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About mboxler

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  1. Sorry for the confusion. I thought you were interested in a change similar to Bob Crite's A-4500. I'm assuming the components to change a Type A to a Type A-4500 would be identical to the ones needed to change a Type E to a Type E-4500. So, add the .5mH coil to the K-55 leg and replace the 2uF tweeter capacitor with a 4uF. Again, I haven't tried this. Here's the schematic and resulting plot. I'm a "If it sounds good it's right" guy, so experiment. Add the coil first, and hear how it sounds. Add 1uF to the tweeter cap (3uF). Add 2uF to the tweeter cap (4uF). Let us know what sounds best to you! Mike
  2. Here's an E-4500 crossover I've simulated but not built. I was going to use the CT-125 tweeter, though. The T2A autoformer is also replaced with a simulated 3636, using the same taps. Not sure how safe it would be with your EV tweeter. Now you got me thinking about building a pair. Mike Mike
  3. Hey Mark Although not nearly as knowledgeable as Dean, I'll try to answer your question. The purpose of the 10 ohm green resistor across taps 0 - 5 of the autoformer is to keep the load on the high pass capacitor to around 8 ohms. To keep it simple, let's identify the crossover point to be the frequency at which the impedance of the high pass capacitor equals 8 ohms. I use this calculator to determine that frequency. http://www.pronine.ca/capimp.htm If you enter 47uf in the capacitance field, and 8 ohms in the impedance field, you get 423 Hz as the crossover frequency. 49 - 50uf gets you close to 400 Hz. 40uf gets you closer to 500 Hz. If you enter 33uf, you get 603 Hz. Keep in mind that this is a gentle slope electrical filter. Acoustically you may like the sound of a 500 Hz capacitor in a 400 Hz horn. Hope that helps! Mike
  4. Non-inductive resistors are recommended, although the error of an "inductive" resistor will generally not be apparent in the audio band. I can't see a reason why that resistor wouldn't work, although I use these across the autoformer. There is an 11 ohm version if that's what you want. https://meniscusaudio.com/product/10-ohm-10-watt-mox/ Mike
  5. Apologies, @sootshe, but I have a question for @Deang I modified the Type A/AA illustration with a hybrid approach for the 3636 / 10 ohm shunt resistor. By placing the resistor on the 3636 side of the capacitor to common, the intended 1 db attenuations of the 3636 can be utilized. This , too, represents a "Constant Impedance". Connect tap 0 to common (input '-' and squawker '-'). Connect capacitor (with shunt resistor) to tap 5 (+0 db), tap y (+1db), or tap x (+2db). Connect tap 1 (-12db) , 2 (-9 db), 3 (-6db), or 4 (-3 db) to "output " squawker '+'. I know you feel that both "outputs" to the squawker must float, but I don't understand why? I like the ability to get attenuations in 1 db increments. Thanks, Mike
  6. It's unfortunate that the terms Plus and Minus. Positive and Negative, and even Ground worked their way into speaker terminology. They are either misleading or flat out wrong. I wonder if you changed the crossover input and output labels from "+" and "-" to Red and Black? The only purpose of the labels is to help with the amplifier and driver connections. Perhaps things will be a little clearer??? Mike
  7. Sorry, but I don't seem to follow, unless you want to connect tap 0 to input IN- ? That wouldn't hurt, but tap 0 is already connected to the common bar at Mid+. Let's say you do. Connect IN- to tap 0. Connect the "output" of the .2mH inductor to either x,y, or 5. Two connections I drew 4 possible connections "above" the 3636 indicating either 1,2,3,or 4. Connect this wire to Mid-. Connect tap 0 to Mid+. Two connections. Regarding the crossover photo. It's hard to tell from the 3619, but it appears that... Tap 0 to common Tap 5 to inductor and Mid + Tap 2 to Mid -. So, input 0 - 5, output 2 - 5. Not your normal connection, but if my calculations are correct, you get a 1.546 turns ratio, (3.78 db attenuation), and phase reversal. It will work, but attenuation levels of taps 1 - 4 are not standard. I'm not sure how to wire the 3636 that way. Sorry I'm not helping. Mike
  8. Looks like the output to the squawker is inverted, so think I allowed for that in the attached. The "output" from the .2mH inductor should connect to Tap 5, x, or y, as well as one end of the resistor. The other side of the resistor to common (tap 0). Mid - should connect to Tap 1, 2, 3, or 4. I moved the common bar connection from Mid - to Mid +, so that Tap 0 is always connected to the common bar. So, for -6 db, input 0 - 5, output 3 - 0 . Hard to tell, but the pictures show only three wires attached to the 3636 as well. Tap 0 is both input and output and connected to common. I reserve the right to disagree with myself later, but for now this seems right. See what you think. Mike
  9. More like this. I missed something earlier, and deleted the wire from the "top" of the 40uf cap to tap 0. Sorry for the poor "Paint" job. I may find something else after my coffee kicks in.
  10. If you know what mid driver you will be using, and you want the ability to attenuate the tweeter, remove the .2mh inductor from the input, and we can calculate it's replacement and position it between tap 3 and the mid driver. Now, if you want to attenuate the tweeter by 3db, attach the 2.2uf cap to tap 4 instead of tap 5.
  11. The .2mh inductor needs to be in series between the 40uf cap and the 3636, like you have the .15mh inductor between the 2.2uf and 3.9uf caps. The .15mh inductor should not be in series with the 2.2uf and 3.9uf caps. Connect the two caps together, draw a line from the middle of that connection to one side of the .15mh inductor, then connect the other side of the .15mh inductor to common. Place a 10 ohm resistor across taps 0 - 5 of the 3636.
  12. I'm definitely no expert, but... Attached is a schematic of an adjustable Type A that I may build someday. Ignore the 26uf cap on the output. I changed the 3636 to show the taps in a clearer way. In fact, you could put new labels on the 3636, changing... 5 to +0 db y to +1 db x to +2 db 4 to - 3 db 3 to -6 db 2 to -9 db 1 to -12 db The .2mh inductor and 10 ohm resistor should connect to a point on the board, not to the 3636. You then need a wire with a quick disconnect. Solder one end of the the wire to this point, and move the quick disconnect end to +0 db, +1 db, or +2 db taps. Run a wire from the positive side of the K-55 to another point on the board. Again, you then need another wire with a quick disconnect. Solder one end of the the wire to this point, and move the quick disconnect end to -3db, -6db, -9db, or -12db taps. Hopefully, this is a clear way to decrease the voltage to the K-55 in 1 db increments by "adding" the input tap to the output tap. In the attached schematic, input is +0 db, output is -3 db, so the "sum" of the taps = -3 db. I hope that was somewhat clear. Mike
  13. Ahh, the fun with passives. After all the work building them, you always wonder if a component here or there would have made an improvement. If you want the tweeter attenuated, you need even more changes. If I were to go to all the effort to build a pair of speakers, I'd go active. Even bi-amped, with a passive between the squawker and the tweeter, will sound great. You can easily play with the woofer to squawker crossing points and voltages. Six or seven years ago, I had Al build me a bi-amp, extreme slope version of his ES5800. He removed the tweeter autoformer and added the squawker autoformer. The picture of the ES5800T on his website is mine. It sounded great, but I wanted the flexibility to go fully passive as well. I built a simple low pass/hi pass filter to put ahead of it, using a 2.5 mH inductor and two 24uF capacitors. Now I have four options...single wire, bi-wire, passive bi-amp, active bi-amp. Mike
  14. I would think 2.5mH would be okay. This is an electrical low-pass filter. The natural rolloff of the loaded woofer plays into it as well. I have Khorns. Perhaps someone with Belles could jump in.
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