[gilency]

I have compared the 250 with 600 DT880's and was not sure they sounded different. I love the DT880's either way.

 

[stang]

I am just not going to bother with learning about how impedance works. Everywhere I read, I say the same thing in another thread and get told I'm wrong =|

 

[nierika]

Quote:

Originally Posted by MrGreen /img/forum/go_quote.gif I am highly skeptical of the whole 600 ohm thing myself, to be honest.

Do your think there might be a reason that the new flagship T1 only comes in 600 ohm?

 

[Drubbing]

Quote:

Originally Posted by 3602 /img/forum/go_quote.gif It says this everywhere. Chinese forums. Head-Fi. Blogs. I don't get it: higher impedance is easier to drive, but better sound quality?

Higher impedance doesn't = better headphones. Some phones are just made with high power requirements. There are plenty of phones that can run with no, or minimal amping, and produce excellent SQ.

The Grado RS series are low impedance, but are very fine headphones, with excellent detail, clarity and SQ. They don't require amps to run to near their potential, but their price dictates that they deserve one.

It does beg the question why phones are made with high impedance, and one answer is that recording studios need multiple headphones to be shared on common equipment, so need high impedance to protect them from the power put through them.

This doesn't answer why those sold at consumer level are built with higher impedance, except that I think bigger, more robust drivers simply need power to work the way intended. Or, a tad cynically (and a dash of this is healthy on audio forums like this one), maybe the manufacturers are aware that audiophiles are concerned about things like floor noise, jitter and all sorts of other (often inaudible) things that may interfere with their listening peace of mind and/or quest for 'perfection'. And are prepared to pay for it. Handsomely. Multiple times.

 

[Uncle Erik]

Headphone impedance matters most when considering the output impedance of the amp you're using. Impedance, by itself, tells you very little unless you know the output impedance of the amp you're using. Impedance tells you how well power transfers from the amp to the headphones. The closer the match, the better the transfer. If there is a severe mismatch, you can lose power. How much power gets through considered with the sensitivity of the headphones tells you how loud the headphones will get.

Also, you have to keep in mind the impedance curves of the amp and headphones. Impedance (usually) is not constant across the frequency spectrum. Both the amp's and the headphones' impedance varies by frequency. Yes, this is slightly complicated.

When you lay the output impedance curve against the impedance curve of the headphones you find the sound signature of an amp with a particular pair of headphones. This is where amp synergy comes into play. Two amps with the same power output but different output impedance curves will make the same pair of headphones sound different.

It's a complex dance between the amp and headphones and you cannot reduce this to "high impedance is hard to drive" and similar conclusions. Unless you know what is powering the headphones, the headphones's impedance tells you very little. It's like knowing that a vehicle has 300 horsepower. That might sound like a fast car, but what if it is 300HP in a 12,000 lbs. school bus? Would 300HP behave differently in a 2,500 lbs. sports car? You have to look at the vehicle's weight, gearing, torque, and other factors to understand how it will perform. It is much the same with amps and headphones - you have to look at a number of different factors.

 

[MrGreen]

Quote:

Originally Posted by nierika /img/forum/go_quote.gif Do your think there might be a reason that the new flagship T1 only comes in 600 ohm?

No idea, but considering it's a completely new driver it is completely different. It's probably where they thought nominal performance occured.

It could have to do with that driver mass thing though.

 

[Helmore]

Quote:

Originally Posted by MrGreen /img/forum/go_quote.gif No idea, but considering it's a completely new driver it is completely different. It's probably where they thought nominal performance occured. It could have to do with that driver mass thing though.

It's 'simply' a function of the design of the driver. It depends on the shape of the magnet, coil, the strength of the magnet, the thickness of the wire used to make the coil, the length of the cable used and how many windings the coil is made of. Those latter two are also a bit part of the shape and size of the coil of course.

Of you want to change the impedance later on then you can either put a resistor in series with the driver, or change the length and thickness of the wire used to make the voice coil. That latter option is what Beyerdynamic does with their DTXX0 series of headphones and will have some effect on the sound the headphones will produce. The difference in sound isn't too pronounced though, otherwise Beyerdynamic wouldn't claim them all to sound the same. There is some difference though, which is inevitable as you are changing the driver and which version is best is a matter of personal taste.

As for the T1, they simply wanted to make the best driver they could and ended up with a driver that's around 600 Ohm. They can still vary it a little by changing the amount of windings of the coil, but they choose to go for 600 Ohm instead of 550 Ohm or 650 Ohm. It might not even be possible to do a 250 Ohm version of the T1 for Beyerdynamic, but that's only if there isn't enough room for a coil with a thicker wire and that's purely speculation. If they wanted to make one with an impedance of 250 Ohm, while still using the same wire, then they would have to run less than half the windings they use now and that would reduce efficiency as well. It would not make the T1 easier to drive and it will actually reduce the amount of power they can handle.

 

[prone2phone]

noise floor, jitter, whatever. 600ohm sound serious even for people that know little about headphone specs, when you look like this : ibuds 16ohm, px100 32ohm, akg 271 64ohm, hd600 300ohm, T1 - whopping 600ohm

 

[Menisk]

Quote:

Originally Posted by prone2phone /img/forum/go_quote.gif noise floor, jitter, whatever. 600ohm sound serious even for people that know little about headphone specs, when you look like this : ibuds 16ohm, px100 32ohm, akg 271 64ohm, hd600 300ohm, T1 - whopping 600ohm

Wow them with a pair of HD414s at 2000ohms.

 

[Helmore]

Quote:

Originally Posted by Menisk /img/forum/go_quote.gif Wow them with a pair of HD414s at 2000ohms.

Or something like the Stax SR007, with an impedance of 170 000 Ohm. They are not electrodynamic based though

.

 

[Palpatine]

Interesting read...I learned a little bit more about impedance.
I'd also like to hear from Beyer themselves why they chose 600 ohm impedence over other impedances. There must be 'sound' logic in their decision. I suspect the answer is at least partially explained in this thread.

 

[MacedonianHero]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif Headphone impedance matters most when considering the output impedance of the amp you're using. Impedance, by itself, tells you very little unless you know the output impedance of the amp you're using. Impedance tells you how well power transfers from the amp to the headphones. The closer the match, the better the transfer. If there is a severe mismatch, you can lose power. How much power gets through considered with the sensitivity of the headphones tells you how loud the headphones will get. Also, you have to keep in mind the impedance curves of the amp and headphones. Impedance (usually) is not constant across the frequency spectrum. Both the amp's and the headphones' impedance varies by frequency. Yes, this is slightly complicated. When you lay the output impedance curve against the impedance curve of the headphones you find the sound signature of an amp with a particular pair of headphones. This is where amp synergy comes into play. Two amps with the same power output but different output impedance curves will make the same pair of headphones sound different. It's a complex dance between the amp and headphones and you cannot reduce this to "high impedance is hard to drive" and similar conclusions. Unless you know what is powering the headphones, the headphones's impedance tells you very little. It's like knowing that a vehicle has 300 horsepower. That might sound like a fast car, but what if it is 300HP in a 12,000 lbs. school bus? Would 300HP behave differently in a 2,500 lbs. sports car? You have to look at the vehicle's weight, gearing, torque, and other factors to understand how it will perform. It is much the same with amps and headphones - you have to look at a number of different factors.

I was all set to jump in, but Uncle Erik laid it down perfectly. Not bad at all...actually very impressive.

The 600 ohms would mean to give reasonable power, that voltage is more important out of your amp than current (Power = VI = Isquared * R). Lower impedance cans require less voltage, but more current. So which is harder to drive? Depends on your amp...

If your amp can supply high current (as in SS amps) then the lower impedance cans would be easier to drive...look at the K701s, if your amp can supply higher voltage (as in a tube amp), then the higher impedance cans would be easier.

 

[Steve Eddy]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif Headphone impedance matters most when considering the output impedance of the amp you're using. Impedance, by itself, tells you very little unless you know the output impedance of the amp you're using. Impedance tells you how well power transfers from the amp to the headphones. The closer the match, the better the transfer. If there is a severe mismatch, you can lose power.

Dude, we're talking about headphones here, not transmission lines.

The most efficient transfer of power over a transmission line occurs when the source and load impedances are matched because then you're not losing power due to reflection losses.

Reflection losses are only an issue when the length of the line is on the order of the electrical wavelengths of the signal you're sending down the line.

But again, we're talking about headphones here. The shortest electrical wavelengths at audio frequencies are MILES long! Transmission line theory just doesn't apply in this situation and invoking it only serves to cause more confusion and erroneous assumptions.

se

 

[aimlink]

Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif Dude, we're talking about headphones here, not transmission lines. The most efficient transfer of power over a transmission line occurs when the source and load impedances are matched because then you're not losing power due to reflection losses. Reflection losses are only an issue when the length of the line is on the order of the electrical wavelengths of the signal you're sending down the line. But again, we're talking about headphones here. The shortest electrical wavelengths at audio frequencies are MILES long! Transmission line theory just doesn't apply in this situation and invoking it only serves to cause more confusion and erroneous assumptions. se

Your counter to Erik's point is exactly why I almost started a thread the other day on this very issue. I was wondering about all this when I had ordered the T1, but for other reasons I decided to cancel the order and I lost interest in the topic.

Impedance matching seems to be especially important with transmission lines, i.e., telephony and such. However, I was getting the impression that with Headphones, it's not such a big issue and at times, severe mismatching is deliberately achieved to allow parallel use of headphones off the same source without significant degradation of the signal. To do this, they'd plug multiple high impedance cans into a very low impedance source amp.

I came away thinking that impedance wasn't really an issue for the hobbyist but more for professional applications. Erik is now saying that my assumption was wrong so:

 

[Steve Eddy]

Quote:

Originally Posted by aimlink /img/forum/go_quote.gif Your counter to Erik's point is exactly why I almost started a thread the other day on this very issue.

My counter was only to Erik's misunderstanding and subsequent misapplying transmission line theory to headphones vis a vis impedance matching and power loss. Specifically, "Impedance tells you how well power transfers from the amp to the headphones. The closer the match, the better the transfer. If there is a severe mismatch, you can lose power."

Just the opposite is true in the situation here.

The most efficient power transfer occurs when the source impedance is effectively zero. Compared to a headphone impedance of say 300 ohms, that's quite an impedance "mismatch."

Now let's say the source's output impedance is 300 ohms. A perfect match.

But now the output impedance of the source is burning up as much power as is being delivered to the headphone. And in order to deliver the same power to the headphone as from the zero impedance source, the "matched" source has to produce twice the power.

se