Jump to content


  • Posts

  • Joined

  • Last visited

Profile Information

  • Gender
  • Location
    Golden CO

Recent Profile Visitors

4390 profile views

mboxler's Achievements

Forum Veteran

Forum Veteran (4/9)



  1. This may help with I2S https://hackaday.com/2019/04/18/all-you-need-to-know-about-i2s/ Yes, the amp has a built in DAC, otherwise it's pretty much identical to the MA12070. In fact, all of the analog input pins on the MA12070 are digital input pins on the MA12070p. Since I can't get analog out of the ESP32 (I2S or SPDIF only), the MA12070p is a great fit. Here's the MA12070p datasheet. Infineon-MA12070P-DS-v01_00-EN.pdf Mike
  2. This took a lot longer to get going than it should have 🙁 This is an ESP32-WROVER (running Squeezelite-ESP32) connected to a Merus MA12070p (Class D) reference board (on the left). The MA12070p chip is I2S input only, hence the wires for bit clock, word clock, and data. Other wires are for I2C connection. I'm a Squeezebox fan, and with this setup I can stream Tidal, Spotify, Radio Paradise, etc. Playing through a pair of full range speakers now but really sounds nice! Mike
  3. An example of this setup. The resistors are there for testing only 😎
  4. I guess I should have asked what the high pass frequency is from the DSP. If it's low enough, and the slope is steep enough, you won't notice a difference. Sorry about that. I have a pair of ALK ES5800t crossovers in the Garage Sale that would replace the ALK-3 top hat section and give you more control over the high pass signal to the squawker/tweeter. Mike Mike
  5. I assume you are sending the full signal to the top hat crossover and not the high pass from your DSP???
  6. Sorry, need to get my eyes checked (which happens to be this Thursday). What I meant was drastically increase all the inductor values. I changed all my mH to H. In your case 5.83m becomes 5.83, or 5.83h. I should have said multiply all the inductor values by 1000 (?). In my screenshot, I placed a 13uf capacitor in series with each load, using a 14.6 ohm resistor across taps 0-4. The plots are the voltage drops across the capacitor. Gray is the autoformer in Herry. Green is mH. Red is the DATS sweep. Sorry again for my poor explanation.
  7. Kind of. If you were to plot V(Tap5)/I(V1) you will get the impedance across taps 0-5 of the autoformer. The impedance plot of my DATS test was much closer to the "Henry" vs the "MilliHenry" values. I can't guarantee my DATS test was accurate, but the results were surprising.
  8. Thanks for the link. I had a DATS V3 sitting around and tried it out. I attached the DATS to taps 0 - 5 of a 3636 and a 14.6 ohm resistor to taps 0 - 4, and was able to use the exported file as an LTSpice sub circuit. I compared that to my 3636 simulation and was bummed that it didn't match. As far as I can tell, the real 3636's inductance had no effect on the lower frequencies. I got the idea to change my 3636 simulation inductors from Mh to full Henrys 😮. Reran the simulation and got an almost identical match. I don't understand why it worked, but I was wandering if you could try this yourself and see what happens. Mike
  9. Hey @Wirrunna Actually, the network will see the 10 ohm resistor in parallel with the impedance reflected across taps 0 -5 of the autoformer. In the case of the tweeter network, if the tweeter is running off taps 0 - 4, the impedance across taps 0 - 5 will be around 16 ohms. 16 ohms in parallel with the 10 ohm resistor is around 6.1 ohms. If using output taps 0 - 3, it will be 7.6 ohms. Sorry if you already know this, but I stumbled upon a neat Spice directive, the .step param. Instead of giving the resistor a fixed value (10 in your case), you can assign it {R_Value}. Then, add a Spice directive (the .op tab on the top right), and paste something like this .step param R_Value list 6.1 7.6 When you run your simulation, and click on the voltage across the resistor, you will get two plots, one for the 6.1 value and one for the 7.6 value. I find this handy when simulating capacitor and inductor values as well. Mike
  10. These are the bi-amp versions of Al's ES5800 crossovers. They split the high pass signal, sending frequencies below 5800 Hz to the squawker and frequencies above 5800Hz to the tweeter. I had Al modify the ES5800, eliminating the tweeter autoformer and moving the squawker autoformer from the ES400 to the ES5800t. The idea behind the design is to attenuate the squawker to match the tweeter, then adjust the gain of the high-pass amp to match the low-pass amp/woofer SPL. Although these are designed for an active bi-amp system, I have also run these fully passive, using an simple inductor/capacitor network ahead of the ES5800t. $320 shipped to the lower 48. Mike
  11. Again, thanks for measuring. I realize the inductance is not important to you. That said, I believe there must be an error with your T2A #1 measurements(?). For example, taps 0 - 1 represent 1/4 of the total turns of the autoformer, and therefore the inductance should be 1/16 of the total inductance. If you were to measure the inductance of taps 0 - 5, I doubt if it's 8.96mH * 16 or 143.36mH. Mike
  12. Thank you for measuring! I've been trying to determine if the inductance differences between the 3636 and the T2A are noticeable using stock Klipsch schematics. I'm also considering building an AK-3 to replace my AK-2 and don't know how different the parallel 5mH inductor would be 3636 vs T4A. It probably won't make much of a difference but it's fun to run the simulations.
  13. Perhaps I don't understand what this means. I believe you demonstrated that the autoformer itself doesn't change phase. But when used with a series capacitor, as @Deang mentions above, won't the inductance of the output taps increase the phase shift of the circuit, creating a 2nd order high pass to the squawker? A capacitor/l-lad circuit will still be first order. Again, I believe the inductance of the T2A is close to half that of the 3636, so the T2A phase shift increase would be greater. Mike
  14. I don't fully understand your predictions, but here are the 3636 and T2A. The 3636 is based on 76mH taps 0-5. The T2A on 44.8mH. Mike 3636.asc T2A.asc
  15. I for one have always wondered if the autoformer's inductance is as irrelevant as some have claimed. The spec sheet for the T2A states that the inductance between taps 0 - 3 is 11.4mH +- 15% (at 1000Hz?). My meter measures 8.5mH on one of my T2A's, taps 0 - 3. I'm sure your equipment is better that mine. What is the inductance across taps 0 - 3 on the 3636? Do you have a T2A to measure? I assume your tests were conducted without a series capacitor, therefore the autoformer's inductance would have no affect on the voltage across the driver. It would be interesting to run similar tests with appropriate series capacitors to see how the shunt inductance affects the frequency curve. Thanks, Mike
  • Create New...