solderdude
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measureutternutter
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Post by solderdude on Jun 27, 2018 17:56:04 GMT
That’s good to hear! From your initial impressions, did that sub-bass sound rolled off? Maybe a bit too early to ask. Hopefully extensive mods aren’t necessary There is some subbass roll-off. The prototype did not have this. The mods I came up are easy. Just insert a foam disc (AKG K240 or Superlux foam disc) with 1 ply of toilet paper and use the HD681 velourspads. When using the original pads it is a bit the same. To improve subbass just add the foam disc + 1 or 2 plies of toilet paper under the pads. More info when I have time. It has a similar 'clarity/presence' dip in the driver as the HD688 but didn't bother me as much. Again the prototype had a different driver and no 'clarity' dip. Measurements aren't that great (distortion) but it sounds quite good. Measurements are taken at 90dB but I don't listen at 90dB so maybe its way distortion is higher.
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Post by miiksu on Jul 1, 2018 17:11:38 GMT
Production's model a bit steep drop between 3-5 kHz. Otherwise it seems OK. Is there a way to improve subbass?
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Post by retroe83 on Jul 2, 2018 1:27:24 GMT
Luckily the bass-roll off isn’t as steep as the production HD688, and doesn’t take much effort to improve it. At this price level I was really surprised at the channel matching, and when modded it isn’t horrible.
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solderdude
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Post by solderdude on Jul 3, 2018 4:50:12 GMT
The prototype could be modified to perform really well. The production version doesn't measure as well and lacks clarity but certainly at lower listening levels sounds quite nice. An enjoyable headphone for sure but requires 10 Euro extra for pads but is 10 Euro well spend. Can't turn it up to loud levels though.
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Post by miiksu on Jul 3, 2018 14:11:35 GMT
The prototype could be modified to perform really well. The production version doesn't measure as well and lacks clarity but certainly at lower listening levels sounds quite nice. An enjoyable headphone for sure but requires 10 Euro extra for pads but is 10 Euro well spend. Can't turn it up to loud levels though. Could it be just lower quality materials / assembly of the driver? They did not give u any answer of that?
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solderdude
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Post by solderdude on Jul 3, 2018 15:56:42 GMT
I asked why changes were made but they simply don't reply. Suspect it to be a cost thing.
The drivers do look the same, they just don't perform the same. Nor the HD687 nor the HD688. Too bad.... they had an excellent prototype driver.
Fortunately the HD671 and HD672 did improve after the prototype.
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Post by miiksu on Jul 3, 2018 17:07:04 GMT
Mm. That I was thinking too. It's a shame. Retailers sold approx 70€ and now its only 50€. Superlux as company could have made it better or perform atleast same as the protoype.
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Post by miiksu on Jul 17, 2018 12:41:11 GMT
I got the HD687. For my quick impressions they sound OK. Deep bass slacking and slightly too much highs. Not as good as HD688 but not bad. I finally got my measurement microphone. Not sure is it positioned right but here is my first measurements. It have Frans TP mod and my thick hybrid pads from ebay. Probably need more TP. Left channel only
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solderdude
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Post by solderdude on Jul 18, 2018 13:20:20 GMT
The HD687 with mods and HD681EVO velours pads measures like this: The treble peak around 9kHz is only 2 or 3 dB above 100Hz. In your measurements its about 20dB difference. There doesn't seem to be a dip around 3khz either. Do you measure with inear mics ? Could also be the pads so I ordered the pads to see what they do on other models. They look comfy and could solve pad thickness issues for some owners when FR is not too affected. What would be interesting is if you measured the stock HD687 and compare to my measurements. These are the exact same headphones so all differences should be in the seal and mic/measurement system.
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Post by miiksu on Jul 18, 2018 18:58:57 GMT
Treble was too high for my first measurement. Not sure what caused this. I try later on with original pads. My mic is ECM888B. I made better mod for the HD687. Now they really sound good. Placed cotton pad (oval) the front side and leaved two closed holes not covered (need to be exactly on right spot). Also removed original foam sheet. Not anymore that unusual high treble. It may be my bad measurements. For my ears sweep tone is also smooth. No drops. I need to get that treble still down. Too much for my ears. Now it's 'only' +6dB. Edit. Two oval cotton pad on the front and foam pad removed. Yay! Let's rock baby. Leveled the sound more. I think this is the best I can do at the moment. Slightly elevated mid bass and treble. I tried many combinations of TP, foam pads, microfiber and active carbon fiber. You only need oval shaped cotton pads and these ear pads: www.ebay.com/itm/For-AKG-K240-S-K241-K242-K270-K-Series-Headphones-Ear-Pads-Seals-Velour-thicker/122893437911?hash=item1c9d050bd7:g:Ji4AAOSwg8taTEcr Edit2. I made 3 dB lined zone. With two cotton pads it's more balanced sounding. Even on the first look one cotton pad may look better. The first picture's quality is bad. Sorry about that.
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Post by miiksu on Dec 9, 2018 18:20:25 GMT
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Post by miiksu on Dec 16, 2018 19:15:21 GMT
Another interesting measurements. They sound now snappy on bass side, no sibilance on upper frequencies. Got bigger dip around 3 kHz and after 10 kHz. Kinda heavy sound but enjoyable. Brainwavz sheep skin xl pads and two layers of oval cotton pads.
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solderdude
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Post by solderdude on Dec 16, 2018 20:26:29 GMT
Looks promissing but the scale is a bit misleading making it look really flat..
2-3khz is -17dB opposite 300Hz.
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Post by miiksu on Dec 16, 2018 21:37:03 GMT
Looks promissing but the scale is a bit misleading making it look really flat.. 2-3khz is -17dB opposite 300Hz. Yep. Bass is good but relaxed middle and upper frequencies. I got misleading scale sorry about that. I tried many thinks and that seemed to work best for now. Felt did not work good as cotton with these headphones. Foam, toilet paper worked best on HD688 with velours. I need to try toilet paper and cotton with HD687 with the sheep skin pads.
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Post by miiksu on Dec 28, 2018 17:05:04 GMT
Hmm. Look at this. They now sound good and after few click EQ's they sound excelent. No expensive sheep skin pad needed. Thick pleather pads and few easy mods. I added cotton to pack of the driver and two felts and cotton to the front. The cotton may be slight problem to correct one I take some screenshots later on of the mods. Mods and thick pleather pads. Roughly +6 / -7 And few click EQ - Left only. +3.29 / - 4.75
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