1. As is universal for this forum, nobody has any reliable idea what is the size of the drive signal passing through the coil when playing music on this system at home.
2. Not clear how much distortion matters to your ears when we are talking about only the loudest moments or just when instantaneous peaks appear.
3. I think I am not the only one on this forum that smirks during any discussion of passive XOs. Time to retire the idea?
B.
2. Not clear how much distortion matters to your ears when we are talking about only the loudest moments or just when instantaneous peaks appear.
3. I think I am not the only one on this forum that smirks during any discussion of passive XOs. Time to retire the idea?
B.
I don't know, before I build an amp I connect a scope across the driver (and crossover if there is one) and watch it while I listen.
I don't think it is that difficult to calculate the current flow through an inductor in series with a woofer.
That is true of almost all distortions from every source in the signal chain. It is diffucult to quantify what is audible distortion with music and program material.
Some of the inductors tested had alarming levels of distortion even with small signal levels of 2-5 V RMS.
My last several projects have been active systems, but I intend to design passive systems in the future. Passive crossovers are far from obsolete.
It is worth saying again... The study presents very useful information, and it nicely documented.
The problems this thread addresses are very real and the info is important, specifically for higher power 3 way builds that use large inductors for BSC. This inductor distortion is more of an audible problem than most people know. I notice it more with efficient pro audio drivers. The distortion is being significantly magnified with lower level midbass content and it never gets masked, as more input into the LP section just makes it worse. Its very audible with some specific music that contains complex sustained notes (piano, string bass, solo cello) and cheap ferrite based inductors are by far the worst sounding.The Erse I core coils sound best to my ears due to their higher mass of core (and likely higher quality as well) especially with lower impedance loads and more efficient drivers.
Interesting, since they need less current to drive. Could it perhaps be crosstalk that's the problem?
I recently chased a weird issue on an older JBL 3 way with custom xover suspected of crosstalk (inductor placement less than optimal), but it was resolved after swapping a larger Jantzen sintered iron coil for laminate steel core. Both coils were rated for similar power, but the underlying distortion was most audible in the upper bass to lower mids and didn't respond favorably to driver swap either. The more efficient the driver I tried, the louder the distortion. It was also fairly constant and didn't significantly increase with power until it was masked by the other audio. A different amp was also used to eliminate crossover distortion. It was apparent the inductor was to blame after swapping it out.
Good point, higher DCR inductors can flatten the woofer before upper rolloff taming a slightly rising curve. Sometimes that's desirable other times it's not. so, a coil that works well for one woofer might too flat or too raise for another.
I was connecting a XO board to an amp (live and playing music) and had not connected the speakers yet. Nearby was a XO connected to the speaker but no amp. I heard faint music playing from the speakers!
I had accidentally discovered crossover crosstalk. It reaches a good 12in or more away if coils are aligned.
I had accidentally discovered crossover crosstalk. It reaches a good 12in or more away if coils are aligned.
I appreciate your findings. Seeing how the crossovers have to be really close to each other to demonstrate the effect, I am relieved.
Many thanks for the testing and reporting.
FWIW, the Purifi PTT8.0X04-NAB-02 stays below -65 dB HD3 (~0.05%) down to almost 200 Hz when playing at 98 dB in half-space. https://hificompass.com/en/speakers/measurements/purifi/purifi-ptt80x04-nab-02
FWIW, the Purifi PTT8.0X04-NAB-02 stays below -65 dB HD3 (~0.05%) down to almost 200 Hz when playing at 98 dB in half-space. https://hificompass.com/en/speakers/measurements/purifi/purifi-ptt80x04-nab-02
yep find in 1990 when we put a stereo car xover on a single box... and one speakers sing with no amp connect🙄
Comparing chokes is a bit like comparing amplifiers, since their actual performance depends not only on the core material and orientation, but also on conditions such as:
1) The air (or equivalent material) gaps (if any).
2) Number of turns.
3) The magnitude and frequency of the current through the coil.
4) DC bias current (if any).
Unfortunately, the above conditions may vary on a case by case basis.
1) The air (or equivalent material) gaps (if any).
2) Number of turns.
3) The magnitude and frequency of the current through the coil.
4) DC bias current (if any).
Unfortunately, the above conditions may vary on a case by case basis.
As in the distortion in an under-biased class AB amp. Yes, I tried another amplifier to rule that out.
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Try that demonstration with a cored inductor in series with a load resistor and an amp driving it to 50W. You can hear the byproducts of partial saturation distortion in the cored inductor through the air (non) cored inductor. Its like comparing the input to output error in a cheap, poorly designed class AB amp. People think inductor distortion is often negligible as well as cross talk. Its far from negligible.