Superlux HD-681 modifications

[Deleted]

they do not have the needed inductors: (470uH with a DC resistance of 2.5Ohm or lower)

1uF cap= 55046633

resistors they will have as well as the 3.5mm stereo socket and plug

I still have the inductors, caps and resistors in stock.
Not the other parts (plug, socket)

[zspy1985]

How many of each part would I need?

I found this inductor: parts.digikey.com/1/parts/2158575-inductor-470uh-300ma-smd-srr5028-471y.html

Would that work?

[Deleted]

Mar 17, 2012 4:51:28 GMT zspy1985 said:

How many of each part would I need?

I found this inductor: parts.digikey.com/1/parts/2158575-inductor-470uh-300ma-smd-srr5028-471y.html

Would that work?

Yes..

you need 4 caps and 4 inductors.
resistor values depends on the filter.

[caliparo]

hello guys

i'm new on this forum read the whole thing damn big threat but nice info
but i still have one question for
mister frans: about the hd 681 second edition filter ? you've made for the samson sr 850 i really great tutorial drawing ,can you please send me a tutorial drawing for the hd 681 or did i missed something
thanx in advance
if it isn't to much trouble please in dutch
regards marco

[Deleted]

Hi Marco,

Welcome to this forum.

See post 1 of this thread and click the upper link, this gives about the same info.
Also you can PM me (click the folder below my avatar).

I speak: Nederlands, Deutsch, English, Vlaams et un petit peut Francais.

[caliparo]

ok thanks

marco

[mrarroyo]

Well, yesterday (April 20th) I received an stock HD681 and a modified HD681 to try. I have been doing so and do like the modified HD681 although the top end is a bit too tamed as compared with the stock unit. The mids and bass are much better in the modified unit. I will take pictures and post them soon.

[mrarroyo]

Received the pair of Superlux HD681 on 4/20/2012. I have wanted to listen to this unit specially due to its price point and some of the impressions I had read on the net. Aesthetically they are not as gaudy as I expected, actually they look alright. I should mention that my perspective on sound is biased by my age (53) since as most know the frequency response is reduced as we age.

The modified HD681 sports a dual entry, a nice job was done and the cable used is Mogami part number 2893 hi definition mini quad microphone cable terminated in a 1/4” amphenol plug. The Mogami cable is a bid larger in diameter than the stock cable and a bit stiffer, not by a lot but noticeable. I do not know if the finish product will come in just one length, I measured 69” from the tip of the 1/4” plug until it reaches the headphone. I am sure this will be sufficient for most users, however having the option to have a longer length 96” or 120” would be nice. Since I am in the “wishing mode” having the option to terminate the cable to a 1/8” or better yet to a 4-Pin plug could be of great use to a few users.

I started the comparison using an older Musical Fidelity X-Can V2 modified by PinkFloyd of Rock Grotto. Not many may remember this amp since it has been out of production for a few years but it remains one of my favorite amps specially with PinkFloyd’s mods and with one of his Little Pinkie regulated and linear power supplies. For those who are interested in the details the music path was: Apple Lossless files from an iMac - Optical cable - Monarchy Audio DIP Combo - Monarchy Audio DR1 solid teflon coaxial cable - Monarchy Audio NM24 - Signal Cable Silver Resolution w/ Silver Bullets - Musical Fidelity X10-D modified by PinkFloyd w/ Little Pinkie - Signal Cable Silver Resolution w/ Silver Bullets - Musical Fidelity X-Can V2 modified by PinkFloyd w/ Little Pinkie.

Enough! How do they compare? First thing I noticed was that the modified HD681 was a bit louder than the stock unit. I used a Radio Shack sound meter (30-2055) and found the modified unit was on average 1-2 dB louder playing the same passages. Next I noticed the stock unit has a presentation with a lot of bass and treble, not unpleasant but when compared with the modified unit very noticeable. The modified unit tames the presentation of the bass and treble, perhaps tame is not the right word but in the end you hear more of the mids making the overall music presentation much more enjoyable. I will say that I wish the treble was not as attenuated so much in the modified unit since I believe it would benefit from a bit more treble extension.

The Monarchy Audio NM24 has a line stage which can be used with the right pigtail as a headphone amp. Well, I used a pigtail made by Warrior and the same differences I heard via the Musical Fidelity were heard again. I should mention that although the differences were heard the sound from the Musical Fidelity was IMO superior in the level of detail, clarity, and impact.

I was going to call it quits but since the Monarchy Audio NM24 also feeds a Singlepower MPX2 SE Slam I had to try the combo and I am very glad I did. These cans have some kind of mojo going on with the Singlepower, the modified HD681 sounded the best out of the Singlepower. Yes it should be expected considering the price difference, but usually the difference in sound between the amps although noticeable is not this pronounced.

One other area that may or may not be of interest/concern are the pleather pads. They are comfortable and fit well around my ears, however being synthetic they made me sweat just as every other pleather/plastic earpads have done in the past. Since these cans are semi open using an small quiet fan may help or for an additional cost you could try velour pads.

Overall the modified HD681 are IMO a step up from the stock unit and the only significant improvement would be to see if the top end could be extended a bit by changing the value of the components. The rest of the recommendations are minor in comparison.

Pictures can be seen at: picasaweb.google.com/109437154048011247077/HD681?authkey=Gv1sRgCIbv3-a5rPHr1QE

[Deleted]

Miguel,

as you say the top end can be lifted by changing the component values. I love mine and they still get lots of head time.

Btw, don't know if you've managed to hear the 668's, but they're a great listen to though they might not have enough top end for you.
Like all Superlux cans though, a good headphone at a give-away price.

Jeff

[mrarroyo]

Hi Jeff, the only Superlux headphones I have listen too are the HD681.

[horribletoaster]

Do these ear cushions fit on the 681?

www.amazon.com/Sound-Blaster-Warcraft-Headset-Cushions/dp/B004N8J64Q

I heard they are similar to the earpads on Sony XB's

[ruinevil]

Hi Rock-Grotto.

I just joined here. So I am purchasing a 681 from Amazon, and was wonder what the different between the MK1 and MK2 filters are. The frequency graphs look roughly the same to me; the only difference is the switched resistors between the serial and parallel circuits, so I assume the RC circuits is manipulating different frequencies?

Also, if you solder these into the headphones themselves, how do you secure them?

Thirdly, other than Nick's really nice aluminum rings, has anyone found any washers/gaskets that you can replace the rings with?

ruin

[Deleted]

Hi Ruin,

Welcome to the forum.

There are no alternatives to Mick's rings other than painting them if you want to change the color.
The differences between the filters is the second version filters somewhat more highs to make it 'flatter'.
The first filter keeps the peaked highs but removes the 'edge'.

They parts secure themselves (soldering them on the pads) but you can always secure them with blu-tack or something like that.

[ruinevil]

So, I was calling the electronic shops in the area, and no one has the 470uH inductor in stock. They do, however, have 390uH inductors and 82uH inductors in stock. Would the 472uH inductor I would make by putting them in series work effectively?

[Deleted]

yes it would, but takes up more space most likely.
Also the total DC resistance should not exceed 3 Ohms.

Another option (but the filter will sligthly alter) is 390uH with 1.2uF
The 1.2uF could be made from 1uF with 220nF (or 180nF) in parallel or 1uF with 2x 100nF in parallel.

[ruinevil]

Inductors in general have higher ESR values, so adding to capacitance would be better?

[Deleted]

The ESR of an inductor is dependent on the wire diameter and wire length and is always higher than the DC resistance.
well upto and just over it's own resonance point where the inductance of the wiring also starts to play a role but this is FAAAAAR above the audible range.

Changing the inductance to say 47uH and 10uF will give the same centre frequency of the filter but depending on the resistance in the circuit itself (damping of that LC) changes the bandwidth and maximum attenuation as well.

The bandwidth of the filter and attenuation is optimal with 470uH.
a small deviation will not hurt that much but deviating too far alters the filter action substantially.

If possible stick as close as possible to the recommended values.

[ruinevil]

So I bought the 390uH inductors and 1uF and 220nF capacitors (ceramic). I also got the 39 and 56 ohm resistors in 0.25W metal-film resistors.

What program do you use to build the frequency curves images.

Also a bunch of components for the MUSE amp that's coming, but I'll talk about those in a different forum.

www.head-fi.org/t/611129/ksc75-in-igrado-body <--- what happened the last time I picked up a solder iron.

[Deleted]

What program do you use to build the frequency curves images.

I use Multisim but there are other programs as well.
The differences between 390 with 1.22uF and 470 with1uF are quite small in simulation.

blue trace = 390uH and 1.22uF
red trace = 470uH and 1uF

[ruinevil]

So... I ripped off a pad and half a trace... thanks god Superlux PCB are redundant. I just used part of a resistor as a jumper and tied it into the other solder pad.

It worked!

[coil]

Hey everybody!

I ordered Superlux`s HD-681B and HD-662F and soon will be modding them. But before that I have one question (might be stupid). I am planning to buy Aune T1 Tube DAC and wanted to ask about filter components - do I need to change filter components to higher W value because of T1 output mW (1000mW @ 32 Ohm HP`s) ? For example atm I have resistors with 0.25W value. Should I change them to 0.5W for example?

For tease, I will be re-making those HP`s cups from quality hardwood (Oak+Mahagony propably) and use some quality leather for headband and pads ;P Want some Alu rings too but seems they are not available anymore and propably have to make my own CAD drawings and lasercutting.

[Deleted]

Hi Ken and welcome to R.G.

I wouldn't imagine you would have to change anything in the filter but I'm sure someone with real technical knowledge will give you advise.

For tease, I will be re-making those HP`s cups from quality hardwood (Oak+Mahagony propably) and use some quality leather for headband and pads ;P Want some Alu rings too but seems they are not available anymore and propably have to make my own CAD drawings and lasercutting.

If you do make the cups in a nice wood, remember to post lots of pictures - and then get ready for lots of orders from jealous R.G. Superlux owners - with me at the front of the queue

[Deleted]

I wouldn't imagine you would have to change anything in the filter but I'm sure someone with real technical knowledge will give you advise.

Will SOME technical knowledge do ?
I would leave the resistor rating as is.
If anyone is stupid enough to listen at such a high level as to burn them out, then the smell of smoke might help them realise that their hearing has probably already been irreversibly damaged !

[coil]

Ok, seems that was really stupid question, sorry for that

Here is another one - should I play in my new headphones with or without filter? Will it affect "burnt in" sound quality or characteristic in some way?

E: Btw, I luckily got to change my order and took HD-681 instead HD-681B because I want one HP`s for more bassy electronic music and HD-662F for rock etc. Both HP's will still have HFrq mod (1st solderdude mod). Can`t wait to get them already and start modding them!
Btw, I found good airproof material to use inside custom made leather pads (used around conditioner pipes and can be bought cheaply from builders shop).

[coil]

About that earlier question about T1 output and filter components wattage level, I happened to read this -> rockgrotto.proboards.com/index.cgi?board=b&action=display&thread=6057

So, having read that, I came to conclusion it is not needed to raise filter resistors W value. Or am I wrong?
If i understood correctly Aune T1 should have output resistors that will avoid HD-681 to be overdriven?

What ppl in here think about Aune T1 coupled with HD-681/HD662F?
Or should I go with cheaper Audinst HUD mini / Aune X1 / CFA3 Fiio E10 ?

Sorry if this is too offtopic, just want to be sure I get good combo with HD-681/HD-662F

E: Got my answer from another thread and will go with Aune T1 (6922). Should be freaking good bang-for-a-buck setup !