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Superlux HD 668B?

post #1 of 38
Thread Starter 

So I was reading http://www.headfonia.com/superlux-hd668b/ review and was floored by how much praise those had gotten. I've heard of them talked about as being really good but never to the extent that article went too.


I was wondering about what Head-fi's thoughts were and if anyone had any first hand experience and could echo or refute that article.

post #2 of 38



There's my review. If you have any questions in particular, feel free. Unfortunately, I have yet to see what they can really do. My source is onboard audio with integrated amp, so judging them now would be unfair. I plan to get the Essence ST for Xmas and I'm sure it will be capable to drain every last bit of juice out of these headphones. Until then, I have to enjoy them for how they are. Sounds pretty good, but...feels like something is missing. My Z-5500 sounds pretty terrible from the onboard audio, and way better with it's own DAC via coaxial. If the improvement for these headphones with the Essence is at least that big as the onboard<->own DAC for the Z-5500, then I think they are not only going to sound amazing but, for the price, insanely good.

Edited by WrxSTI - 11/13/10 at 5:02pm
post #3 of 38
Just ordered a pair and will throw up some impressions after I get them sometime next week.
post #4 of 38

Just do a search here. They haven't received the praise that other site have given them.

Originally Posted by SoSpecial View Post

So I was reading http://www.headfonia.com/superlux-hd668b/ review and was floored by how much praise those had gotten. I've heard of them talked about as being really good but never to the extent that article went too.


I was wondering about what Head-fi's thoughts were and if anyone had any first hand experience and could echo or refute that article.

post #5 of 38

Which they deserve, IMO...

post #6 of 38

I find these are a real sleeper. They are very easy to modify but sound very good unmod'd once broken in. Several others besides myself have modified them and discovered a real keeper in these headphones.


They are dynamic, balanced well, detailed yet not irritatingly so, but sound (to my ears) a little distant or "dark". Compared to my K701, D5000, or especially my HE-5LE, they cannot compete in resolution and sound soft in the top octave. You don't get the sense of "air" or room acoustic compared to the top headphones.


The 668B has a slight emphasis in the sibilance region that can get mildy edgy with lesser electronics, and their bass, to me, sounds a little discontinuous with the rest of the range.


There are many ways to modify these headphones to eliminate the mildly wooly bass and balance the top octave slightly better. The best start is to replace the gawd-awful ear pads with AKG 240/270 velour pads. Then replace the cable, then damp all the internal plastic bits.


From the start I listened to these more than my K701. True, they are not in the same class but I simply enjoy the 668B more and am more engaged in the music. With the 668B - better punch, better dynamics, I can differentiate individual vocalists from a chorus easier, and I also enjoy their representation of the upper two octaves more than the K701.


After modifying the 668B, I am ready to sell my K701 and just sold the D5000. Again, I am not saying the 668B is in the same league as these others; I am saying they spend more head time with me than the others. It's all about being engaged in the music. That the 668B is pretty neutral is icing on the cake.

post #7 of 38

My initial impressions are cautiously promising. The treble is splashy right now and seems a bit out of control with a tendency towards being sibilant (some AC/DC is just unbearable), these have a definite V shaped sound out of the box and seem a bit hollow in the middle. Bass wise they also seem a bit uncontrolled and they don't seem overly fast. Having said that the treble seems to work well with female voices.


Build wise these seem very well done aside from the pads which I do think I will replace with AKG velour pads. I also like the replaceable cable system and the different lengths given.


For kicks I grabbed the velour type pads that came on my QNN headphones and threw them on and they don't sound bad but when only using them with their very thin cover they increase the treble energy to much so I have put the foam insert that came with the original pads  in with them. I will be buying actual AKG 240 velour pads though as I think they would be a lot better and more comfortable.


I am going to let these burn-in for the next week or so using my burn-in files and see what happens. I hope the treble energy subsides along with the bass a bit and the mid-range opens up. If they don't change a lot though I think they may be a nice switch up from the warm sounding QNN headphone.


As they stand now I prefer the signature of my QNN though even though these are technically a bit better.


Will report back in a week or so :-).


BTW I bought these from a Canadian online retailer called Paws, I ordered them Friday and they arrive today, so amazing service. I posted their website in another Superlux thread.

post #8 of 38

OK I have over 100hrs of agressive burnin on my pair and the change is pretty dramatic. They went from being sibilant and slightly out of control in the highs to a much more natural sound and the bass also tightened up quite a bit. I did do one small very reverseable modification though. I took some foam I had handy and cut a small disk about an 1/8 of an inch thick and slightly smaller than a quarter and placed that directly over the center of the driver underneath the original foam covering the driver. This has helped tame the treble a bit more making them less fatiguing and more enjoyable for me. I am trying to track down the AKG velvet pads and also the foam cover for the AKG driver as I think this may help the treble be even a bit more balanced.


Over all right now I prefer the Superlux to my QNN headphones for comfort, quality, and sound reproduction but will keep both as the QNN offers a darker signature that works very well for some of my music.

post #9 of 38

I've had my HD-668b's for 5 days now. When I first put them on I was horrified, I thought they sounded like crap the upper mids were terrible and the bottom end was muddy. After about 15 hours of listening though they have improved to the point where if they don't get any better I'll still be happy for the money I paid. One thing that I don't get it a lot of people described the phones as bass light, that is not my experience at all plenty of bottom end almost too much in fact.

post #10 of 38

teaken - you and I are in the minority. The 668B's bass was over the top for me. Giving them at least 150 hrs will really smooth things out in the bass but you may find it still out of control. However, I find it addicting to listen to. Nice and punchy with good drive and emotion (--> dynamic).


Once the internal cheapo parts are damped, the 668B can really show you what it is capable of.

post #11 of 38

Roth_s when you mention damping how are you doing it? Just using bluetak on the plastic parts?


As for bass I found it to much out of the box, with serious improvement after 100+hrs of burnin and I found the treble calmed down a lot as well.

Edited by dweaver - 11/25/10 at 8:43pm
post #12 of 38

First off, it is very easy to take apart the 668B. The logo caps on each ear piece pop off with a sharp knife blade and the remaining disassembly is simple.


Using the AKG K240/270 velour pads, I used a closed cell foam weatherstrip approx. 3/8" x 3/8" cross section (self adhesive, graphite gray color) and ran a strip around the perimeter of the cup, under the ear pad and applied to the plastic cup. This gives a little spacing so one's ear is not resting against the driver grill. I have tried increasing this distance and it only enhances the discontinuity I hear between the bass and upper ranges, even after full break in. Increasing the distance also harms the balance in the upper mids, creating too much of a "V" sound.


Too much to go into detail here, so please PM me for more info. I am sorry for not taking pics along the way!


I use good 'ole Mortite hand-applied caulk rope to damp all the "in-between" spaces around the face of the driver grills (behind the ear pads). I appreciate that Mortite is heavily mineral filled and very acoustically dead. Other rope caulk brands are too lightweight and are not as efficient (in killing resonances). Because of how I modify the 6 vent holes around the driver grill (behind the ear pad), I could not use something similar to Dynamat. To do so would make a mod irreversible.


Except for my method of rewiring the left ear cup all the operations are simple.


VERY IMPORTANT: The internal "yoke" that allows the articulated movement and holds the driver in place, as well as other areas inside the cup, need damping. Without internal damping of these items, the entire frequency range - especially the bass - will greatly suffer. This I accomplished by using a simple formula of 1 part grout (the "filler" between ceramic flooring tiles) and 3 parts liquid electrical tape (or vinyl dip used for coating tool handles to create a better grip). I applied this with a fine, stiff bristled artist brush. Several coats are required but each coat dries quickly.


I rewired with Mogami W2534 quad microphone cable and Techflex sheathing and regret using the Techflex - it is very noisy when rubbed. Also the Mogami is very heavy for such a lightweight 'phone. Though I "cheaped out" in my choice of cable because this has been an exploratory project with no proven outcome, I highly recommend one uses their favorite/best quality cable because I have discovered the 668B truly deserves it.


I especially wish to thank audiofil for his helpful direction and sharing his experiences with the Superlux HD-668B.

post #13 of 38
Thread Starter 

Gah the way some of you guys type about these makes me really want them. I may have to end up with a pair in the near future.


Any and all experiences welcome I'd love for more information to be publicly known about these headphones.

post #14 of 38

I must be approaching the 50 hour mark with my HD-668b's now and the bottom end is tightening up which is having the added affect of widening the soundstage substantially, these really are fantastic phones. They also seem well matched with the Audinst HUD-mx1 I purchased about the same time. Bear in mind this setup replaced my 10 year old HD-25 SP's which = so much improvement it's hard to describe. I'm going to try a few different op-amps in the Audinst soon which is going to be a fun experiment.

Anyway considering the price I'd recommend these to anyone, I purchased mine from CMI Australia if anyone in NZ or AUS is looking for somewhere to buy.

post #15 of 38

Just wanted to revitalise this thread after getting myself a pair of HD668B's and HD681's.


These headphones are phenomenal for the price, although they do require burning in to sound their best and perhaps some mods to tame the edges. Especially the HD681 has somewhat sibilant highs, but several filter modifications are described in the Rock Grotto forums.


I'm just burning in my pair of HD668B's. The upper register is very harsh when new, but I'm expecting it to sound good when burned in. I think these complement my HD650's well when I'm in the mood for something different.

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