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mboxler

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Everything posted by mboxler

  1. mboxler

    T9A AUTOTRANSFORMER HOOKUP QUESTION.

    The T9A actually has -3db attenuation. The T4A has -4db attenuation. Looks like the T4A was used in the Belle AB-2 crossover. If using the T9A... Hook input - to 0 output - to 0. Hook input + to 5, output + to 4. Mike
  2. mboxler

    Basic KHorn XO Question

    Since the woofer is getting all frequencies, his crossover looks like a first order band pass to the autoformer/squawker and a third order high pass to the tweeter.
  3. mboxler

    Basic KHorn XO Question

    There should have been a 4mh inductor and two 70uf capacitors in the bass bin. If you removed them, and have only wire between the input and the woofer driver, than yes the woofer is receiving all frequencies.
  4. mboxler

    La Scala crossover

    Not sure if you want to know what the current rating of the stock 2.5mh inductor is, or how much current can pass through the inductor. I don't know the stock inductor rating, but... I believe the K-33 can handle 150 watts. If we assume the lowest impedance is 4 ohms, and use Ohm's Law, that equates to around 24 volts and 6.1 amps. Since the inductor is in series with the K-33, current through both will be the same...6.1 amps. Perhaps over simplified, but I hope that helps. Mike
  5. mboxler

    A DIY Single Ended Class A Kit

    If memory serves, it's 5.5 x 2.5. If you're currently using a laptop PS, the connector size is usually printed on the label. Mike
  6. mboxler

    ALK universal crossover

    Oddly enough, I'm currently "rebuilding" my ALK Universal kits I purchased quite a few years back for my K-horns. It was my first soldering project, and it looked like gray gum wadded around the connections. I'm seriously considering replacing the 1.3mh woofer coil that came with the kit with the 2.5mh value used in the type A and AA. I know Al argued for the 1.3mh, but I find it odd that his Super AA upgrade keeps the stock 2.5mh woofer coil. While testing the rebuilt crossovers, I wanted to find out the frequency where the voltage across the 1.3mh inductor equals the voltage across the K-33 (the -3b voltage point). It turned out to be around 1400 hz! As it turns out, the impedance of a 1.3mh inductor at 1400 hz is 11.4 ohms, which must be the impedance K-33 at 1400 hz??? For fun, I hooked up a 2.5mh inductor between the amp and the K-33, and found the -3db voltage to be closer to 400 hz, or 6.2 ohms. Seems like replacing the ALK Universal woofer coil might be an interesting experiment. Mike
  7. mboxler

    Klipsch Balancing Network Mysteries

    Using this calculator http://www.pronine.ca/capimp.htm Change Capacitance to uF and Frequency to Hz. A first order rolloff (-3 db) occurs when the impedance of the capacitor equals to impedance of the series load. This occurs at a specific frequency. The tweeter capacitor ALWAYS has a 8 ohm load (the K-77). Using the calculator, plug in 2 uF and 8 ohms. When you click Calculate, the Frequency will show 9947.1875 Hz. That's the crossover frequency to the tweeter. Moving the tweeter tap will not change this, because the cap is after the autoformer. The K-55 cap (4 uF) is before the autoformer. Since it is using input 0-5 and output 0-3, the impedance of the K-55 appears 4 times bigger. Assuming the impedance of the K-55 is 15 ohms, the load on the 4 uF capacitor will be 60 ohms. Plug those numbers into the calculator, and you will get a frequency of around 663 Hz. If you change the output tap to 0-2, then the load is 8 times bigger, or 120 ohms. If you want to keep the same 663 Hz crossover frequency, plug in 120 Ohm, 663 Hz Frequency, and the calculator will determine that a 2 uF capacitor is required. Hope that helps! Mike
  8. mboxler

    Bi-Amp question / thought

    Interesting. Are you running a 400 hz low pass signal from the Xilica XP 4080 straight to the K-33, but a delayed full signal from the Xilica XP 4080 to the HP section of the original crossover? The 13 uf capacitor of the HP crossover is still the high pass filter for the K-55? Mike
  9. mboxler

    Bi-Amp question / thought

    What passive are you using for the mid to high crossover?
  10. mboxler

    Bi-Amp question / thought

    Not sure if this helps, but here's a Type-A-BA (bi-amp) crossover I'm working on. SInce the active crossover replaces the 2.5 mh inductor (low pass filter) and the 13 uf capacitor (high pass filter) of the Type-A crossover, all that remains is an autoformer and 2 uf cap. I even went so far as to reverse the function of the autoformer. Instead of attenuating the mid by 3 db, the autoformer passes a 3 db gain to the tweeter. Since I'm using the same amp type for the low and high pass, I run the low pass amp at full volume, and the high pass amp at around 12 o'clock. Mike
  11. mboxler

    Bi-Amp question / thought

    PM sent.
  12. mboxler

    Bi-Amp question / thought

    I've been curious about the Xkitz products too. If you are willing to do some DIY, I'd be happy to send you a pair of Marchand XM1's with 500 hz modules, as well as the power supply for them. They are unbalanced input/output only. Regarding Al's crossover, hopefully someone smarter than me will chime in. It appears that the ends of the 33uf cap are soldered to copper (?) posts. If one were to connect a 14 AWG wire with alligator clips to the two posts, would that not bypass the capacitor completely? Now the crossover will only passively split the high pass signal from the active crossover to the mid and high drivers. Mike
  13. mboxler

    Bi-Amp question / thought

    It shouldn't be that hard to bypass the hi-pass portion of the passive crossover and drive the mid/high drivers using the hi-pass of the active crossover. If you could post a picture/schematic of the passive crossover, we could find out. Mike
  14. mboxler

    PC computer question

    If your motherboard has SPDIF out pins, and you have an open slot, this works great. I have one on my ASUS motherboard. https://www.ebay.com/itm/SPDIF-Optical-and-RCA-Out-Plate-Cable-Bracket-for-ASUS-Gigabyte-MSI-Motherboard/273133351510?epid=1247152598&hash=item3f98043256:g:Lf0AAOSwUIFavPhf
  15. mboxler

    12volt amplifier for la scala vintage

    The TDA7297 is a wonderful chip amp!
  16. mboxler

    SOLD Reckhorn DSP-6 Digital Crossover - SOLD

    Hey Warren Yes, it is still available! Mike
  17. Like new Reckhorn DSP-6 digital crossover, purchased new 2 years ago. Could never get a manual, but I was able to figure out the basic way to configure. I'll be happy to preload the unit with a specific configuration if requested (slopes, crossover points, delays, gain). According to the webpage... "The program is running on all operating programs Window XP to Windows 8 up to 32-bit, but not on 64-bit versions and Apple." I installed it on Windows 7, and it still running on 64 bit Windows 10. Original box. Will include a better USB cable than the one shipped with the unit, as I was having trouble connecting with the stock cable. https://www.reckhorn.net/pages/active-x-over/dsp-6-digital-speaker-crossover.php http://www.tnt-audio.com/sorgenti/reckhorn_dsp6_e.html Currently selling new on Amazon for $399. $175 shipped to conus, including PP fees. Mike
  18. I'm in the process of re-capping my H2's, even though the original caps measured very close to 2uf. However, I was surprised to find out that the ESR measured from .85 ohm to 1.1 ohm on the originals caps. I then measured the inductor...4.17mh, but DCR of 1.6 ohms. I agree that inductors don't wear out, but I'm replacing it with a .22 ohm DCR inductor to see if the amp can better control the woofer. I'm curious if anyone else has measured the DCR on the original woofer inductors. Mike
  19. Did Al make these universals specially for you or are these Bob's A-4500's?
  20. mboxler

    Active Bi-Amping/Tri-Amping FAQ

    I'm sure this distance is buried somewhere in this thread, but using 48LR, at 400hz, introduces a 2.5ms/86cm delay times two, or 5ms/172cm delay. How many cm or inches does one add for the physical distance between the K-33 and the K-55 on a Khorn? Thanks, Mike
  21. mboxler

    Class D

    Curious how you came up with those voltages. The maximum TPA3255 input voltage is 7 volts p-p; however, at a 21.5 db voltage gain (or 11.9 times), that would equate to 83.3 volts p-p. With a 53.5 volt power supply, you're clipping. 4.5 p-p, or 1.6 rms gets you to max, so I would think your max input voltage would be 1.6 rms unbalanced and 3.2 rms balanced. Am I missing something? Mike
  22. I had tested this before, thought I'd try again. I find this stuff fun, but I'm weird. I applied a 5.05 volt, 1160 hz signal to a dummy crossover (yes, I named it after myself). I picked this frequency because at 1160 hz, the impedance of the 6.66 uf capacitor I used = 20.6 ohms, and the impedance of the 10.3 ohm resistor I had across taps 0-4 should double. This would be the resonance frequency, the frequency at which the voltage across the load (taps 0-5) should be down 3 dB. 6.66 uf cap between input positive and tap 5 of autoformer. Wire between input negative and tap 0 of autoformer. Wire between tap 0 of autoformer and one end of 10.3 ohm resistor. Wire between tap 4 of autoformer and the other end of the 10.3 ohm resistor. Input voltage, 5.05 volts at 1160 hz Voltage across cap, 3.61 volts Voltage across taps 0 - 5, 3.66 volts Voltage across taps 0 - 4, 2.58 volts Now the fun part. The impedance of a 6.66 uf cap in series with a 20.6 ohm load is 29.135 ohms. The current of 5.05 volts thru a 29.135 ohm load is .17334 amps. .17334 amps thru a 20.6 ohm load (the capacitor) = 3.57 volts...pretty close to the 3.61 I measured. Voltage across taps 0-4 should be 3.61 * .707, or 2.55 volts...again, pretty close to the 2.58 I measured. This confirms to me that the autoformer (at least when using it to attenuate the K-55 by 3 dB), doesn't have much if any affect. Mike
  23. mboxler

    Measuring K-33 impedance in K-horn.

    A first order filter is doesn't do much within a couple hundred Hz either side of resonance. If everything was perfect (2.4 mH inductor, 6 ohm load, 400 hz), the voltage to the K-33 is down 3 dB. At 500 Hz, it's down 4 db. At 600, around 5 dB. If both the K-33 and K-55 were perfectly crossed (first order) at 400 hz, they would each be down 3 dB. The voltage across both drivers combine at 400 hz, resulting in a 0 dB summed voltage. It would be a 3 dB bump when summed, but the voltages across each driver is 90 degrees apart. As you can imagine, even if the K-33 were crossed at 400 hz and the K-55 at 500 hz, the combination would be down less than .5 dB around 450 hz (I didn't do the math). Too little to make any difference. Again, this is voltage only. Driver sensitivity, cabinet, room, and kids will change everything. That's my theory anyway! Mike
  24. I would like to measure the impedance of the K-33 in my K-horns at 400 hz. I've assembled a "patch cable" to place between my amp and the bass bin. The cable contains a 101.5 ohm 10 watt resistor that will end up in series with the woofer. The resistor actually measures 101.5 ohms. I have a free product on my Windows PC (fg_lite from Marchand Electronics) that allows me to generate the 400 hz signal. The chain will be PC-->DAC-->amplifier-->speaker cable-->patch cable-->right K-horn bass bin binding posts. These binding posts are connected directly to the K-33. When the signal is generated, I will turn the amp up until the tone becomes somewhat loud. I will use my Fluke 115 Trus RMS meter to measure the voltage across the right amplifier binding posts. I'll call the Vin. I will then measure the voltage drop across the 101.5 ohm resistor. I'll call this Vr. I will then calculate the current through the resistor. This will be Ir. Ir = Vr / 101.5. I will then calculate the voltage drop across the K-33, which should be Vin - Vr. I'll call that Vk33. Since the current passing through the resistor must be equal to the current through the K-33, I can calculate the impedance (resistance) of the K-33, I'll call that Rk33. Rk33 = Vk33 / Ir. This is what I ended up with... Vin = 6.325 volts Vr = 5.995 volts vk33 = .33 volts (man that's loud!) ir = .059 amps Vk33 = 5.887 ohms Does this method correctly measure the impedance of the K-33 at 400 hz? If so, I think I'll plot a few other frequencies just for fun. Sorry if this has been tried before. Thanks, Mike
  25. mboxler

    Measuring K-33 impedance in K-horn.

    Thanks for doing that! Odd that the impedance is lower at 50 hz in the horn than in free air (which I assume is the black graph). Mike
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