Kurosawa Koncept System

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  • Evil Twin
    Super Senior Member
    • Nov 2004
    • 1531

    I ordered a pair each of the T34A-4 and the T34-B from Solen last week and received them this week.

    None of them passed incoming QC and quick checks. All four have rubbing voice coils and relatively high distortion- this is quickly noticed by ear on the first sine chirp sweep. Test level is 3V P-P.

    I expect that in order to get the high reported sensitivity they may have a very minimal VC gap dimensions. This may be problematic in manufacturing. A number of other tweeters were checked at the same time, including relatively budget parts like the Peerless DA25TX00-08. No other tweeters exhibited any problems or unusual behavior on the exact same test setup.

    This will be followed up on and investigated with Solen today.
    DFAL
    Dark Force Acoustic Labs

    A wholly owned subsidiary of Palpatine Heavy Industries

    Comment

    • cochinada
      Senior Member
      • May 2014
      • 658

      Originally posted by Evil Twin
      I ordered a pair each of the T34A-4 and the T34-B from Solen last week and received them this week.

      None of them passed incoming QC and quick checks. All four have rubbing voice coils and relatively high distortion- this is quickly noticed by ear on the first sine chirp sweep. Test level is 3V P-P.

      I expect that in order to get the high reported sensitivity they may have a very minimal VC gap dimensions. This may be problematic in manufacturing. A number of other tweeters were checked at the same time, including relatively budget parts like the Peerless DA25TX00-08. No other tweeters exhibited any problems or unusual behavior on the exact same test setup.

      This will be followed up on and investigated with Solen today.
      That is most unexpected! Moreover due to the high praises in this regard that we have seen published by a few testers. Did you take measures for comparing?
      Joaquim

      DIY 4 way speakers.
      DIY subwoofers.
      Zaph ZD3C.

      Comment

      • fish fingers
        Senior Member
        • Apr 2015
        • 189

        Oh dear. Maybe tight tolerances and shipping from europe. I had some ribbons which were stretched - initially it was thought to be customs checks, but turned out to be dropped consignments

        Comment

        • Scottg
          Senior Member
          • Nov 2006
          • 335

          -yes, a slightly different definition for drop-shipping. 8O

          Comment

          • Scottg
            Senior Member
            • Nov 2006
            • 335

            Comment

            • Juhazi
              Senior Member
              • May 2008
              • 239

              ^Downshifting experiment - how outrageous!

              "When I began this downsizing journey, after years of owning six-figure flagship speakers, I didn’t think I could be this happy with speakers costing under $40,000/pair. But these German beauties retailing for a “mere” $38,000/pair have exceeded my expectations in virtually every parameter of sound."
              My DIY speaker history: -74 Philips 3-way, -82 Hifi 85B, -07 Zaph L18, -08 Hifitalo AW-7, CSS125FR, -09 MarkK ER18DXT, -13 PPSL470Dayton, -13 AINOgradient, -18 Avalanche AS-1 dsp, -18 MR183w

              Comment

              • Scottg
                Senior Member
                • Nov 2006
                • 335

                ..another project time-lapse from Palpatine Heavy Industries:

                This is a personal project that I worked on with my brother. I enjoyed watching a little bit of Death Star assembly in Rogue One, but I wanted to see more. I came…

                Comment

                • Evil Twin
                  Super Senior Member
                  • Nov 2004
                  • 1531

                  Originally posted by Scottg
                  ..another project time-lapse from Palpatine Heavy Industries:

                  https://vimeo.com/246936220

                  Ah yes.... some would say, "The good old days of the past..."

                  But we must move on to new challenges... different challenges.
                  DFAL
                  Dark Force Acoustic Labs

                  A wholly owned subsidiary of Palpatine Heavy Industries

                  Comment

                  • Evil Twin
                    Super Senior Member
                    • Nov 2004
                    • 1531

                    Solen's Technician will not be in the office today, I'm told, but will review the technical data sent to them tomorrow.

                    This is an example measurement for one of the T34A-4 tweeters. All of the tweeters were very similar with problematic impedance measurements. Clearly damaged or fault at some point.


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                    For reference, a correlation measurement of a Satori TW29BN was done at the same time and also sent to Solen.

                    Click image for larger versionName:	image006.jpgViews:	1Size:	72.8 KBID:	864132


                    This is a normal presentation for this type of high frequency transducer.
                    Last edited by theSven; 21 May 2023, 18:46 Sunday. Reason: Fix image css
                    DFAL
                    Dark Force Acoustic Labs

                    A wholly owned subsidiary of Palpatine Heavy Industries

                    Comment

                    • cochinada
                      Senior Member
                      • May 2014
                      • 658

                      Unless that can be explained as damaged because of the shipping that is most unacceptable.
                      Joaquim

                      DIY 4 way speakers.
                      DIY subwoofers.
                      Zaph ZD3C.

                      Comment

                      • ergo
                        Senior Member
                        • Mar 2005
                        • 675

                        This is a Bliesma T34-B from OLA project. I'll measure both later today. I'm pretty sure I've subjectively verified both but not it's nagging me too. Very sad and poor experience indeed.

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                        Comment

                        • Evil Twin
                          Super Senior Member
                          • Nov 2004
                          • 1531

                          Much has transpired since these last posts...
                          • I have since received more BlieSMa tweeters from other production lots, and am having more success with those parts. However, at this time I do not anticipate changing over the tweeter selection- the current implementation with the D2904-7140 appears to be "adequate".
                          • I have new measurements for the D2904-7140 tweeter, full polar out to 44kHz, also prepared for the Osiris work for Michael Bell. These were incorporated into the development of the updated version of the crossover posted below.
                          • The midrange polar measurement set has not yet been updated since the rear damper system was developed and briefly tested on axis. So the existing developmental Proof Of Concept (POC) crossover proposals still show this aberration in the 1500Hz area for amplitude and phase.
                          • The updated midrange crossover employs series notch filters for the breakup mode as well as the 7140 crossover; I have done this with some designs since the Natalie P, but for some filter configurations is it more tricky to implement, as one cannot just modify the last inductor in a 3rd order configuration. This technique has been proven over and over again- most recently with the SMJ Calliope for the Peerless DA25TX.
                          • Juhazi's link for the Stereophile test of the Tidal Akira, the inspiration for this design effort (after hearing them with a colleague at the Munich High End show, who was almost persuaded to buy the show samples) reveals some interesting data but also some curious contrasts in design choices. Understand that the drivers used by Akira are ALL custom OEM version for Akira, whereas I have been working with lowly off the shelf equivalents. Some comments will follow regarding information gleaned from that review and the design premises of the Kurosawa, including my own observations of the "standard" factory parts and choices made for working with them.
                          • Do note John Atkinson's comment about "character" in the upper midrange and his measurement in the area between 1 and 2 kHz. His measured results mirror my early ones also. It seems to correlate well with the physical design of the driver and the issue I identified and for which I believe I have implemented a workable solution.
                            Last, note the step response. This is indicative of a 2nd order system with the midrange connected out of phase from the woofer and tweeter... rather like a Duelund three way configuration, as originally proposed for this implementation.



                          Tidal Akira Step Response

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                          This reminder of the ad hoc method of addressing the tunnel resonance of the C90-6-724 magnetic structure.

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                          Last edited by theSven; 18 June 2023, 22:47 Sunday. Reason: Update image location
                          DFAL
                          Dark Force Acoustic Labs

                          A wholly owned subsidiary of Palpatine Heavy Industries

                          Comment

                          • Evil Twin
                            Super Senior Member
                            • Nov 2004
                            • 1531

                            Some interesting takeaways from the Stereophile Tidal Akira review

                            Reviewing Stereophiles comments and John Atkinson's test data for the Tidal Akira is interesting in retrospect, if partly because this review was released more than two years after my design approach was locked in and cabinets were being constructed. Some aspects I noted partly, such as the passive radiator count. However, this this the first public disclosure of many of the design and fabrication details of the OEM drivers as well as the cutaway image of the cabinet.

                            Interesting... Most interesting, as today is my first exposure to this material, given how events and tasks have circumscribed my available time. So this post will be a bit of a contrast and compare, perhaps just to explore how close the original design and it's inspired tribute, and how far apart they are in some regards.


                            In no specific order, some "interesting, most interesting" facts about the Akira. Some previously well known, some of them new to myself.
                            • One diamond tweeter, one 5" diamond midrange, three aluminum honeycomb 7.5" diaphragm dome woofers, and 5 aluminum honeycomb passive radiators, all custom OEM Accuton
                            • 348 lb weight, of which 80 lb is reportedly a 3mm thick lacquer finish. Constructed of a proprietary material 42mm thick consisting of multiple layers, including glass hard layers with softer damping layers of MDF and HDF.
                            • Nominal impedance of 4 ohms, estimated voltage sensitivity of 87.5 dB/2.83VRMS.
                            • Impedance minima for reflex system at 40Hz- this is the system Fb.
                            • A "soft" 0.5 way crossover system, with the upper woofer running up to meet the midrange all the way to a 250Hz crossover, and lower woofer rolled off progressively lower in frequency (interesting... most interesting.)
                              One common acoustic space for 3 woofers and 5 passive radiators.
                            • Massive crossover offers "close to 12dB/octave slopes", with massive custom made inductors and capacitors - a 16mH inductor with just 30 milliohms of DCR. Precision Mundorf and Duelund parts used. Crossover parts cost what a decent motorcycle will run you, according to Janczak. This is a metric Jonmarsh could relate to, I believe...
                            • Early quote from the reviewer: "The half-step–spaced tonebursts on Editor's Choice spoke clearly down to their 32Hz lower limit, but with less energy in the upper bass than I was anticipating, and a slight emphasis around 1kHz". (This assessment would require using program material with which one has familiarity, unlike, for example, listening in a show environment with unfamiliar material).
                            DFAL
                            Dark Force Acoustic Labs

                            A wholly owned subsidiary of Palpatine Heavy Industries

                            Comment

                            • Evil Twin
                              Super Senior Member
                              • Nov 2004
                              • 1531

                              Thoughts regarding this information and alternative design paths...

                              It seems the height of foolishness to propose commenting or critiquing in any manner a $200k loudspeaker of this superlative build quality and credentials. The workmanship and effort spent on numerous aspects of this design put it in a rarified territory.

                              However...

                              Some aspects raise a disturbance in the Force for me... as well as a sense of puzzlement. Without access to more inner technical details, note that in some cases I am only pondering and speculating...

                              Low Frequency passive radiator system
                              • with the non-equal number of PR's and drivers, and a non-integer relationship between them, it is highly likely that all the woorfers and PR's share a common low frequency volume.
                              • The impedance curve shows an unequal height pair of impedance peaks, with the lower one almost half of the upper. This implies a significnat offset of the Fb tuning from the sealed Fb or driver Fc.
                              • The impedance curve shows a curious anomaly in the trajectory from 90 Hz to about 175 Hz, compared with what I have observed in AS190 measurments.
                              • The system sensitivty of 87.5 dB/2.83VRMS as estimated by John Atkinson is lower than I would expect, especially for ultra low impedance/low insertion loss inductors; in fact, two "standard" AS190-9-251 in parallel should have a net sensitivity over 90 dB, given their individual sensitivity of 85 dB. And based on my measurements and the data sheet, I expect the LF sensitivity with the planned crossover to be about 92 dB for the Kurosawa.
                              • A layered 3.5 way might have some interesting characteristics- it would avoid having a tall LF course at the crossover frequency. But, it might also account for the weaker than expected midbass capability. OTOH, that also could be a factor of the listening room and setup.
                              • The impedance discontinuity he noted at 90 Hz correlates with the area where I found the behavior to be atypical for this driver familiy.


                              Akira impedance

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                              It is certainly possible that there are more differences between the AS190 custom to Tidal and the standard one, which I do not have knowledge of, accounting for these issue. For example, the voice coil design may be altered, perhaps for longer throw, or longer throw and a higher impedance to make the paralleling more benign, even with unusual crossover component values. The standard AS190 has a reasonable Xmax, +/- 9 mm.

                              AS190-9-251 Impedance


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                              As can be seen, the actual impedance of the AS10-9-251 is not 9 ohms, but 10 ohms. However, three in parallel, excluding crossover components, will have a net minimum impedance of about 3.3 ohms.


                              The other curious aspect is the PR complement and tuning. For this large and expensive a system, a 40Hz Fb followed by a sharp roll of seems to be a curious choice, in light of market expectations. Perhaps the purchares of this speaker will not be listening to Saint-Saen's Symphony #3 in C minor, the "organ symphony" as it is referred to, though a misnomer. For a high end speaker covering classical music's possiblities, the ability to do credit to the low E on the organ might seem mandatory to some. Such as myself.

                              Hence, after evaluating many potential configurations, using two Wavecor PR223BD01 passive radiators per AS190 was settled upon, and each driver and PR set is in it's own acoustic space, avoiding quarter wave column resonances that can be a problem with many tall columnar cabinets.


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                              Midrange

                              I can only imagine what it is like to have the opportunity to work with a 4" diamond midrange, with a break up resonance at 16kHz. However, at 9kHz, the 724 is still fairly easy to work with, and their are known techniques I have employed for well over fifteen years successfully, starting with the original Modula MT and Natalie P. The main challenge, for this part, appears to be the resonance formed by the tube like magnetic structure.

                              Stereophile's comments allude to it's audibility, and it is measurable in their response plots. Until the system build is completed, or at least, driver measurements in the actual cabinets are performed, the jury will be out on this topic. I'll be very curious to see how the distortion plots look with the crossover filters in place.



                              Crossover Parameters


                              A few points to ponder...
                              • The comment about the crossover filters "approaching" 12 dB/octave would seem to indicate that design measures were taken to reduce the slope below that of a convential 2nd order configuration, which, with standard components, IS 12 dB/octave.
                              • The upper crossover frequency makes complete sense to me, based on driver polar response. But the lower frequency at 250Hz is surprizing for this driver, espeically if full 12 dB/octave slopes are not used.
                              • Note that the proposed Duelund apparoch is not a straighforward 12 dB/octave, but derived from a complex equation for which the ultimate bandpass slopes are 12 dB/octave, but the low frequency and high frequency slopes start in the neighborhood of 12 dB/octave and increase ulitmtely to nerly 24 dB/octave, in a tradational Duelund implementation- a configuration which can be challenging to complete. For this reason, the target curves are calculated seperately in an XL file, then imported into the crossover tool as a reference.
                              • The desired crossover frequencies in initial planning were 300Hz and 2200Hz. For this reason, an aleph coefficient of 3 was chosen (basically determines bandwidth of midrange, with a center frequency of 850Hz. This are the only parameters needed for calculating the complete crossover transfer function.
                              Last edited by Evil Twin; 19 April 2022, 10:14 Tuesday.
                              DFAL
                              Dark Force Acoustic Labs

                              A wholly owned subsidiary of Palpatine Heavy Industries

                              Comment

                              • Evil Twin
                                Super Senior Member
                                • Nov 2004
                                • 1531

                                Crossover targets- showing the Duelund calculated transfer function and phase:

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                                Note, my opinion for an effective implementation is that the woofer, midrange, and tweeter should track the target function down to at least -20dB, and preferably to -24 dB.


                                Perhaps just to highlight differences in conceptual basis and execution, I could share the simulated impedance curve of the current system concept with crossover...


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                                Last edited by Evil Twin; 19 April 2022, 10:19 Tuesday.
                                DFAL
                                Dark Force Acoustic Labs

                                A wholly owned subsidiary of Palpatine Heavy Industries

                                Comment

                                • duvixan
                                  Member
                                  • Sep 2012
                                  • 55

                                  Is this project cancelled or postponed? Thank you

                                  Comment

                                  • technodanvan
                                    Senior Member
                                    • Nov 2009
                                    • 998

                                    He still has all the parts in storage if I remember correctly (he moved fairly recently), but final assembly has not occurred at this time.
                                    - Danny

                                    Comment

                                    • Evil Twin
                                      Super Senior Member
                                      • Nov 2004
                                      • 1531

                                      That is correct...

                                      Relocating to a new sector outside the reach of the Rebel Alliance has been a time consuming endeavor, and currently I am assisting the new Chancellor with priority projects such as the CC Supreme, which is progressing in a most interesting manner.

                                      ​​​​​​​There is also the matter of investigating the modifications to the midrange driver to ascertain if the necessary perfomormance modifications are fully realized. Should that not be the case, it may be necessary to seek a replacement, possibly such as the BlieSMa M74-4, and some adjustment of the crossover concept.


                                      For now, this is deferred until construction of the POC crossovers and testing of the CC Supreme prototype is complete. It may also be that the potential for a tower system using this concept may receive a higher priority, due to the relatively value proposition, if the experimental aspects of the asymmetric minimum phase MF to HF crossover should be realized.

                                      Initial test are promising, most promising.


                                      DFAL
                                      Dark Force Acoustic Labs

                                      A wholly owned subsidiary of Palpatine Heavy Industries

                                      Comment

                                      • Evil Twin
                                        Super Senior Member
                                        • Nov 2004
                                        • 1531

                                        Originally posted by Evil Twin
                                        Solen's Technician will not be in the office today, I'm told, but will review the technical data sent to them tomorrow.

                                        This is an example measurement for one of the T34A-4 tweeters. All of the tweeters were very similar with problematic impedance measurements. Clearly damaged or fault at some point.


                                        Click image for larger versionName:	image003.jpgViews:	1Size:	73.2 KBID:	864131


                                        For reference, a correlation measurement of a Satori TW29BN was done at the same time and also sent to Solen.

                                        Click image for larger versionName:	image006.jpgViews:	1Size:	72.8 KBID:	864132


                                        This is a normal presentation for this type of high frequency transducer.


                                        It should be noted that since this problem with early shipments, I have received later shipments with proper functioning. But there also seems to be a clear progression of characteristic behavior from early functional T34's to the most recent ones- the latter being superior, in my estimate. While I have a set of the SS 7140 tweeters to use of this project on hand, updating this component is still under consideration, should the right combination of characteristics be found.
                                        Last edited by theSven; 21 May 2023, 18:47 Sunday. Reason: Fix quote
                                        DFAL
                                        Dark Force Acoustic Labs

                                        A wholly owned subsidiary of Palpatine Heavy Industries

                                        Comment

                                        • Evil Twin
                                          Super Senior Member
                                          • Nov 2004
                                          • 1531

                                          Not in the least bit surprising, as the smaller Vimberg Mino was the inspiration for the Ardent D. It is my understanding that they will be updated with BlieSMa M74B's at some point...
                                          DFAL
                                          Dark Force Acoustic Labs

                                          A wholly owned subsidiary of Palpatine Heavy Industries

                                          Comment

                                          • duvixan
                                            Member
                                            • Sep 2012
                                            • 55

                                            That's interesting

                                            The latest Marten speakers also employs the M74B-6
                                            Marten creates high end speakers for the home. Our premium speakers are proudly designed and crafted in Sweden using exclusive technology.


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                                            Last edited by theSven; 21 May 2023, 18:48 Sunday. Reason: Add image of the speaker

                                            Comment

                                            • Evil Twin
                                              Super Senior Member
                                              • Nov 2004
                                              • 1531

                                              The mid bass 200-800Hz are most likely one of the C168 variants, the 890 would be preferred, based on my own testing of both, and the woofers appear to be the AS90. I would readily wager that the tweeter is a custom Accuton OEM component. And the upper midrange does appear to be an M74B under a decorative fascia.
                                              DFAL
                                              Dark Force Acoustic Labs

                                              A wholly owned subsidiary of Palpatine Heavy Industries

                                              Comment

                                              • duvixan
                                                Member
                                                • Sep 2012
                                                • 55

                                                The mid bass 200-800Hz are most likely one of the C168 variants
                                                Would you choose the C168 for that range, after having worked with Purifi PTT6.5 ?

                                                Comment

                                                • Evil Twin
                                                  Super Senior Member
                                                  • Nov 2004
                                                  • 1531

                                                  For this design, the effective time alignment is a key factor, and one that the PuriFi drivers operate in a conventional manner, with a delayed acoustic origin in the Z axis. The Accuton drivers all claim an effective time origin at the mounting plane, and that is a criteria the original C168 meets. However, I have also obtained a pair of the C168-6-890, which is a wider range driver at the low end. But using it over the original C168-6-990 would require a rework of the midrange enclosure. Further driver evaluations would be necessary.

                                                  One should note that this project and the driver acquisition were started long before PuriFi was a glimmer in anyone’s eye. The PuriFi midrange driver requires a very careful approach to the filter design to realize good performance in the upper range. But for the proposed range of 200Hz to 800Hz, matters are straight forward. However, in that range, if sensitivity is adequate, for a conventioanal Z axis design, I would recommend the -NAA aluminum purify 6.5” driver series, based on my own measurements.

                                                  Of course, it is not reasonable to ignore the cost disparity either- the C168 variants are about 2-1/2 times more expensive now than when I purchased.

                                                  In recently working a storage container left in a remote sector, it was interesting to come across some truly “vintage” components- I will have to characterize the 3 MB Quart 2” titanium dome midranges just to establish perspective on their performance compared to modern components. they were used in some interesting experimental configurations many years ago, but never discussed on HT Guide.
                                                  DFAL
                                                  Dark Force Acoustic Labs

                                                  A wholly owned subsidiary of Palpatine Heavy Industries

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