A new home for the BG ribbons?

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  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15311

    A new home for the BG ribbons?

    A few weeks ago a little birdy whispered in ThomasW's ear that it might be interesting to see what his B&G ribbons could do mated to his large system- suggesting what is essentially a four way configuration, with the Acoustat panels and B&G ribbon forming a "lateral" MTM- with possibly the addition of the Technics ribbons as a super tweeter.

    Thomas hasn't been idle, and this weekend we spent a bit of time (while I'm in Denver on business) tweaking up this setup.



    We're both quite pleased with the results- the B&G RD75 covers the area from 600 Hz to 7 kHz, which is pretty much ideal for it- and makes for a much larger sweet spot than when the Acoustat panels were trying to handle up to 7 kHz, even with our "enhancements" to placement to improve dispersion. It's definitly taken Thomas's system up a big step- now, it' compares well with the big Apogee system's I've heard, and it wasn't close to that league previously. I think this is the ideal range to use the B&G ribbons, as it avoides the dispersion issues in the top octave and a half, and it keeps the overall ribbon travel and distortion down by not running down to 400 or 250 as some try to do.

    It also gave us a good excuse to check out ETF and get that MLS measurement system dialed in and calibrated on his HTPC.

    Regards,

    Jon




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    Last edited by JonMarsh; 08 May 2004, 14:17 Saturday.
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  • Pat
    Super Senior Member
    • Aug 2000
    • 1637

    #2
    Whoa, now that is wild.
    I can't imagine the pain that was endured taking those big panels apart 8O

    Glad it turned out for the better.

    Thomas, are you going to keep that configuration or put them back???




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    • Kevin U
      Junior Member
      • Jul 2002
      • 4

      #3
      I'm long over due joining the forum, been lurking about for the last year or so. I appreciate the time Jon and Thomas put into the forum. Lots of QUALITY information!

      Thomas,


      I thought your speakers sounded great.
      The inner midrange envelope micro dynamics had excellent rythm and pace.(inside joke) Ha! Ha!

      Look forward to hearing the changes you and Jon made the next time I'm in Denver.

      Kevin

      Comment

      • ThomasW
        Moderator Emeritus
        • Aug 2000
        • 10933

        #4
        Hi guys!

        Pat

        Actually separating the panels isn't difficult, the stone base was fabricated as 2 separate pieces. The array was/is literally held together with transparent packing tape. The weight keeps everything stable

        The changes will definitely stay. The differences in clarity/detail/dynamics are quite literally stunning.

        Kevin

        While Jon was here we ran a series of MLS tests and dialed in the various output levels. Compared to what you heard the above 600Hz output has been raised +4db and the above 7.5Khz +2db

        Next on the list is to fabricate a proper (and slightly more attractive ) baffle for the RD-75 with the leafs and new mounting base for the whole array.

        At my age I'm glad to have anything that keeps 'pace' LOL....




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        • Pat
          Super Senior Member
          • Aug 2000
          • 1637

          #5
          LOL...packing tape

          Thomas, I remember seeing another array of tweeters in an aluminum column in your basement...going re-use that column?

          Very exciting to hear that they sound even better than when I heard them. Hopefully I will be able to hear them again next time I am near your neck of the woods.

          So I guess the Swan klones are out now since you have found another use for the B&G ribbons???




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          • ThomasW
            Moderator Emeritus
            • Aug 2000
            • 10933

            #6
            Pat

            The tweeter arrays you saw in the basement were the first ones built when I created the double ESL panel arrays. The Techincs leafs I wanted weren't available at that time, so I bought every Fostex planar I could find (they were discontinued). A year or so later I finally located a source for the Technics EAS-400 that are now in the HT.

            BTW, I'd be glad to give away the tweeter columns in the basement to a deserving friend. Be advised the tweeters are attached to the column with hot glue.

            I'll likely be buying more B&G planars 8)




            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

              #7
              As long as the packing tape is 3M brand, that's fine
              I bet it sounds great. BTW, where can I get me some of those "micro dynamics". I'm tired of just macro dynamics alone.
              Okay, Thomas and Jon, for the sake of keeping a line source "affordable" as opposed to your unlimited $$$ designs, what do you think about a stack of, say, six B-G NEO 8's on top of a cabinet with a couple of 10" drivers ala Linkwitz dipole arrangement? Narrow NEO-8 tower designed as detachable.

              Comment

              • JonMarsh
                Mad Max Moderator
                • Aug 2000
                • 15311

                #8
                Okay, Thomas and Jon, for the sake of keeping a line source "affordable" as opposed to your unlimited $$$ designs, what do you think about a stack of, say, six B-G NEO 8's on top of a cabinet with a couple of 10" drivers ala Linkwitz dipole arrangement? Narrow NEO-8 tower designed as detachable.
                Hi Hank,

                You're getting a little too close to the "Black Ops" Arvo Part MkII for comfort...

                I am testing Neo8's, it's probably not realistic to use them much lower than 500-600 Hz or so....





                This was measured in a 2' X 4' baffle, in dipole mode. 15 and 30 degree off axis look pretty decent, though on axis is a little hot in the top end.

                IMO that's not low enough to work with any 10's or 11's that really have enough "grunt" for the dipole bottom end... and that low you will still need some reasonable baffle area.

                OTOH, in combination with a good midwoofer line array, the Neo8's might sing reasonably well. How good remains to be seen, but I would rather see a dipole, and I would rather stick with a familiar metal cone driver with fairly low distortion and high Xmax.

                I've also been kicking around ideas for a more conventional "cheapie" line array, using the cast frame MCM 6.5" carbon fiber woofer and the Neo8's. 8 - 6.5" woofers at a minimum. More ideas than time, though.

                One thing I've seen a lot of folks do with the intent to reduce costs that *doesn't* work well is to combine a line array in part of the frequency range with what is effectively a point source in the rest. This can be especially a problem if the transition occurs in the midrange somewhere. Because of the difference in the fall off with distance between a line array and a point source radiator, the balance can be right at only one distance, and the room power response will be rather squirrelly.... I don't like squirrel meat much, even though I did live in Arkasas for a while when I was growing up. :LOL:

                Regards,

                Jon




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                • Pat
                  Super Senior Member
                  • Aug 2000
                  • 1637

                  #9
                  Thomas,
                  I didn't realize the tweets were mounted with hot glue...I was just thinking that you could remove the old tweeters and re-use the matching aluminum column to mount the B&G.




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                  • Hank
                    Super Senior Member
                    • Jul 2002
                    • 1345

                    #10
                    Hee-hee. Hank's Delta Force covert project is exposed! Am I crazy to say I'm more concerned about the broad dip in response from that 600 Hz point down to about 1200 Hz and all the "bobbles" along the way than I am about the "hot" peak at the upper end?

                    Yes, the NEO 8's do sing alongside a stack of good woofs. I built Danny Richie's personal Alpha LS cabinets and we gave them a listen at my house. They sounded really nice. BUT, for a lower cost and for a narrow baffle, I'm saying what about just a stack of NEO 8's in a tower on top of a woofer cabinet. Now between Thomas and you I'm being cautioned that two 8" or 10" drivers dipole won't push enough air, so two 12" (maybe Adire's dipole-designed 12"er)
                    may be the only way to go. Keep in mind that I propose that the woofs only handle bass down to 60 - 80 Hz flat and the system would be augmented by a subwoofer with freedom of room placement. Also, Thomas says a 2", 3" or 4" driver stack just can't push enough air for realistic SPL/dynamics.
                    Well, maybe a "budget" line source for in-wall mounting, using the TB W2-803SB 2" (155 - 20kHz although looking at the response graph I call it a 300 Hz - 20kHZ driver) coupled with a "fast" sealed 10" driver woofer might be of interest to some people.

                    For a "higher-end" line source, how about a stack of NEO 8's alongside a stack of 6 1/4" woofs. What woofs would you recommend in different price ranges? I assume a higher-price range driver would be the Hi-Vi you guys like.

                    Thanks,
                    Hank

                    Comment

                    • JonMarsh
                      Mad Max Moderator
                      • Aug 2000
                      • 15311

                      #11
                      As I mention above, once you have one driver in line source, you're really committed (IMO) to doing *all* of them that way.


                      Since I haven't done detailed near field studies yet (I've just gotten some Neo8's back in CA this weekend) I can't say definitively what the minor ripples in response are, but my first guess is diffraction effects on the baffle and from the driver case.

                      I don't think the shallow dip between 800 and 2.5 kHz would be that hard to deal with in voicing the crossover - but maybe I'm being optimistic! Wouldn't be the first time that's happened....

                      As to what driver's you could use, since running the Neo8 down to at least 1 kHz should be a cake walk, there's a lot of possible matches in 6-1/2 drivers. At the bottom end, I'll still say the MCM carbon fiber cast basket drivers (55-2321) look attractive, particularly for a "budget" sealed or ported line array.

                      If I was doing a dipole setup, though, and had a few coins to rub together, I'd still lean toward the 8" HiVi M8a, because of the Xmax as well as swept Sd. The 6-1/2" has only 1/2 the Xmax, 1/2 the Sd, which is a serious issue for a dipole.

                      If money REALLY wasn't a concern, I'd use the Seas Excel 7" driver. Very nice trade offs between efficiency, Xmax, and pistonic upper end response. Almost over kill to use it, considering the price, and that you don't need a woofer that goes quite so high (unless you want to use low order networks in conjunction with RLC trap filters, in which case you better get out your checkbook and plan on ponying up for the good stuff.....).

                      Otherwise, a column of revlator 5" scanspeak's would be cool... assuming you'd won the lottery.

                      The six would have to be quite clean up to 1 kHz; I don't have enough current familiarity with current Vifa's and Seas plastic and paper drivers to have a worthwhile opinion; I'm sure some of those could work OK, but would they be better than the MCM? It's got OK travel, a flat vented spider, a fairly well designed basket, and it's pretty affordable.

                      I'm still toying with the idea of something like 2-4 8" M8's, and if not the Neo8's, then I'd consider a 28" BG ribbon- this would have a reasonable vertical window when seated. Though considering the small cost difference, maybe the 40" would make more sense.

                      The trouble is, it's too easy for the design to run away just saying, "let's make this part a little better, and spend just a little more here", etc. Been there, done that.

                      My Arvo Part is only intended to go down to 75 or so on it's own- I'll use a sub (dipole or otherwise) below that. If you use "standard" drivers, such as 8's with 6-8 mm Xmax, I think you'd need at least 4 drivers. I decided it might be worth trying to optimize them more for their range, perhaps with some overlap in the midbass (125 to 200 Hz), so that in that range you'd get a good control in the vertical source.

                      Keep us posted on what you try.

                      -Jon




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                      Comment

                      • Lex
                        Moderator Emeritus
                        • Apr 2001
                        • 27461

                        #12
                        Very interesting. Welcome to the Guide Kevin, and also Hank. 5 posts, your still welcomeable.


                        Yeah, Kevin, what took yo so long?

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

                        Comment

                        • Hank
                          Super Senior Member
                          • Jul 2002
                          • 1345

                          #13
                          Okay master, you won't let me do a stack of ribbons on top of a dipole woofer box - must do a stack of mid woofs along side the ribbons. Thomas won't let me use smaller than 5" diameter mid woofs.

                          I just ordered a 55-2321 data sheet from MCM.

                          If I was doing a dipole setup, though, and had a few coins to rub together, I'd still lean toward the 8" HiVi M8a, because of the Xmax as well as swept Sd.
                          So you'd do a dipole stack of cones next to the monopole stack of NEO 8's?
                          ... and if not the Neo8's, then I'd consider a 28" BG ribbon- this would have a reasonable vertical window when seated. Though considering the small cost difference, maybe the 40" would make more sense.
                          Problem with the B-G RD series is they are too expensive. A stack of 5 NEO 8's is 39 3/8" tall and at P.E. prices, $291.50. An RD40 is 40" tall and costs $445.00. Seems to me an RD40 should cost less than 5 NEO 8's - less labor to build them?

                          If you use "standard" drivers, such as 8's with 6-8 mm Xmax, I think you'd need at least 4 drivers.
                          What do you think about a stack of 5 NEO 8's alongside a stack of 6 of the MCM's? Would adding another NEO 8 be worth the cost?
                          Also, what's your opinion of "power tapering" the drivers to overcome the different path lengths from the end drivers vs the center drivers?

                          Comment

                          • ThomasW
                            Moderator Emeritus
                            • Aug 2000
                            • 10933

                            #14
                            Hank

                            There are economies of scale involved with the Neo-8/Neo-3's. They are mass manfactured in the far east.

                            All the large RD/Radia planars are assembled by hand at the B&G plant in Utah




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                            Klone-Audio

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                            "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
                              • 15311

                              #15
                              Hi Hank,

                              Problem with the B-G RD series is they are too expensive. A stack of 5 NEO 8's is 39 3/8" tall and at P.E. prices, $291.50. An RD40 is 40" tall and costs $445.00. Seems to me an RD40 should cost less than 5 NEO 8's - less labor to build them?

                              You know, there's lots of ways of looking at the cost thing.... when I total up the hours I put into a project like this, and when I think about what nice dinner out on the town costs, kickin an extra hundred or two into a speaker project seems relatively trivial... of course, once you make that decision a few times in the formative stages of a project, then pretty soon you're talking about "real" money. But even for my "dinky" little 8" two way box, the total hours of development and documentation make the component expenses look relatively modest.

                              The 28" RD is about 385 each. Not cheap. As you note, the 40" is even more. The RD's in principle can work down to 150. They can really sing and handle a lot of power from about 400-500 and up. They are a "stunning" midrange unit. The Neo8 doesn't have the same class of lower mid power handling and output. I'll probably use them crossed over about 800 Hz with one of my wacky crossovers. If I remember correctly, Danny uses them with a low order crossover around 1400 Hz. That would dictate having a midwoofer that is really clean up to 3000 or more, a demanding requirement which may compromise other aspects of performance. I think I could make an Excel 7" behave well enough to work that way, but there's few drivers that are pistonic above 3 kHz.

                              Midwoofers smaller than 6-1/2" (or the Scanspeak 5") generall have such dinky Xmax that they really of questionable use, IMO, especially in a dipole array.

                              Note that the Neo8's are dipole; the choice about how to use them is individual; I don't think the back wave is necessarily an asset in that freqquency range, so it may be better to go monopole, or perhaps just to plan on some room treatment, like we did the speaker end of ThomasW's living room- it can be quite disconcerting to some folks to be talking and walk in through the door/portal between the speakers and have your voice swallowed up... but it works.



                              What do you think about a stack of 5 NEO 8's alongside a stack of 6 of the MCM's? Would adding another NEO 8 be worth the cost?
                              With a 4th order L-R or better crossover, the configuration you suggest could work very well, crossed over around 800 - 1 kHz. I'd go for 800. -

                              The incremental cost is minor... but if for reasons of size or arrangement, you can always wire a resistor in stead of a driver to make a network complete.

                              The theory and practice behind power tapering is sound, but probably unnecessary as well as impractical on this "short" an array. If you extended it in height, then that's another matter. Remember that the size of the dipole baffle will have to be taken into account, and you'll need some equalization in the low end (below 400 Hz or so) to compensate for the dipole roll off.


                              I just ordered a 55-2321 data sheet from MCM.
                              I have four of these, the first cone mode is a very minor one, but it is just above 1 kHz. There's no peak, just a small dip. But I like the idea of staying away from it.

                              Best regards,

                              Jon




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                              Comment

                              • Hank
                                Super Senior Member
                                • Jul 2002
                                • 1345

                                #16
                                Thomas, okay, RD's hand assembled in the U.S. Now I understand the cost differential versus the NEO 8's. Thanks for cluing me in.

                                Jon, I get your point about development time versus the incremental cost of adding a ribbon, or moving up a notch in mid-woof performance. Speaking of that, I take it from your earlier post that there's nothing in between the MCM and the Hi-VI M8 that warrants spending more than the MCM cost.

                                The NEO 8's are dipole? I would have sworn that the ones we installed had a solid back the was not removable (riveted). The NEO 3's do have a removable back plate so they can be used monopole or dipole.

                                Comment

                                • JonMarsh
                                  Mad Max Moderator
                                  • Aug 2000
                                  • 15311

                                  #17
                                  Other drivers worthy of investigation in the price range between $30 and $100 would include the SEAS L18RCY/P (aluminum cone, phase plug, ~$62), and the 8" version, the L21RN4X/P (~$68 ) - note they don't have as high an Xmax as the HiVi, but their price is attractive.

                                  However, I've heard that phase plug configurations are sometimes a problem for diples because of noise between the cone and plug from high bass movement which isn't masked by correspondingly high midrange output- but that is heresay.

                                  One last thought... "inexpensive line array" is something of an oxymoron, I believe...

                                  -Jon




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                                  Comment

                                  • ThomasW
                                    Moderator Emeritus
                                    • Aug 2000
                                    • 10933

                                    #18
                                    Hank

                                    The Neo-8's I received were pure dipole, no removable back plate.




                                    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

                                      #19
                                      Thomas had me seriously considering the tall B&Gs until I realized, and he confirmed, the top end would be a little "soft". So, if considering an array, say monopole not dipole, what could be used to carry the 10-20K region? Now you're left with an ever increasing baffle width, assuming you could use a 6.5" - 8" woofer line. And, as Tom recommended, a verticaly tapered baffle added to the mix and we're left with some monstrous enclosures. Sure would be fun, tho!

                                      Pete
                                      Birth of a Media Center

                                      Comment

                                      • ThomasW
                                        Moderator Emeritus
                                        • Aug 2000
                                        • 10933

                                        #20
                                        Pete

                                        Some people don't mind the soft top end of the B&G's. Since I'm used to the Technics leafs I found the B&G's lacking the 'air' and 'space' the leafs create

                                        There are several supertweeter options none are cheap. I'm sure we'll cross that bridge when we come to it with the Black-Ops Arvo

                                        Some possibilities are Ravens, Phillips, ADT, ESq

                                        You can find info about all the above here


                                        Also there's the B&G Neo-3. I'll probably grab a pair of them for test purposes.

                                        Or if there was a pair of used Maggies or a pair with the bass panels trashed, the tweeters could be salvaged. That might be the best and most reasonably priced option available. One would need to be pretty handy with power tools though




                                        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
                                          • 15311

                                          #21
                                          Some people don't mind the soft top end of the B&G's.

                                          If I had to choose between an excellent extended top end and a so-so midrange, or truly nailing the midrange and just having a decent top end out to about 16 kHz, I think I'd pick the latter.

                                          Without question, the big BG ribbons are probably the best transducer you can buy now for the range between 400 Hz and 4 kHz. In Thomas's setup we're using the upper end notch filter, and crossing a bit higher, at 7 kHz. This still works pretty dang well.....

                                          Now, imagine an Arvo Part configuration that's a little taller, with two DPL12's, and 4 - 8" M8a drivers, an RD40, and a stack of Raven 2's for the treble- let's crossover at somewhere between 400 and 600 Hz for the mids, 4 kHz for the highs, and use a "soft crossover" between the 12's and 8's at about 150 Hz so that in the midbass and lower midrange we have a really tall source for good vertical directivity.

                                          Makes my mouth water (and provokes other physical reactions just thinking about it....




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                                          Comment

                                          • Hank
                                            Super Senior Member
                                            • Jul 2002
                                            • 1345

                                            #22
                                            Jon, down boy! I started reading your Part description and I was thinking, this is almost affordable if I substitute a stack of NEO 8's for the RD40. THEN I got to the Raven part and you left me behind dollar-wise.

                                            Am I reading between the lines that you think the RD's are better-sounding than the NEO 8's? Quite a cost delta.

                                            Yep, inexpensive line source is an oxymoron.

                                            I looked at the high-end tweeters on Thomas' link, and saw some VERY smooth curves. But, as in other areas of life, the smoothest curves cost big bucks!

                                            Comment

                                            • Hank
                                              Super Senior Member
                                              • Jul 2002
                                              • 1345

                                              #23
                                              PMazz: baffle width? monstrous enclosures? Yes, you can end up with huge enclosures. Here's what I built for Danny Richie/ GR Research:
                                              http://www.harmonicdiscord.com/forums/viewtopic.php?t=5448
                                              Huge, heavy and NOT WAF acceptable in this life.

                                              Comment

                                              • ThomasW
                                                Moderator Emeritus
                                                • Aug 2000
                                                • 10933

                                                #24
                                                Hank

                                                Yup high performance ribbons/leafs are big $$$$$. This is one reason something like the Maggie MMG's are such a steal at $550/pr delivered

                                                We're going to compare an array of the Neo-8's against the RD-40 and see what the differences are. It's quite possible that many people would be happy running the little planars as mid/tweeters.

                                                My goal is of course the ultimate in performance so there will be some supertweeter used. I'm researching ALL the various sources and products to see what the best cost vs performance one is..




                                                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
                                                  • 15311

                                                  #25
                                                  As Thomas implies, there's still some more legwork to do on this one- but we're pretty confident the results are going to justify the effort.

                                                  Re the Neo8 vs. the big BG ribbons, I think it's fair to say we're talking two different classes, both in cost and some aspects of performance.

                                                  Hank, if you haven't ever cuddled up close to the one of the RD series, it might be hard to "grok" the differences (just using the pictures and published info- ) in both build quality and performance.

                                                  Keep in mind the RD series doesn' roll off on the bottom end until below 200 Hz- that's a substantial extension compared with the Neo8. Our own measurements show a "raw" response nearfield on a dipole panel which doesn't roll off until below 150 Hz. There's a front cavity resonance centered at 5 kHz which has to be compensated with a notch network, and the top end holds up until about 18.5 kHz, though the dispersion isn't very good.

                                                  The Neo8 appears to have a lower diaphragm resonsnce around 350-375 Hz. I probably wouldn't try to run it below a crossover point of 800 Hz, and that's with my high slope crossver (48 dB/octove). That is still a pretty nice mating point for lot of 6-1/2" drivers, and for the M8a HiVi, or the Seas Aluminum drivers I mentioned above. The response plot is well documented above- this is one fo the flattest published curves I've ever seen for the Neo8; certainly better than what they publish, and no one else seems to want to post any specifics....
                                                  The top end holds up OK to about 16 kHz.

                                                  The RD series can be run down to 200-250 for smaller rooms and less demanind SPL applications, or crossed over at 400 - 600 if you really want to kick some b*tt. We've still got a lot of work to do to investigate the "optimum" top end solution, but it's probably not going to be far off from the freuqency range where we're crossing it right now.

                                                  Everyone that has heard the updated system in ThomasW's main room so far with the RD's intstalled has literally been "staggered" or "slack jawed" at the performance- and this is having heard it in the previous incarnation- we're not talking any "newbies" who haven't heard this system before without the RD's.

                                                  The RD's are so good, that a lot of folks have done some relatively "non-optimal" systems with them which STILL are pretty killer compared to a most available systems.... take for example, the Soundline SL2's and SL3's, which John Kotches is pretty fond of...



                                                  SL2




                                                  SL3

                                                  This is basically a BG ribbon (RD50 for the SL3's) combined with a small dynamic woofer (8" for the SL3) in a ported enclosure, with a second order passive crossover at 250 Hz.

                                                  Gee, supposed we could go them a little better by using a larger baffle wing, tapering it, and using two M8a drivers in a box?

                                                  Unfortunately, that wouldn't address the transistion from a line source to a point source at 250 Hz, which can only be balanced correctly at one listening distance, due to the different acoutic fall off rates. Also, it gives up dipole operation in a very important part of the spectra...

                                                  Anyway, I think you catch my drift...

                                                  This is something closer to what the RD ribbons deserve if mated to dynamic drivers....





                                                  -Jon




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                                                  Comment

                                                  • JonMarsh
                                                    Mad Max Moderator
                                                    • Aug 2000
                                                    • 15311

                                                    #26
                                                    Okay, Thomas and Jon, for the sake of keeping a line source "affordable" as opposed to your unlimited $$$ designs, what do you think about a stack of, say, six B-G NEO 8's on top of a cabinet with a couple of 10" drivers ala Linkwitz dipole arrangement? Narrow NEO-8 tower designed as detachable.

                                                    Hank,

                                                    It's been done, by Newform, but with the RD series ribbons....







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                                                    Comment

                                                    • ThomasW
                                                      Moderator Emeritus
                                                      • Aug 2000
                                                      • 10933

                                                      #27
                                                      The reality of line arrays is this.

                                                      One can have either high performance, OR high WAF, OR low cost.




                                                      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
                                                        • 15311

                                                        #28
                                                        Pick any one. One only.



                                                        -Jon




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                                                        Comment

                                                        • Jack Gilvey
                                                          Senior Member
                                                          • Aug 2001
                                                          • 510

                                                          #29
                                                          Now, imagine an Arvo Part configuration that's a little taller, with two DPL12's, and 4 - 8" M8a drivers, an RD40, and a stack of Raven 2's for the treble- let's crossover at somewhere between 400 and 600 Hz for the mids, 4 kHz for the highs, and use a "soft crossover" between the 12's and 8's at about 150 Hz so that in the midbass and lower midrange we have a really tall source for good vertical directivity.
                                                          Such a tease. I can't afford to read either your or Thomas' posts anymore.

                                                          Comment

                                                          • PMazz
                                                            Senior Member
                                                            • May 2001
                                                            • 861

                                                            #30
                                                            Wow, those SL 2s are pretty sharp looking!

                                                            I would be strongly tempted to try something like that just to "see". Maybe a couple of the DPIIs in the base (pun intended). Given my tendency towards unfinished cabinets, they sure look like a quick build, even if the experiment fails and parts are re-used to do a real line. Are they dipoles?

                                                            I've got to pick up an electronic Xover like the Marchand units, or something similar, as my limited skills at Xover design really stop me in my tracks when it comes to these type of "let's try" projects. And then some more amps....and then....

                                                            Hank, I saw the pics you've posted of the GR lines. They turned out great. I was researching the Linus array and got kind of intrigued by the concept.

                                                            Pete
                                                            Birth of a Media Center

                                                            Comment

                                                            • JonMarsh
                                                              Mad Max Moderator
                                                              • Aug 2000
                                                              • 15311

                                                              #31
                                                              Hi Pete,

                                                              They are dipoles, built using RD drivers.






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                                                              We'll screw up the other planets later....
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                                                              Comment

                                                              • ThomasW
                                                                Moderator Emeritus
                                                                • Aug 2000
                                                                • 10933

                                                                #32
                                                                Such a tease. I can't afford to read either your or Thomas' posts anymore.
                                                                People need to understand that my large ESL/planar array has been a work in progress since 1984. I didn't start out with all the pieces you see in the photo. First I bought one pair of 1+1's, then later added another. Then came the leaf tweeter array and finally the RD-75's. So over a period of 18yrs. I've spent a total of $3700, but realize that averages only $205/yr.

                                                                Also I bought ALL the components as closeouts, special offers, group discounts, preproduction specials or knew someone with wholesale connections. Had I paid 'list' prices the speakers to date would have cost in excess of $7000

                                                                Making the Arvo line array Jon describes doesn't need to break the bank. It can be built as a modular and upgradable project. Start with a sealed or ported MTM, this isn't very costly (under $500 if you make DIY cabinets). Next when the budget is there add the Titanic or similar woofers. Next add additional M8a's and finally add the B&G planar. The only things not recycled with this approach are a few XO components and the cabinets.

                                                                The really cool thing about this approach to speaker building; is that with every upgrade, one gets the thrill of a completely new speaker system without the financial pain.......




                                                                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

                                                                  #33
                                                                  Thomas, I know. Newform is where I got the idea. I discovered them a few years ago. In April of last year, I asked you about them and here's one of your replies:
                                                                  "Regarding woofers/mid-bass drivers for planars; my feeling is that the range of about 250Hz - 2500Hz is the critical area for the reproduction of human voice. So not having a XO point in this region is important, IMO. NewForm Research puts the XO point at 900Hz. Right smack in the middle of this area, so it's very important that they have excellent XO's and drivers so as to create a "seamless" match between the cones and planars. This in my experience is hard to do. So I do my best to avoid this and that's where the B&G planars come into play. The RD75 can go as low as 150-175Hz but for safety reasons should be XOed at about 300-350Hz. The other nice thing about the RD series is that they can be built either as dipole or monopole, so they are quite flexible as far as placement is concerned."
                                                                  "My thinking is that if the planar element is dipole, and if the builder wants the woofer/midbass driver's dispersion properties to match that of the planar, then yes it should be built as a dipole line array. If the ribbon is monopole then a sealed or ported box, but also built as a line array"
                                                                  Your words led me to believe that NewForm Research was NOT using B-G ribbons but some others that don't extend anywhere near as low as the B-G's. I understand your reasoning about wanting to keep XO's as low as possible. You suggested to XO B-G's at 300-350Hz, but nowdays you're recommending 600Hz.

                                                                  UNCLE! I GIVE! Jon and Thomas, you have convinced me that I can't have best sound quality and low cost in the line source arena.
                                                                  But would it be fair to say that for the same amount of money spent, I'll have better results building a line source than a conventional pistonic speaker. Let's say I do a stack of 6 NEO 8's (around $300) on top of a dipole box with 2 of the Adire dipole 12" woofs (around $300?). That's $600 per side plus cabinets and XO's. Could I beat the sound quality (insert all the descriptive nouns) with conventional cones for the same money? I assume not, but I value you guys' opinions greatly.
                                                                  Thanks for "listening".

                                                                  Comment

                                                                  • Lex
                                                                    Moderator Emeritus
                                                                    • Apr 2001
                                                                    • 27461

                                                                    #34
                                                                    Guys, really an interesting thread. I have enjoyed just scrolling, spot reading, viewing the photos. But where's the photos with the scadily covered women at?

                                                                    Wow, Thomas, those speakers you been working on for 18 years, must truly be something!

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

                                                                    Comment

                                                                    • JonMarsh
                                                                      Mad Max Moderator
                                                                      • Aug 2000
                                                                      • 15311

                                                                      #35
                                                                      Uh, Lex, the scantily clad photo's are a stealth feature; they only show on your system (regardless of Netscape vs. Stinkernet Explorer) if you're a card carrying charter member of the Mission Possible DIY section, which means you have to have posted at least one DIY project of your own in this area. That excludes commerical/for sale projects.

                                                                      Sorry. Forum policy.


                                                                      -Jon




                                                                      Earth First!
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                                                                      Comment

                                                                      • ThomasW
                                                                        Moderator Emeritus
                                                                        • Aug 2000
                                                                        • 10933

                                                                        #36
                                                                        Hank

                                                                        Sorry if I caused confusion. My origional post about the B&G was based on our initial Clio testing of the RD-75's in the prototype baffle with the Eton 8" woofers. Now after having completed more extensive testing and listening it appears that the higher XO points are even better.

                                                                        Regarding the XO point being in the 'midrange'. Yes it is desirable to have the lowest XO point possible. Many people are using low XO points with the large B&G planars. And B&G itself says 175Hz. But I'm not into destroying a $1500/pr set of RD-75's. And based on our follow up testing we feel that the higher XO point is the prudent one to use.

                                                                        We only started working with the M8a's 6mos ago until then I'd yet to hear a cone driver that has it's amazing level of transparency. Obviously in my big system there's not a problem transitioning from the ESL panels to the B&G planar. We'll see how good a job we can do when we try that same transition using the M8a.

                                                                        Now to your question. Dan Wiggins says the highest XO point for the DPL-12's is 450Hz. If you look at the response of the Neo 8's then you see that they need a 700Hz XO point for a margin of safety and to get the flattest response. That's why we recomment using the Hi-Vi M8a's with the Neo-8's. One could put a couple of M8a's in a sealed box ala NewForm hybrid design, then later make a line array using more of the M8a's. The bottom end of the M8a's in a ported box is quite strong to ~30Hz. So they would easily mate up with a tube sub. For a dipole line array one would need not only more drivers, but something to fill the gap in the frequency response between the M8's and the sub. This is needed because in free-air the M8a's won't go very low with any significant SPL's




                                                                        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
                                                                          • 15311

                                                                          #37
                                                                          Hank, re your post, all the info posted is generally true and a good thing to keep in mind. Good crossovers can be done, even smack dab in the middle of the vocal region, but you have to be careful considering the radiation characterisitcs and phase of the drivers.

                                                                          For example, an 8" two way project that I did with the M8a drivers has very good reproduction of voice, though it has a 1200 Hz crossover; I attribute this to using drivers with extended pistonic operation, and a fairly sophisticated crossover desgin. Reproduction of voice and other midrange instruments is excellent on this system.



                                                                          This is a "conventional" box system, with only about $160 of drivers per side.

                                                                          Now, if you're considering spending $600 per side on drivers, you've got a much bigger selection to chose from.

                                                                          But, the DPL 12's probably shouldn't be crossed over any higher than about 450 Hz. The Neo8's shouldn't be run much lower than 600-750 Hz on the lower crossover, and that's assuming something at least like a Linkwitz 4th order network. That leaves a bit of a hole....

                                                                          So What's a guy to do? If you're really planning on running with an external sub for the stuff below 75 or so, as previously stated, and want to go dipole, I'd suggest several possibilities.

                                                                          First, if you want to stay with the Neo8's, run with six of those (about $360), and go with 4 of the SEAS L18RCY/P, ~ $240. For experimentation, consider a forth order active crossover. For the ultimate in flexibility, the new Marchand XM44 crossover, available in kit form, offers a lot of flexibility plus the option of special boards for equalization such as baffle step or dipole compensation.





                                                                          This could put you in the ball park for what you're looking for- assuming midrange performance is a real priority.

                                                                          You could start this off as just the 8's and the Neo8's side by side on a tallish baffle to where the midrange and treble output covers both sitting and listening heights - by leaving two feet of clean baffle in the bottom. Later, as finances allow, you could add the dipole woofers and unload the 8's a bit. But it probably wouldn't be necesssary, unless you like fairly loud playback.

                                                                          The other possibility would be upping your budget a bit, retaining the DPL 12's, and going with a set of RD28's or RD40's at the get go, with a two way crossover around 350 - 400 Hz. But I don't think you'll get the Neo8's to work happily that low, since that appears to be at their fundamental resonance. Of course, I'm a pretty conservative guy, so maybe I'm not making the right call - you could always try it. But it seems problematic to me.

                                                                          Regards,

                                                                          Jon




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                                                                          Just ask Mr. Ohm....

                                                                          Comment

                                                                          • Brian Bunge
                                                                            Super Senior Member
                                                                            • Nov 2001
                                                                            • 1389

                                                                            #38
                                                                            Jon,

                                                                            Just for clarification, is the system you're proposing above for Hank a monopole or dipole design for the Seas drivers and the Neo8's?

                                                                            How tall would you envision this enclosure being with the extra 2' of baffle space below? Somewhere between 5-6' tall?

                                                                            Thanks,

                                                                            Brian

                                                                            Comment

                                                                            • JonMarsh
                                                                              Mad Max Moderator
                                                                              • Aug 2000
                                                                              • 15311

                                                                              #39
                                                                              Hank is interested in a dipole, and that's what I'm doing these days, too, so it is a dipole system we're proposing.

                                                                              You're right, with the 2' of space "reserved" for the woofers, we're talking something in the range of 60 to 72" tall; I suspect the shorter end would be slightly more palatable esthetically, though once you hit 4', it's pretty much machs nicht.

                                                                              For a somewhat higher cost in drivers, roughly, one could do what I'm considering for the MkII Arvo Part, which is 4X Neo8, two M8a mid-woofers, and 2 12" woofers (if we don't use the 11" Titanic MkII). This will have to be a bit taller than the roughly 50" (with base) MkI. Probably about 56 -60". Whether I build that version depends on how the Neo8 evaluations go. There will be a single test baffle version built, for certain.

                                                                              Another idea rattling around, closer to Hank's original concept, is something more like the Dulcet Klone Thomas was originally considering; but closer to a full range speaker by itself, an initially only two way: An RD50 ribbon driver, and six Titanic MkII's (nominally 10", actually 11"). A lot depends on the Titanic's overall dipole behavior, currently under evaluation. The first real cone peak is at about 700, so a 350-400 Hz crossover is doable, though not trivial. A larger baffle is required to optimize the RD performance, but using it on the outside of a moderate size baffle (like the Arvo Part width) may still work; it would result in skewing the lower mid beam in towards the center, and more outside cancelation, which could actually be a desirable "feature". The woofer array would have a nominal impedance of 6 ohms, and with the natural roll off (6 dB/octave) of the Titanic MkII 10 above 75, wouldn't need much dipole EQ per se.

                                                                              There are a lot of potentially interesting configurations, and while it's always fun to do "bench racing", there's really only one thing that matters- how it works in the real world. That takes construction, development, and evaluation of "competing" approaches, not just fixating on one idea.

                                                                              Best regards,

                                                                              -Jon




                                                                              Earth First!
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                                                                              M8ta
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                                                                              Resistance is not futile, it is Volts divided by Amperes...
                                                                              Just ask Mr. Ohm....

                                                                              Comment

                                                                              • Hank
                                                                                Super Senior Member
                                                                                • Jul 2002
                                                                                • 1345

                                                                                #40
                                                                                Oops, double post.

                                                                                Comment

                                                                                • Hank
                                                                                  Super Senior Member
                                                                                  • Jul 2002
                                                                                  • 1345

                                                                                  #41
                                                                                  Thomas and Jon, thanks as usual for sharing your extensive knowledge and experience. Thomas, I assumed you had changed your XO recommendation due either to further testing or changing your mid-woof choice.
                                                                                  Well, if a stack of NEO 8's and four 8" mid/woofs are $600 per side, then it's a no-brainer to go with an RD40 at $445 per side and skip the 8"-ers, crossing to woofers.
                                                                                  Now the big decision remaining would be woofer type. The RD40's would be in monopole enclosures, and Thomas said that a sealed or ported woofer implementation would work with monopole ribbons, as long as they're a line array. So, maybe two 10" or 12" drivers, maybe Adire shivas, stacked in a sealed cabinet below the ribbon cabinet? Do the woofs have to be alongside the RD40, or can they be in a separate cabinet beneath a narrow RD cabinet? Sorry for the newbie question ops: , I don't understand the interaction between a line of mid/tweets and a line of woofs.

                                                                                  Comment

                                                                                  • Hank
                                                                                    Super Senior Member
                                                                                    • Jul 2002
                                                                                    • 1345

                                                                                    #42
                                                                                    This time I apologize for any confusion. I haven't intended this to be a dipole configuration. I don't know if the RD's have a closed, sealed back, but at any rate I would put them (or NEO 8's) in a sealed enclosure, so they would be monopole. I don't really want to deal with the rear wave of a dipole, as I assume it would be much more placement sensitive, especially it would need to be placed quite a ways away from walls. One thing I am confused about: Thomas said his NEO 8's are dipole, but they have a closed, sealed back on them. Isn't that monopole - radiating forward only?

                                                                                    Comment

                                                                                    • Brian Bunge
                                                                                      Super Senior Member
                                                                                      • Nov 2001
                                                                                      • 1389

                                                                                      #43
                                                                                      Hank,

                                                                                      I have a Neo8 out in my car and I'd definitely say it's dipole. The back is not sealed on it.

                                                                                      Brian

                                                                                      Comment

                                                                                      • Hank
                                                                                        Super Senior Member
                                                                                        • Jul 2002
                                                                                        • 1345

                                                                                        #44
                                                                                        Brian, thanks for the correction. My plan all along has been to do a sealed enclosure, thus monopole for whatever ribbons I choose, for the reason stated above. However, being a neophyte, I'm open to being convinced otherwise if dipole makes for better sound.

                                                                                        Comment

                                                                                        • JonMarsh
                                                                                          Mad Max Moderator
                                                                                          • Aug 2000
                                                                                          • 15311

                                                                                          #45
                                                                                          Hi Hank,

                                                                                          Line sources don't follow the square law drop off that using one or two "point source" drivers do. So, inherently, using a big line source, and matching it to a more or less point source woofer is going to present room power balance problems and system voicing issues. At best, you'll be able to balance it for one listening distance; closer, and the woofer will be too loud; farther away, and it won't be loud enough. So we definitely favor using a line source array of comparable height for the mid-woofers. Having a 12 or two on the ground won't be comparable- it can be optimized for roughly one distance. But that may work in your circumstances for a smaller room... Note B&G's recommendation for minimum listening distances for the different models also.

                                                                                          Re dipoles vs. closed boxes, here's a quick overview of the main points:

                                                                                          Dipole vs. closed cabinet. Pros and Cons


                                                                                          Closed cabinet:

                                                                                          Pros:
                                                                                          High LF efficiency because rear wave is prevented from combining out of phase with front wave. This results in a relatively small speaker, and lower cost

                                                                                          System Q can be manipulated by cabinet design to a limited degree

                                                                                          Seeming freedom of placement; but in reality, due to boundary interaction, many placements in room will result in significant frequency response errors not due to fundamental system peformance

                                                                                          Can be designed for smooth performance if located directly at a boundary interface (wall)

                                                                                          Benefits from side and rear wall treatments


                                                                                          Cons:
                                                                                          Rear wave must be abosrbed by cabinet or contained by cabinet

                                                                                          All adjacent boundaries are excited by the low frequency output, through midbass and lower midrange- resulting in multiple time paths and reflections. Careful room placement and room treatments required for smooth response, to minimize modal interactions.


                                                                                          Dipole:

                                                                                          Pros:

                                                                                          Figure 8 or cardiod radiation pattern, greatly reduced interaction with room boundaries- side wall interaction nearly non-existant

                                                                                          No enclosure wall radiation as secondary sound source- no box sound

                                                                                          Benefits from rear wall damping treatments


                                                                                          Cons:

                                                                                          Requires about 4X the radiating swept area for same low frequency extension and SPL - more expensive

                                                                                          System Q dependent on driver design

                                                                                          Obviously restrictive placement- can't be placed close to rear walls - but has more lateral placement flexibility

                                                                                          Less side wall interaction and comb filtering- usually better imaging.



                                                                                          In practice, dynamic cone dipoles, such as Thomas's Whisper Klones, even in a live room without treatments (his family room) produce sound much more like "headphones" than conventional speakers.




                                                                                          -Jon




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