It would be interesting to compare against an air-core inductor with a combined 4 ohm DCR in series. I want to wind a couple of inductors for a roughly 0.5-1 kHz 1st order filter. The 10" woofers I use (STX W.27.400, which are really sold as subs) are "usable” when run full-range together with 3.5" mid-tweeters, but sound way smoother with 22 ohm in series. (The resistors are rated at 2W and barely get warm during normal domestic duties like background music and tv, so the massively overpowered 20W class-D amp is getting upgraded to class-a. A small living room vs. something like a place of worship with 20x more space will make a difference, so YMMV.)
An inductor should also smooth out the sound, but the effect may be in proportion to the rising impedance at HF. So as the higher frequencies are attenuated, they should also become less harsh (sometimes leading to confusion about what a frequency plot shows, because these are 2 different effects working in tandem.) However, if you try to get the same slopes with a resistor and parallel capacitor, the capacitor will give a very low output impedance at high frequencies. It may be worth trying in case of surprises, but my bet is that it won't sound as good as a small air-core in series.
How do you think this may affect the attenuation rate. With a first order crossover we have a inductor to block signals getting into the drive unit and gives an attenuation rate of 6db/octave, adding a capacitor acroos the drive unit gives us a second order crossover and an attenuation rate of 12db/octave. But what about the resistor and capacitor combination, what attenuation rate do you think that will give
I feel I should repeat that the 40 µH inductor shown is not suitable for crossover use.
The resistor and cap will also be (up to) 6dB per octave. Like I said, it's probably not worth doing it that way, but doing a quick test in the name of science sometimes gives surprises.
Going to a higher filter order may not always be an upgrade.
Suppose you were to use an 8 ohm resistor in series with an 8 ohm woofer. The resistor would degrade the damping of the woofer, introduce a 6 dB loss and dissipate as much power as the woofer.
That is why we prefer to use a series inductor instead of a resistor. The inductor does the required job while introducing essentially no resistance loss.
P.S. I can thank JM Fahey for this information!
I'm not deaf, what makes you think i can't read and understand plain english. Why does everything need repeating. I don't appreciate your derogatory comments
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That was really a little in-joke between me and TNT regarding his mention of highfalutin design software.
It was not my intention to be derogatory to you, and apologise for implying you are a novice.
I am trying to be helpful as is my wont, and simply thought you had missed my comments regarding your cpc choice.
I've used a resistor and inductor as a tweeter filter on a few occasions. It works fine. It's necessary to have the inductor resistance significantly lower than the series resistance to allow sufficient attenuation before it turns into a shelf.
This is a second order LR high pass at 1kHz with 6dB of tweeter attenuation.
While it sometimes presents a compromise between low impedance and meeting the response target depending on the amount of attenuation, the cascaded style is common at line level.
While it sometimes presents a compromise between low impedance and meeting the response target depending on the amount of attenuation, the cascaded style is common at line level.
I suspect that is because the original crossover design took into account the DC resistance of each component. Swapping components for lower resistance ones could certainly mess things up.
For a greenfield crossover design I think lower resistance is better. It is probably not the most important thing, but it does help with damping factor and sensitivity, especially for the woofer.
I was looking at a U-shaped laminate core:
https://www.ebay.com/itm/153142979819
What might be the downsides? This seems to save a lot of copper and is going to have a really low DCR.
https://www.ebay.com/itm/153142979819
What might be the downsides? This seems to save a lot of copper and is going to have a really low DCR.
cyberstudio, it's one of those things.. More iron may mean more inductance, the more the inductance is increased compared to the same coil without the core, the more you have to lose when the core saturates, but with more core... In a sense, each coil really should be tested to the particular application.