Just a question and looking for advice:
Scenario: Car audio system that offers no real control over EQ. Speakers are harsh around 2.7kHz and 4kHz. Has anyone seen or designed a passive filter to cut frequencies like this on the speaker terminal itself (as in a crossover, but only to subdue specific frequency ranges)? Like the illustration below, I'd love to tailor the "Semi-Treble" but to adjust the Q. Would this be a relatively easy design? Once I find the right values, I can build exact resistor/capacitor values for all the other speakers. Any ideas? Thanks so much!
Scenario: Car audio system that offers no real control over EQ. Speakers are harsh around 2.7kHz and 4kHz. Has anyone seen or designed a passive filter to cut frequencies like this on the speaker terminal itself (as in a crossover, but only to subdue specific frequency ranges)? Like the illustration below, I'd love to tailor the "Semi-Treble" but to adjust the Q. Would this be a relatively easy design? Once I find the right values, I can build exact resistor/capacitor values for all the other speakers. Any ideas? Thanks so much!
Its not going to work like a normal graphic EQ with what you have. You would need inductors too, then maybe a buffer amplifier for the output. Or you can use opamps to make synthetic inductors, etc.
That would be a series RLC network, connected in parallel with the driver.
https://www.omnicalculator.com/physics/rlc-circuit
https://www.omnicalculator.com/physics/rlc-circuit
If it helps, this is generally what I'm trying to accomplish:
Unfortunately, it would be massively expensive and require installing all new equipment to do this any other way. iPhone doesn't offer an EQ that covers all apps (just Apple Music), Spotify has an EQ, but I prefer Qobuz. And I couldn't find any type of CarPlay USB-C or standard USB device that would offer a programmable EQ.
So, I'm open to any other ideas as well. Right now, my solution is to put foam over parts of the speaker driver that lessens the amount of reflection onto glass of the windshield.
Thanks again!
Unfortunately, it would be massively expensive and require installing all new equipment to do this any other way. iPhone doesn't offer an EQ that covers all apps (just Apple Music), Spotify has an EQ, but I prefer Qobuz. And I couldn't find any type of CarPlay USB-C or standard USB device that would offer a programmable EQ.
So, I'm open to any other ideas as well. Right now, my solution is to put foam over parts of the speaker driver that lessens the amount of reflection onto glass of the windshield.
Thanks again!
Fixing the acoustics might actually be better than trying to EQ it. If the problem is caused by something precisely equivalent to EQ to begin with, then corrective EQ will not be the exact inverse function.
I agree with the acoustics, but I can't put acoustic materials on the windshield that will obstruct my view (as a test: I placed 1" acoustic material there and it did solve the problem). The good news is, corrective EQ can be helpful if cutting vs. boosting due to a null.
Separately, I have been searching for a CarPlay device that might offer an onboard EQ (no luck yet), and Apple decided to lose the analog jack, coupled with their on-board EQ only affecting Apple Music, which I don't use.
Alpine and Jeep engineered an "OK" system, although, neither are audio experts, and both have to work with acoustics of a top on or top off. It's quite clever how they do it, but I just have these dash speakers that are spikey at 2.7kHz and 4kHz due to the windshield reflection.
Hope this helps!
Separately, I have been searching for a CarPlay device that might offer an onboard EQ (no luck yet), and Apple decided to lose the analog jack, coupled with their on-board EQ only affecting Apple Music, which I don't use.
Alpine and Jeep engineered an "OK" system, although, neither are audio experts, and both have to work with acoustics of a top on or top off. It's quite clever how they do it, but I just have these dash speakers that are spikey at 2.7kHz and 4kHz due to the windshield reflection.
Hope this helps!
Is there or could there be a passive crossover in series with the speaker that needs the equalization?
I think it's all active crossover points from the factory amp. One thing I'm going to try is some transparent gel pads (clear wall-bumper) circles, that should act as some diffusion. I've tried absorption up to this point, but haven't tried spherical diffusion.
I don't know where you intend on placing those pads but many speakers form a sort of lens in front of the tweeters to do what it sounds like you're trying to do. If so, you may be able to stick those on the inside of the tweeter/midrange grill.
If it had a crossover or if you could add one, you could install an RLC network to the speaker signal, shunting the peak to ground. The crossover would be needed to add some level of impedance to the circuit so that the shunting network was not working directly against the amplifier at those frequencies. Perform a ctrl-f search on the following page for:
conjugate
https://www.parts-express.com/cross...SnaHiYqEXMhKYBXX9eLAubpXVdwBG50a2v-t5t_KA71Ev
Also search online for:
conjugate networks crossover
impedance compensation networks crossover
If it had a crossover or if you could add one, you could install an RLC network to the speaker signal, shunting the peak to ground. The crossover would be needed to add some level of impedance to the circuit so that the shunting network was not working directly against the amplifier at those frequencies. Perform a ctrl-f search on the following page for:
conjugate
https://www.parts-express.com/cross...SnaHiYqEXMhKYBXX9eLAubpXVdwBG50a2v-t5t_KA71Ev
Also search online for:
conjugate networks crossover
impedance compensation networks crossover
Passive notch filters are used in speaker systems all the time. The impedance at the target frequencies is needed otherwise components calculation is guesswork which still might be good enough.
Can the gain on these be faded down? Might be the easiest compromise?
Can the gain on these be faded down? Might be the easiest compromise?
You may want to try using a doughnut-shaped piece of felt or foam. Varying the outer diameter and/or the hole in the center may get you what you need.
A notch would be useful, but it would need to be a several frequencies. I think just lowering the gain in the 2.7kHz - 5kHz range by 2-3 dB would be enough.
One thing I considered using were bra pad inserts. However, I don't want to use those specifically, so I'm cutting up an old mouse pad to use as a sort of foam cup over the speaker. We'll see if that helps.