Superlux HD-681 modifications

[andy]

Will,

I got the same ringing but much worse listening to Sr80's, even after listeing to one track, so it happened fast.
I dont listen at huge volumes either, it may be that i am still youngish and have always taken care of my hearing having worked in the sound/lighitng insustry for several years, so i may be able to hear the higher stuff still?

I will try them tonight playing a cd in my rega apollo and listening through my solo, should give a good benchmark as to how high i go!!

Some of this may be batch issues as others have noted but i got mine from the same supplyer within one week of eachother (i have two pairs) so i would guess they are the same batch.

Andy

[Will]

It's bit hard to qualify how loud I do play them, but to give a reference, I use an AK Class A, and when using my K701, the volume is at 12pm, with fully off at 6pm. This gives enough volume to enjoy the music, but still hear when someone speaks to you. I also get no ringing in my ears. Like Andy, I've always looked after my hearing (part of coming form an engineering background, and wearing safety glasses and ear protectors as the norm)

In comparison, the HD681 are at 9-10pm when listening, and give the same apparent volume level, although being closed it's harder to hear someone talking to you.

I was thinking it was either me having sensitive ears or as has been said, a batch variation. I'll get the filter parts ordered up next month and see what happens.

[Deleted]

Well gentlemen.
The filter (or should I say damper) cures this annoying habit of the HD681.
It can be clearly seen in the graphs... the HD681 has a 6 to 10dB TOO much high frequencies.
The filter brings that to the desired proportions and it does only that.
The character of the can remains the same but the 'over the top' highs dissappear.
Easy as that..

[puffin]

Jan 19, 2010 12:59:26 GMT @solderdude said:

Well gentlemen.
The filter (or should I say damper) cures this annoying habit of the HD681.
It can be clearly seen in the graphs... the HD681 has a 6 to 10dB TOO much high frequencies.
The filter brings that to the desired proportions and it does only that.
The character of the can remains the same but the 'over the top' highs dissappear.
Easy as that..

If one was to experiment with the filter, would different values of inductor and resistors be required, or just one or the other?

[Deleted]

Only the resistor values are to be altered.

You can vary the resistor value of R3 and R4 (now 39 Ohms) between 27 (to little damping of high freq) to 120 Ohms (a bit too much damping of high freq.)
You can put a 100 Ohms potentiometer in it's place and fiddle with the settings for instance.

If the resistor value of R3/R4 is between 25 and 50 Ohms use 56 Ohm resistors for R1/R2
If the resistor value of R3/R4 is between 50 and 75 Ohms use 47 Ohm resistors for R1/R2
If the resistor value of R3/R4 is between 75 and 150 Ohms use 39 Ohm resistors for R1/R2

The capacitor and inductor need not to be changed as these are the frequency determining parts of the filter.

Resistor R3/R4 determines the Q factor of the filter AND amount (dB) of filtering at the filter frequency.
The center frequency is around 7.2kHz.
L1,C1,R1,L2,C2,R2 are for compensating the impedance peak which is caused by the filter network L3,L4,R3,R4,C3,C4.

You can leave L1,C1,R1,L2,C2,R2 out IF you want if you are ONLY going to use these cans on a low Z output amp (around 10 Ohms)
In all other circumstances (output impedance between say .. 20 Ohms and 600 Ohms or unknown) this part (L1,C1,R1,L2,C2,R2) of the filter network is ESSENTIAL in obtaining the right amount of damping.

Frans

[puffin]

Frans. Thanks very much for such a comprehensive answer

[PinkFloyd]

First of all...... NOTE TO SELF! : Do NOT glue two pence pieces onto the side of headphones with araldite because they are a BASTARD to remove!!

Mick, your end caps arrived today and, after spending almost an hour removing the two pence pieces, I am happy to say they went on like a dream Your workmanship is absolutely top notch mate, the 'phones now look, feel and sound totally superb.

I don't know what all this talk of harshness is about, to my ears (and at moderate volume levels) they sound just right.... sure, at high volume levels, they can have a tendency to be a bit screechy.... that guy who said they have "loudness button" tuning was pretty much spot on..... at low to moderate levels they are full bodied and informative, it's only when you crank the volco up a bit do they start to grate.

The end caps have brought about further sonic improvements, especially to the bass and midrange..... no doubt about it, the added mass certainly does help.

I had a few days there exclusively listening to the Beyer DT-770 and let me tell you it was literally a breath of fresh air going back to the HD-681.... the DT-770 are like listening to your music through thick carpeting compared with the HD-681..... 681 are soooo much more open, detailed and dynamic. I've also reverted back to the stock pleather pads, the red leathers just didn't do it for me but, hopefully, the ones Claus is sending will be better with his "cone" mods

Frans, I'll buy one of your offboard filters, please PM me with the total cost, shipped. I have a lot on at the moment and just don't have the time to make one... PLUS, I'd like one made by the filter designer himself You have contributed a lot towards this thread and it's only right you get some work out of it.

I noticed somewhere in this thread that someone had removed one of the acoustic grilles and positioned it in the same direction as the other one..... on all the pairs of HD-681 I have seen one side is positioned up the way and the other down the way, I think this is how they are supposed to be

Anyways, I just checked in to say a big thank you to Mick for his work on the end rings / end caps.... his work has really helped transform these cans into something very special..... thanks Mick

[andy]

Mike,

It was me that turned the whole ear assembaly arround so that the acoustic sticky plate was in the same position on each ear.
After listening to it oth ways i decided that the plate should be at the front of the headphones, sounded better to me, not sure how though!!!

I would guess that there is only one ear assembally made on teh production line and one is turned 180deg when put onto the headphones.

Personal preference but i couldnt see any reason why they shouldnt be the same way around.

if anyone knows any better please shout!!!

Andy

[clausdk]

Your pads are almost ready, they have been worked over and stretched for almost 48 hours now My "cone" is getting sore though..

I will send them tomorrow..so hopefully they will be there for the weekend, when you are going out to town with your pimped out 681.

Frans: I would also like an offboard filter (and if I could get the other filter we have been talking about also, it would be perfect).

Also about this padthing, I have been doing a little thinking about making some myself, and am a little bit in love with silk, how cool would that be ?

[clausdk]

Jan 19, 2010 21:36:56 GMT andy said:

Personal preference but i couldnt see any reason why they shouldnt be the same way around.

if anyone knows any better please shout!!!

Andy

Maybe because one is for the left ear and the other for the right ??

[clausdk]

Oh and how do you get the signal from left to right ?

[Deleted]

Frans: I would also like an offboard filter (and if I could get the other filter we have been talking about also, it would be perfect).

If its not to late Frans, can i change from internal to EXTERNAL filters please,Thank you.

Mick.

[andy]

The standard phone has the filter covering the front of one ear and the rear of the other.

I thought that having the sticky metal filter covering the same part of each ear would work better and it appears to for me.
try it and see, i did!!!

I just couldnt see why the filter should be covering different parts of each ear other than for cheeper manufacture, and as they are a built to a budget, that was my thought.

Thanks
Andy

[covenant]

Sigh.....those aluminium rings look the biz. Wish there was a green with envy emoticon.

[Deleted]

I would guess that there is only one ear assembally made on teh production line and one is turned 180deg when put onto the headphones.

I can not understand why Superlux would make one side fit different to the other, if they can both be fitted in the same orientation, they must feel that this design is beneficial to the SQ Andy, perhaps you have proved them wrong, interesting one this!!

[PinkFloyd]

Jan 19, 2010 22:29:04 GMT @heliharris said:

I would guess that there is only one ear assembally made on teh production line and one is turned 180deg when put onto the headphones.

I can not understand why Superlux would make one side fit different to the other, if they can both be fitted in the same orientation, they must feel that this design is beneficial to the SQ Andy, perhaps you have proved them wrong, interesting one this!!

Ever seen a pair of speakers with tweeters that were symmetrical?

[Deleted]

EXACTLY!!!, that`s my point Mike, must be a reason. Pleased your happy with the end caps, think i might have took some mounting caps off another pair, rather than getting a ba`st`rd on trying to remove Araldite.GOOD EFFORT!!
If your in agreement, will have a word with an engraver i know, with regard to getting a few MK3 end caps engraved with RG, with all the work that`s gone into these, i think your Forum deserves its own branded recognition.

[Deleted]

Hi Andy,

I think you're right on the sticker part.
They just make 1 earpiece and it is the same for Left and right. (cheaper to make)

What I can't figure out is why the hell they didn't rotate it 90 degrees.
This way the sticker would always be in the same position be it up or down.
Also why is the sticker not opposite the connections on the back.
This WOULD make sense because the membrane would be damped equally in front and back of it on the same spot.
I guess the sticker was meant to be mounted above the connections and they goofed.

There is NO deep reason (I think) why the sticker is situated as it is.

Andy is right in believing that the left and right channel should be identical in all ways.
I can see no acoustic reason whatsoever to contradict this.

I will be trying it too (rotating one speaker 180 degrees) when I will be modding more of these cans.

to all:

Pads have been ordered and filter components will be ordered today.
boxed filters will be produced next week probably when I can find the time.
When all is ready to ship I will contact those who have placed an order.
If I have parts/boxed filters/pads left I will mention this on this tread.

Frans (Solderdude)

[andy]

Ever seen a pair of speakers with tweeters that were symmetrical?

Nearly all floorstanding and most standmount, certainly over a certain price and size, have symmetrical tweeters. though remember that speakers are standing quite away from you where as headphones sit a little closer!

Andy

[PinkFloyd]

Jan 20, 2010 9:42:14 GMT andy said:

Ever seen a pair of speakers with tweeters that were symmetrical?

Nearly all floorstanding and most standmount, certainly over a certain price and size, have symmetrical tweeters. though remember that speakers are standing quite away from you where as headphones sit a little closer!

Andy

Yes, of course.... "symmetrical" was the wrong word..... I meant one speaker with treble unit at the bottom and the other with treble unit at the top.... ignore me I'm in a world of my own here! Next question...... I wonder what they sound like with the plates removed?

[Deleted]

I wondered about this myself too.
I can't bring myself to the point of ripping the stickers off (and having to stick them back on again) on such a very expensive HP .
Would hate it when I destroyed one.
But the warning text on it ... it is so hard to control myself.

[covenant]

Many thanks to Frans for designing the filter which has transformed a painful listening experience into a pleasurable one. There is still some sibilance but now its seems to be just occaisional poor recordings rather than part of everything. Its altered the bass which has become more pronounced-is this because it was masked by the excessive treble? Whatever the reason it now seems more balanced and listenable.
(Thanks also to Puffin for making the filter and lending me his cans)

[Deleted]

The 39 Ohm resistor in the filter can be replaced by 47 Ohm or even 56 Ohm for ever so slightly more damping of the highs... just might fit your personal taste better.
The character of the cans will remain.

Indeed the bass seems more pronounced (and the mids somewhat 'better') because of a masking effect.

Your brain wants to 'calculate' an accurate sound reproduction and in this process alters the way you perceive the mids and lows too. (causing listening fatigue also)

Now that all this is more balanced you and your brain can relax...

Frans (Solderdude)

[puffin]

Jan 17, 2010 14:05:17 GMT puffin said:

Carried out Frans's mods. I was hoping that these would not change the sonic signature of the original. Pleased to say that it does not. It retains the clarity and sweetens the highs and alos seems to tighten the bass. Well worth it for a few quid.

I made mine so that I can use it with more than one pair.

Covenant. I am glad that it has mostly cured the harshness.

[dean0]

some pictures of my HD-681 with the metal rings fitted, still to be filtered... Again big thanks to heliharris!