[BrotherKathos]

the "at least" 1/8 rule of thumb is like a crossroad where various ideas can coexist pretty well:
1) simply getting an efficient system. ideally you'd want the amp with as close to zero ohm as possible to achieve https://en.wikipedia.org/wiki/Impedance_bridging

2) limiting frequency response variations. when the lowest impedance of a headphone is already 8 times or more that of the amplifier, you get a stability within about 1dB in the response compared to another amp with a different impedance but also at least 1/8th of the headphone's impedance. obviously when I'm talking about 1dB or less, I'm assuming that the amps are identical in response into such load. this only help limiting the FR impact due to impedance.
here with the hd650, a high impedance amps will boost around 100hz a little compared to a low impedance amp. not really a big deal here thanks to the lowest impedance of the phone already being quite high. for multidriver IEMs, it can become very important and ruin the signature of an IEM(or make it subjectively better if we're super lucky).
2a) same idea when there are protective caps at the output of the amp. the caps will roll off the low end, and the smaller the impedance ratio(amp/headphone), the smaller the roll off. so getting a headphone at least 8 times the impedance of the amp will mitigate the roll off if protective caps are present at the output.

3) electrical damping. the movement of the driver is determined by mechanical damping(how stiff is the membrane, how heavy is the coil...). there is also how easily the air can flow when moved by the driver and how much air is being moved. and of course one hell of an important parameter is the electrical signal itself making the coil move ^_^.
http://hyperphysics.phy-astr.gsu.edu/hbase/oscda2.html in that link you can see the oscillating behavior for underdamped, critically damped, and overdamped conditions. you don't have to care about why or how,, just know that better electrical damping results in better control of the diaphragm. as I said, it's only one damping parameter for how the driver will move. but it still makes sense to avoid a massively underdamped behavior. unless you happen to like how it sounds. all those concepts are more or less important when it comes to fidelity of the signal reaching our ears, but they don't give the recipe for euphony or personal taste.

4) irrelevant for the HD650. looking at the amp this time, not all designs will be happy when a low impedance headphone is used. in an indirect way, sticking with the "at least 1/8th" rule, might on occasion help us stay within nominal use of the amp.



the 1/8th rule of thumb tends to increase our chances for stability and correct use of the gears. so it's a good rule as soon as we're not too sure about the gears we're using. of course audiophiles who constantly seek change might decide to take this the other way around. and to never follow the idea of impedance bridging for the opportunity to perhaps get bigger changes. ^_^

Thanks for posting this. It was very helpful to me in understanding impedance bridging. I’ve also been interested in whether or not bridging or matching is the best way to go. I know there is no way for this to work wih a hd650 since the impedance swings with frequency, but I think it might be possible with planar magnetics. Would they sound better if the amp matched their impedance, or should they still be bridged? My Audeze lcd 2c are 70 ohm flat so if i had a 70 ohm amp would that work better than a .1 ohm amp?

 

[castleofargh]

Thanks for posting this. It was very helpful to me in understanding impedance bridging. I’ve also been interested in whether or not bridging or matching is the best way to go. I know there is no way for this to work wih a hd650 since the impedance swings with frequency, but I think it might be possible with planar magnetics. Would they sound better if the amp matched their impedance, or should they still be bridged? My Audeze lcd 2c are 70 ohm flat so if i had a 70 ohm amp would that work better than a .1 ohm amp?

sorry but I know very little about planar drivers. they show a behavior that looks pretty much completely resistive(the flat impedance response), so the electrical side of things is indeed fairly easier to address than dynamic drivers. at the same time, it suggests that the damping ratio probably doesn't matter as much as it might on dynamic drivers(within reason). at least that's what my educated guess makes me imagine.

 

[Pharmaboy]

Right, but they provide a very useful look at power output into various impedances. I was surprised to see that Woo states "OK" for 30 to 600 ohms. Also looks like 300 is a sweet spot. My WA6+ puts out more power into all impedances, but I would now like to scare up a WA3 among Seattle head-fiers for some quality listening. Wouldn't be surprised if the WA3 was more "pure".

Have done similar listening at the Bottlehead Spring meet with Crack and S.E.X.

Well, far be it from me to refute anything Woo says (great products, nice people). But...I established to my own satisfaction that:

• Any headphone less than ~70 ohms will probably not sound great on the WA3, at least from the lower midrange on down. The worst effects of impedance mismatching to low impedance HPs are in the bass, I find, with boosted/boomy sound quality
• And above ~70 ohms up to 300 (pre-fazor LCD-2.1; ZMF Eikon; HD650) the effects vary quite a bit depending on the headphone. Getting a closer impedance match is not a magic act: sometimes the effects are quite noticeable & enjoyable (ie, cherry Eikon), but somewhat more subtle on other headphones.
  • For example, I expected the HD650 (and a heavily modded HD650 I compared it to) to excel on the WA3, but I actually preferred both on SS amps. Still not sure why that is...

Regardless of impedance of the headphone, traditional tube benefits are found here--primarily a more dimensional, 3D quality to midrange & treble notes. I find overall that the sonic benefits of tubes on headphone are more subtle, less unmistakable that in big 2-channel speaker setups, which is the reverse of what I expected. Also unexpected is how solid & impactful the bass is on the WA3 w/higher impedance headphones, also how powerful the amp sounds, regardless of specifications (that's audio for you, a surprise-a-minute).

 

[demevalos]

Has anybody had to go through Massdrop because of faulty HD6XX's? I got mine 7 months ago and I'm noticing only now that the left driver is significantly louder than the right. Other cans on the same setup don't have this issue, and when I flip the headphones the wrong way the problem still persists. What is their warranty like? Will I have to pay to get them fixed?

 

[439598]

Is everyones impression of the coin mod positive? I did notice an increase in clarity as advertised but maybe something else was lost, its hard for anyone to be sure of the changes with an irreversible mod unless they have a pair of back up foams to compare.

 

[Tuneslover]

Is everyones impression of the coin mod positive? I did notice an increase in clarity as advertised but maybe something else was lost, its hard for anyone to be sure of the changes with an irreversible mod unless they have a pair of back up foams to compare.

Personally I prefer to listen to a headphone as the designer and manufacturer intended, but inevitably I can't help but wonder if perhaps I tried this or that how it might "improve" the headphone. So yeah I'm guilty of exploring. I suppose the mods I have undertaken on HD650's are easily reversible so I can convince myself that I haven't bastardized them. Shortly after purchasing the Jotunheim I just had to hear how they would sound balanced. So I bought another stock headphone cable and re-terminated it to XLR (minor improvement in sound but appreciable scalability). Next, I decided to replace the stock ear pads with a pair of Dekoni elite hybrids (extends the bass and alters the soundstage somewhat). Finally, I purchased a Schiit Loki in order to give me the flexibility to tailor/tweak the sound further (by far the most versatile tool to dial in a desired sound).

So yeah I have dabbled with mods, however they are easily reversible (or default-ible). When Massdrop and Sennheiser released the bargain priced HD6XX I just had to get one to use in my other headphone systems but occasionally enjoy comparing to my "modded" HD650.

 

[stemplar]

One question: Does someone Fiio Q5 use the HD650? Balanced cable is added, with HD660s (balanced) FLAC silent for approx. 40-50% is enough for him.
The amplifier module is the same as the Fiio X7ii Am3a (540mW), but there is also an AM5 mosul which also has 800Mw, but it is not balanced out, it's just unbalanced. Thanks for the reply .
....................
edit : Meanwhile, the Hd650 came. The performance of FiiO Q5 seems pretty, but in the balanced mode the real (this is also HD660S )
approx. -20% minus 660s in balanced volume mode.
... back and forth is a family of two Sen, but the 660s, not back to the roots ..

 

[SilverEars]

I know @DavidA and I suspect there were some changes from HD650 (most likely older?) to the Massdrop HD6XX.

Here is a video of Tyll taking HD6-- series apart, and he does point out material revisions of the insides.

 

[Deftone]

It could be this



Red: New out of box pads
Blue: well worn old pads

If possible someone could try a pad swap between an old HD650 and new HD6XX if they have them to hand to see how it sounds

I remember my older 650s sounding less aggressive and shouty but when new if your in to rock music it sounds like your sitting on stage with your head next to the amplifiers. In that aspect they calm down with age.

 

[DavidA]

@Deftone, I did a pad swap with my HD650, HD6XX and HD58X and didn't notice any differences between them. FWIW while my HD650 is about 4 years old it doesn't get much use and I bent the headband since the stock clamping force was giving me a head ache. Also bent the headbands of HD6XX and HD58X so I suspect that my pads don't get flattened out much so for me the pads are ruled out as a possible difference in sound

 

[SilverEars]

It could be this



Red: New out of box pads
Blue: well worn old pads

If possible someone could try a pad swap between an old HD650 and new HD6XX if they have them to hand to see how it sounds

I remember my older 650s sounding less aggressive and shouty but when new if your in to rock music it sounds like your sitting on stage with your head next to the amplifiers. In that aspect they calm down with age.

When I had the HD650 (the one from 2010), even the first impression was warm and a bit veiled. I had it for a couple years, and sold it. So, I can't attribute my HD650 impression to pad wear.

HD6XX does initially give you that impression that it's somwhat shouty and agressive in the upper mids. But also, it's pretty filled in the general mids area as well. This is I think why music just pops out, and sounds engaging. It's a bit forward (if I do not use the word agressive) with bass impact as well as I would say heft. Although HD58X looks graphically more extended, HD6XX doesn't seem to have as much lower bass graphically, but interestingly, it sounds more impactful. Not sure if it's due the large bass impedance hump. I do use a 2 ohm output impedance solid-state amp that has quite a bit of power, so it may not warm it up all that much as I wouldn't consider it warm sounding with it's open nature. I think people expect these to have a warm tilt nature. It may have a warm tilt in response, but doesn't seem warm in a sense of lower-end reverb.

I can't help but to speculate that HD6XX is different from my HD650 from 2010.

 

[prymortal]

When I had the HD650 (the one from 2010), even the first impression was warm and a bit veiled. I had it for a couple years, and sold it. So, I can't attribute my HD650 impression to pad wear.

HD6XX does initially give you that impression that it's somwhat shouty and agressive in the upper mids. But also, it's pretty filled in the general mids area as well. This is I think why music just pops out, and sounds engaging. It's a bit forward (if I do not use the word agressive) with bass impact as well as I would say heft. Although HD58X looks graphically more extended, HD6XX doesn't seem to have as much lower bass graphically, but interestingly, it sounds more impactful. Not sure if it's due the large bass impedance hump. I do use a 2 ohm output impedance solid-state amp that has quite a bit of power, so it may not warm it up all that much as I wouldn't consider it warm sounding with it's open nature. I think people expect these to have a warm tilt nature. It may have a warm tilt in response, but doesn't seem warm in a sense of lower-end reverb.

I can't help but to speculate that HD6XX is different from my HD650 from 2010.

Could be.
I found my HD6XX shouty in vocals & cutting in/out imaging/Sound seperation to fall well short of expected levels. So i swapped the HD6XX cable for the HD650(660s) cable & it balanced out the HD6XX vocals a lot (still some male vocal shouty songs) & full imaging no cutting off/out/lacking, much better sound seperation e.t.c. The overall Sound was similar but improved to the ears. I also made a balanced cable from the HD650 cable & used it with the jotunhiem with a similar result. then i go back to the Massdrop cable & it sounds like a trashy shouty $50 headphone again....
Originally thought "meh placebo" so i used the HD6XX Cable on the HD660s & well it wasnt placebo..... similar issue, sounded well off, weak & lacking, "sound signature" was more or less the same but it lost a lot of its "liveliness" to the ear.

The HD600, HD6XX & HD660s all had issues with that cable. Its like the signal or power is lower then drops out when using it. I've actually retried this independently a few times to date same result until i threw it away.
Might be a 1 off failure with my massdrop cable (or 6.3mm adaptor) though.

 

[kman1211]

When I had the HD650 (the one from 2010), even the first impression was warm and a bit veiled. I had it for a couple years, and sold it. So, I can't attribute my HD650 impression to pad wear.

HD6XX does initially give you that impression that it's somwhat shouty and agressive in the upper mids. But also, it's pretty filled in the general mids area as well. This is I think why music just pops out, and sounds engaging. It's a bit forward (if I do not use the word agressive) with bass impact as well as I would say heft. Although HD58X looks graphically more extended, HD6XX doesn't seem to have as much lower bass graphically, but interestingly, it sounds more impactful. Not sure if it's due the large bass impedance hump. I do use a 2 ohm output impedance solid-state amp that has quite a bit of power, so it may not warm it up all that much as I wouldn't consider it warm sounding with it's open nature. I think people expect these to have a warm tilt nature. It may have a warm tilt in response, but doesn't seem warm in a sense of lower-end reverb.

I can't help but to speculate that HD6XX is different from my HD650 from 2010.

That’s likely due to driver excursion differences. Something not really shown in graphs. The HD 58X may simply lack some excursion. The HD 660 S lacked excursion compared to the HD 650. It could simply be because of the lower impedance voice-coil which physically alters the drivers excursion behavior. A headphone with better excursion will be able to produce more impact and a more dynamic sound when driven properly and at louder volumes. One reason a HD 650 is considered ‘scale’ better than a HD 660 S is likely due to better excursion.

 

[FastAndClean]

i can get HD650 for 50 dollars, is that a good deal?

 

[RickB]

i can get HD650 for 50 dollars, is that a good deal?

That's a steal.