Impedance and sound. - AVS Forum
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post #1 of 12 Old 07-08-2014, 03:08 PM - Thread Starter
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Impedance and sound.

While speaker impedances are within a few ohms of each other, the same is not true of headphones. Headphones vary from impedances similar to those in speakers up into the hundreds of ohms or more.


Since amplifiers are designed with a given output impedance does sound reproduction vary with the input impedance of headphones?
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post #2 of 12 Old 07-08-2014, 05:52 PM
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Quote:
Originally Posted by FMW View Post
While speaker impedances are within a few ohms of each other, the same is not true of headphones. Headphones vary from impedances similar to those in speakers up into the hundreds of ohms or more.


Since amplifiers are designed with a given output impedance does sound reproduction vary with the input impedance of headphones?
It shouldn't with most solid state output stages which have impedaces in the fractions of ohms. Now if you are using a tube headphone amp, then there might be a sonic difference as tube amps have higher output impedance and the loading of the output transformer effects the feedback loop (if one is used).

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post #3 of 12 Old 07-09-2014, 03:08 AM
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Quote:
Originally Posted by FMW View Post
While speaker impedances are within a few ohms of each other, the same is not true of headphones. Headphones vary from impedances similar to those in speakers up into the hundreds of ohms or more.

Since amplifiers are designed with a given output impedance does sound reproduction vary with the input impedance of headphones?
The above is a bit of an over simplification. Amplifiers are designed to drive minimum impedances, and handle higher impedances wonderfully.

The same is true of headphone amps. The ones that drive low impedance headphones well, drive higher impedance headphones well.
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post #4 of 12 Old 07-09-2014, 03:49 AM - Thread Starter
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Thanks guys. I'm trying to figure out where all the headphone amp sound signature claims come from. I'll assume it is no different than the same claims we hear about amps that drive speakers. I ordered some new headphones for the computer. My plan was and still is to drive them with the receiver that powers my computer speakers. No need for a headphone amp. Take care.
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post #5 of 12 Old 07-09-2014, 04:27 AM
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Quote:
Originally Posted by FMW View Post
Thanks guys. I'm trying to figure out where all the headphone amp sound signature claims come from. I'll assume it is no different than the same claims we hear about amps that drive speakers. I ordered some new headphones for the computer. My plan was and still is to drive them with the receiver that powers my computer speakers. No need for a headphone amp. Take care.
Fact is that while a tiny minority of high end audiophiles use SETs to drive speakers despite their high source impedances, headphone amps that provide a source impedance that is high enough to cause audible coloration are pretty common.

A lot of AVRs drive their headphone jacks with dedicated headphone amps, which can be positive for a nice low source impedance, but there are no guarantees.

When in doubt get a Fiio E5 headphone amp for a < $25 which pretty well guarantees a low source impedance, or measure the impedance of the headphone jack that you have.

Here is a good paper on the topic:

http://test.benchmarkmedia.com/discu...nce-Part-2.pdf
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post #6 of 12 Old 07-09-2014, 06:57 AM - Thread Starter
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Originally Posted by arnyk View Post
Fact is that while a tiny minority of high end audiophiles use SETs to drive speakers despite their high source impedances, headphone amps that provide a source impedance that is high enough to cause audible coloration are pretty common.

A lot of AVRs drive their headphone jacks with dedicated headphone amps, which can be positive for a nice low source impedance, but there are no guarantees.

When in doubt get a Fiio E5 headphone amp for a < $25 which pretty well guarantees a low source impedance, or measure the impedance of the headphone jack that you have.

Here is a good paper on the topic:

http://test.benchmarkmedia.com/discu...nce-Part-2.pdf

I understand. Thanks. I ordered a pair of 600 ohm planar magnetic cans and just wanted to make sure my existing receiver and preamp headphone jacks would handle things properly.
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post #7 of 12 Old 07-09-2014, 02:16 PM
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What are the sensitivity of the headphones? You may run in to a situation where you might not have enough voltage out to provide enough power at that ohm value.
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post #8 of 12 Old 07-10-2014, 06:29 AM - Thread Starter
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Originally Posted by 12B4A View Post
What are the sensitivity of the headphones? You may run in to a situation where you might not have enough voltage out to provide enough power at that ohm value.

That isn't a problem. I think using an Ipod to power them might be a challenge but I'm not worried about a stereo receiver being able to handle the job.
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post #9 of 12 Old 07-10-2014, 06:34 AM
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High probability it will work out. If not, there's always the Hammond 119DA.
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post #10 of 12 Old 07-18-2014, 04:05 PM
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Quote:
Originally Posted by FMW View Post
While speaker impedances are within a few ohms of each other, the same is not true of headphones. Headphones vary from impedances similar to those in speakers up into the hundreds of ohms or more.
Although ironically not true for your profile pic--the HE-400:





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post #11 of 12 Old 07-18-2014, 05:57 PM - Thread Starter
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Quote:
Originally Posted by cel4145 View Post
Although ironically not true for your profile pic--the HE-400:





Pretty stable I would say. I didn't mean that the impedance changes a lot with frequency. Obviously it doesn't. I meant that the rated input impedance can cover a wide range. My headphones are rated at 32 ohms although, apparently, your graph shows them at 50 ohms. Some of the popular phones are up in the hundreds of ohms for an input impedance.

The frequency response of the HE-400 certainly doesn't look like that graph. This headphone has a U shaped response curve with a depressed midrange and peaked bass and treble. The sound is calm and luscious. A bit dark with lots of detail in the high treble. You have to spend a whole lot more to do much better than these. These are at a sweet spot in the price/performance curve. Try a pair. They are very nice.

So what is your cat wearing?

Last edited by FMW; 07-18-2014 at 06:00 PM.
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post #12 of 12 Old 07-18-2014, 06:22 PM
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Quote:
Originally Posted by FMW View Post
Pretty stable I would say. I didn't mean that the impedance changes a lot with frequency. Obviously it doesn't. I meant that the rated input impedance can cover a wide range. My headphones are rated at 32 ohms although, apparently, your graph shows them at 50 ohms. Some of the popular phones are up in the hundreds of ohms for an input impedance.

The frequency response of the HE-400 certainly doesn't look like that graph. This headphone has a U shaped response curve with a depressed midrange and peaked bass and treble. The sound is calm and luscious. A bit dark with lots of detail in the high treble. You have to spend a whole lot more to do much better than these. These are at a sweet spot in the price/performance curve. Try a pair. They are very nice.

So what is your cat wearing?
Sorry. I misunderstood that you meant that headphones have wide impedance variance. And many do. Just not the HiFiMan planar magnetics

Not my cat. That's a Sony April fool's day image: http://mashable.com/2013/04/01/sony-animalia/

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