Folks,
Does anybody here know of a manufacturer of air core inductors suitable for audio power amp applications? Something like 1.0 - 1.5 uH capable of handling 10 - 20 A RMS.
In the output of a power amp, you often see a Thiele or Zobel network consisting of an inductor in parallel with a resistor. For distortion reasons, it is desirable to use an air core inductor. Winding an inductor for a DIY amp is no big deal, but if one wants to do automated assembly, having a ready made part would be really handy.
I've tried the high-current iron core inductors commonly used in Class D amps, but they distort pretty badly, especially at high frequencies (>10 kHz).
Thanks,
Tom
Does anybody here know of a manufacturer of air core inductors suitable for audio power amp applications? Something like 1.0 - 1.5 uH capable of handling 10 - 20 A RMS.
In the output of a power amp, you often see a Thiele or Zobel network consisting of an inductor in parallel with a resistor. For distortion reasons, it is desirable to use an air core inductor. Winding an inductor for a DIY amp is no big deal, but if one wants to do automated assembly, having a ready made part would be really handy.
I've tried the high-current iron core inductors commonly used in Class D amps, but they distort pretty badly, especially at high frequencies (>10 kHz).
Thanks,
Tom
They may be able to make larger inductance ones. Coilcraft 1010VS, 1212VS, 2014VS Power Air Core Inductors
It would be gross and ugly distortion. Never use other than air core on the output.
Yes, maybe a dozen turns around a large diameter PS cap. This does add a little distortion, though.
I bought a large air core from https://www.madisoundspeakerstore.com/compare-solen-perfectlay before. It was pricey, but plenty current capable.
To be precise - I asked for measurements, not for opinions. Are there any numbers available?
I made a quick check on a 5µH/10A choke like this one:
An externally hosted image should be here but it was not working when we last tested it.
With a 1KHz, 10A^ current (7.07Arms), the voltage appearing across the choke had 0.8% distortion.
Of course, that is not the distortion value for the current, because of the HP filtering effect on harmonics.
Taking this into account, the parasitic resistance, plus the fact that it's mostly 3rd harmonic translates into ~0.25% distortion for the current.
Just wind 20 turns of 1.2mm enamelled wire around a pencil (and then pull said pencil, it's just a winding core) .
Since wire diameter and turns is constant, all will measure the same, so you can consider it a commercially bought part and design your PCB accordingly.
Some wind said inductor around a 1W to 2W 10 ohms resistor, but if you want not the least iron inside, so be it, mount them side by side on the PCB.
Since wire diameter and turns is constant, all will measure the same, so you can consider it a commercially bought part and design your PCB accordingly.
Some wind said inductor around a 1W to 2W 10 ohms resistor, but if you want not the least iron inside, so be it, mount them side by side on the PCB.
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