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Headphone cable - Page 2

post #16 of 35

 

That's much more like it!

 

I'm not familiar with any of those headphones, but based on the super wonky impedance, I'd guess they're all balanced armature IEMs. Is that right?

 

So does someone care to explain what a 100m of W2549 with 0.058 Ohm/m, 11pF/m  between conductors, and 0.8µH/m between conductors does to one of these goofy little guys?

 

On second thought, forget it. If these things have a bunch of passive crossovers in them then there is probably little hope of knowing what exactly these things look like electrically on the inside.

 

On the other hand, if anybody wants to show the effect on a pair of regular headphones.....

 

Cheers


Edited by ab initio - 5/8/14 at 6:28pm
post #17 of 35

Notice these are BA drivers.  I thought it was the crossovers for multi-BA drivers caused this, but now I know even single drivers has some wacky impedance curves.

post #18 of 35
Quote:
Originally Posted by ab initio View Post
 

 

That's much more like it!

 

I'm not familiar with any of those headphones, but based on the super wonky impedance, I'd guess they're all balanced armature IEMs. Is that right?

Yup - BA IEMs have the craziest impedance-frequency curves I know of in any headphones.

post #19 of 35

Oops, I edited my previous post while you guys were posting.

 

So these things are single driver IEMs? no crossovers?

 

Cheers

post #20 of 35

I'm not allowed to post it here because of rules of the forum, but Rin measured FR of an iem with two different cables.  The impedance graph had very minor variance, but the FR had a huge variance.  It's either the measurement was bad or there is something besides impedance that will vary the FR. Only changes were swapping of the cables for the iem.

post #21 of 35
Quote:
Originally Posted by ab initio View Post
 

Oops, I edited my previous post while you guys were posting.

 

So these things are single driver IEMs? no crossovers?

 

Cheers

I believe X10 and UM1 are.  I know others are more than one, but don't know about GR8.


Edited by SilverEars - 5/8/14 at 6:33pm
post #22 of 35
Quote:
Originally Posted by SilverEars View Post
 

I'm not allowed to post it here because of rules of the forum, but Rin measured FR of an iem with two different cables.  The impedance graph had very minor variance, but the FR had a huge variance.  It's either the measurement was bad or there is something besides impedance that will vary the FR. Only changes were swapping of the cables for the iem.


Why wouldn't you be able to post actual data/measurements here?

post #23 of 35
Quote:
Originally Posted by ab initio View Post
 

Oops, I edited my previous post while you guys were posting.

 

So these things are single driver IEMs? no crossovers?

 

Cheers

It's a mixture - some (like the X10) are single driver, while others (like the Triple-Fi and SE535) are multi-driver with crossovers.

post #24 of 35
Quote:
Originally Posted by cjl View Post
 


Why wouldn't you be able to post actual data/measurements here?

There is a rule we're not allowed to post anything related to banned members.  The product is of a banned member of the trade.


Edited by SilverEars - 5/8/14 at 7:00pm
post #25 of 35
Quote:
Originally Posted by ab initio View Post

You're right, I might have over exaggerated a bit! tongue.gif

A bit. tongue.gif

Quote:
This is an important distinction to make. Interconnects are for voltage bridging  a relatively low impedance source (~ 75 Ohms?) to a high impedance input (~ 10 kOhms?)---here, the only real electrical aspect of any sane length of interconnect that one needs to worry about is noise rejection.

Depends on what you consider a "sane length." Going back to your "hundreds of meters," assuming a cable capacitance of say 100pF per foot, and a 75 ohm output impedance from the source, you're looking at being down about 6dB at 20kHz.

Quote:
I'm not really sure how this significantly changes the results. Are there headphones whose impedance changes by an order of magnitude over the audible range?

Why would the headphone impedance need to vary by an order of magnitude?

Quote:
Dynamic headphones should be modeled as an inductor in series with a resistor, right? Ignoring electostatics, are there any drivers that exhibit significant capacitance?

They model more like an RLC seeing as they're resonant. To the left of the impedance peak, they look inductive. At the peak (the resonant point), they're resistive. Moving to the right of the resonant peak, capacitive. Then resistive again as you get down to the voice coil resistance after which they start looking inductive again due the voice coil's inductance.

se
post #26 of 35
Quote:
Originally Posted by SilverEars View Post
 

I'm not allowed to post it here because of rules of the forum, but Rin measured FR of an iem with two different cables.  The impedance graph had very minor variance, but the FR had a huge variance.  It's either the measurement was bad or there is something besides impedance that will vary the FR. Only changes were swapping of the cables for the iem.


I am fully aware that some IEMs can do some pretty wonky things in terms of impedance and response to poor output impedance, etc... but admittedly, I never  use IEMs and don't usually considering them when thinking about headphones, etc. As unfair as that may be.

 

I think it's a little ironic and quite funny that of all the headphones that might benefit the most from beefy cables, it's precisely the headphones that would most easily get ripped right out of your ears by a bigger, bulkier cable.  :tongue:

 

Cheers

post #27 of 35
Quote:
Originally Posted by ab initio View Post
 


I am fully aware that some IEMs can do some pretty wonky things in terms of impedance and response to poor output impedance, etc... but admittedly, I never  use IEMs and don't usually considering them when thinking about headphones, etc. As unfair as that may be.

 

I think it's a little ironic and quite funny that of all the headphones that might benefit the most from beefy cables, it's precisely the headphones that would most easily get ripped right out of your ears by a bigger, bulkier cable.  :tongue:

 

Cheers

These are cables, and they cannot have that much impedance, but guess what, I found this article from Tyll's blog.

 

Here is an interesting exerpt from this article  http://www.innerfidelity.com/content/headphone-cable-measurements-wrap

 

An Avenue for Exploration
I did manage to stumble into what seems to me as a particularly interesting avenue for further exploration and development. I had a discussion with Dr. Kevin Gilmore (who many of you know from his terrific work designing commercial and DIY electrostatic headphone amplifiers) in which he stated that the effectes of impedance matching with headphone cables could be of an order strong enough to influence the listening experience.

All cables have a characteristic impedance. For example, I use Canare 4E5C cable for my cable building needs. This cable has a 40 Ohm characteristic impedance. If I were to build a headphone cable for a Sennheiser HD 600, which has a 300 Ohm impedance, there would be a point at the headphones where the signal went from the 40 Ohm impedance in the cable to the 300 Ohm impedance of the driver. This impedance mismatch would cause a point of reflection for the signal. There is an instrument call a Time Domain Reflectometer that is able to send a signal down a cable and see the various points of reflection caused by impedance mismatches (and other things). The reflected signal from the impedance mismatch can, depending on the topology of the amplifier in use, have an effect on the signal from the amp. To properly impedance match the cable to the headphones in this example case, you would have to put a 40 Ohm resistor between the signal and ground at the headphone end of the cable. This would dramatically reduce the reflected signal.

A further twist on cable impedance matching is to impedance match the output of the amp to the cable. This works better for interconnects where the damping factor between the source and load isn't as important.

It seems to me this is a readily available avenue for further development by custom headphone cable makers.

post #28 of 35
Quote:
Originally Posted by SilverEars View Post
 

These are cables, and they cannot have that much impedance, but guess what, I found this article from Tyll's blog.

 

Here is an interesting exerpt from this article  http://www.innerfidelity.com/content/headphone-cable-measurements-wrap

 

An Avenue for Exploration
I did manage to stumble into what seems to me as a particularly interesting avenue for further exploration and development. I had a discussion with Dr. Kevin Gilmore (who many of you know from his terrific work designing commercial and DIY electrostatic headphone amplifiers) in which he stated that the effectes of impedance matching with headphone cables could be of an order strong enough to influence the listening experience.

All cables have a characteristic impedance. For example, I use Canare 4E5C cable for my cable building needs. This cable has a 40 Ohm characteristic impedance. If I were to build a headphone cable for a Sennheiser HD 600, which has a 300 Ohm impedance, there would be a point at the headphones where the signal went from the 40 Ohm impedance in the cable to the 300 Ohm impedance of the driver. This impedance mismatch would cause a point of reflection for the signal. There is an instrument call a Time Domain Reflectometer that is able to send a signal down a cable and see the various points of reflection caused by impedance mismatches (and other things). The reflected signal from the impedance mismatch can, depending on the topology of the amplifier in use, have an effect on the signal from the amp. To properly impedance match the cable to the headphones in this example case, you would have to put a 40 Ohm resistor between the signal and ground at the headphone end of the cable. This would dramatically reduce the reflected signal.

A further twist on cable impedance matching is to impedance match the output of the amp to the cable. This works better for interconnects where the damping factor between the source and load isn't as important. 

It seems to me this is a readily available avenue for further development by custom headphone cable makers.

 

Headphones, speakers, etc. and the cables that connect them are not transmission lines. The 40 Ohm characteristic impedance of the cable is completely irrelevant for non MHz signals. If an amplifier oscillates, etc. because it get's a back reflected wave from a cable that wasn't impedance-matched to the speaker load, it was an awfully designed amplifier.

 

I like Innerfidelity, but transmission line effects in non kilometer cables at audio frequencies is bollocks.

 

Cheers

post #29 of 35
Quote:
Originally Posted by ab initio View Post
 

 

Headphones, speakers, etc. and the cables that connect them are not transmission lines. The 40 Ohm characteristic impedance of the cable is completely irrelevant for non MHz signals. If an amplifier oscillates, etc. because it get's a back reflected wave from a cable that wasn't impedance-matched to the speaker load, it was an awfully designed amplifier.

 

I like Innerfidelity, but transmission line effects in non kilometer cables at audio frequencies is bollocks.

 

Cheers

Hi, I found this on a website:

 

"A cable becomes a transmission line when it has a length greater than λ/8 at the operating frequency"

 

I've calculated 1.356 Inches for 10khz signal(but this was airborne audio frequency), and headphone cable is longer than 1/8 of this.

 

How do you calculate the electrical signal wavelength?

post #30 of 35

 

Speed of light is 3 x 10^8 meters per second in a vacuum. In a cable, it will be some percentage of that, usually around 80-90%. But even if it were 50%, the wavelength at 10kHz would be 15,000 meters or about 9 miles long.

 

se

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