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Crashpc

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Crashpc last won the day on January 29

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  1. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    Right there, in the first step. Welp, there is probably no way to blame the box, or driver break-in, or material fatique. It´s the driver. Then I possibly have nothing in my hands to help. At least product support is good. Hope it is solved for good at B&C.
  2. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    Hey Paul, I might be slow on things - If they repaired yours under the warranty, while they didn´t find the issue, what was the solution then? (recone, replacement of drivers), and do you have your repaired driver back in fully working order without those issues? Was the original issue repeatable with free air driver, so B&C got better chance of finding it? I had small ticking noise with 18SW115 due to terminal leads, and maybe something with 21DS115, but only under very extreme conditions, while it solved itself after burn-in or with slight bending of those leads. Nothing like "diesel engine" as you guys describe it. I´m so used to B&C quality that I might feel childish butt-hurt at first, when I´d found less than flawless product from these... Anyway, I would blame the enclosure on first sight, but again, it´s hard to tell. You might need to do more detailed break-in procedures from now on, and break down all your steps between getting those drivers shipped and getting to the failure, to get to the issue.
  3. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    Hello. Depends what does it mean "problems" in some cases. Unglued coil is quite obvious, other issues might not be that obvious. I believe B&C speakers takes this seriously. Everytime I have slightest issues with those drivers, they requested serial numbers to check things up, and they were most helpful to solve the issue directly, so I didn´t even had to deal with the seller. Strong noise in suspension is very broad claim. Could you document it somehow, and specify more in detail? Aluminium four layer coil is probably hard to make reliable. It has lower melting point, it has more thermal expansion, and four layers with additional motor force also add trouble to the adhesives on voice coil, former and spiders. Anyway, I recommend you to deal with B&C, as we might not be of great help with already damaged product. I haven´t seen single damaged product from B&C in any similar way yet. Only second hand stories from far away, which sounded like miraculous occurrence. Also B&C Is one of those brands, which are copied by eastern countries a lot. Make sure you get original reliable product made by B&C Speakers.
  4. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    Bennett chimed in on another forum. It´s what you expected - different coil topology, possibly slightly different motor assy. Then with resting aspects offsetting the "apparent mathematical issue" make things doable. Thank you for all that technical chat and unwrapping my head from the maddness...
  5. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    I think that even that one about same motors have been claimed, but I might dig too long to even find it. It would make sense if it was little different, even when not counting on gap widths. It is true that coils of those speakers might not be specified precisely, and that can be why I cannot make it work. I only saw Quasi-split voice coil mentioned in 21SW152 specs on B&C site, but not for other speakers. Who know which models are made that way, which models are not, and what differences might be in the same coil topologies between drivers. It would definitely mess up some of my guesses about wire lengths and so on. One other thing flew over my mind. Copper is more diamagnetic, while Al is more paramagnetic material. Can it be, that the Aluminium actually alters the flux in the gap some more, compensating for some of the losses in greater gap? Just an idea. And also less back EMF. Yes, I fell into this deep rabbit hole for last month. It seems that I have no real use for it - Knowledge of speaker behavior as an "user" is enough to develop stuff. Yet human mind has this bad habit of exploring all kinds of rabbit holes. We even like to play with things that can easily kill us... 16 layer winds? OMG, how large magnet this one needs.... //repaired mistake in magnetism part
  6. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    That short version of your answer is not that bad at all. I actually wanted to hear something like that, because only "more wire in the gap" didn´t work well in my book. I touched some modeling, getting custom transformers made. Sometimes counted, sometimes physically "iterated" to expected performance. My nature is of "random electronic engineering". I might not know precisely, but at least there is some imagination. 🙂 All those compromises are understandable, but there is this main representative claim, that this advancement between virtually identical drivers with identical motor structures happened by replacing copper wire for Al wire (like 21SW115 and 21DS115, while IPALs don´t have these copper counterparts). That is my image of things, and how these are portrayed. Once it was claimed, I started to count for real, and it looks to me the way the wire easily cannot fit in the gap to make this change.... Like if B&C left one piece of some magic fact in that claim away from readers/listeners. It possibly is not just the wire, which is what you wrote. Then, I´m keen on finding what is it then...
  7. Crashpc

    B&C 21-IPAL Driver and Measurements Discussion

    Hey. I was digging deeper in some speaker parameters and detailed relations of voice coil work. It has been said for some B&C drivers, that they used Aluminium voice coil winding instead of Copper, to get more turns in the gap, to get greater motor force. That is easy to say, but it doesn´t seem that easy to do. For example with 21SW115 vs 21DS115. IPAL drivers also have Aluminium voice coils (wire) for that reason. The motor force is there, yet I still cannot wrap my head around it due to “apparent physics” of things. One needs to have 1,6x of wire area/volume of Aluminium to get to the conductivity per length compared to Copper. Then Accounting for Bl, (21SW115 vs 21DS115), on top of that, one needs double the wire length to get to the adequate outcome of Bl in slightly wider magnetic gap. Then the 21DS115 has longer coil with smaller Resistance, which again means, more wire. We´re talking about 3,5x more wire volume here. How come it works? It looks like to me like it cannot work "just like that". Even worse, the Mms of the Aluminium "aided" driver is more. IPALs are the same thing. Even greater motor force, but at least half of it can be attributed to greater flux density in the gap. It is not the case with other drivers. Can anybody help me solving this obvious thing mathematically (Resistance, wire length and volume) so the outcome makes sense? Thanks.
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