Can I still press down the frequency bump between 2.5k - 4.5k ?

[da_bsg]

Hi experts, I purchased Homepod horn tweeter from ebay and trying to play with it.
The original output frequency tested in yellow waveline highest.

I tried used 1st order crossover 4.7uf cap (green) 3.3uf (pink) and 2.2uf, (lowest yellow line)

I also tried 2nd and 3rd order crossover, the wave doesnt have much difference or improvement compare to 1st order.

So I guess I am settled with 1st order crossover method.

My question is there a way to press down the bump +5db in between 2.5k-4.5k frequency.

Is there any method to add components? Series or parallel (Caps, resistor or inductor) to make the bump more flat?

All constructive advice are welcome.

Thank you.

 

[kevinkr]

I wasn't able to find any information about these tweeters on eBay so I am not sure what you are dealing with here. On the face of it they look a bit unusual, can you share a few more detailed pictures? (I admit I am really curious)

What did you use to measure them? Are you sure that that unusual response is entirely the tweeter and not some artifact due to measurement hardware/mic?

You can use a parallel RLC trap filter in series between the tweeter and the crossover. There should be online design tools - just something to experiment with to gain understanding.

 

[wchang]

Thanks for posting the measurements. The HomePod was probably more sophisticated than most or all designs on this forum!

The hump is centered about 3.5khz so mathematcally the parallel LRC notch filter (mH | ohm | uF note units) connected in series with the driver, should satisfy sqrt(mH*uF)~5khz/3.5khz~1.43 so mH*uF~2; L and C each depended on the actual driver impedance there but their product didn't. So if you have a small (labelled) inductor you can pair it up and ought to hear a sharp trough precisely there (unless it perfectly cancelled the bump); then fill in the trough with R but probably not necessary.

For details see near the bottom of
https://www.diyaudio.com/community/...ge-drivers-and-a-tweeter.391053/#post-7143129

(edit) You might try a bigger mH, mH*uF~2.6 to reshape the whole response curve.

 

[da_bsg]

This is dismantled from homepod 1，very difficult to fix into DIY casing, so I modified the fitted into another horn.

 

[da_bsg]

Thanks for posting the measurements. The HomePod was probably more sophisticated than most or all designs on this forum!

The hump is centered about 3.5khz so mathematcally the parallel LRC notch filter (mH | ohm | uF note units) connected in series with the driver, should satisfy sqrt(mH*uF)~5khz/3.5khz~1.43 so mH*uF~2; L and C each depended on the actual driver impedance there but their product didn't. So if you have a small (labelled) inductor you can pair it up and ought to hear a sharp trough precisely there (unless it perfectly cancelled the bump); then fill in the trough with R but probably not necessary.

For details see near the bottom of
https://www.diyaudio.com/community/...ge-drivers-and-a-tweeter.391053/#post-7143129

(edit) You might try a bigger mH, mH*uF~2.6 to reshape the whole response curve.

Thanks for your suggest, I will try out by adding some inductor.