the rear wave with the room. That to me creates the 'air & space' all dipoles have. Jon seems to think he can reproduce that with a sealed system (RD-50 w/line array of the MCM drivers) IF everything is properly done. I have my doubts about it, so only time will tell




                                                                                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

                                                                                • PMazz
                                                                                  Senior Member
                                                                                  • May 2001
                                                                                  • 861

                                                                                  #41
                                                                                  Why did you build the ribbon cabinets so large? Did you use any fiber stuffing?
                                                                                  The RD enclosure was simply based on the size of the CSX enclosure. I wanted a .7Q alignment for the bass, which turned out to be a box 12"w x 14"h x 16"d, IIRC. The RD enclosure is 10"w x 56"h x 11.5"d, fully stufffed with polyfill. No bracing, tho, if that makes a difference. I can't seem to feel any vibrations in the enclosure.

                                                                                  1983 Tom? I guess that's long enough to figure out if you like them or not.

                                                                                  Pete
                                                                                  Birth of a Media Center

                                                                                  Comment

                                                                                  • Dennis H
                                                                                    Ultra Senior Member
                                                                                    • Aug 2002
                                                                                    • 3791

                                                                                    #42
                                                                                    A third alternative might be an open baffle with light damping material on the back side. Arguments in favor.... SL crosses to monopole tweeters at 1500 so there's little rear radiation by 3K or so. He says he doesn't think a second rear firing tweeter adds anything. As well, many of the AA Maggie crowd put a lot of effort into wall treatments to kill the HF backwave as they think it destroys imaging.

                                                                                    Pete, how do you like those 10" CSX? I'm wondering if the HF is good enough to use a line of them on an open baffle with an RD? Any chuffing from the back side?

                                                                                    Comment

                                                                                    • PMazz
                                                                                      Senior Member
                                                                                      • May 2001
                                                                                      • 861

                                                                                      #43
                                                                                      The CSX sound pretty good. They have loads of bass output in the sealed alignment, crossed at 450 Hz. I didn't lsten to them as dipoles but I would think with a 4 spoke basket they would do pretty well. The only thing I didn't like about them was the basket. Stamped frame didn't seem too well constructed. Probably fine for these, but I'm so used to seeing those big heavy cast frames on the larger diameter drivers.

                                                                                      Pete
                                                                                      Birth of a Media Center

                                                                                      Comment

                                                                                      • PMazz
                                                                                        Senior Member
                                                                                        • May 2001
                                                                                        • 861

                                                                                        #44
                                                                                        Well, I haven't fallen off the face of the earth.....Just been lazy!

                                                                                        Here's the latest:





                                                                                        Sealed Pioneer CSX 10" with dipole RD50 above. Still using 450 Hz xover.....Remember the part about being lazy....

                                                                                        Back to the wonderful open soundfield of the dipoles!

                                                                                        If it ever warms up around here, I may get inspired to work back out in the garage. But not so far.....

                                                                                        Pete
                                                                                        Birth of a Media Center

                                                                                        Comment

                                                                                        • Andrew Pratt
                                                                                          Moderator Emeritus
                                                                                          • Aug 2000
                                                                                          • 16507

                                                                                          #45
                                                                                          Looking good!




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