Superlux HD-681 modifications

[puuzi]

wow!
First post..
What a thread! What a forum!! It's taken me the best part of 3 days to go through the entire thread and, I must admit, this place, RG, seems to be a congregation of the best brains ever in one Forum and who's ever so willing to help and share their knowledge.
Having learnt so much, I took the plunge and ordered a pair of these marvelous HP. The wait is excruciating to say the least!! From what I read here, I know i'll love them, even un-modded.
Soon as I receive them, I will set about doing the filter mod first. The rings looks nice from the pics posted here, but this been an old active thread, I don't know the chances of getting some for my pair.
Anyway, thank you to all who contributed to this thread, especially, Frans, Mick and Mike.

[Deleted]

Welcome to the forum puuzi !

The HD681 is the most fun and extended (to both ends) of the cheaper headphones I have ever come across.
For a bit of money the can be made even more enjoyable.
Not very suited for those that do not like deep rumbling bass and brilliant highs.

The filter and pads are recommended and would call Mick's rings that too, but these are not available anymore.
Even with the mods it is still amazing value for money and a nice fit.

downsides..
mids might have been better, the rods are touch sensitive as is the HP cable.
Stock pads are sweaty.
but what can one expect for that price.

upsides:
Fun sound signature and when modded fun and very good sound signature.
Price performance ratio.

b.t.w. Elysions headbands are a nice touch and preferred over the plastic headband that comes with it.
read the 'Samson SR850' thread to see those.

[Deleted]

The filter and pads are recommended and would call Mick's rings that too, but these are not available anymore.Even with the mods it is still amazing value for money and a nice fit.

Hi Puuzi, welcome

As Frans says the filter is absolutely essential unless you're into the kind of treble response that could skin a cat at ten paces
I would also say that the AKG 240 velour pads are essential as well.

I recently had to fit my stock vinyl pads again for a listening session because I had washed my velour pads and had underestimated how long they would take to dry. Going back to vinyl was not a pleasant experience

[puuzi]

Thanks Frans and Bluesboy for the welcome. It finally arrived this morning. Super-fast delivery Amazon UK! And i just couldn't free it out of it's package fast enough! The wait was that unbearable! Already knowing what to expect, I'll say I'm not disappointed in any way.
The sound from this BadBoy is awesome with capital 'A'. Right out of the 'box'(if you'd call it that), it handled everything i have thrown at it beautifully well.
Forgive me if I don't use the fancy terms to describe this divine experience. I'm not an audiophile by a long short, and only have a Goldring 150 and the Panasonic RP-HTX-7 but this has been cooking on my head all day and so confortable i forget it's there sometimes. The rumble from the bass been the type I havn't been expeosed to before. I just love it! And the sound is getting better by the minute.
The stock pad does get a wee bit warm, just that. So, I'll order the ak240 velour pads soon. And, yes, recable it too. As i'm still enjoying it, the mods can wait for now. I just might order another pair just to try out the mods for comparison sake. Or find someone to handle it for me as I dont have the materials.
I can't express my gratitude enough to all those on here who have contributed to make this thread what it has become. I'm so grateful! Keep up the good work.

[UzminiNu]

You will be surprised how much different they will be.Its not a another level.There are worlds apart modded vs. unmodded!
Frans helped me very much .
One pair bass heavy (with a la sennheiser signature) the other with sorted highs having the original sound signature.And they are the newer revisited mod V3 so far i read.The stock are pretty unpleasant with the harsh highs when compared.

[UzminiNu]

Jul 25, 2011 17:08:29 GMT UzminiNu said:

You will be surprised how much different they will be.Its not a another level.There are worlds apart modded vs. unmodded!
Frans helped me very much .
One pair bass heavy (with a la sennheiser signature) the other with sorted highs having the original sound signature.And they are the newer revisited mod V3 so far i read.The stock are pretty unpleasant with the harsh highs when compared.

i had couple of HD681 so compared burned in and fresh out of the box.so far i remember there was differences.probably some production quality differences too but later they sounded all equal;).

[superluxman]

Finally I made a filter for my Superlux HD 668B.
I used a parallel filter only, because I use headphones only with my sound card (it has a low output impedance).
Thus, the ideal filter circuit:

The real filter circuit:

R3 - output impedance of my sound card, R4 – inductors resistance.
The original appearance of the filter:

A filter soldered into the headphones:

Frequency response of the soldered filter, measured using the sound card and software RightMark Audio Analyzer:

Other measurements (connected only one channel):
upload.com.ua/get/902730974/filter.rar
or
letitbit.net/download/72554.76eaa3212d8fa974fa0c01a8ab96/filter.rar.html
Sorry that the measurement results in Russian, but I think it will be clear. As a result, the filter is much increased the level of distortions, but I can’t hear them with my ears. Measurements were made at the maximum output level of my sound card ~ 2.5V. While the music listening on headphones supplied maximum 0.5 V (if more - ears hurts , so in reality distortion can be lower. Offered to me on another forum in order to reduce distortion its need to use inductors without mandrel. And to base target frequency of the filter from swimming at different volume levels needs to use film capacitors. But for me such filter arranges (for a while at least ).

[superluxman]

I quite forgot! Thanks to solderdude for helping me!

[proid]

I'm very interesting in mick ring but now it won't be avaiable anymore, pence mod is a alternative mod but it seem not provide enought mass. So did you guy try to add some mass by blue tak to the cup?

Edit: I have just tried to take off the name plate then the screw but ... what a nightmare. i just used a normal screw driver, nothing special, not a killer one:

But from the stock screw:

It become like this

The "+" now become a hole "o" ... oh my god .... and i didn't even get the cap out yet, it seem like i will stuck with this forever and i have stop my first modding project now, sad story. I really want to hear potential of this can. Plz help me

[Deleted]

Your screwdriver head seems 'worn'
the screw is only seated in plastic beneath it and not locked

Tip 1:
use a small flathead '0' screwdriver perhaps even file an old one down so it fits in the corners.

Tip2:
put a solderiron tip against it for a short period (just enough to melt the plastic) and then with a flat '0' screwdriver try to unscrew it.
Note this is a 1 go approach as when the plastic solidifies again it is even more 'stuck' and only works when warm as the plastic becomes 'syruppy'

You might need to fit a longer screw afterwards or fill the hole with something.

Tip 3:
drill of the head and you can take the cap off.
grab the remaining end of the screw with pliers and turn it out.

There is not much there to damage directly underneath that screw.

Personally I have never had a screw that didn't come out easily though.
And I opened up quite a few I might add.

good tools are essential.

The thick screw beneath this cap is harder to get out but also bigger.

[kingoftown1]

Hi all, I've just purchased a set of 681s (haven't arrived yet), and I had some questions about the sound signature obtained from applying the filter mod.

It's said to 'tame' the highs. However, I enjoy a bright sound signature a la Beyerdynamic and Grado. I also absolutely cannot stand the veiled sennheiser house sound. I was curious as to where in this spectrum the 681 would land before and after the filter mod is applied.

Thanks!

[Deleted]

without filter like Beyerdynamic DT770 but much coarser and sibilant.

with first type filter only the sibilance is taken out.
The bright signature stays with bass sometimes leaning to overblown on some music stays.

with second type filter more tamed highs.
Better suited for those that don't like trebly highs and are more into sennheiser sound.
Still brighter than sennheiser but because the bass is less 'masked' it starts to show overblown lows more.

With 3rd type filter (only on amps with low output impedance) the signature can be called bright with the right amount of lows (normally leans towards too much with some recordings).
It still reaches rumble type deep lows but not 'overdone' anymore.
With higher impedant amps the low filtering effect becomes less but the highs remain bright yet without the sibilance.

[Deleted]

It'll be interesting to see whether that top has been tamed in the new one; ie has the thread been read?

Ian

[proid]

Thank you so much, Franks!
I have just gone to flea market to get a screw driver, it fit the screw and now i can take off the cap but i must say that screw is very poor in quality, may be that's why superlux headphones are cheap

And i also got something need to do the filter mod, i'm a totally newbie about this thing so i just went around the flea market and ask the seller about these parts. Sometime, i'm not sure if they give me the right parts . Maybe i will just take some time try to solder first and do the mod after i can do some soldering. If the part are not right, it wont' damage the driver, right?

[Deleted]

the caps (brown parts) seem to be the correct ones.
The resistors appear to be 560 Ohm (might be the color of the picture is off)
it should be green-blue-black (56 Ohm) and not green-blue-brown (560 Ohm)
If you have a Multimeter (don't cost much) check the value.

The inductors are NOT the proper value they seem to be something starting with 82.... (grey-red-brown ? meaning 820 uH)
the color code on it should be green-violet-brown (470uH) AND the DC resistance (measure with Multimeter) should be 2.5 Ohm or less.
To take the proper reading hold the measuring leads against each other and note the resistance (probably between 0 and 1 Ohm) and substract that value from the measured DC resistance of the coil.

Practice soldering (you can use the parts that are incorrect) quite a few times.
The driver should not be heated longer than 2-3 seconds.

The wires going to the driver are fixed on the driver with some sticky stuff in the earlier production.
Later they changed it to hotmelt glue.
You can soften that by carefully heating the glue with the solder iron.
Wipe the tip after that.

[proid]

Thanks again, Franks!
The resistor i'm quite sure it's precise. But the inductor may be wrong, i have found a place sell the right one, i will buy it tomorrow and start modding . I have tried do some soldering and it's was so exciting :
And what do you think about the idea to add some mass to the cup by using blue tak instead of pence mod?

[PinkFloyd]

but i must say that screw is very poor in quality

The screws are fine mate, if you had used an appropriate screwdriver you wouldn't have shagged the screw

Much like using a hammer to drive a screw into wood.... I remember a guy I was working with saying "these screws are shite, they keep bending when I hit them with the hammer"..... erm, they are meant to be driven in with a screw "driver" not whacked in with a friggin' hammer

[Deleted]

Aug 7, 2011 6:46:24 GMT @solderdude said:

the caps (brown parts) seem to be the correct ones.
The resistors appear to be 560 Ohm (might be the color of the picture is off)
it should be green-blue-black (56 Ohm) and not green-blue-brown (560 Ohm)
If you have a Multimeter (don't cost much) check the value.

The inductors are NOT the proper value they seem to be something starting with 82....

I had a look at the photo in Photoshop, and even before increasing the colour saturation of the photo, I agreed with Frans.
I suggest that you measure the value of those resistors as they certainly appear to be 560 ohms, NOT 56 ohms.
Alex

[proid]

Aug 7, 2011 10:47:56 GMT @sandyk said:

Aug 7, 2011 6:46:24 GMT @solderdude said:

the caps (brown parts) seem to be the correct ones.
The resistors appear to be 560 Ohm (might be the color of the picture is off)
it should be green-blue-black (56 Ohm) and not green-blue-brown (560 Ohm)
If you have a Multimeter (don't cost much) check the value.

The inductors are NOT the proper value they seem to be something starting with 82....

I had a look at the photo in Photoshop, and even before increasing the colour saturation of the photo, I agreed with Frans.
I suggest that you measure the value of those resistors as they certainly appear to be 560 ohms, NOT 56 ohms.
Alex

Can you tell me what is the value of these parts?

[Deleted]

It might be fun to figure it out with the aid of this page for instance:

www.elexp.com/t_resist.htm

if you google 'resistor color code' and look for pictures you can find a thousand of these.
Inductors can be read in the same way, just not Ohms but uH

[Deleted]

Proid,

Rather than going by the colour codes, which can often be difficult to read correctly (e.g. is that orange//yellow/gold or black/red/brown?) you should use a digital multi meter. Even a £2 cheapie will do the trick!

Best guess=

(ignore last one, Inductor )

Attachments:

[Deleted]

Colour chart...

Attachments:

[proid]

Thanks you guy so much for helping me, so i bought all wrong parts except the inductor, it's a yellow-violet-brown one, the resistor are 39k and 560ohm, what a great experience haha . I will go buy the right parts tomorrow, thanks again, u guys are awesome!

Edit: i'm wrong again, the inductor is yellow-yellow-brown-violet, so it's 440uH

[Deleted]

from top to bottom:

resistor 39k
resistor 560 Ohm
resistor 47 Ohm or 470 Ohm (hard to tell from the picture multiplier could be black or brown)
Inductor 820uH or 8.2uH (depends on the multiplier being brown or gold, hard to see)

[Deleted]

Hers's a good link, it has the calculator working both ways on the same page.

colour code to value & value to colour code