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Post by miiksu on Feb 3, 2018 11:59:50 GMT
Is this for a stock HD688 ? Modded. But it's for actually for my modded version. I have added some plasticine to inside the cups to lower resonance and bass. I also added thick paper to cover the driver's all holes of front side but not the grill And lastly I added rubber band to the small cap between the driver panel and cup. To that cap where the original pad's edge goes. Edit. And I almost forgot one last mod. I also added six 20x3x3mm foam stick the driver grill, more focused upper frequencies.
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Post by psych0 on Feb 3, 2018 16:27:40 GMT
Working on a filter that replaces the toilet paper. Also slightly different way of using the bass port (not totally sealed anymore). For now more clarity, more 'open' sounding and slight 'etch' is removed. More sparkle... the toilet paper removes a bit too much 'air' for my taste. takes a week or so to put mods on paper. Requires soldering parts and the driver. Worth the bother to me. Happy to hear further improvement is possible. Hope the soldering is not complicated.
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Post by miiksu on Feb 3, 2018 17:23:07 GMT
Working on a filter that replaces the toilet paper. Also slightly different way of using the bass port (not totally sealed anymore). For now more clarity, more 'open' sounding and slight 'etch' is removed. More sparkle... the toilet paper removes a bit too much 'air' for my taste. takes a week or so to put mods on paper. Requires soldering parts and the driver. Worth the bother to me. Happy to hear further improvement is possible. Hope the soldering is not complicated. I missed that post. But I bet its only some resistors and something else to filter frequencies. I use only resistor on my HP's. I think I'm using 1W creamic resistors on both channels. I don't remember the ohm rating. I think it was something between 150-170 ohm. But its not in the HP's its soldered in the candy box To lower output impedance. I'm happy atm with those my mods and EQ. But if Solderdude can make it even better, I'm interested. Firstly I was oh this headphone has potential but needs tweaking. Now its good but it can be still better but not that much. Surpassed my 700€ book speakers of flatness and soundscape. Edit. Ups. Wrong everything. Right click on the images. They were 3W. Green is 27 ohm and grey is something else. Can't see the rating.
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solderdude
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Post by solderdude on Feb 3, 2018 21:53:53 GMT
Updated the pdf. Here is the schematic of the filter circuit (that replaces the single ply of toilet paper in front of the driver of the modified HD688) Below a picture of what the filter looks like. Below the frequency response of the modified (with filter) HD688. more details (including changes to the baffle port) is found in the pdf.
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Post by miiksu on Feb 4, 2018 8:17:24 GMT
solderdude nice work Looks much better on upper frequencies.
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Post by miiksu on Feb 4, 2018 18:31:13 GMT
I made better EQ setting for my modded HP. Upper frequencies was not smooth enough. Its better now. ufile.io/jockgAll Left Right
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Post by psych0 on Feb 5, 2018 13:01:23 GMT
Switched to 3 ply paper for the port hole - bass is now more pleasant. Will try the filter if i can get the parts this week.
Thank you, Frans.
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Post by miiksu on Feb 6, 2018 17:00:50 GMT
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Post by miiksu on Feb 7, 2018 18:58:06 GMT
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solderdude
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Post by solderdude on Feb 7, 2018 20:33:46 GMT
The question is how they change the tonal balance. Measured a lot of pads and none of them really worked well on this headphone.
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Post by miiksu on Feb 8, 2018 16:25:04 GMT
The question is how they change the tonal balance. Measured a lot of pads and none of them really worked well on this headphone. Hmm. I moved the drivers position because I did not like the tonal balance. Too sibilant if the open port is on my auricle. On the sides not too sibilant. Can't say how those Defean pads perform but they fit nicely as they have told.
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Post by superluc on Feb 9, 2018 0:13:48 GMT
Someone have also try to take away, from the upper part, a portion of the paper circle that cover the other ports, and place it on the hole ? It's better to just use some ply of toilet paper and try to find a personal balance there, than have the same material ?
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Post by miiksu on Feb 9, 2018 15:20:49 GMT
solderdude did u even try active carbon filter on front of the driver? I used thin layers to lower HD681 upper frequencies when I used it. It worked quite well and did not make muddy sound. I have some leftover I could try to mod somehow this HD688 with those. Maybe blocking the holes with that? Or even the driver with one thin layer. But I like the sound atm. Good bass extension not floppy, middle is very persistent, vocals, wood clappers, quitar and upper frequencies but not too sibilant just slightly on some songs. Maybe I need to lower upper frequencies 1-2 dB on EQ. Need to listen a lot songs, enjoy and make adjustment
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solderdude
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Post by solderdude on Feb 9, 2018 17:06:37 GMT
As long as the air flow though the paper, foam or toiletpaper has the same acoustical resistance there will be no problems.
In front of the driver I only tested toilet paper (and 1 ply was already a bit too much) and felt. There are countless other materials like cloth etc. Did not try those. I used a filter instead of the materials in front of the driver which works best IMO.
Whenever I poked on of the paper holes in a baffle I can always get the same measurements when covering with coffee filter or 2 or 3 layers of toilet paper.
The fun of using 1 or more plies of toilet paper is that you can 'tune' the bass to your taste quite easily.
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Post by miiksu on Feb 11, 2018 7:24:57 GMT
So it does not matter how thin or thick the material is if it pass the same amount of air? I need to test more when I have free time.
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