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Superlux HD668B Review (headphone)

L5730

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Just ordered.
Just to let folks in the UK know, the lowest priced seller on Bezos-zon £28.99 is "Deal-Group" but also called BuyersHub in Lancashire. Their own site has these HD668B for £24.99. However, they have a discount code which Save15 percent off the price, so £24.23 inc. £2.99 RoyalMail 1st class. I was going to go that route, but they only offer 14 day returns directly, whereas it's 30 days. I prefer that bit of extra protection.

I'll look into some replacement earpads later, if I find the included ones aren't to my liking.
 

L5730

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At the risk of spurring discussion in another direction...
After EQing all to the same target curve, which is the better headphone, HD681/-B (not the -F) or HD668B?
By better, I suppose I mean most texturally truest to the music and non-gritty?

From spending quite some time reading anecdotal accounts, I am under the impression that 668B is arguably the potential smoothest, whereas the 681 and 681B are a bit more playful in original tuning profile at the expense of post-EQ grit/smoothness? Hence the 668B being a 'boring' headphone. Or, is my thinking just a case of reading too much into things and really, post-EQ they are much of a muchness and any smoothness difference could easily be attributed to unit variance?

Edit: Only using software (or hardware) EQ, no physical disassembly mods.
 
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markanini

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@solderdude might have some input on this. Also HD681 seems silently updated.
1675880480115.png

1675880623607.png
 

sblrog

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Actually, just checked, they’re K240 Monitor.
Did you end up EQing? Unfortunately, they haven't been measured by Oratory or Crinacle. I had to use InnerFidelity measurements and then do some approximate corrections based on graphs from Oratory and InnerFidelity for the K240 Sextett. I can share if you like.

I imagine you're using an amp of some sort?
 

L5730

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My pair arrived today.

The cables are nasty, they crunch in the hand when straightening them. However, they don't seem to be microphonic. Measured about 1 ohm resistance. I checked continuity, normal layout, tip = left, sleeve = ground (thankfully). A 3.5 mm (1/8th in.) TRS male to female extension cable costs only a few pounds anyway so cheap and easy to replace that.

Seem to fit my head OK. Something odd about those wing things. Why the manual suggests adjusting anything I do not know, nothing slides. Maybe I didn't apply enough force? Maybe there is just no adjustment - self adjustment.
Pads are hard, and feel immediately cold on the head. They warm up after a few moments and then probably get too warm over a few hours. So far, so good, I haven't experienced discomfort.

The out of the box sound is OK, I wouldn't call them "treble canons" but there is definitely too much treble for sure. I hear what our host means by the lack of clarity at the same time. Bass is a pleasant surprise.
Sounds like I have a 1 dB channel imbalance favouring the right. So drop the right channel by that much and image shifts to centre/er, easy.

Using the EQ on the first page, with or without the low shelves.

Tempotec Sonata HD Pro has enough volume for me, I haven't maxed out the volume. I've gain at -4 dB from the EQ and music is target to -18 LUFS via ReplayGain.

A change for the better from the TakstarPro82 v1 - although I will keep working on an EQ for them.

edit: daft typo!
 
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markanini

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BTW it looks like Samson SR850 might be a HD668B with a different headband.
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EDIT: I'm not 100% sure now after noticing pad differences.
Either 1. The drivers are tuned similarly and, the Samson pads are close to the Superlux pleather's acoustically.
or 2. The drivers are tuned different, the Samson pads brings the responce closer to Superlux pleathers.
1675993632484.png
 
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L5730

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Samson SR850 = 32 ohm
Superlux HD668b = 56 ohm
Not the same driver impedance, but seeing as Superlux HD681 have multiple variants I wouldn't be at all surprised for yet another tuned version of that [HD681]to be made that closer matches the HD668b. Presonus HD7 looks like another variant, again 32 ohm.
 

solderdude

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These models/brands, along with quite a few other 'unknown' brands are all manufactured by Superlux but do not have the exact same drivers/tuning.
 

Samuelsmash

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I've been using the same pair of 668B for almost 9 years already, very happy with how long they have lasted, can't say the same for all the pairs of ksc75 that I had, and also two pairs of UR20 that broke in less than 2 years.

The only thing is that the short male cable thingy that comes out of the headphone broke (I think it was in 2017 that it happened) and I replaced it with a regular female jack instead.

F1SQdlM.png
 

solderdude

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yes, that dongle thingy will surely fail over time.

broken-wire-sl.jpg
 

L5730

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After wearing these for a while, I am finding that the pads seem to be a weak link in comfort. A slightly wider opening and may be deeper, softer and perhaps not sticky pleather would be better.
Are there suggestions for suitably low priced pads for these? When these headphones cost less than £30 it seems a bit of a stretch (no pun intended) to go for pads that cost £20 or more. However looking around, it seems the ones that cost around £10 or less aren't well received or last only five minutes.

Brainwavz look nice but spendier.
 

FlanjeUK

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After wearing these for a while, I am finding that the pads seem to be a weak link in comfort. A slightly wider opening and may be deeper, softer and perhaps not sticky pleather would be better.
Are there suggestions for suitably low priced pads for these? When these headphones cost less than £30 it seems a bit of a stretch (no pun intended) to go for pads that cost £20 or more. However looking around, it seems the ones that cost around £10 or less aren't well received or last only five minutes.

Brainwavz look nice but spendier.
PXL_20230114_113053618.jpg

I got this set recently for my 681b, they are literally exactly what you described, I wanted them for the same reasons as you. They are the softest pads I've ever used and not sticky at all. It's the Protein Skin option from here: (cost £10 delivered) http://aliexpress.com/item/4000765600874.html
 

L5730

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@FlanjeUK Thank you for your input and the AE link. They look awfully deep/full, but if they are squishy I guess that won't put additional pressure on the head/ears. How about the inner size, is it smaller than the original pads or is there more 'ear room'?
Ah, I think I see your review - you got the "cool and sweat" ones too.
Might be worth buying a coupe of different ones, I've a feeling we'll be grabbing another pair of Superlux headphones for the house.
 

abm0

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After wearing these for a while, I am finding that the pads seem to be a weak link in comfort.
Hello understatement! LOL

The latest ones I got for the 662-Evo are these: https://www.aliexpress.com/item/100....order_list.order_list_main.10.7f381802qk5xIQ
I wanted them perforated to compensate for the extra bass that comes with taping up the baffle holes according to Solderdude's mod, and soft and non-sticky where they touch the skin. Also great that they come in multiple sizes including 110 mm, the pretty uncommonly large diameter you need for them to be just-right on these older Superlux 6xx models. I don't expect the pleather on the sides to last more than a few years, but at least the polyester touching the skin should do very well for a long time. They're not as deep as my Obama ears would like, but a lot better than the stock ones anyway.

Before these I had HiFiMan-like hybrids with velour on the skin contact side and perforations only on the inner ring. Those started peeling to pieces in like 3-4 years.

For a deeper option with soft pleather and way more comfort, this is what I put on my HD669: https://www.aliexpress.com/item/326....order_list.order_list_main.70.7f381802qk5xIQ
Not exactly the right diameter at 105, but from what I remember I just cut away half of the attachment lip to allow it to stretch to a larger size and I got them on securely. No perforations for sound quality as here I was looking for maximum isolation to use them at the office. Super cushiony and comfortable but also a bit sweaty because of the flat protein leather contact surface and no breathability. No idea about durability as I couldn't stand the "two fingers" headband on the 669 for too long so I stopped using them in less than 2 years.

For maximum durability I suppose it would have to be real leather, but good luck trying to find real leather + perforations + velour/fabric contact surface + 110 mm diameter. :)
 
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solderdude

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HD668B review is up and has some simple but effective modifications making it more 'hi-fi'.
Distortion is a bit high at louder levels but at background to 'normal all day' listening levels this is fine.
Sharp treble. Especially at higher SPL levels.
The HD681 velvet pads and lowering the clamping force increases comfort.
 

mc.god

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I'm using a Samson SR 850 for some years now, I think they sound very similar to the Superlux HD668B or HD681B, not the standard HD681, they come with velour pads (this was my choosing factor over the Superlux ones since I hate pleather) and looking at the measurements made by Oratory I had some confirmation.
I made the toilet paper mod by Solderdude long ago after reading his great article about "taming the trebles" and since then i always enjoyed listening to these phones for the little money they cost. I recently tried the eq profile for the HD668B with velour pads (obviously after removing the toilet paper) and it sounds nice but in the end I prefer using it without eq with the paper mod since it's more simple and I don't have to apply negative preamp needed by the eq.
They are a bit uncomfortable making my ears hurt after some time, pressing them to the glasses temples. I tried these pads, they are softer and more comfortable than the original but not solved the problem, I'll try more deep ones sooner or later.
 
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