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mboxler

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Everything posted by mboxler

  1. Poking around on the Web, it looks like there is a switch on the front to control the tweeter? Perhaps it's a variable series resistor to pad down the tweeter? Also, sounds like the original capacitor was a 2uf non-polar electrolytic. If so, it's probably dried out and not functioning properly. I'd replace the capacitor with a 2uf polypropylene, and check the switch to make sure it's not faulty. BTW, a 2uf capacitor at 2500hz is around 32 ohms. The switch could be adding 24 ohms to an 8 ohm load to achieve that crossover point. Mike
  2. Looks like you got the rare dual phase plug K-55V with solder lugs!
  3. Correct me if I'm wrong, but phase can play into this as well. My memory may be fuzzy, but if an amplifier is driving a load with a -45 degree phase shift, only 70% of the supplied power is transformed into work. The remaining power is reabsorbed by the amp and dissipated as heat. In other words, to supply 100 watts of power to a driver @ -45 degrees, the amp will need to supply 140 watts and absorb 40 of those "unused" watts.
  4. I'm a little confused. Do you already have an AL-3 crossover? If so, it already has a T4A.
  5. I'm not sure what I had for breakfast this morning 🙄
  6. Sounds like we are in agreement. If the Atlas is only flat to 4500hz, and the AL3 tweeter filter has a steep 6000hz high pass, then there would be a hole in the 4500 to 6000hz range.
  7. The squawker is allowed to drop naturally on the AL3...there is no 6000hz low pass.
  8. I've always assumed that when Klipsch went back to the single phase plug K55, they added a 4500hz low pass to the squawker (AL4) to avoid the high frequency "shortfall"???
  9. The dual phase plug K55M is flatter to 6000hz, then drops like a rock. I assume this required the change from the AA type tweeter filter, which crosses closer to 5000hz, to the steep elliptical filter in the AL and AK series crossovers that cross at 6000hz. I would think that a K55V solder tab would work as well in the AL/AK crossovers, since it also is a dual phase plug.???
  10. As I understand it, there's a lot going on regarding the impedance of a K-33E in a Klipschorn... Voice coil DCR Voice coil inductance The loading of the horn itself Other things??? Bottom line, the impedance at 400hz ends up being around 6 ohms @ 28 degrees. That's equal to a 1.1mh inductor with 5.2 ohm DCR. At 800hz, it's 8 ohms @ 40 degrees, which equates to a 2mh inductor with 6.2 ohm DCR. It's a moving target that I assume shows up in your REW measurement. Mike
  11. It looks like a hybrid Type A/Universal. The black inductor is probably 2.5mh(?). Can you read the capacitor values on the left side of the picture? I'll guess they are 2.2uf and 6.8uf? Are there any labels on the black and red inductors that indicate the values?
  12. I don't see any obvious wiring errors. Perhaps the issue was with the woofers instead of the squawkers. It is a little hard to see inside the bass bin.
  13. That's the crossover frequency from the woofer to the squawker. Any chance you may have accidentally reversed the polarity to either of the drivers during the switch?
  14. Depends on what you mean by "proper" 🙂 Crites will use input taps 5 - 0 and output taps 4 - 0 to achieve a 3db attenuation to the squawker. The T2A's tap 4 used in the Klipsch Type A is actually -3.3db. If you want what I would consider proper, use input taps X - 0 and output taps X - 1. This will get you -3.3db and get you really close to the inductance of a T2A. Hopefully my poor drawing helps. Notice that the tweeter circuit now uses input taps X - 0 and output taps X - 0. Mike
  15. Looks like it. I'm playing with a severely underdamped filter consisting of a series 1.2mh inductor and 245uh worth of capacitance across the K33E. Seems to create a much flatter response up to 400hz compared to no filter at all.
  16. That looks like C2 on the pcb, so it's probably a capacitor. Hopefully you can remove it and find some legible markings to identify it.
  17. They are Khorns 🙂, but I've been listening to CT-125's. They are at least 6db quieter than the K77M.
  18. Thanks, Andy That kinda blows my theory out the window. I'm very tempted to buy a pair of alnico K77's just to see what's going on.
  19. Thought I'd post my conclusions here for so I can easily find my results. Like Dean said, it appears that the AA Network was designed for the K77 alnico tweeters. Research indicates that the K77M is hotter than the K77. I'll assume the AA was also designed for the K55V single phase plug drivers, as they are not as flat as the K55M from 4.7 to 6khz(?). Again, I don't have these drivers, but I'll assume my AA build is correct for the K55V/K77 driver combination. I am surprised how hot the K77M is. I finally got the idea to measure the raw frequency response of the K55M (200 to 20000hz) and the K77M (4500 to 20000hz). Around 4.7khz the K77M is actually 1db hotter than the K55M. The tweeter circuit of the AA isn't designed to handle the K55M/K77M driver combination. The steep slope of the AK tweeter filter, on the other hand, knocks off most of the voltage to the K77M below 6500hz. Mike
  20. Would you agree that it's odd that the SPL graph on Sweep 3 is different than the voltage graph?
  21. I believe so. This morning I ran a few more tests to ease my mind. My LTSpice model vs the REW plots come out very close. One thing that's difficult to model is the K77, as I believe it resonances in the 4 - 5khz range. I'm not smart enough to determine if that's why the SPL peaks sooner than the voltage. I appreciate all comments. Perhaps I'll install new diaphragms and try again. Again, thanks. Mike
  22. Thanks for the kind words. Your post is a great seqway to another measurement I took this morning (sorry Dean 😎). Without a zobel across the K33E, there's really no way to achieve a classic first order 6db per octave low pass. The inductance of the voice coil continuously raises the impedance of the woofer as frequency increases. With a series 2.5mh inductor, the result electrically is a much flatter transfer function (blue plot). Then there's the SPL itself. Even without an inductor, the SPL drops dramatically after 180hz. In my room, with a 2.5mh series inductor, the SPL is down around 12db at 400hz (green plot). I believe this creates my dip in frequency response between 160 and 410hz??? Mike
  23. That's confusing but you may be right. I assumed the switch dictated phone or aux. The manual isn't very clear.
  24. Without a schematic it's impossible to know. That said, it appears that the fives use DSP for crossover/equalization. If that's the case, I would think that an analog signal would first need to be converted to digital, processed, then converted back to analog. An input digital signal would not necessarily need the extra ADC step. FYI, don't connect anything other than a turntable to the phono jacks. A phono preamp is expecting the very low voltage generated by the phono cartridge which then gets amplified/corrected to a line level voltage. Use the aux input for line level input signals, such as your DAC.
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