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WMcD

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About WMcD

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  1. WMcD

    What value Capacitor ?

    I see the spec sheet has a contraction to some extent. In text it recommends a 12 dB crossover designed to crossover above 7000 Hz. This will require a cap and inductor. But they show a schematic with only a cap, which results in a 6 dB rolloff. If I were doing this I'd use a 12 dB or even 18 dB (two caps and an inductor for this highpass application). You can find calculators on line to figure values. WMcD
  2. WMcD

    K horn backs

    A lot of questions. By nutsers I believe you mean the brass device which has a bore to take a machine screw and a coarse threaded outer. I tried them a few decades ago when I made 3/4 ply SK's with backs It was very difficult to get the nutsers square into the edge of a 3/4 inch piece of ply, and get everything to line up. I eventually gave them to my nephew. He could not keep them and eventually they were donated to a church group in Texas. A long time ago I took a look at the claims for the K-Horn patent. U.S. patents are not required to point out the "point of novelty." But in many claims it appeared to me that it was that the walls of the room were part of the structure but independent from the horn. Therefore a K-Horn with a built-in back was not covered by the patent and to some extent would avoid it. Of course the patent term ended and PWK did not market a closed-back unit even then Rather, he present the artificial corner. I can't help but think it was an inventor's pride. Also, some clever fellow even at the start could put a closed back on K-Horn and challenge him to sue. Essentially, if PWK put a back on his K-Horn, it would not be his patented K-Horn. It seems to me that the build of the K-Horn would have to work with base boards in those days. However, baseboards are not used in modern construction too much and the theory that an external trihedral wall structure is needed for patent protection, or right to sue, was long gone. I'll point out that the Jubilee has a sealed back and no cut out for base boards. So to with the newer K-Horns. WMcD WMcD
  3. WMcD

    Can you tell me more about these speakers

    You should open your picture in MS Paint which is present in all Windows versions. Use the Image tab to select resize and skew icon (overlapping white rectangles). Try 25% horizontal and vertical to start. The idea is to show the entire image on your screen. Save that and post using "choose files." WMcD
  4. WMcD

    New Klipschorn AK6 coming out?

    Hmm . . . if the AK-5 is no longer in production, being replaced with the AK-6, then maybe Klipsch will release a schematic of the AK-5. Whooo Hooo! WMcD
  5. WMcD

    La Scala crossover

    Good to hear from you John. So if Power = I*I*R, we have 3.2 amps to make 63 watts into 6 ohms. (Neglecting whatever resistance is in the inductor.) 63 watts is 18 dB above 1 watt at which a K-Horn is rated for 105 dB. So we would have an output of 123 dB. The spec sheet says that max output is 120 dB. Overall, It makes sense. (I hope my math is correct. Back when PWK made the statement the rated sensitivity was probably 104 dB. ) John, I look forward to seeing the interview if it is convenient for you to post it. I recall reading one where PWK said he ran K-Horns with the inductor shorted out and "its worth a couple of dB." (Wish I could find it now.) But this means that the boss's favorite inductor for an A in a K-Horn is no inductor at all. I wonder if that goes for the LaScala too. Smile.
  6. WMcD

    La Scala crossover

    To start, I have never seen a spec for the transformer-like inductor used in the A type woofer series. Also, current rating for inductors would probably be used when they are used as a "choke" in a power supply where they are used to choke off 60 Hz in a power supply circuit. They have to pass amounts of d.c. current on a continuous basis. In crossovers we are dealing with music with no d.c. We have a complicated mix of a.c. It is difficult to find a consensus on the equivalent power in a music signal. It is certainly less than a continuous sine wave. There is a standard someplace which I don't have. But essentially, noise which a spectral distribution of frequencies is used to test drivers and, I suppose, determine at what level they fail. That signal was to simulate music, very roughly. My favorite example is an old rating of a T-35 tweeter which is about 2 or 3 watts of sine wave continuous. Yet the tweeter in a Forte (probably similar enough for discussion) was tested up to about 1000 watts at it high freqs as I recall, if the sine wave of that power was pulse on and off so there was time for cooling. So, it seems a tweeter is good for 2 watts of continuous sine waves and maybe 1000 watts if the input is band limited and not continuous. Looking at the autoformer we don't have specs. The Atlas driver is rated for 40 watts "power level." I doubt that is 40 watts continuous sine wave. I'll guess at 15 watts. The autoformer might have a similar rating. If you have to put a number on it. It is probably the same for woofers. A "150 watt" woofer rating is probably established with this noise simulation of music. Going to the woofer inductor. Generally the main concern is the d.c. resistance. Again, we don't have that for what Klipsch used on A series. OTOH there are specs to be seen on more recent crossovers. You can take a look in the Technical / Modification section for schematics. I put together a compilation which appears at page 11. There is, there, a requirement for less than 0.25 ohms for some. Looking at Parts Express we see that generally, iron/steel core inductors using 18 awg windings have higher but 16 awg have lower. The more recent crossovers use inductions of this physical form. https://www.parts-express.com/erse-super-q-25mh-16-awg-500w-inductor-crossover-coil--266-908#lblProductDetails Another issue is at which current the core saturates, which is bad. I've never seen a spec on that although you'll see ratings in the 100s of watts. Some people are very concerned about d.c.r. I'm not so sure. We have 4 or 8 ohms in the circuit and then wring hands over 0.5 vs 0.2 additional. Overall if you want to simulate an A, I think an 18 awg is okay. If it bothers you, you could use a 16 awg. WMcD
  7. WMcD

    wedding, hospital, birthday...

    Condolences. My one-year-younger "twin" sister passed 10 years ago. Just today the thought crossed my mind that I should call her. Late last year her son and daughter-in-law had twins and the girl has my sister's name as a middle name. Nice. WMcD
  8. WMcD

    La Scala crossover

    I would not apply 50 or 60 Hz to the autotransformer. In the design it is handling 400 to 15000 Hz. So try maybe 1000 Hz if you're experimenting. As far as I know that is the info for the T2A. The table re Vout is saying that if 10 volts a.c. are applied between terminals 0 to 5, the outputs are had between terminal 0 and 4, 3, 2, and 1 at the listed voltages. In the A type crossover the terminals 0 and 4 are used as the output to the midrange. This set up steps down the voltage by a factor of 6.8 to 10 (as shown in the table). We usually use dB in audio matters. The dB "gain" re volts is calculated by 20 log (6.8 / 10) which equals -3.35, or about 3 dB loss. This is because the mid driver and horn is about 3 dB more sensitive than the tweeter or woofer. You'll see the dB loss in the table is "3" and the use of quotes shows it is not exactly 3 (actually it is 3.35 by the above calculation). Maybe the above is a bit confusing in the minus sign. + dB is voltage, power, current increase. - dB is voltage, power, current decrease. Here were stepping down voltage and we use minus gain or -dB. I'll think about current rating for the inductor for a while or someone can chime in. WMcD
  9. WMcD

    La Scala crossover

    Here is the timeline on the LaScala. It gives information on crossovers used. Lascala Timeline cached.pdf
  10. WMcD

    La Scala crossover

    Here is a spec sheet for an early LaScala. It could be that the crossover type listed was renamed the "A." WMcD https://2d73e25b29782b6d6766-9c8af5cbfef16739445bc76457060528.ssl.cf2.rackcdn.com/Spec_650000_LaScala_635120758436390000.pdf
  11. It sounds like you have the situation well in hand and therefore I have nothing to add. Odd things can happen in warehouses. A long time ago I visited Computer Discount Warehouse (a big reputable operation) to buy some memory. An older fellow was at the counter along side me with a shipping box. He told the clerk, "I ordered one of the new hard disks for my PC and this is what was in the box. It doesn't look like a hard disk. " Indeed, it was a less expensive floppy drive. Some reprobate, probably in the warehouse, had made the switch. CDW did the right thing of course as the law requires. WMcD
  12. WMcD

    Spring clip connections

    Could you send pictures. It could be that one pair is for connection to a 70-volt distribution system and the other for connection to a regular amplifier. Do you see any labels like that? WMcD
  13. An interesting story: https://en.wikipedia.org/wiki/Hook_and_loop_fastener WMcD
  14. The article in the link shows that Mark IV acquired many audio companies including EV and University Sound. Now it seems Bosch owns a similar collection. http://proaudioencyclopedia.com/a-historical-look-at-electro-voice/ My understanding, too, is that the companies were separate for decades before. I have no idea why management would take products originated by EV and sell them as University. WMcD
  15. The spec sheet for the T-35A from University T35A University Spec Sheet.pdf
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