solderdude
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Post by solderdude on Dec 7, 2018 5:46:30 GMT
Try to 'soften' up the felt by bending it etc.
Perhaps measure the same headphone with and without the felt.
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Post by denonic on Dec 10, 2018 8:31:12 GMT
Measured with felt, removed felt, and then reseated felt while only pressing down on the very edges. All measured with mesh removed.
This left side didn't show too much low end improvement:
The right side on the other hand did:
The little tremors at 60Hz seem to be an anomaly with the felt mod and the mesh removed. When measuring with the mesh covers attached, they flatten out.
P.S. disregard the 'rs' in the bent felt name. Was meant to delete that.
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solderdude
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Post by solderdude on Dec 10, 2018 16:22:39 GMT
There is also small wiggles at 180Hz so could also be 60Hz hum + harmonics. (If you live in a 60Hz country)
Easy to determine by listening to a recording made with the EARS.
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solderdude
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Post by solderdude on Dec 13, 2018 20:22:40 GMT
Here are some preliminary results of the felt discs with various size holes. Very enlarged scale (1dB/div) This isn't the whole story though. Distortion in the lows increases and a peak around 4kHz develops. 3.5mm hole seems optimal. More will be posted on the website and in an updated article. Probably around X'mas time.
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Post by denonic on Jan 1, 2019 22:49:49 GMT
So whats the go to for your personal pair now solderdude? 3mm hole or the K240 foam?
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Post by Mr Trev on Jan 2, 2019 0:04:27 GMT
Was browsing the HF thread and somebody posted a link to a reddit where somebody has been making EQ profiles for various headphones, so I thought I'd share it here too. The EQ profiles are made to match the Harmon target response. Tried the 58x profile myself… not too bad, but my phones are still felt modded so I'm not getting the fully intended response. https://www.reddit.com/r/headphones/comments/9o2f5n/psa_oratory1990s_list_of_eq_presets/
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Post by denonic on Jan 7, 2019 4:09:13 GMT
Did the 3mm punched felt disc mod. Bass came back up compared to the original eco-fi felt.
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solderdude
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Post by solderdude on Jan 7, 2019 22:23:28 GMT
I have resorted to the Superlux foam disc instead of the eco-fi felt and use it with the cloth towards the driver. The felt disc mod is a good alternative but did not like the increase around 4kHz (even though that is small). Others may welcome a bit more clarity though.
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Post by miiksu on Jan 7, 2019 22:40:29 GMT
I have resorted to the Superlux foam disc instead of the eco-fi felt and use it with the cloth towards the driver. The felt disc mod is a good alternative but did not like the increase around 4kHz (even though that is small). Others may welcome a bit more clarity though. Maybe mixing with one individual toilet paper sheet? I have not tried that. It may work.
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Post by headroc on Feb 16, 2019 22:43:30 GMT
Below the schematic diagram of the passive filter circuit. Hi solderdude, I have a question regarding the notch filter: What happens if the output resistance of the source is higher than 10 ohms? For example around 30 to 40 ohms? Or even higher? Do I have to use a different inductor or capacitor in this case? Or maybe add some resistance on the drivers side to compensate that?
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solderdude
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Post by solderdude on Feb 16, 2019 23:20:10 GMT
Then the filter becomes 1dB less effective So instead of a 5dB drop you get a 4dB drop. There is a way around it but requires adding 3 components from the input of the original filter to the ground connection. Don't know if it is worth the extra dB. With such a filter it can be used with any output Z between 0 Ohm and 200 Ohm. It requires adding the 47mH inductor, 330 Ohm and 15nF capacitor.
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Post by headroc on Feb 17, 2019 0:18:17 GMT
Wow, thank you very much for the modified circuit! Nice to hear that the original filter just becomes less effective, so I can simply try it out. Thanks again!
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Post by headroc on Feb 17, 2019 20:19:15 GMT
It requires adding the 47mH inductor, 330 Ohm and 15nF capacitor. Do these three additional components have any special requirements? Like the current and resistance of the inductor or voltage of the capacitor? Any quality requirements for the resistor?
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solderdude
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Post by solderdude on Feb 17, 2019 22:24:10 GMT
Well the inductor can be very small (low current) and may have a resistance up t0 20 Ohm or so. The resistor can be very small 0.2W rating is already high. Cap can be small film type, or C0G/NP0 or even X7R. voltage rating is >25V
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Post by headroc on Feb 18, 2019 6:12:30 GMT
Ok, thank you very much!
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