https://www.dibirama.altervista.org...aital-4fe35-8-full-range-4-8-ohm-60-wmax.html
Not on the same baffel but no it doesn’t have the dip.
Edit: not as big of a dip, but there is something there.
The issue is not baffle related even though I purposely did nothing to mitigate diffraction issues. Except the felt.
The impedance measurement shows in box and free air. The notch is present in both.
I did try to find the issue by placing weights on different places on the cone and measure. I found nothing that affects it.
The cone treatment did nothing to it. So maybe rear suspension or something else is the cause.
Not on the same baffel but no it doesn’t have the dip.
Edit: not as big of a dip, but there is something there.
The issue is not baffle related even though I purposely did nothing to mitigate diffraction issues. Except the felt.
The impedance measurement shows in box and free air. The notch is present in both.
I did try to find the issue by placing weights on different places on the cone and measure. I found nothing that affects it.
The cone treatment did nothing to it. So maybe rear suspension or something else is the cause.
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With the rising response I can use it as a passive way of attenuating little above ~1000hz. But mostly for the looks, and I had them laying around from a previous project with 4fe35 that was mounted from the front. I simply layered felt around the driver until it was hidden.
I tried this passive attenuation before with fleece fabric. 0, 2, 4 layers of fabric in front of a 3fe25. Quite linear attenuation.
I tried this passive attenuation before with fleece fabric. 0, 2, 4 layers of fabric in front of a 3fe25. Quite linear attenuation.
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The felt is not in front of the driver, but around the driver. I've done the same with 4FE32 drivers in the narrow TABAQ enclosures.
Helps with baffle diffraction.
https://www.diyaudio.com/community/threads/felt-to-help-with-baffle-diffraction.389457/
It's unorthodox... 
but on axis it might work. But if you think what happens off axis, the felt thickness will be thicker and thicker as the angle increases and thus, the signal need to travel through an extra millimetre or 2... This will make an already beamy speaker act like a laser up top.
but on axis it might work. But if you think what happens off axis, the felt thickness will be thicker and thicker as the angle increases and thus, the signal need to travel through an extra millimetre or 2... This will make an already beamy speaker act like a laser up top.I had to revisit this paper,
https://www.klippel.de/fileadmin/kl...ement_and_Visualization_Cone_vibration_06.pdf
A extreme near field measurement of the surround/front suspension does not show this dip. So my suspicion is that we are dealing with a ring resonance where the furthest part of the cone is moving out of phase compared to the center.
And a measurement extremely close to the top of the phase plug shows a narrow and deep dip, that indicates that it’s the sum of a ring that reaches the center at the same time out of phase.
Time to bring out the laser and some sine wave stimuli at the problem frequency.
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Well my filter parts came and today I measured the effect.
And I`m done, don`t see any point going further until I chose to ad a DSP in to the equation.
Its not perfect but fun to listen to, they are good enough for the intended purpose.
And I sadly came to the conclusion that I like them better without felt cover.
First image is 30cm on axis with filter but no felt cover.
Second image is no filter or felt in yellow only treated with LTS 50, Purple is with filter no felt, and green is filter and felt.
Last image is around 15cm distance to the baffle, 0,10,20,30,40 degrees of axis.
Level matched at 100Hz.
And each and every measurement result is frequency dependent gating.
Filter component was a 2mh Jentzen audio inductor, and a 20ohm resistor I showed in previous post.
And I`m done, don`t see any point going further until I chose to ad a DSP in to the equation.
Its not perfect but fun to listen to, they are good enough for the intended purpose.
And I sadly came to the conclusion that I like them better without felt cover.
First image is 30cm on axis with filter but no felt cover.
Second image is no filter or felt in yellow only treated with LTS 50, Purple is with filter no felt, and green is filter and felt.
Last image is around 15cm distance to the baffle, 0,10,20,30,40 degrees of axis.
Level matched at 100Hz.
And each and every measurement result is frequency dependent gating.
Filter component was a 2mh Jentzen audio inductor, and a 20ohm resistor I showed in previous post.
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That is a great question, I still have six 4fe35 on the shelf so I simply have to try, if I didn’t glue the inductor behind the magnet I could simply drop one in and do a comparison. Pretty sure the depth of the ferrite magnet would be a problem.
Palm to the forehead moment..
Palm to the forehead moment..
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Well to me they sound lovely. I’m not going to try and put words to the experience but there is nothing that catches my attention or gives listening fatigue. Nothing bugs me and that’s a good description.
They are limited to only play above 150Hz so without any bass support the mind have to fill in the blanks. And amazingly it actually does this to certain degree.
I took them outside and listened only to these without anything else. And I wasn’t feeling that something was missing. And that might say more about my ability to listen critically..
I usually say that my latest builds somehow always sounds the best. Placebo is a powerful thing and I’m taking full advantage of it.
They are limited to only play above 150Hz so without any bass support the mind have to fill in the blanks. And amazingly it actually does this to certain degree.
I took them outside and listened only to these without anything else. And I wasn’t feeling that something was missing. And that might say more about my ability to listen critically..
I usually say that my latest builds somehow always sounds the best. Placebo is a powerful thing and I’m taking full advantage of it.