I recently added a pair of tweeters to my car's front pair and what "baffles" me is that after adding them, I hear more bass besides the added highs, so my question is whether adding these simple items in parallel can somehow affect the low frequencies too?

I guess the capacitor and tweeter offer another current path for high frequency signal, but low freq. should remain unchanged, or is it?.

The head unit and front speakers are OEM. The front speakers are marked 25W 4 Ohm, and are 5.5 inches diameter, dual cone (The type that has a single coil and a small cone attached to the center of the main one, where the dust cap usually is. This is not a 2-way coaxial speaker). And they remain installed in its default location, in the door panel.

The tweeters are "Audiopipe APET-H300". I saw they have a 3.3 uF capacitor inside the case, but I could not see any other component in there, particularly, I did not notice a coil that some cheap piezoelectric tweeters come with.

The connection was done by "jamming" the tweeter's included cable female spade connectors around the factory speaker connector terminals, the cable coming from the radio was not affected in any way.

Could it be that adding the tweeter changes the impedance (or some other parameter) that the head unit sees and it changes equalization in response? This head unit has that feature that lowers the bass progressively as you turn up the volume. I understand this is a protection feature.

If this is the case, can this simple tweeter in parallel damage the radio or the speakers in the mid-long term?

I have fiddled several times with speaker drivers before, but never experienced a perceived bass response by adding tweeters. Sadly I do not have any measurement equipment, and the installation requires removing the door panel and some more screws, so a quick A-B comparison is not possible.

To illustrate what I hear: I usually had this radio tuned with the treble adjustment to the max (And it was never enough, so I added the tweeters) and the bass adjusted about 3 notches bellow max, somewhat 5 notches over it's neutral point. After adding the tweeters I use treble one or two notches up and bass about three notches up and still think I hearing louder bass than before.

If this is electrically nonsense, I'll accept this is some psychoacustic effect, but I'd like to know if it has a name in order to read further. I doubt it is simple "placebo" as I was expecting no effect on bass.

I have some experience empirically building bookshelf speakers (with mixed good and bad results, so I thrust my ears more than not). Also, I've had this car for more than 11 years. The H.U and front speakers are the original O.E.M ones, and the only prior change I made to the system was connecting aftermarket speakers to the previously unused rear channels, and it was done more than two years ago, that is, I'm pretty confident "I know how it sounds".

I recently added a pair of tweeters to my car's front pair and what "baffles" me is that after adding them, I hear more bass besides the added highs, so my question is whether adding these simple items in parallel can somehow affect the low frequencies too?

I guess the capacitor and tweeter offer another current path for high frequency signal, but low freq. should remain unchanged, or is it?.

The head unit and front speakers are OEM. The front speakers are marked 25W 4 Ohm, and are 5.5 inches diameter, dual cone (The type that has a single coil and a small cone attached to the center of the main one, where the dust cap usually is. This is not a 2-way coaxial speaker). And they remain installed in its default location, in the door panel.

The tweeters are "Audiopipe APHE-T300". I saw they have a 3.3 uF capacitor inside the case, but I could not see any other component in there, particularly, I did not notice a coil that some cheap piezoelectric tweeters come with.

The connection was done by "jamming" the tweeter's included cable female spade connectors around the factory speaker connector terminals, the cable coming from the radio was not affected in any way.

Could it be that adding the tweeter changes the impedance (or some other parameter) that the head unit sees and it changes equalization in response? This head unit has that feature that lowers the bass progressively as you turn up the volume. I understand this is a protection feature.

If this is the case, can this simple tweeter in parallel damage the radio or the speakers in the mid-long term?

I have fiddled several times with speaker drivers before, but never experienced a perceived bass response by adding tweeters. Sadly I do not have any measurement equipment, and the installation requires removing the door panel and some more screws, so a quick A-B comparison is not possible.

To illustrate what I hear: I usually had this radio tuned with the treble adjustment to the max (And it was never enough, so I added the tweeters) and the bass adjusted about 3 notches bellow max, somewhat 5 notches over it's neutral point. After adding the tweeters I use treble one or two notches up and bass about three notches up and still think I hearing louder bass than before.

If this is electrically nonsense, I'll accept this is some psychoacustic effect, but I'd like to know if it has a name in order to read further. I doubt it is simple "placebo" as I was expecting no effect on bass.

I have some experience empirically building bookshelf speakers (with mixed good and bad results, so I thrust my ears more than not). Also, I've had this car for more than 11 years. The H.U and front speakers are the original O.E.M ones, and the only prior change I made to the system was connecting aftermarket speakers to the previously unused rear channels, and it was done more than two years ago, that is, I'm pretty confident "I know how it sounds".