Superlux HD-681 modifications

[gomez]

Jan 28, 2010 9:23:16 GMT andy said:

Spent a few mins fitting some of heliharris's and caps.
Look fantastic and i think i can hear a slight difference in the sound but not sure what yet.

They certainly feel better to wear now, they never felt hugely comfortable to me but that extra weight appears to help.

Just need to get some more muff to try!

Joining two therads but these sound really good with that little bravo amp.

[/color]

Hi Andy
Care to elaborate on the 681 + Bravo amp combination ? Myself & a few others have the 681s already & the Bravo on it's way. I would be interested to hear your thoughts on the combination as I expect a few other members would.

[Deleted]

According to the specs of the Bravo amp and the low-ohmic (32 Ohm) HD-681 they don't seem to match very well given the fact that the THD rises very rapidly to significant values at these low impedances.

Tube distortion can sound pleasent even though it is not true accurate reproduction.
This distortion, however, isn't caused by a tube but due to non-linearities in the MOSFET output stage as it is a Source follower WITHOUT any feedback.
This works reasonably well with higher impedant loads but not with low ohmic loads

You could make the match better by switching a resistor of say ...somewhere between 68 and 120 Ohms in series with the output of this amp.

Would change the sound a bit also but the distortion would be far less.

But.. if it sounds good ... then it's fine with me !
Specifications and perception don't seem to go hand in hand in most forums anyway. ;D

On paper it is NOT a good match though.

Solderdude

[andy]

I would agree that it dosnt look like a good match, and with some music it really dosnt work. You also get to hear a lot of the tube hiss in quiet bits.

I would say the sound is less hi-f iand more musical, deefinately not accurate. The bass sounds as though you have a sub woofer in the room!

I have also found that listening to fast electronic music (D&B) sounds as though the amp is lagging behind. Rock sounds fantastic and the new Norah Jones album is amazing.

I only have the HD681's and a pair of W1000's to listen to so i may not be the best to do a comparison.

I like the sound enough to have purchased two of the bravo amps though, so that must say somthing?

Oh my only other amp at the moment is a 2008 solo with psu1. much more detail but no where near as much bass presence (much as expected).

Using cd mainly as well as an ipod with lossless files.

[andy]

really need to get my SCHA finished.......

[andy]

Ok my finished HD 681



I have heliharris alloy parts all round, Solderdude filters and mogami star quad cable with a neutrik silver plated plug.



polished most parts and painted the L and R black with some gloss. Looks fantastic to me!!!

[Deleted]

Hi Guys,
To get this thread back on topic - no offence anyone, honest ;D , - some of you may be interested in the following. I know that there have been varying experiences with the HD681s, particularly with regards to sibilance and I wonder if my experience today may throw any light (or sound? ) on this problem.
This afternoon I 'bit the bullet' and re-wired my 681s. Being a complete novice at soldering I was influenced by others reports not to try to solder a new jack plug so I bought a Maplin 'special offer' Nikkai 5m twin phonos into 3.5 mm jack plug. This has 2 lengths of cable stretching the full length from plug to phonos, making soldering leads to both earpieces easier.
Whilst gently (GENTLY) probing the wires in the left ear piece, the soldered joint to which the black (screen?) lead was connected, two of the wires, still soldered together, came away from the main joint. No force was applied, I was just seperating the tangle of wires to assess what was involved.
I know nothing of such matters but that joint was obviously less than perfect, so could this be an indication of why some people are less than totally happy with the sound they get from these? Personally I did not experience any sibilance so in my case this dodgy joint did not have this effect, but might it, in different conditions, cause such problems for others? It certainly may be worthwhile for other owners to give their soldered joints the 'once over'.
Which leads me onto my next question. The original lead has 5 wires, 2 pairs plus the black screen lead. My replacement lead does not have the screen lead. What effect might this missing lead have on the SQ - just keen to learn.
Last but not least, did the re-wire improve the SQ of the headphones? On the basis of a 2 minute listen, it is certainly no worse and I think it is better, not night and day as they say, but better - time will tell.
Polite comments invited.

[Deleted]

The black wire is a 'common' wire that leeds to the 'sleeve-end' of the plug.
via this wire 'travel the 'return' signals of BOTH drivers.
If this wire would have a lot of resistance the stereo-image would be affected.
A faulty soldering in this case could end up in DISTORTED or lower level signals on the side where no cable entry is.
This has nothing to do with the reprted sibilance as you already suspected.
If you do or do not hear sibilance has only to do with how you perceive sound.
I have modded about 15 of these cans now and must say that there is little spread of quality and if there is, it is in the amount of bass.

All of these 15 cans were sibilant in a similar amount/way.
Also I have not seen any bad solderjoints in any of these cans but they are produced in a cheap fashion so there will always be a lot of 'duds' amongst them.

The original lead does not have 5 but 3 wires.
1 black (common) and 1 red and white (for both channels 1 wire)

the black (common) wire is soldered together with a white wire (-) of left earpiece onto the rods that make the connection to the white lead on the other side (right earpiece).

the red wire is soldered directly to the red wire (+) of the left earpiece and tucked away in a corner of the plastic cup.

the white wire is connected to the other rod and on the other end connected to the red wire of the R earpiece (+)

Yes ... some will say ... ahh usually the red wire means right and the white means left.
Not in the HD681's case for some obscure reason.
And this is similar in all 15 HP's I modded.

It seems there is no leads missing in your can and given your assesment that the sound is no worse and you think it may even be better, so I would not worry about this.

If (for instance) you replace the cable for a screened version single the black wire would have to be replaced by the screen of the new cable.
The resistance of this screen will be lower in resistance then if a single wire were used.
Given the fact the drivers are low ohmic there can be a difference in stereo-imaging noticeable.

The original cable is a bit stiff but the cable has low capacitance and a low resistance so electrically the cable isn't half bad.
But it is a cheap cable for a cheap headphone..

[PinkFloyd]

Fran's (solderdude) filter arrived today and I am pleased to report it is extremely well made using top quality parts. The jack plug is a Neutrik type, the cable is Van Damme classic pro patch with noise rejecting braid and the headphone socket is a top quality gold plated type which is very smooth in operation.

Inside the dinky little enclosure is a professionally made PCB and the soldering work is first class, this is not something that's been slapped together in a hurry.

Included with the filter is an instruction sheet which explains the principle of the filter and a section on tweaking the filter to your own personal taste.





I am listening to the HD-681 right now, with the filter in place, and it definitely seems to open the detail up and the bass also appears to be more "full". It's not a huge difference (which I'm happy about) but definitely does what it says on the tin.... it balances the high frequency (takes out 10dB between 5 and 10kHz) so that it doesn't remain "dominant" over the rest of the freq. range with the result that the bass and mids become more prominent / better integrated.....

All I can say is...... it works and is a "must have" if you feel the HD-681 are a bit too "shouty" for your ears.

Nice job Frans

[Deleted]

Thanks for the write-up Mike.. !

The PCB I used was leftover from crossfeeds I produced a while back and could be used quite well for this project.

Have some anti-RIAA PCB's too that could be used but these were slightly bigger and wouldn't fit in these boxes.

Frans

[PinkFloyd]

Jan 28, 2010 21:19:03 GMT @solderdude said:

The PCB I used was leftover from crossfeeds I produced a while back and could be used quite well for this project.

Meier circuits?

[Deleted]

Hi Frans,
Sorry, you are right, as everyone else must realise - my eyesight is failing as well as my brain ;D . I was concentrating on trying hard not to right off my expensive headphones and expensive new lead and did not notice much else. Men cannot multi-task can they? .
The wires that came away on their own were the black one and one other - sorry but I now can't remember which (failing memory as well ).
My replacement cable had only 2 'proper' wires, one red and one white, but each of these was shielded by a fine wire mesh. In one ear piece I soldered red to red with the mesh shield being soldered to the white and in the other ear piece I soldered white to white with the mesh shield being soldered to the red - DID I GET IT RIGHT or are my earphones now out of phase or something? I am listening to the headphones as I type and they don't seem to be out of phase and I am getting more certain that the new lead is an improvement over the old lead. My hearing is also badly failing if you think that they may be out of phase or otherwise wrongly wired .

[Deleted]

Inspired by Meier and other X-feed schematics I found.
I also made it a little less 'efficient' as usually is the case and called it 'natural crossfeed' as the effect is very subtile.
Some crossfeeds have a big effect, this one only slightly.
One is in the schematics I sent you earlier, the solid state amp.
The hybrid has no crossfeed.

Should post some of these schematics and pics but have not searched yet where to post them.

The hybrid amp I designed because I saw the 'indeed/bravo' amps (now explored on RG I believe) and researched this concept which seems fun and minimalistic.
Had some old tubes lying around and finally thought I'd do somethin' with them.
didn't like the low anode voltage and it's disadvantages and the end stage solution so cooked up my own version. (which you also have)

But we are getting off topic... again.

Oh... wait.. I'll just mention the HD-681 sounds good on these things also and we're back on topic again ;D
But they sound good on almost anything ... no points for me there !

[Deleted]

@ Dave.

As you describe it the mesh on white on 1 and the mesh on red with the other one they MUST be out of phase.
If they ARE out of phase you'd know (try it for the fun)
There would be no bass and everything would sound 'strange'.

So memory must be failing again (or eyesight) ?

If it sounded the same as it did before (or slightly better as you want the mod to be successful) you must have done it right after all.

[Deleted]

Hi Frans,
Thanks for your interest. At the moment I'm beginning to think these are the best headphones that I've ever heard - I've not heard a lot but these are the best, So, ............... either Ive got very strange hearing, or my memory is letting me down AGAIN!!
I can't be arsed to open them up to check tonight (enjoying the music too much! ), but I will have a look tomorrow, if I can bear to look again at my soldering .
Kind Regards,
BTW I've just listened to Barber's Adagio for Strings - if there was ANY sibilance surely it would be heard in the upper reaches of that piece, but none at all did I hear - great!!

[Deleted]

@ Andy

How did you get rid of the 'Superlux' name on the headband ?
Simply by polishing it ?

Frans

[nd74]

Hallo People.

First post

I recieved Frans filterbox yesterday and i must say, it makes the headphones a much more enjoyable experience.
Before the filter i had to turn down the music often, even though i don't listen at high volume, vocals sounded thin and piercing to my ears. Don't have that problem anymore, with the filter everything just sound more natural and balanced.

Thank you Frans for cooking up these little boxes!

Nikolaj

[MaN227]

yes those look quite nice andy,

[toad]

Welcome Nikolaj

[matt7941]

Ditto, welcome Nikolaj. There seems to be an agreement re the HD681s. Without the filter they are a bargain, with the filter they are the bargain of the century. I know with the filter and recabling they are the dogs. Nice to see newbies joining the forum just on this thread alone. I would suggest that this qualifies as unbiased agreement. Mike, you've started something here.

Matt

[dean0]

thanks to solderdude for the filter design, it is working great and realy takes these 'phones to another level!

[andy]

Frans,

I used some paper towel soaked in acetone, dont rub it as it does melt the plastic a bit, so by patting it the paint came away but the headband plastic wasnt affected much. Afterwards i used some car interior polish to give it the shine back.

All the other parts where sanded using 1800 grit wet and dry paper, to give a matt finish.

The plastic end caps sitting on top of Mikes stainless steel caps are sanded as above, then polished with a slightly gritty glass cleaner and them polished on a mop wheel at work to give a high shine, looks nice.

The cable is only 1M in length, more than enough for my needs, though i have also made an extention if I need it.

Andy

[Deleted]

Hi peeps,
Just in case that it may help anyone wondering about the rewiring of these headphones I'll throw the following into the knowledge pool.
I have now listened to my rewired 681s for a few hours and my first impressions are confirmed. The rewiring has lifted what was a very good pair of headphones onto another level. Being a total novice at soldering and knowing nowt abaht wiring, (do I Frans? ), I opted for a 2 phono into a 3.5mm jack plug lead and cut off the phonos, thereby avoiding the need to wire and solder a small jack plug. For no other reason than it was on special offer at Maplins I bought a Nikkai 'Pure Connectivity' lead.
It may well have been a fortunate choice in that the lead may be particularly well suited to these headhones, despite my crap soldering. The sound now, to me, is bloody marvellous - others may differ, it's all down to each individual's perception, but I recommend anybody thinking of trying it to go this route.
Hope this helps someone.

[puffin]

[PinkFloyd]

Afterwards i used some car interior polish to give it the shine back

You can also use WD-40 or GT-85.... brings plastic up beautifully

[andy]

ooooh fish oil.........