Adding impedance to headphones

[mwallace573]

Quote:

Originally Posted by jcx /img/forum/go_quote.gif what do you want to acheive?

I just remember hearing a while back that adding resistance to certain headphones (like the KSC75) would help improve their overall sound. I was just looking for some kind of confirmation before I went through the trouble of adding some resistors in place of the volume pot I was about to remove.

Quote:

Originally Posted by grndslm /img/forum/go_quote.gif Since when do people start using words/abbreviations they don't know. Some people are just a Pain In The Azz...

I didn't know exactly what it meant, but I knew what situation that particular acronym was normally used in. Thanks for the clarification.

Glad I learned something in this thread, cause other than that I have no clue what you guys are talking about.

 

[grndslm]

Fo' Real...

Jung comes in with the sidekick and tells me I need to add a 94ohm resistor... more likely 100ohm, resistor for best results, right???

...just confused as to who Clutz was saying was silly (prolly me). . .

 

[grndslm]

Where can I buy a good 100ohm resistor if I'm recabling myself??

 

[Clutz]

I'm not saying anyone was silly, just that the logic was bad, and so applying said logic probably wouldn't end up having the desired result.

 

[Clutz]

you can order good resistors (vishay-dale's) from mouser- but you'll pay an arm and a leg (relatively) for shipping for the cost of a few resistors. Post a thread in the DIY forum and you can probably buy a few resistors from someone in there, or maybe they'll just mail them to you.

 

[lmfboy01]

by adding impedance, wouldn't it lower your battery life?

 

[NoPants]

after purchasing the AD2000, I am also worried about impedance additions due to the rated 40 ohm impedance of the headphones. I was under the impression that they would be more susceptible to noise if the impedance was too low, similar to how iems pick up nosie easily. To combat this ( so I read/assumed/ whatevered), impedance adapters could be used so that the noise would be "subject to more resistance"

I'm not sure how that logic comes about or if it's even correct, but could someone clarify this?

 

[jung]

Quote:

Originally Posted by Clutz /img/forum/go_quote.gif There is absolutely no 'logic' to that logic. There is nothing to say that the distribution of impedance across the frequency bandwidth is uniform, so adding the enough so that the "middle" between impedance between 60 and 150 ohms is silly. It would make more sense to either work with the minimum impedance so that you know at least you always have X impedance, or work with the nominal impedance.

Majkel's logic:

By adding a 94ohms resistor, when the headphones are at 60ohms, 39% (60/154) of power goes to the headphones, while 61% (94/154) is wasted on the resistor. When the headphones are at 150ohms, 61% (150/244) of power goes to headphone, and 39% is wasted. But when at 60ohms, the voltage drive output more power than when at 150ohms. So the end result is, by adding a 94ohms resistor, the headphones get the same amount of power, both when they are at 60ohms and 150ohms.

Without the 94ohms resistor, the voltage drive output more power when the headphones are at 60ohms than when at 150ohms.

 

[jung]

Quote:

Originally Posted by lmfboy01 /img/forum/go_quote.gif by adding impedance, wouldn't it lower your battery life?

Yes. But it might not be much, if the player spends a lot of battery power on other things like digital processing, instead of on audio output, or if the amp is class A that "wastes" a lot of power on bias.

And it may produce better sound.

 

[jung]

Quote:

Originally Posted by NoPants /img/forum/go_quote.gif after purchasing the AD2000, I am also worried about impedance additions due to the rated 40 ohm impedance of the headphones. I was under the impression that they would be more susceptible to noise if the impedance was too low, similar to how iems pick up nosie easily. To combat this ( so I read/assumed/ whatevered), impedance adapters could be used so that the noise would be "subject to more resistance" I'm not sure how that logic comes about or if it's even correct, but could someone clarify this?

Some noise is distributed to the resistor, so less noise goes to the headphones.

Or, since less power goes to the headphones after adding the resistor, you have to increase the volume control, so more signal is reproduced.

Noise is fixed. Signal can be increased by the volume control. To get the desired signal to noise ratio, the volume may be too loud. So by adding a resistor to reduce the volume, the signal can be listened to at a comfortable level, while the noise is also reduced.

 

[jung]

Quote:

Originally Posted by mwallace573 /img/forum/go_quote.gif I just remember hearing a while back that adding resistance to certain headphones (like the KSC75) would help improve their overall sound. I was just looking for some kind of confirmation before I went through the trouble of adding some resistors in place of the volume pot I was about to remove.

Since the volume pot is a resistor, it will have the same benefit as adding resistor to headphones without volume control. And since it is variable, it is more flexible in searching for a better sound. After you found the best sound you like by adjusting the volume pot, you can further improve it by replacing the pot with a better quality resistor.

 

[ericj]

Quote:

Originally Posted by lmfboy01 /img/forum/go_quote.gif by adding impedance, wouldn't it lower your battery life?

Increasing the impedance (all other variables being the same) requires you to turn up the volume to get to the same SPL as stock.

OTOH having doubled the impedance you've halved the current sinking ability of the drivers. But then when you turn up the volume you make up the difference.

I'm sure I'm missing a third variable, kirchoff is shaking his head at me from the beyond.

Very efficient high-impedance headphones actually increase battery life, because the headphone system requires less current for a comparable SPL.

"Earhugger" is marketing a line of efficient 200 and 300 ohm headphones with the marketing angle that they will increase battery life.

It's a shame their headphone SQ ranges from poor to low-mediocre.

(Since Earhugger HQ is a 10 minute drive from my house, I'd be happy to come over and let you guys try and prove me wrong, if you're reading this)

 

[Clutz]

Quote:

Originally Posted by jung /img/forum/go_quote.gif Majkel's logic: By adding a 94ohms resistor, when the headphones are at 60ohms, 39% (60/154) of power goes to the headphones, while 61% (94/154) is wasted on the resistor. When the headphones are at 150ohms, 61% (150/244) of power goes to headphone, and 39% is wasted. But when at 60ohms, the voltage drive output more power than when at 150ohms. So the end result is, by adding a 94ohms resistor, the headphones get the same amount of power, both when they are at 60ohms and 150ohms. Without the 94ohms resistor, the voltage drive output more power when the headphones are at 60ohms than when at 150ohms.

I understood the logic, I'm just pretty sure that it's simple, straight forward and wrong.

 

[jung]

Quote:

Originally Posted by Clutz /img/forum/go_quote.gif I understood the logic, I'm just pretty sure that it's simple, straight forward and wrong.

Would you explain why it is wrong? Why 94ohms will be worse than an arbitrary number like 75ohms?

 

[Clutz]

It isn't that it is any worse- it's just that there isn't any point to trying to use 94 ohms to obtain the specified goal of having the middle of the nominal impedance range set so that it will be equal to 150 ohms.