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Post by miiksu on Jan 11, 2018 19:09:04 GMT
Quite different.... quick measurements. HD688 proto with HD681 velours padsstock HD688 productionstock HD688 with port (hole) closedLook at terrible response around 3kHz. The prototype was lovely there, this one has a severe dip there which with various mods/pads I tried I could not make smaller. Seems like a driver issue alas. Maybe when I mod the driver itself closer to that of the prototype but think it may be a different membrane that is used. I hope not. Very disappointing. Superlux was soooo close yet manage to bodge it up. Yes, bass response is a bit more linear and rolled off in subbass but the upper mids have suffered immensly. When you mention those two drops I can hear it on sweep tone. Its quite fast drop but audible. But I still like this more than HD662F even its cost double the price. Also I did hear extent on low bass when covered all holes with thick paper not taped.
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Post by superluc on Jan 11, 2018 19:28:06 GMT
Can you try to also measure them with 681 velours pads and the foam disk, with the hole closed ?
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Post by psych0 on Jan 11, 2018 19:43:33 GMT
The unmodified proto also had big dip at 5k - which change reduced it? Perhaps something similar would work here for the 3k and 5k dips?
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solderdude
Administrator
measureutternutter
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Post by solderdude on Jan 11, 2018 22:26:10 GMT
Already measured it with HD681 velours + felt + hole closed. Makes no difference for the 3-5k dip.
Will try a lot more, including modding the rear damping of the driver.
Time is limited though...
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Post by miiksu on Jan 11, 2018 22:35:13 GMT
solderdudeCan't wait. Hopeful u figure something. My HP's dips did not seem that bad or just ny hearing is not thad good.
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Post by superluc on Jan 11, 2018 22:45:52 GMT
Already measured it with HD681 velours + felt + hole closed. Makes no difference for the 3-5k dip. Will try a lot more, including modding the rear damping of the driver. Time is limited though... They really messed up... Now we can only wait and hope for your findings
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Post by superluc on Jan 12, 2018 15:04:03 GMT
Anyway, even if solderdude find a way to clean a bit this mess, and i very hope so, wait all the time is needed and thank him for anything can find and do, i don’t buy any Superlux headphone anymore. Build-wise they can’t sell this crap over 30€, and i can’t stand the fact that they have said to solderdude that the 688 in production was the same as the prototype, as you can see in the 687’s thread. We also don't even know if they have do that on purpose, like for reuse or sell the original driver, or just mod and listen like a bunch of amateurs. Pay them blindly something overpriced, with a lot of already said negatives on the construction, was like a test of trust on them, that they didn’t pass. Sorry if i bother about it, but this is my point of view. Good modding to everyone
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garyc
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Posts: 45
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Post by garyc on Jan 12, 2018 22:14:13 GMT
superluc , I’m sympathetic to this viewpoint: I expected a lot more (no blame attaches to solderdude: I went ahead and ordered these all by myself, there was no gun to my head). But really Superlux have done nothing to the build quality, even gone backwards with no extra velour pads. Yes,I think they are overpriced by about 100%. Ok, so I am not enough of an audiophile to spot the suck-outs in mid range, but if nothing else they sounded not really much different to the 662evo but with severely attenuated low bass and uncomfortable wearing with no velour pads. I expected a lot more for double the price. Now, the upside is when comparing I have rediscovered my Takstar Pro 80s and my eye is on the Pro 82s. Will I never learn?
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solderdude
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Post by solderdude on Jan 12, 2018 23:21:35 GMT
I did a lot of experimenting and measuring as well as listening and have it sounding a lot better now but still not on par with the proto. The suckout at 5kHz is smaller now and the subbass is there ... in spades. This can be tuned with the port though.
The sound is now dynamic again.
Will post the mods in a few weeks or so as I need to make a pdf for it which takes a lot of time. Nope ... still measures like shit and when looking at the measurements one would easily think the sound sucks but ... it isn't bad. No ... not reference quality but quite enjoyable to me.
What it involves: Opening up the cups. Do slight (easy to do) mods to the driver. Put some anti-reflection materials in the cups on the inside. I used double sided tape with some dense rugliner but 2mm felt will work equally well here. It is VERY important the foam strip on the inside of the cups near the edges where it is folded downwards to cover the swivel points of the cup need to be cut away and removed at the spot where the swivel actions occurs. The tape on the 'bridge' can remain there and does not have to be removed. Failing to do this makes the bass fatty and compressed. The small 'holes' that are present near the swivel point of the cup is just enough to give the bass the needed boost and open-ness. Then screw it back together.
I put some cotton in the port (its not just a hole) and then used a few layers of cellotape to close it completely (I like sub-bass)
Then used the Superlux HD681-EVO velours pads (which can be ordered separately) and are not expensive. Order code = EPK681EVO-V (4710423844889) With it come 2 foam/cloth discs. You can use this with the velvet pads directly in which case the treble is somewhat elevated and clear.
Oh yeah ... lower the clamping force by bending the rods locally. The clamping force is painfully high. I had to bend the rods in 3 places to get the clamping force where I want it.
Will I recommend this headphone now ?
Difficult one. It becomes 10 Euro more expensive when buying the pads making it 70 Euro. When You already have one the mods are almost obligatory and make it sound a lot nicer.
The driver by itself is not as good as the prototype (which has very different rear damping) but is better than the HD681EVO/HD662EVO driver.
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garyc
contributing
Posts: 45
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Post by garyc on Jan 12, 2018 23:59:46 GMT
Well that’s some good news. I have ordered the 681 velours ($15 on eBay, shipped from Shenzhen) then at least they should become as comfortable as my 662evos. I think I will take the 688s to work and live with them for a while and then perform the mods. But I still somehow feel that I’ll end up with something that is only slightly different to the 662 evos at more than twice the price. A bit of a pig in a poke really. Ah well.
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Post by psych0 on Jan 13, 2018 10:39:39 GMT
Thank you Frans for the new info. Perhaps even more improvement is possible as your time allows it and you figure out what changes superlux made to the driver. Can't wait for the detailed mod guide
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Post by fhvioo on Jan 13, 2018 12:00:07 GMT
How do stock HD688 + SL velvet pads compare to a modded HD662 EVO?
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Post by miiksu on Jan 13, 2018 17:18:00 GMT
solderdude It goes to >100€ euro if u buy genuine leather pads. But I like comfort and leather. It's a shame they shanged it too much of ur personal experience of the prototype. Let see what is in ur sleeves.
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solderdude
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Post by solderdude on Jan 14, 2018 9:51:50 GMT
I did some more experiments.
Only have Brainwavz pleather pads here and hybrid pads. (their velourspads won't work here). Turns out the Brainwavz pleather pads (+ mods) work really well here. These pads won't fit normally but mine don't have the elastic bands any more (came off) and taped them on the cups. I reckom the sheepskin pads won't be far off from their pleather ones.
These pleather pads (needs the XL round pads, the smaller ones simply don't fit) sound a tiny bit better than the Superlux velourspads. More comfort and deeper as well (the Brainwavz).
I made another mod when using the Superlux HD681EVO velourspads (Chinese e-bay pads may differ, they may not) The pads were 'raised' a few mm with window sealing stuff creating more space between the driver and ear. This resulted in slightly more clarity and more room.
Will take pictures and post them. Maybe even produce a modfication guide.
will do a comparo with modified HD681, modified HD681-EVO and HD662-EVO and (maybe leading to frustration) the proto HD688 when I have some time.
I don't even want to know how they changed the HD687.... not investing another 60 Euro. Maybe it improved... maybe it did not at all.
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Post by miiksu on Jan 14, 2018 12:20:38 GMT
solderdude If u can Everything tips and quides help us modders. I have at the moment atjusted those two dips on middle to higher frequency with equalizer. It's now for my ears much smoother. Gain 5 dB, quality 10, 3350 Hz Left channel, gain 5 dB, quality 10, 5050 Hz Right channel, gain 5 dB, quality 10, 5010 Hz
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