solderdude
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Post by solderdude on Jan 16, 2018 19:31:17 GMT
Would it be difficult to move the 688 production driver into the modified proto enclosure? Maybe this would reveal more details about the changes in the production model and it could be improved further. And thank you again for all the latest info. The baffle is different so is the way of mounting. As the drivers are glued you cannot swap them without risk. Don't want to damage the prototype. The difference in sound is not due to the enclosure or baffle. It is the driver that differs.
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solderdude
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Post by solderdude on Jan 16, 2018 19:32:55 GMT
HD681EVO(modified) < HD681(modified) < HD662EVO < HD688 modif < HD687 proto modif < HD688 proto modif. Frans, where would you position the Sennheiser HD 569 in that lineup? It's more expensive, but at around 100 EUR still low cost. And a lot more comfortable I bet I never heard the HD659 so can't really say. It is comfortable one and better build quality for sure. Also has a suckout in the upper mids but most likely not as bad.
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solderdude
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Post by solderdude on Jan 16, 2018 19:44:52 GMT
The dip seems to be caused by resonances and break-up of the cone. It may be hard to equalize without negative effects. Too bad A liitle bit of EQ does seem to help in bringing it closer to the prototype. Can't use too much or starts to sound 'shrill' with poorer recordings. Do think, with some EQ it improves but not reaching the prototype quality. The dip seems to consist of resonances. The mods do improve the considerable ringing it has in stock condition. Will keep tinkering for a few more days before I post the mods. So far: Modifying the driver (removing some 'paper' from the rear of the driver) Placing damping felt/material in the cups. Sealing the bafflehole (used foam rubber) Opening a small port in the rear of the cup (enclosure) that is covered with black paper. using 1 ply of 2-ply toilet paper over the entire driver/baffle. Placing foamrubber 'spacers' on the outer edge of the baffle. Using Superlux HD681EVO velours pads + foam disc. Lowering the clamping force considerably, had to bend the rods in several places along the rods. Some EQ (+a few dB around 4kHz) In this case an improvement over the HD662-EVO as the treble is much nicer/smoother/less coarse.
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Post by miiksu on Jan 16, 2018 20:25:57 GMT
solderdude So much modding. I'll definetely wait for ur final impressions and measuring before I will start to do more modding. I like my sound atm but seem u are overhauling whole HP. If u can use better cable and make impressions of that too I would be pleased.
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solderdude
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Post by solderdude on Jan 20, 2018 22:17:23 GMT
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Post by psych0 on Jan 20, 2018 22:53:30 GMT
Oh thank you, was hoping you would finish it this weekend. Will mod it tomorrow. Much appreciated.
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Post by superluc on Jan 20, 2018 23:46:26 GMT
Thanks a lot.
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Post by superluc on Jan 21, 2018 0:20:38 GMT
Every single slit of the drivers need to be half open ? EDIT: What exactly there is to gain on doing that ? I'm a bit afraid...
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solderdude
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Post by solderdude on Jan 21, 2018 8:07:52 GMT
Only the 2 slits in the blue circles... but you can try to open them all.
I expected the bass to rise in level when opening up the slits but the difference in level was marginal. Will write this down a little more clearly it does read as if every slit needs to be opened... The sound did appear to 'relax' a little but may well have been placebo. It doesn't hurt to open them up. Most drivers with paper covered holes have 1 hole 'pierced' and the prototype driver had one entire hole open. When that one was closed the driver was overly damped and did not sound right. I did not remove the paper from the magnet hole though as Superlux did in the production model.
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Post by miiksu on Jan 21, 2018 8:23:13 GMT
solderdude Nice, I appreciate it. Good reading for sunday morning
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solderdude
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Post by solderdude on Jan 21, 2018 10:17:50 GMT
An updated version of the pdf will be uploaded later today.
I have to say that when you are listening to the modified version exclusively the listen is quite nice and an improvement over the HD662-EVO, especially in the treble.
Not decided yet whether or not I will put the modified version up for sale here.
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Post by psych0 on Jan 21, 2018 11:21:20 GMT
Mods done. I used a dense felt inside the cups (only thing i had at home). Did not use any foam under the pads to lift them since i do not have issues with the fit/comfort - might try it later. To my ears they are a significant improvement over the HD662-EVO across the board. I've been trying some EQ, but i'm not sure exactly how to proceed and how much to compensate (some EQ between 2k and 4k does seem to make it more "lively"). Frans, could you please help? Playing with something like this: Also, if you ever decide to sell the proto, please let me know and thank you again for the guide.
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solderdude
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Post by solderdude on Jan 21, 2018 12:18:39 GMT
Well done psycho..
I would use less EQ and pull up one slider only 3kHz center frequency... around 5dB or so. Make the BW so that it works from 1.5kHz to 5kHz. Experiment with the level.
Have been listening to it for a few days without comparing it and 'brain-in' says it sounds quite pleasant.
Raising the pads also has some small but positive influence to the tonal balance. Similar to the difference between a HD650 with fresh and worn pads.
When the pads are raised a few dB the headphone becomes somewhat less 'dark'.
You could also experiment with other materials under the pads as long as it raises the pads 2 to 3 mm.
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Post by miiksu on Jan 21, 2018 12:26:20 GMT
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Post by psych0 on Jan 21, 2018 16:14:18 GMT
Using something like this at the moment. Will continue to tune it...seems fine Thank you for the help.
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