[Steve999]

After some reading, thinking and some follow-up listening, I have come up with a theory that the Senn HD580s/HD600s were designed for a 120 ohm jack, and are engineered such that they would sound better to most people out of a 120 ohm jack than a 0 ohm jack. But from someone like me with at best only a lay-person's understanding of electronics, there is always the possibility that I am completely wrong.

I've taken up listening to the HD580s out of the 120 ohm jack rather than the 0 ohm jack on my Corda amplifier.

I'm a fan of the stock cables, FWIW. Could we please assume for this little thread that the stock cable is just the cat's meow, and that an amp that could power a freight train is not necessarily going to sound better?

Any education or experience to share on the subject of a 120 ohm jack vs. a 0 ohm jack with the Senn HD580/HD600 would be very welcome. I am thinking the 120 ohm jack smooths out the top end of the HD580/HD600 a little. Subtle, but audibly better.

From my reading I infer that a 120 ohm jack is the industry standard for a headphone jack (apart from portables and sound cards and some headphone amps, which tend to be 0 ohms) and that the HD580s were designed for a 120 ohm jack.

I also infer that it takes a little more juice to power a 120 ohm jack as opposed to a 0 ohm jack, thus portables and soundcards tend to go with 0 ohms. True? False?

 

[fiddler]

Some Beyer phones reportedly were designed to be driven from a 120 ohm jack. I don't think this is true for the Sennheisers. Even Jan said so. (I think.)

I owned a Corda HA-1 (first gen), and I thought the HD600 sounded better out of the "0 ohm" jack.

 

[Steve999]

Fiddler, I appreciate your impressions!

BTW, straight from Meier's web site:

"Normally a headphone amplifier has a very low output impedance which gives the amp tight control over the headphone action. However, many headphones have been sonically optimized to be driven by an output impedance of 120 Ohm. This output impedance is an international standard."

To me (that is, Steve999), with the HD580, it seems you may get more high energy mid and upper treble at 0 ohms, but smoother low treble at 120 ohms. And there's plenty of energy in the mid to upper treble of the HD580s, so the trade-off at 120 ohms is worth it.

Again, though, I do not fully understand this stuff.

Quote:

Originally posted by fiddler Some Beyer phones reportedly were designed to be driven from a 120 ohm jack. I don't think this is true for the Sennheisers. Even Jan said so. (I think.) I owned a Corda HA-1 (first gen), and I thought the HD600 sounded better out of the "0 ohm" jack.

 

[PeterR]

Quote:

Originally posted by Steve999 After some reading, thinking and some follow-up listening, I have come up with a theory that the Senn HD580s/HD600s were designed for a 120 ohm jack, and are engineered such that they would sound better to most people out of a 120 ohm jack than a 0 ohm jack. But from someone like me with at best only a lay-person's understanding of electronics, there is always the possibility that I am completely wrong.

Actually, you are...

From a post by Jan over at headwize, A visit to the Sennheiser factories:

We discussed the high impedance value of the HD600 and I was told that Sennheiser prefers a high impedance for their premium models because these sound better. There are two methods to dampen/control the movements of the driver membranes. First you can use mechanical damping (by the air behind the membrane and by the suspension) and secondly you can use electromechanical damping (dissipation of the electrical energy that is generated by the coil if it moves freely in the magnetic field). Sennheiser prefers electromechanical damping as this one stays linear at higher sound pressures. However, for proper electromechanical damping the ratio of the output impedance of the headphone jack and the impedance of the driver should be as small as possible. Therefore driver impedance is rather high and therefore the HD600 sounds best at an output impedance near zero Ohm (Note that the international standard for headphone jacks gives 120 Ohm!).

 

[Steve999]

See, I told you I might be completely wrong!

Cool, I really appreciate it.

I still prefer the sound from the 120 ohm jack, it seems to even out the highs to me, but I know when the other guy has the best of the argument.

Quote:

Originally posted by PeterR Actually, you are... From a post by Jan over at headwize, A visit to the Sennheiser factories: We discussed the high impedance value of the HD600 and I was told that Sennheiser prefers a high impedance for their premium models because these sound better.... Therefore driver impedance is rather high and therefore the HD600 sounds best at an output impedance near zero Ohm (Note that the international standard for headphone jacks gives 120 Ohm!).

 

[JefferyK]

Quote:

Originally posted by PeterR However, for proper electromechanical damping the ratio of the output impedance of the headphone jack and the impedance of the driver should be as small as possible. Therefore driver impedance is rather high and therefore the HD600 sounds best at an output impedance near zero Ohm (Note that the international standard for headphone jacks gives 120 Ohm!).[/I]

Can someone please do the math for me?

Following this formula, the ideal headphone jack impedance for the Sennheiser HD-580 would be 300 ohms, for a ratio of 1:1.

Does not compute!

Jeffery

 

[JefferyK]

Quote:

Originally posted by JefferyK Can someone please do the math for me? Following this formula, the ideal headphone jack impedance for the Sennheiser HD-580 would be 300 ohms, for a ratio of 1:1. Does not compute! Jeffery

Sorry, sorry, sorry. Answered my own question. Had the formula wrong.

Jeffery

 

[PeterR]

Quote:

Originally posted by Steve999 See, I told you I might be completely wrong! Cool, I really appreciate it. I still prefer the sound from the 120 ohm jack, it seems to even out the highs to me, but I know when the other guy has the best of the argument.

Doesn't mean of course that the 120 Ohm jack couldn't make the sound more pleasant to you, that's a different matter altogether and entirely your business...

 

[Fenster]

I own a modded corda HA-1 (corda blue), and from my experience, the 120 Ohm jack suits brighter phones much better. I use my grado SR-225 out of the 120 Ohm Jack, and my Beyer DT250-250 out of the 0 Ohm jack, if that's any indication

To me, SR225s out of a 120 Ohm jack represents the most neutral, balanced sound any current Grado phone can deliver. It just rounds off that 'grato' harshness perfectly, IMO.

 

[Steve999]

Maybe you could show me the right math, because I find it confusing myself. Best I can tell, this theory would always warrant a 0 ohm output jack for any phone (0 divided by anything equals zero, a low ratio indeed) so the mathematical model has no explanatory value whatsoever, in fact, it would appear to border on a nonsequitar.

Further, the formula would be contradictory to the concept of most phones being designed for the industry-standard 120 ohm jack, and we do know some phones are designed to be driven by a 120 ohm jack, and that many of these phones (Beyers, for example) tend to have high impedences; this is real-world evidence against the mathematical/sonic theory that a high impedence phone will tend to sound better out of a low ohm jack.

Further, if true, it seems a higher-ohm headphone would be better suited to a 120 ohm impedence jack with this formula than a lower impedence headphone would, for example:

120/300 is a lot smaller number than, say, 120/60.

I must be in error, or the math has no explanatory value, or at best supports a conclusion nearly opposite of what it is proposed to stand for.

What am I missing?

Quote:

Originally posted by JefferyK Sorry, sorry, sorry. Answered my own question. Had the formula wrong. Jeffery

 

[Steve999]

That's helpful, that's my general impression of what the 120 ohm jack does, too. It casts doubt on the impedence-matching theory, IMHO... it just indicates that phones with a lot of high frequency energy, whatever the impedence, are for some people best suited for an industry-standard (120 ohm) jack.

Quote:

Originally posted by Fenster I own a modded corda HA-1 (corda blue), and from my experience, the 120 Ohm jack suits brighter phones much better. I use my grado SR-225 out of the 120 Ohm Jack, and my Beyer DT250-250 out of the 0 Ohm jack, if that's any indication To me, SR225s out of a 120 Ohm jack represents the most neutral, balanced sound any current Grado phone can deliver. It just rounds off that 'grato' harshness perfectly, IMO.

 

[JefferyK]

Quote:

Originally posted by Steve999 Maybe you could show me the right math, because I find it confusing myself. Best I can tell, this theory would always warrant a 0 ohm output for any phone (0 divided by anything equals zero, a low ratio indeed) so the mathematical model has no explanatory value whatsoever, in fact, it would appear to border on a nonsequitar. Further, the formula would be contradictory to the concept of most phones being designed for the industry-standard 120 ohm jack, and we do know some phones are designed to be driven by a 120 ohm jack, and that many of these phones (Beyers, for example) tend to have high impedences; this is practical doubt on the mathematical/sonic thoery that a high impedence phone will tend to sound better out of a low ohm jack. Further, if true, it seems a higher-ohm headphone would be better suited to a 120 ohm impedence jack with this formula than a lower impedence headphone would, for example: 120/300 is a lot smaller number than, say, 120/60. I must be in error, or the math has no explanatory value, or at best supports a conclusion exactly opposite of what it is proposed to stand for. What am I missing?

Okay, I'll give it a shot...

DISCLAIMER: This is what I was told in response to a message I posted about a similar subject. I don't know if it's right, this is just what I was told.

First of all, the formula in the quoted message seems to get the language backwards.

The damping factor (I have no idea what that means, exactly) ratio is obtained by dividing the headphone impedance by the jack impendance. You want the ratio to be 1 or higher, the higher the better.

Sennheiser HD-580s:

300/120 = 2.5
300/220 (my amp jack's output) = 1.36

Let's try Grado SR-80s:

32/120 = 0.26
32/220 = 0.14

Using this formula, Grado headphones would always require a jack impendance of less than 32 ohms. Which I find hard to believe.

And you're right: Using this formula, a 0 ohm jack would ALWAYS be best with ALL headphones. I find that hard to believe, too.

Something must be missing from the formula, no?

Math was never my thing.

!

Jeffery

 

[NeilPeart]

Without getting into the technical details, I'll just say that I prefer my HD580 out of the 0 ohm jack (gives tight control and power) and my SR225 out of the 120 ohm jack (it tames the sometimes harsh treble and makes the SR225 much more pleasant while still retaining its famous slamming dynamics).

 

[Steve999]

Disclaimer fully taken into consideration.

I'm with you, something's not making sense at all. If that's the formula (as you say it was explained to you), ANY use of a 0 ohm jack will result in a "ratio" of infinity, the best possible result under the theory!!! (X divided by zero is always infinity.) Something is indeed missing, something is very wrong. It seems nothing beyond elementary school mathematics, and the forumla doesn't work either way, at this point it's a matter of refutation by reduction to absurdity. There's no way it seems to make sense. I'm beginning to think it's gibberish, a non-sequitar, and that it deserves to be fully discredited.

Quote:

Originally posted by JefferyK Okay, I'll give it a shot... DISCLAIMER: This is what I was told in response to a message I posted about a similar subject. I don't know if it's right, this is just what I was told. First of all, the formula in the quoted message seems to get the language backwards. The damping factor (I have no idea what that means, exactly) ratio is obtained by dividing the headphone impedance by the jack impendance. You want the ratio to be 1 or higher, the higher the better. Sennheiser HD-580s: 300/120 = 2.5 300/220 (my amp jack's output) = 1.36 Let's try Grado SR-80s: 32/120 = 0.26 32/220 = 0.14 Using this formula, Grado headphones would always require a jack impendance of less than 32 ohms. Which I find hard to believe. And you're right: Using this formula, a 0 ohm jack would ALWAYS be best with ALL headphones. I find that hard to believe, too. Something must be missing from the formula, no? Jeffery

 

[Steve999]

Thanks, I appreciate the impressions. It seems that a lot of people think the 120 ohm jack takes down high energy treble.

Now if someone could tell me WHY an industry standard 120 ohm jack audibly reduces high-energy treble as compared to a zero ohm jack, I'd be very interested.

Nice pic, by the way.

Quote:

Originally posted by NeilPeart Without getting into the technical details, I'll just say that I prefer my HD580 out of the 0 ohm jack (gives tight control and power) and my SR225 out of the 120 ohm jack (it tames the sometimes harsh treble and makes the SR225 much more pleasant while still retaining its famous slamming dynamics).