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  • SB Acoustic 3W

    Hi,

    I have been looking for a while for a 3 way project using SB Acoustic drivers. I wanted to have a small tower that can deliver good base extension and a great midrange for jazz and rock music. I have heard such a project in our regional DIY annual meeting but a lot of thing wheren't exactly what I wanted...
    I found eactly what I wanted at Rabu Acoustic.

    http://rabu-acoustics.dk/byggesaet-4...coustics-p1256

    Since I am mostly a cabinet maker, I am not capable of designing crossover or calculating phases etc... Rabu Acoustic is a Danish vender of Sb Acoustic that has designed a 3 way using on each side:

    1 x SB-Acoustics SB29RDC-C000-4
    1 x SB12MNRX25-4
    2 x SB17NRXC35-8

    I know that this combinaison of drivers is a winner, the only things I am worried about is the crossover design. As I said, I know nothing about crossover design but if you read the writup of the design, his first music test was done with AC/DC and Megadeth....!!! I am no stranger to metal music but is it possible to evaluate a crossover design with that type of music ??

    Here it is...

    Please reassure me ....I am about to start this great project!!!

    THX

  • #2
    Re: SB Acoustic 3W

    Since they're all on the flat-baffle, I find it unlikely that the electrical slopes should all be 12dB.

    Other than that, the coil on the woofers seems a bit small.

    Just a penny or two...
    Wolf
    "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
    "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
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    "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

    *InDIYana event website*

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    Comment


    • #3
      Re: SB Acoustic 3W

      yeah, the woofers must be crossing quite high.
      " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

      Quote Originally Posted by hongrn. Oct 2014
      Do you realize that being an American is like winning the biggest jackpot ever??

      http://www.midwestaudioclub.com/spot...owell-simpson/
      http://s413.photobucket.com/albums/pp216/arlis/

      Comment


      • #4
        Re: SB Acoustic 3W

        I think the low pass on the mid is a little odd.

        Considering they measured in an anechoic chamber gives them quite a bit of credibility over us hacks, but they don't show the FR. They do show this: http://rabu-acoustics.dk/popup_image...780&height=800

        Hard to read the FR off a CSD plot, but I'd say the FR looks bad based on that...

        That's not a cheap speaker. I wonder if there isn't better for the money out there. Why all SB? Can you go with a larger woofer?
        https://www.youtube.com/channel/UCm2...oSKdB448TTVEnQ

        Comment


        • #5
          Re: SB Acoustic 3W

          That's not a cheap speaker. I wonder if there isn't better for the money out there. Why all SB?
          Because I know what I am getting into...I've heard those drivers SB17 and SB12 ( except for the tweeter) and I can tell you that they really sound much more expensive then they really are...! Problem; getting a fine Xover design!

          Comment


          • #6
            Re: SB Acoustic 3W

            I think this thread should have been in the Tech talk Forum...!! Sorry!:D

            Comment


            • #7
              Re: SB Acoustic 3W

              the sb29 is a fine tweeter.
              " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

              Quote Originally Posted by hongrn. Oct 2014
              Do you realize that being an American is like winning the biggest jackpot ever??

              http://www.midwestaudioclub.com/spot...owell-simpson/
              http://s413.photobucket.com/albums/pp216/arlis/

              Comment


              • #8
                Re: SB Acoustic 3W

                Don't underestimate other high-value drivers. SB Acoustics products are very good, but frequently lose to similarly priced speakers using parts from other manufacturers in DIY competitions. The SB12 has the same limitations as many cone midrange drivers, and the SB17 may distort more than larger woofers at high output.

                Comment


                • #9
                  Re: SB Acoustic 3W

                  Originally posted by pierre666 View Post

                  As I said, I know nothing about crossover design but if you read the writup of the design, his first music test was done with AC/DC and Megadeth....!!! I am no stranger to metal music but is it possible to evaluate a crossover design with that type of music ??
                  I use music I'm familiar with when designing/voicing a speaker, since that will be its final use. Besides, who would want a speaker that can't play metal? Those drivers look good on paper. I think it would be a good idea to sim the design first. Crossover count seems small for 12db slopes, no notches...

                  Comment


                  • #10
                    Re: SB Acoustic 3W

                    Here is another one...is this one any better ?
                    Attached Files

                    Comment


                    • #11
                      Re: SB Acoustic 3W

                      It's tought to tell Pierre. The low end bump is strange, but that might be BSC is they just used FR traces. If you're set on those drivers, try both cross overs... If they suck, mail them to me and I'll use them ;)
                      https://www.youtube.com/channel/UCm2...oSKdB448TTVEnQ

                      Comment


                      • #12
                        Re: SB Acoustic 3W

                        so here a look at the ''almost'' finish product

                        Comment


                        • #13
                          Re: SB Acoustic 3W

                          Those are absolutely stunning! You REALLY need to nail the crossover. You wouldn't want people to be disappointed in their sound after you put so much time & effort into their aesthetics, right?

                          OK TT guys, how can we help him smash this out of the park?

                          You definitely need to measure this puppy and import everything into Jeff's PCD software. I agree with WOLF... it's possible, but unlikely... that all of the electrical slopes would be 12dB/octave.

                          I would guess that your speakers would probably sound "ok" with either of the two crossovers shown above. BUT YOU DON'T WANT TO SETTLE FOR "OK"... you want jaw-dropping awesome! And that's going to take some testing and optimizing of the acoustic and electrical responses (simultaneously taking into consideration the acoustic phase and electrical phase response as well.)

                          Is there anybody out there in cyber-space that lives nearby and can measure his speakers???

                          After the .FRD's and .ZMA's are measured, I'm sure that several of us would offer to play with those files in PCD for him. Then he could build the PCD optimized version and run them through another round of testing to confirm the results.
                          ~Marty

                          Baby Eidolons
                          Sapphos
                          Cables (Post #54)
                          Other speakers (Post #21)
                          Design Thoughts (Posts: 6,10,13,33,35)
                          Boundary Augmentation
                          Dispersion/Interference

                          Comment


                          • #14
                            Re: SB Acoustic 3W

                            Originally posted by ReissM View Post
                            Those are absolutely stunning! You REALLY need to nail the crossover. You wouldn't want people to be disappointed in their sound after you put so much time & effort into their aesthetics, right?

                            OK TT guys, how can we help him smash this out of the park?

                            You definitely need to measure this puppy and import everything into Jeff's PCD software. I agree with WOLF... it's possible, but unlikely... that all of the electrical slopes would be 12dB/octave.

                            I would guess that your speakers would probably sound "ok" with either of the two crossovers shown above. BUT YOU DON'T WANT TO SETTLE FOR "OK"... you want jaw-dropping awesome! And that's going to take some testing and optimizing of the acoustic and electrical responses (simultaneously taking into consideration the acoustic phase and electrical phase response as well.)

                            Is there anybody out there in cyber-space that lives nearby and can measure his speakers???

                            After the .FRD's and .ZMA's are measured, I'm sure that several of us would offer to play with those files in PCD for him. Then he could build the PCD optimized version and run them through another round of testing to confirm the results.
                            I have already modified the original Xover design with someone that really knows what he is doing, in fact I am in the last phases of voicing....I have upgraded 2 caps ( C1 & C2) with Obbligato caps. For now I must say, the precision of the mids and high have dropped my jaw. Now I have to adjust the image between mid-High notes and bass....for now the bass is too powerful....
                            here is the schematic modified

                            Comment


                            • #15
                              Re: SB Acoustic 3W

                              Originally posted by pierre666 View Post
                              I have already modified the original Xover design with someone that really knows what he is doing, in fact I am in the last phases of voicing....I have upgraded 2 caps ( C1 & C2) with Obbligato caps. For now I must say, the precision of the mids and high have dropped my jaw. Now I have to adjust the image between mid-High notes and bass....for now the bass is too powerful....
                              That's great to hear! Are you going to post some measurements after you finalize everything? Thanks.

                              P.S. - Don't forget that the loudspeakers' placement in the room can significantly affect their bass response due to Boundary Augmentation. Try varying the proximity to nearby boundaries to see if the bass still seems too much.

                              Additionally... axial, tangential and oblique room modes can inject weird "hot spots" and "dead spots" within a room, so be aware of those "environmental" issues that can sometimes make an excellent speaker seem to perform poorly. If you can walk 3 feet over and the bass response appears to change very dramatically, you might have some room mode issues, not speaker issues. There are several ways to deal with this problem if it becomes necessary. Let us know how things go. Thanks.
                              ~Marty

                              Baby Eidolons
                              Sapphos
                              Cables (Post #54)
                              Other speakers (Post #21)
                              Design Thoughts (Posts: 6,10,13,33,35)
                              Boundary Augmentation
                              Dispersion/Interference

                              Comment

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