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EQ or mods can transform shrill psycho into cheerful companion.

A Review On: Superlux HD661

Superlux HD661

Rated # 227 in Over-Ear
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Review Details:
Audio Quality
Purchased on:
Price paid: $35.95
Posted · Updated · 1207 Views · 4 Comments

Pros: Good isolation. Detachable cable. Can sound very good. Comfortable. Huge value.

Cons: Unmodified the sound is intolerably harsh and piercing.


I bought these new from a UK ebay shop (kmagencies) for £22.50 which is US $35.95 or €26.56. Price included next day live tracked delivery with the delivery timed accurately to within an hour slot so if you're in the UK and want a pair of these this has to be both the cheapest and most convenient deal you will find.

Some context:

I have had some bad luck with full size headphones:

My Sennheiser HD 500 died after about 10 years. I bought Sony MDR ZX700 to replace but they have a design fault which leads to pinched internal cables and are doomed to fail, which they did. I tried some AKG 451 but they were muddy and a bit booming and had obviously recessed upper mids so I took them back and got a refund. So for a long time I've been using IEMs and Koss KSC75 even at home but I am really bored both of sticking stuff in my ears and of headphones with no isolation (I live by a busy road). Last week I bought Sennheiser HD215-II but took them back after a couple of days because they gripped my ears uncomfortably, were incredibly hot and sweaty and, despite the specs, were not sensitive enough to use without a powerful amp. I got a different model as a replacement but they were faulty and I got a refund the same day and went home feeling very fed up indeed with budget closed headphones due to poor design, poor sound, poor manufacturing quality and the hours I'd wasted.

What I wanted is pretty simple: isolation, comfort, enjoyable sound, compatibility with a small headphone amp and maybe even my personal players. None of this has to be perfect, only unobjectionable but it had started to look like a mirage, at least without spending hundreds. I had read reviews of various Superlux products including the HD661 but noticed most of the very enthusiastic reviews that had driven big interest were by a handful of people selling them and this wasn't always made clear. I also saw that reviews by people who do their own measurements and analysis do not correspond to the promotional reviews but do tally with customers reporting less satisfying experiences, so I dismissed the Superluxes as stuff to avoid. However I saw someone on another forum describe how he makes a correctional filter which he solders into the headphones and tames the highs and that the HD661 can sound really nice. This was not someone who claims nirvana achieved after listening to some mp3s on his new 'phones so I paid attention. I'm not skilled in soldering but I can definitely use a parametric equalizer to do the same thing. So I decided to risk a little money and hunted around until I found the cheapest deal in UK and bought a pair of black Superlux HD661.

Features, design, fit etc.

In the box you get the headphones, a short straight cable, a long straight cable, a cable clip, and a 3.5mm to 6.5 mm adapter. Some reviewers seem excited by the accompanying bag. It's pretty nasty, being made of the type of cheap synthetic material that might be used to clothe a child's doll. It has no padding and is basically ugly, unpleasant to the touch and pointless.

You might have read that these headphones clamp very hard. This is true but is fixed easily by just pulling the things apart a bit wider. They stay wider. I have a pretty big head, about 23" around, and have been wearing these for many hours today (maybe eight) and don't have a problem with them. They are quite light and the bits that touch the head are very flexible and don't press. The shape of the cups is very good as it is elongated. I found small round circumaural headphones intolerable because they squash the ears but ones with a more rectangular ear cup are very comfortable even if snug like these. The pads are better than I expected and I haven't had sweaty ears even after hours. By comparison the budget Sennheisers I tried last week started cooking my ears after just a few minutes.

The cable enters on the left and the signal is carried to the right driver by the metal rods that make the headband. I've had various headphones and IEMs fail due to lousy cables and lousy cable routing so I like anything that makes this less likely. The cable on the left is only about an inch long and you attach either of the main cables to it. Everything is standard 3.5mm jacks, no proprietary nonsense. The cable clip prevents the attached cable from coming loose. It doesn't seem to me like it would come loose and anyway I'd prefer a cable to pop out than the headphone to get tugged but the clip does work and supplying it is a nice touch.

The sound:


flac derived from CD and played with:

PC SPDIF to Yamaha HT receiver
PC to FiiO E7 USB DAC/amp
iRiver H140 (Rockbox) headphone out
iRiver H140 (Rockbox) line out to FiiO
Sansa Fuze+ (Rockbox)

The iRiver can drive these easily and the Fuze+ drives them OK but it is at or near maximum volume to do so. The FiiO has no trouble, nor does the Yamaha amp.

Sit back and press play:

Ouch! It's OK until you hear a powerful female voice or a violin or lead guitar or similar powerful high pitched sound and then it is piercing, harsh, and sibilant. It's really bad and if you ever saw the innerfidelity review of other Superlux models you might recall Tyll Hertsens saying it was like listening to good headphones through razor blades. Great description! Probaby the same drivers do duty in lots of the Superlux products with the sound differing a little according to the type of enclosure and the impedance difference of the other components.

I also thought the sub bass was limited and the bass overall was too polite and lacking the small boost that helps with headphone listening. I also think that Superlux's own frequency response charts have to be interpreted as being promotional material first and measurements second (that's the polite version).

Anyway in other respects I liked the headphones. They isolate well, they are pleasant enough to wear and apart from the terrible high frequencies the sound seems quite open and dynamic with detail and real clarity (not the same thing as the harsh highs). So I got to work with parametric EQ in Rockbox and so far have arrived at this:
eq enabled: on
eq precut: 0
eq low shelf filter: 210, 7, 30
eq peak filter 1: 64, 10, 0
eq peak filter 2: 125, 10, 0
eq peak filter 3: 250, 10, 0
eq peak filter 4: 500, 10, 0
eq peak filter 5: 1000, 10, 0
eq peak filter 6: 2000, 10, -10
eq peak filter 7: 3500, 10, -20
eq peak filter 8: 5000, 10, -20
eq high shelf filter: 7500, 7, -60

edit: I think these revised settings are better:
eq enabled: on
eq precut: 0
eq low shelf filter: 220, 7, 30
eq peak filter 1: 64, 10, 0
eq peak filter 2: 125, 10, 0
eq peak filter 3: 250, 10, 0
eq peak filter 4: 500, 10, 0
eq peak filter 6: 2000, 10, 0
eq peak filter 7: 3500, 10, -20
eq peak filter 8: 5000, 10, -20
eq high shelf filter: 7500, 7, -80

I'm definitely not claiming these settings as anything special or definitive and they will inevitably change with extended listening and familiarity but so far it achieves some important things:

No more feelings that my ears are about to split and bleed from screaming razor blade attacks.
A more natural upper midrange (female singers still have natural presence and timbre but no longer sound harsh and edgy)
A bit of boosted bass and some warmth (the bass boost is a matter of taste whereas the adjustments to the higher frequencies are a matter of necessity, being remedial).

I also got as close to this as I could using alsaequal on my desktop.

The headphones now sound truly enjoyable. Naturally with extended listening I'll make some adjustments and notice other qualities good and bad but for the moment I've been listening to a variety of rock, orchestral, choral and instrumental music and enjoying these more than the other small closed headphones I've tried recently. I think this might be the first cheap closed headphone I've heard whose sound doesn't keep reminding you that it's closed amd cheap - very refreshing.


I think my Koss KSC75 will be getting a bit less use and my various IEMs can go back to only being for urban and travel use and my ear canals can finally have a break.

I would strongly caution against buying these if you won't have the facility to either modify them physically or to use them with an equalizer. However if either of those is practical for you and you want some closed, circumaural headphones of reasonable sensitivity then these are a very attractive bargain giving you a more enjoyable experience than some closed headphones that cost two or three times more. Comfort is very good, they work well with a small amp or more powerful personal player, and the sound can be made very enjoyable. Also cheap, cheap, very very cheap biggrin.gif


I`m glad to hear that your torture stopped. This is the saddest review I ever came across in this forum you sound like a user of torture devices rather than  a happy camper to me.
It's better in comments on a review to try to offer a constructive insight, some pertinent information or to ask a question. The idea is to contribute something useful or interesting on the subject of the item in question such that others might find it helpful. Passing through only to leave a weird personal remark is boring and pointless. If you feel the need to offer amateur pyschiatric evaluations and describe personal feelings about others please do so elsewhere, thank you.
I really wish you try more superlux because i'm eyeing them right now. Another nice to read review.
Sorry, I won't be trying any more Superlux ;-)

I think they have their place and they have some good qualities but I stand by my assessment that these can only sound reasonable with a hardware mod or with a good equaliser, and that those faults which cannot be corrected by altering frequency response mean that they can never sound truly impressive.

Right now I have some Sennheiser Momentum (circumaural), some Shure SE215 IEMs, and some Koss KSC75. Every situation is accommodated to my satisfaction (satisfaction, not perfection or mystic trance or ecstasy), so I don't anticipate trying or buying another headphone or IEM until or unless one of those breaks.

My conclusion from trying, buying and returning quite a few different headphones is that cheap or moderately priced closed headphones are generally terrible but with open headphones you can get something very good with minimal outlay. IEMs are a bit like closed headphones: you have to hand over a lot of money or else you get something fragile that sounds inadequate and/or feels uncomfortable and breaks three days after the too short warranty expires. If you can tolerate exaggerated bass then the budget Sennheiser IEMs are surprisingly good.

If I was starting over with small budget but some knowledge and experience I would definitely not be looking at Superlux. For something sound isolating but at a reasonable price I would look for *genuine* Sennheiser CX300-II and use them with expanding foam tips. This isn't audiophile territory but it is extremely listenable and enjoyable. For a budget open headphone the Koss KSC75 is just ridiculously and outrageously good. Closed headphones? I think you just have to forget the cheap stuff because in the end it's always horrible in some way. If you find something that sounds OK it is so badly made that it fails. If you find something robustly made it sounds terrible or, if you are really lucky, merely dull.

So I won't be buying or reviewing another Superlux or similar "too good to be true" or head-fi fotm or "giant killer" headphone. Of the very cheap headphones I've tried only the Koss KSC75 is good enough to recommend irrespective of price.
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