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Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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Willing to do some modeling for the Tang Band W6-789E 6.5" midbass (BF Specials)

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  • #61
    Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

    Having never heard either of those tweeters, what is the audible difference between the two for the TM version?

    One being $48, and the other being $14?

    Is the SB Acoustics one worth 3 times the price?


    Also, I am looking forward to my first project where I have to come up with the outside dimensions myself. But, if there is an efficient way to do that, I would love to know.
    Otherwise, I have to go steal a math book from a kid at the bus stop....
    My projects
    https://picasaweb.google.com/112307725038877176664

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    • #62
      Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

      Originally posted by Mayhem13 View Post
      Phase tracking of the MT is exceptional at the crossover point......shoulbe very smooooth. Nice Job Jay.

      For those tuning in, given the Facts and Jay's box modeling for tuning, i don't find the ported options to be very viable but the sealed version with it's acoustical 2nd order rolloff combined with the HP of most AVR's at 80hz should be as good as it gets for sub integration. Let the 6.5" driver play the midbass and the subs do the low stuff. These will get pretty loud with only a few watts of power......we're talkin 110db with only 50watts for the sealed MTM. Pretty not bad for those with entry level AVRs.
      Perfect phase tracking is not necessary for MTM. In fact, I took advantage of MTM's symmetric lobing intentionally. Drivers' phase integration is sort of between LR4 and BW3. MTM's power response dip is notorious. I wanted to mitigate this problem by making drivers' overlap a bit larger than LR4's---their rolloffs are 3rd order. But the resulting phase tracking is closer to LR4's rather than to BW3's due to the tweeter's acoustic center being behind the midwoofer's.

      You summarized the strength of these designs very well. People say watts are cheap these days, but high-power, low-distortion amps are not exactly cheap. Especially if one likes watching movies loudly with speakers driven by an inexpensive (< $1000) mid-quality receiver, high efficiency design really pays off. Of course, a pro 10"-12" midrange mated with a compression driver will play even louder without distortion. But it takes higher costs, too. I believe these designs make a really good compromise. They will produce cleaner, louder sound than most hi-fi speakers when driven by a mid-fi receiver.

      Lastly, I still think a vented version has its value if one does not listen very loud and not bother to use a subwoofer (e.g., for musing listening). Although the vented bass extension in 0.8 cu ft is not that deep (1.0 to 1.2 cu ft looks much better), it provides in-room usable bass down to 45 Hz while the sealed version does not. Note that the vented response in my modeling has a wide 1 dB hump at 120 Hz. A sealed response does not have this and rolloff starts earlier.

      jAy

      P.S. It is a misconception that a sealed speaker is always better when integrated with a subwoofer than a vented one. Phase tracking can always be optimized by the phase control on a subwoofer plate amp as well as AV receiver's speaker distance settings. In fact, when high-passed, a properly tuned vented speaker has higher power handling due to port unloading at Fb.
      Last edited by jkim; 12-02-2009, 12:07 AM.

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      • #63
        Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

        Yes, thank you for all the work you put into these Jay. I will probably build the ported MTMs, but have not decided on which tweeter yet. As much as I like the DQ, I would like to try something SB if funds allow. It will be some time before I start on these though, with 2 other projects on the bench right now...so I have time to waffle!
        Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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        • #64
          Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

          Originally posted by jkim View Post
          jAy

          P.S. It is a misconception that a sealed speaker is always better when integrated with a subwoofer than a vented one. Phase tracking can always be optimized by the phase control on a subwoofer plate amp as well as AV receiver's speaker distance settings. In fact, when high-passed, a properly tuned vented speaker has higher power handling due to port unloading at Fb.
          Yeah, but that's a lot of work if you ask me......and then there's the group delay thing as well.

          Otherwise, as always a solid design and looks to be quite a few on board to build it.....and rightfully so. It'll be interesting to see the variants come out of this. PE needs to keep these on sale as it's the only time they draw any interest. At $45, there's a lot better values out there but at $20-25.....not so much.

          I think after much consideration, i'll do the MT.

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          • #65
            Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

            Originally posted by ckmoore View Post
            Having never heard either of those tweeters, what is the audible difference between the two for the TM version?

            One being $48, and the other being $14?

            Is the SB Acoustics one worth 3 times the price?


            Also, I am looking forward to my first project where I have to come up with the outside dimensions myself. But, if there is an efficient way to do that, I would love to know.
            Otherwise, I have to go steal a math book from a kid at the bus stop....
            The Vifa is a high-value tweeter. I don't think the SB is 3 times as good as the Vifa. Technically, however, the SB has lower distortion and better motor structure. It will perform better especially at high SPL. How audible will the difference be in TM? Probably not much.

            Don't steal a math book from a kid. I don't want you to go to jail because of my speaker designs. Try to come up with some dimensions and put those here. I'll let you know the resulting intenal volume. Sound good?

            Comment


            • #66
              Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

              Originally posted by Mayhem13 View Post
              Yeah, but that's a lot of work if you ask me......and then there's the group delay thing as well.

              Otherwise, as always a solid design and looks to be quite a few on board to build it.....and rightfully so. It'll be interesting to see the variants come out of this. PE needs to keep these on sale as it's the only time they draw any interest. At $45, there's a lot better values out there but at $20-25.....not so much.

              I think after much consideration, i'll do the MT.
              In fact, you can try both sealed and vented versions in 0.8 cu ft per driver. With port plugged and medium amount of polyfill, sealed Qtc will be .71. With port unplugged, if you tune it low (e.g., 34 Hz Fb by 2" ID, 7" long vent), the result will emulate sealed response and group delay with increased power handling. Exactly what Curt describes here:

              http://www.geocities.com/cc00541/Sealed_v_Vented.html

              By the way, why TM rather than MTM?

              Comment


              • #67
                Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                Welll......I came across those Dalquist 6.5" buyout subs and i'm thinking to do some bass bins with them as stands for under some TM's. I'm already doing this with the ZA5.2's so maybe a second set for the den with these...nice and cheap with the Vifa tweeters. We're talkin less than $200 for 4 subs and two of the TB MT's including those buyout plate amps.

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                • #68
                  Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                  Mayhem, there was another B-20 offered up on Ebay last week. I didn't need another one, but I think PassingInterest bought it.

                  Comment


                  • #69
                    Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                    Also, I am looking forward to my first project where I have to come up with the outside dimensions myself. But, if there is an efficient way to do that, I would love to know.
                    There are a few volume calculators out there that can help. I use this one- http://www.the12volt.com/caraudio/boxcalcs.asp#rec It's not fancy, but gets the job done. You may need to convert liters to cubic feet and back again, but that's no problem, thanks to the web!

                    Jay, Do you have any idea what volume the 2 woofers and the port would be? At 2 cu ft or more does it even need to be factored in?

                    Tom
                    Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

                    Comment


                    • #70
                      Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                      Originally posted by tom_s View Post
                      Jay, Do you have any idea what volume the 2 woofers and the port would be? At 2 cu ft or more does it even need to be factored in?

                      Tom
                      In an MTM cabinet, drivers, port, braces, and crossover will take 2.5 to 3 liters.

                      Comment


                      • #71
                        Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                        I agree, the lack of time alignment seems to plague most DIY speakers and most commercial speakers. A well designed wave guide can make working out the crossover so much easier. Not to mention the improvements in power handling and directivity!

                        I have been toying with the idea of machining some waveguides out of solid wood with integral mounting for the tweeter on the rear of the guide and also on the front to mount it to the enclosure. If I got enough interest I could bring the price per part down quite low. Say 15-20$ each with maybe 5 different choices of wood?. Anyone have a vote for the top 4 tweeters they would like to see "wave guided" preferably in a few different price categories. Ideas on the "optimum" profile for the waveguide anyone?


                        Cheers,
                        Nathan Allen
                        www.cncbydesign.com

                        Comment


                        • #72
                          Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                          This is something I would be interested in.

                          May I suggest a Waveguide following Zaph's modified MCM waveguide?

                          Additionally, a slightly shallower version of both Dayton elliptical waveguides might be nice too. I'd like a set in maple or cherry. I like the smaller 4.5" elliptical waveguide but it limits the XO to 3.5Khz or higher which might limit its demand. I've had good luck with it with some 5.5" and 4.5" midwoofers.

                          If it were set up to allow the use of a compression strap to hold in the tweeter, the use of pressfit neo tweeters would also be possible.

                          Bill

                          Originally posted by Cncbydesign View Post
                          I agree, the lack of time alignment seems to plague most DIY speakers and most commercial speakers. A well designed wave guide can make working out the crossover so much easier. Not to mention the improvements in power handling and directivity!

                          I have been toying with the idea of machining some waveguides out of solid wood with integral mounting for the tweeter on the rear of the guide and also on the front to mount it to the enclosure. If I got enough interest I could bring the price per part down quite low. Say 15-20$ each with maybe 5 different choices of wood?. Anyone have a vote for the top 4 tweeters they would like to see "wave guided" preferably in a few different price categories. Ideas on the "optimum" profile for the waveguide anyone?


                          Cheers,
                          Nathan Allen
                          www.cncbydesign.com
                          The first one through the wall always gets the bloodiest...

                          Comment


                          • #73
                            Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                            I find with waveguide's you need the throat opening to match the dome very closely or you get a ragged response, however that doesn't mean we can't find a way around it for testing.

                            The larger the guide, the more machine time. A waveguide as large as 9-10" could be done quite affordably. The smaller waveguide would be quick to machine and use very little raw materiel so we wouldn't need such high demand to keep the price low.


                            Cheers
                            Nathan Allen
                            www.cncbydesign.com
                            Attached Files

                            Comment


                            • #74
                              Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                              Originally posted by Cncbydesign View Post

                              I agree, the lack of time alignment seems to plague most DIY speakers and most commercial speakers.
                              This is not true. In MOst cases, physical time aligment has nothing to do with a speaker's performance in the time domain. With analog crossovers, time alignment of drivers is required only by a transient-perfect system with acoustic 1st order filters. It is useful for acoustic 2nd order filers, too, but it is mainly to obtain good on-axis phase tracking (and thus flat summation of drivers), not to improve the finished system's performance in time domain---the sytem's total phase wrap is 180 degrees, anyway. The most popular, easy-to-use crossover type is the Linkwitz-Riley acoustic 4th order filter, which must be employed by over 90% of commercial and DIY speaker designs with drivers mounted on a flat baffle (w/ 5.25" or larger midrange and no-wave-guided dome tweeter). In this case, we typically use what we call asymmetric filter to obtain drivers' good phase tracking. If it is implemented correctly, it exhibits virtually no difference in terms of the system's phase behavior from a time-aligned LR 4th order system.

                              And in the case of LR4, an asymmetric crossover with drivers on a flat baffle generally takes less components than time-aligned LR4 because we can obtain a relaxed rolloff on the woofer by using only a 2nd order electrical filter.

                              jAy

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                              • #75
                                Re: Willing to do some modeling for the Tang Band W6-789E 6.5&quot; midbass (BF Specials)

                                The waveguide pictured solves a lot of issues, but yet doesn't correct for time alignment in that configuration.....surface mounted i presume? The hyperbolic profile should eliminate edge diffraction.

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