Build Thread: jkim's "Poor Mans": SB/Vifa TM

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  • tom_s
    Seasoned Veteran
    • Nov 2005
    • 1581

    Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

    I know that in all of Jay's designs that I have seen, he gives the builder some voicing options. And I know from personal experience with the Peerless projects, slight changes in tweeter attenuation can make quite a bit of difference in the overall presentation of the finished speakers. Did he offer any voicing options with this design?
    Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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    • jkim
      Seasoned Veteran
      • May 2007
      • 1290

      Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

      Excellent review, Dan! And big thanks for being my guinea pig ;)

      It is highly likely that I'll increase BSC for the standard design I publish at my website.

      jAy

      Comment

      • jkim
        Seasoned Veteran
        • May 2007
        • 1290

        Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

        Originally posted by tom_s
        I know that in all of Jay's designs that I have seen, he gives the builder some voicing options. And I know from personal experience with the Peerless projects, slight changes in tweeter attenuation can make quite a bit of difference in the overall presentation of the finished speakers. Did he offer any voicing options with this design?
        Yes, I did, and he tried at least the tweeter padding options. A bit forward midrange is related to the amount of BSC in the design, which can't be addressed by tweeter padding adjustment alone.

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        • jclin4
          Seasoned Veteran
          • Oct 2005
          • 2237

          Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

          Jay did the XO modeling for my Tiny TiMMs project and he provided voicing options for tweeter padding. I ended up going with the highest serial and lowest parallel values for the resistors for the ranges he recommended.

          Now the tonality/balance is excellent. So much so that I'm reluctant to put them back into their casual listening set up and want to use them for more critical listening.

          Comment

          • parodielin
            Midrange Member
            • Oct 2009
            • 450

            Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

            Dan,

            How would you compare the bass or mid-bass between SB and Seas? The SB mid-bass is so good that I don't want anything less in that department for my next project. It will not go as deep as my subwoofer but the quality is superb. Not sure what words I should use to describe my feeling - it increases the depth and adds another layer, in my mind, to the music.

            I never though mid-bass would make such a difference to music. If SS Revelator is better than SB, I might be willing to pay the price...

            Thx!

            Comment

            • lunchmoney
              Seasoned Veteran
              • Jul 2008
              • 4603

              Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

              Originally posted by Wushuliu
              Not sure if you've already done so but it does pay to play w/ the woofer and tweeter values Jay provides for individual voicing. His default values tend to be, from the two designs of his I've built, on the brighter side of neutral from my experience. Otherwise, I definitely agree with your assessment of the PMHEMs... beautiful build btw.
              Thanks!

              Yes, jkim did provide three different options for the tweeter resistor... he specs 4.7 ohm in the x-over schematic, and to try anything between 4 and 5 ohm.

              I tried 4, 4.7 and 5.1... 4.7 was the clear winner

              Comment

              • lunchmoney
                Seasoned Veteran
                • Jul 2008
                • 4603

                Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                Originally posted by parodielin
                Dan,

                How would you compare the bass or mid-bass between SB and Seas? The SB mid-bass is so good that I don't want anything less in that department for my next project. It will not go as deep as my subwoofer but the quality is superb. Not sure what words I should use to describe my feeling - it increases the depth and adds another layer, in my mind, to the music.

                I never though mid-bass would make such a difference to music. If SS Revelator is better than SB, I might be willing to pay the price...

                Thx!
                It's a bit tough to compare, as the SB's have the benefit of being in a substantially larger cabinet (.8 vs .5 cubic feet)

                Both are wonderful drivers.

                Comment

                • lunchmoney
                  Seasoned Veteran
                  • Jul 2008
                  • 4603

                  Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                  Originally posted by jkim
                  Excellent review, Dan! And big thanks for being my guinea pig ;)

                  It is highly likely that I'll increase BSC for the standard design I publish at my website.

                  jAy
                  And someday I might build that crossover for fun and see which my friend prefers... in the meantime, I'm sure he'll be happy with them as is... I'm not even going to mention to him that "you might like them better if..."

                  Comment

                  • jkim
                    Seasoned Veteran
                    • May 2007
                    • 1290

                    Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                    Here's an interesting observation.

                    All the designs mentioned above including TiMMs for John, the two designs built by Wushuliu, the Peerless buyout design built by Tom all uses the Vifa DQ25 tweeter.

                    You know what? I recently found out that impedance data for the Vifa tweeter I used for modeling is lower (about 0.6 ohm) than actual. Also, it seems that the frequency response of the particular tweeter Zaph originally tested, which I also used for modeling, is a tad less sensitive than ones from recent production.

                    All these factored in, the tweeter response in my modeling should be up to 1.2 dB weaker than actual, which means the actual response must be 1.2 dB hotter. This must be audible. So, I corrected this in my recent modeling for the designs with TB W6-789E and Vifa DQ25.

                    I don't think that it's a general tendency that I choose a hot tweeter level by default

                    -jAy

                    Comment

                    • jclin4
                      Seasoned Veteran
                      • Oct 2005
                      • 2237

                      Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                      Originally posted by jkim
                      Here's an interesting observation.

                      All the designs mentioned above including TiMMs for John, the two designs built by Wushuliu, the Peerless buyout design built by Tom all uses the Vifa DQ25 tweeter.

                      You know what? I recently found out that impedance data for the Vifa tweeter I used for modeling is lower (about 0.6 ohm) than actual. Also, it seems that the frequency response of the particular tweeter Zaph originally tested, which I also used for modeling, is a tad less sensitive than ones from recent production.

                      All these factored in, the tweeter response in my modeling should be up to 1.2 dB weaker than actual, which means the actual response must be 1.2 dB hotter. This must be audible. So, I corrected this in my recent modeling for the designs with TB W6-789E and Vifa DQ25.

                      I don't think that it's a general tendency that I choose a hot tweeter level by default

                      -jAy
                      The thought occurred to me as well, although I didn't realize there was a DQ25 connection. I knew that you, like many of us, rely on Zaph's measurements (before you got your own measurement set up), and maybe his measurements were off.

                      Then I dismissed this thought. :D

                      Comment

                      • jkim
                        Seasoned Veteran
                        • May 2007
                        • 1290

                        Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                        Originally posted by jclin4
                        The thought occurred to me as well, although I didn't realize there was a DQ25 connection. I knew that you, like many of us, rely on Zaph's measurements (before you got your own measurement set up), and maybe his measurements were off.

                        Then I dismissed this thought. :D
                        Zaph's measurements are very accurate if his data are provided in high resolution plots. The impedance data I originally used was traced from Tymphany's spec sheet. This time I found that in some of Tymphany and SS plots, impedance scale marks are not precise. For example, it doesn't make sense that a tweeter with a voice coil DCR of 3.0 ohm goes below 2.8 ohm on impedance curve.

                        jAy

                        Comment

                        • jclin4
                          Seasoned Veteran
                          • Oct 2005
                          • 2237

                          Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                          I guess this is why all the serious DIYer's say you have to measure, and tracing is not good enough. And Zaph does not encourage tracing of his graphs, he publishes them for comparison purposes only.

                          Through direct experience, I now see the wisdom of the elders (although personally I'm not quite at the point to make the jump).

                          Comment

                          • jkim
                            Seasoned Veteran
                            • May 2007
                            • 1290

                            Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                            Originally posted by jclin4
                            I guess this is why all the serious DIYer's say you have to measure, and tracing is not good enough. And Zaph does not encourage tracing of his graphs, he publishes them for comparison purposes only.

                            Through direct experience, I now see the wisdom of the elders (although personally I'm not quite at the point to make the jump).
                            In fact, in a broad sense, this concern applies to all people who build another person's design whether the design is based on full measurements or only based on IB measurements and modeling. Of course, the former has a less possibility of being off the mark, but in my experience the real great benefit of using one's own measurements is confirming that each and every part behaves as expected. All analog/mechanical products are prone to errors and tolerance issues.

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                            • lunchmoney
                              Seasoned Veteran
                              • Jul 2008
                              • 4603

                              Re: Build Thread: jkim's "Poor Mans": SB/Vifa TM

                              All this being said, it's simply incredible that Jay can design a speaker that sounds this good without even hearing it!

                              Comment

                              • mzisserson
                                Seasoned Veteran
                                • Nov 2007
                                • 4866

                                Kind of a review.... FWIW

                                I was lucky enough to hear these poor man's at Dan's casa yesterday. We spent a great deal of time with them in several different configurations.

                                First, their construction was just another testiment to how a well build cabinet is the foundation for good sound. These cabinets were DEAD, and it showed. No bloominess or "cabinet honk" as I call in in the midrange, just good clean sound. If the seams stay tamed, the cabs look as smooth and clean as the pictures posted. Awesome.

                                We listened to just about everything from Primus, to Coltrain... They image extremely well for a floor-stander (easily like a mini-monitor), however are quite sensitive to vertical position. The tonal balance was lively at times, but never had any teeth that hurt the eardrums. It was actually a very different speaker compared to the hundreds I have listened too. Very much it's own animal. In a very good way.


                                We went back and forth quite a bit with the SR-71's.....;)


                                They did well with everything. I hate blanket statements, but it is true. For rock, the guitar was gritty with great harmonics, and Spanish guitar has body, attack, and a great sense of "being there". Drums were presented with a good amount of attack, and rolls on the hi-hats and snare were lightning fast with a wonderful snap.

                                Female vocals particularly turned my head. They were some of the best I have heard in years, easily rivaling the Sonus Farber "Electa Armator".

                                They are easily as good as any retail speaker out there in the 2K+ range, though lacked the deep inner detail which would have put them over the edge in my book. Though I only got to spend a couple of hours with them, I am unsure the Vifa tweeter was doing justice to the SB woofer.

                                It is awe inspiring that someone can design a speaker that good and have never built/heard them!!!! I would put this on the short list of kits to consider for anyone looking to build a great all around speaker in a very crowded kit price range.
                                .

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