# Benefits of High Impedance Headphones??



## tosehee

Can someone explain, in layman's term, the benefits of the high impedance headphones?

 I did the search on google, and all I have found are..

 * you can hook up to multiple headphones in parallel..

 What. Is this it?

 I am total noob in regard to audiophile (just recently got interested). So, please, bear with me with some of these stupid questions.

 Thanks in advance.


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## tosehee

any experts?


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## epaludo

Search and you shall find what you're looking for ...

http://www.head-fi.org/forums/showth...high+impedance
http://www.head-fi.org/forums/showth...high+impedance
http://www.head-fi.org/forums/showth...high+impedance
http://www.head-fi.org/forums/showth...high+impedance


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## tosehee

thanks a lot. For some reason, I couldn't find those...

 Off to read.. thx again.


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## MaZa

This means that in studio enviroments with studio amplifiers with multiple headphone-outs, you can plug multiple high impedance headphones without ruining the sound or stressing the amplifier. Low impedance, while efficient in volume, need more current so its not very effective to put a lot of them to singler amplifier.


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## tosehee

I read all those threads.. So, to summarize..

 The high and low impedance is really the opposite. Most low headphones does crappy job with noise, distortion, and bass reproduction. In order for these headphones to reproduce them properly, they need low voltage, high current amps. 

 On the opposite, the high impedance headphones are harder to drive with, but adding amps that provides high voltage and low current essentially provides the same sound quality.

 The benefit, in this case, is most amps can provide more voltage and less current in easier manner. Also, the noise, distortion, and clipping is less likely to happen with high impedance headphones when properly powered by amps.

 Is this about right?


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## lerio

Quote:


  Originally Posted by *tosehee* /img/forum/go_quote.gif 
_The high and low impedance is really the opposite. Most low headphones does crappy job with noise, distortion, and bass reproduction. In order for these headphones to reproduce them properly, they need low voltage, high current amps._

 

I'll let Pro here reply about that but earing fantastic sound of my Grado particularly for bass something is wrong here 
	

	
	
		
		

		
			





 MaZa, you say high impedance headphones are mainly suitable for studio use (which it's true as i know), why people use high impedance for home use ?


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## BIG POPPA

You are less likely to blow the phones with the high resistance. That is good enough for some.


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## LeonvB

Quote:


 Is this about right? 
 

No, that's oversimplification. Truth is it's much more complex.

 Most circuits are intended for high impedance loads. Take opamps for instance: most only work well with high impedance loads (600 and up). That's one of the reasons fi. the K701 is "hard" to amplify. With the low resistance it has and the relatively high power requirements, it simply needs more amps than most headphone circuits are able to provide.

 @Lerio: The cheapest solution for headphone out in todays market is an opamp. Want to guess what is most commonly used?


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## fortney

Look at the Szekeres or Poorman's Zen amps if you want to drive low impedance (or other) phones with lots of bass and current. Of course they are DIY, but not so hard.

 F


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## lerio

Quote:


  Originally Posted by *LeonvB* /img/forum/go_quote.gif 
_@Lerio: The cheapest solution for headphone out in todays market is an opamp. Want to guess what is most commonly used?_

 

opamp ? must be a abreviation of a word who should be added on Sticky topic of abreviations and acronyms we still need


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## aaron-xp

it's the operational amplifier (if I am not wrong).


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## MaZa

Quote:


  Originally Posted by *lerio* /img/forum/go_quote.gif 
_opamp ? must be a abreviation of a word who should be added on Sticky topic of abreviations and acronyms we still need 
	

	
	
		
		

		
		
	


	


_

 


 Its a small chip, like this.
http://www.nrgrecording.de/assets/im...en/a_opamp.jpg

 It has different types of uses, and usage in amplifier is one of them.


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## majkel

There is another reason for high impedance headphones being more popular in the past - tube amplifiers. They were much more present in the studios in mid-twenty century. Tubes like high biasing voltages and have limited current efficiency, so high impedances match to these conditions. Nowadays portable sources become more and more popular, and they tend to be supplied from as low voltages as possible in order to lower power dissipation in digital circuits. So there is no sufficient voltage to drive high impedance headphones, and on the other hand, solid state devices have no limits regarding current efficiency. You can use bigger transistors, connect them in parallel, and it won't take much place in the amplifier. Moreover, solid state studio amplifiers don't need to have common output stage, so each heaphone jack might have it's own amplifier without much sacrificing amplifier dimensions. So, low impedance headphones are most probably intended to be universal and listenable from any source.


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## lerio

Quote:


  Originally Posted by *MaZa* /img/forum/go_quote.gif 
_Its a small chip, like this.
http://www.nrgrecording.de/assets/im...en/a_opamp.jpg

 It has different types of uses, and usage in amplifier is one of them._

 

Thank's


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## lerio

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_There is another reason for high impedance headphones being more popular in the past - tube amplifiers. They were much more present in the studios in mid-twenty century._

 

Once again studio, but why they build headphone for home use with high impedance


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## majkel

Quote:


  Originally Posted by *lerio* /img/forum/go_quote.gif 
_Once again studio, but why they build headphone for home use with high impedance 
	

	
	
		
		

		
		
	


	





_

 

Probably to fit better desktop tube headphone amplifiers. I see no other reasons. For SS amps it mostly doesn't matter. If it matters then the amplifier's design needs correction IMHO.


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## lerio

You'll agree with me that at least 90 % of people who buy high priced headphone don't even know a tube amp exist, so look strange to me 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_Probably to fit better desktop tube headphone amplifiers. I see no other reasons. For SS amps it mostly doesn't matter. If it matters then the amplifier's design needs correction IMHO._


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## MaZa

I say that there is no actual universal reason why some headphone makers prefer high impedance and others low. Perhaps it just fits them and their production ways better than other style, who knows.

 Perhaps im wrong, perhaps im not. But then again, does it really matter?


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## lerio

Quote:


  Originally Posted by *MaZa* /img/forum/go_quote.gif 
_I say that there is no actual universal reason why some headphone makers prefer high impedance and others low. Perhaps it just fits them and their production ways better than other style, who knows.

 Perhaps im wrong, perhaps im not. But then again, does it really matter?_

 

No 
	

	
	
		
		

		
		
	


	




 It's just that i suspect you're right and it's strange that many people buy high impedance for bad reason (commercial reason of constructor) rather then for listening reason


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## dmk005

This question is a very good one since impedance is not usually a term thrown around related to quality or audio-fidelity. I sense a trend when reading these boards that many of the regulars here are ordering higher impedance cans and they are judging them as superior to the lower impedance cans but there are no explanations as to why the impedance has made a difference. I have been warned by several product designers and distributors to be careful not to follow head-fi user fads. Would this trend be evidence of a non-technically supported head-fi fad? As a community, I am sure we want to not be seen as fadish or fickle but this is how we are viewed by some.

 Why does it matter (outside of the community reputation pov)? I want to make sure any equipment I purchase now will have the right characteristics to cover the industry direction, if at all possible. My Corda Opera is barely powerful enough to power my 250 Ohm DT 880's how the heck will it support a supposedly superior 600 Ohm version? Now if this is all just a fad, maybe I am less likely to care of how much headroom I have using my current lower impedance cans. 

 So, someone needs to step up and be the bull**** detector and help us less experienced and even novice audio enthusiasts.


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## nikongod

its ALL about voicing. the end result has virtually NOTHING to do with impedance.

 if a manufacturer wanted to make a headphone that sounded like the grado RS-1 with a 300 ohm driver, they could. a senheisser hd650 sound in a 32 ohm impedance-not a problem for a dedicated designer. the questions and comments of amplification do come up, and IMHO its a smaller point. i have found VERY few amps in any price bracket what absolutely struggled with any heapdhone period. 

 as far as beyerdynamic, and that they give you choices with their custom program: the 32, 80, 250, and 600 ohm drivers are TOTALLY different drivers, and have a different sound. while they have certain family traits, they are not the same. sorry.

 on that note: there is a STRONG tendency to "voice" 600 ohm drivers a certain way: namely decently flat for studio use. while a manufacturer who wanted to could build a 600 ohm driver with a bass hump that makes the hd650 sound relatively flat 
	

	
	
		
		

		
		
	


	




 could they dont. the 600 ohm headphone market is a small niche in a small fringe of audio listening, the vast majority of people who buy 600 ohm headphones dont want anything but what is available: flattish frequency response.


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## jellojoe

According to Wikipedia, higher impedance headphones (the load) have a higher damping factor which in turn leads to better control of the driver, particularly the bass frequencies. I don't understand either, I'm just regurgitating.


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## JaZZ

Quote:


  Originally Posted by *dmk005* /img/forum/go_quote.gif 
_My Corda Opera is barely powerful enough to power my 250 Ohm DT 880's - how the heck will it support a supposedly superior 600 Ohm version?_

 

I can't believe what you're saying. Maybe the fact that you have to turn the volume knob unusually high has lead you to this opinion. But it's just a matter of gain -- the Opera can even drive the K 1000 when fed with a strong enough input signal.

 There's no direct relation between impedance and sound quality with headphones. But in the real world chances are that higher-ohm headphones offer better results with a broad variety of _home_ amps -- particularly if you take tube amps into consideration. Higher load impedance makes less sensitive to (high) serial resistance. This prevents the frequency response from being distorted (accentuated bass resonance!). For reasons unknown to me the accompanying loss of electrical damping (and the damping factor itself) seems to have virtually no meaning with headphones (see e.g. ER-4, where a 5-ohm driver sounds best with 22- (P) or 100-ohm (S) serial resistors). 

 Moreover lower current (a result of high voice-coil impedance) may lead to lower harmonic distortion in the amp. Provided that it's capable of delivering high enough voltage -- implied with mains-supplied home amps.
.


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## F107plus5

When I first arrived at this evil place I was simply looking for some phones that matched the sound of my speakers. I found them in the form of MS2i. When I needed something that was more laid-back to fill-in what the MS2i wouldn't do for big classical, I gravitated toward HD600. Did I worry about how many ohms we were talking about?....naw.

 Do I care now?....Yup.

 Where does the average Head-Fi lurker and joiner settle at Head-Fi?....Yup!


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## dmk005

Quote:


  Originally Posted by *JaZZ* /img/forum/go_quote.gif 
_I can't believe what you're saying. Maybe the fact that you have to turn the volume knob unusually high has lead you to this opinion. But it's just a matter of gain -- the Opera can even drive the K 1000 when fed with a strong enough input signal.._

 

Go ahead lay it on me cause I believe what I am saying. 
	

	
	
		
		

		
		
	


	




 I am saying that when measured objectively, my Opera, while being fed by my new Mac Mini remains at the 75 to 100% of gain to reach peaks of 90db with most pop/rock music and barely reaches 72 db peaks with classical music at full volume. This is with all the mac internals cranked up max. Perhaps I have a bum Opera. Here is my measurement approach using my 250 ohm DT880s, will this amp be able to handle the 600 ohm 990's if I order them? :


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## JaZZ

Are you sure that the gain is set to high?

 BTW: Have you tried a CDP via Toslink and line input?
.


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## jcx

Meier Opera tech specs:
 "Gain switch. Maximum gain factors -5 / +8 dB."

 which is simply too low, especially with the claimed 13 V output

 8 dB Voltage Gain = 2.5

 13/2.5 = 5.1 V input V required to drive the amp to full speced output V

 typically desktop CD players max out at 2.0 Vrms, DAPs 1 Vrms or less


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## lerio

Well i had same doubt about gain, i asked Jan about that saying that with Total Bithead i needed to use High gain to listen bootleg with poor volume, he said gain on the Bithead is 10 dB and on the Aria/Opera is 8
 dB. The difference of 2 dB is really very small. If you get enough power with the Bithead then I expect you will also get enough power on the Aria/Opera 

 Then i asked if i can customize gain or Led colour he said he don't do any customization anymore for various reason.

 Hope i'll have enough power with Cantate 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *jcx* /img/forum/go_quote.gif 
_Meier Opera tech specs:
 "Gain switch. Maximum gain factors -5 / +8 dB."

 which is simply too low, especially with the claimed 13 V output

 8 dB Voltage Gain = 2.5

 13/2.5 = 5.1 V input V required to drive the amp to full speced output V

 typically desktop CD players max out at 2.0 Vrms, DAPs 1 Vrms or less_


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## SR-71Panorama

I'm no expert here, all I know is Sennheiser seems to like high impedance, with Grado preferring the opposite. So as I see it, decide what sound you're after and then join whatever camp provides it. In my case, I chose Sennheiser. Done.


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## Frihed89

Yes. That gain is surprisingly low. The gain on most of my headamps (SP and MAD models) is around 10-18 ohms. The SBH I have ordered is 15 ohms. All of these amps have lower Vrms output too. My older 120 ohm HD-595s play louder on both amps than my K-701, but this has a lot to do with the relative efficiency of the two models. To get the listening volume up on the SP (OTL) to the same level as on the MAD (Transfomer coupled) holding the volume control fixed, I need to use relatively high gain inputs (mu higher than 40) and either 5687s or 6BL7GTAs as outputs (not 6SN7Gts), and even then the SP isn't quite as loud.

 Moral of the story: If you love low impedance, relatively inefficient headphones make sure you have an amp that can drive them well.


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## dmk005

Quote:


  Originally Posted by *JaZZ* /img/forum/go_quote.gif 
_Are you sure that the gain is set to high?

 BTW: Have you tried a CDP via Toslink and line input?
._

 

In that test I had the gain set to low, but I changed the settings to see objective results at different settings. My point is that I wanted to make sure I was not "just listening too loud" in my Opera observations. The tests proved me accurate that I was listening at the recommended levels and that my amp is 75% to 100% of it's effort to present much of my content. If higher headphone impedance levels become more of the norm, we all need to make sure our amp output can keep up.


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## dmk005

Quote:


  Originally Posted by *jcx* /img/forum/go_quote.gif 
_Meier Opera tech specs:
 "Gain switch. Maximum gain factors -5 / +8 dB."

 which is simply too low, especially with the claimed 13 V output

 8 dB Voltage Gain = 2.5

 13/2.5 = 5.1 V input V required to drive the amp to full speced output V

 typically desktop CD players max out at 2.0 Vrms, DAPs 1 Vrms or less_

 

You lost me with this analysis of the specs. I understand the Opera gain numbers but from there on....
	

	
	
		
		

		
			





 Would you mind explaining it to the novice level?


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## MaZa

Quote:


 I have been warned by several product designers and distributors to be careful not to follow head-fi user fads. 
 


 Care to clarify? Lemme guess, FOTM?


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## senny-ftw

_You are less likely to blow the phones with the high resistance. That is good enough for some._

 Indeed - between myself and a friend we went through 3 sets of HD595s in a month. We guess that the higher impedance of 600s and 650s have kept them safe for years


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## jcx

Quote:


  Originally Posted by *dmk005* /img/forum/go_quote.gif 
_You lost me with this analysis of the specs. I understand the Opera gain numbers but from there on....
	

	
	
		
		

		
		
	


	




 Would you mind explaining it to the novice level?_

 

I don't know that I can

 Ok with 8 dB Voltage gain = 2.5 x linear amplification factor?

 input V x 2.5 = output V

 iPod max output ~ 1 Vrms

 1 Vrms x 2.5 = 2.5 Vrms output from the Opera's output when the analog input is connected to an iPod

 2.5 V << 13 V where 13 V is what Jan specs the Opera at being able to put out - and might be desirable with some 600 Ohm headphones

 so with a popular source component the Opera with analog input doesn't have enough gain to use its capability

 I assume the DAC portion can drive the Opera to the full 13V spec'd output V


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## rohan575

Hello, i am Rohan an audio engineer and i have just joined head fi so a HI! to all,
   
  Regarding Impedance
   
*What is impedance?*
  Simply the AC resistance of the "voice coil" + magnetic field coupling of the magnet inside the headphone.
   
*What is its impact?*
  From simple electronics,
   
  we know       * Voltage = Current X Resistance*
  and                *Power=  Voltage X Current  (or P=VI)*
   
  now lets take an example,
   
  For a headphone to deliver 2 watts of power (a headphone never outputs such high power just an EXAMPLE)
  it can be
  at *1 Volt with 2 Amps of current *           i.e *P=2X1=2watts*
  also at 1 Volts with 2 Amp's of current the headphone has an impedance* of Resistance = Voltage/Current  thus, R=1/2 Ohm (just an example not actual values) 
   
  Also,
   
  the same output with *2 Volts and 1 Amp. *and R=2/1=2Ohms
   
  *life is int that easy impedance is actually quite complex and different driver designs have different impedance's at different frequencies and amplitude (voltage, instantaneous or loudness)
   
  Now,
     
*Why are high impedance headphones manufactured?*
  1.) The displacement (amount of movement) of the diaphragm (the thing that actually vibrates and produces sound) is better controlled via a more accurate flux (magnetic field to pull and push the diaphragm). This gives better accuracy and more performance at lower frequencies.
   
  2.) The impedance is increased by using a different wire for the voice coil and most importantly more turns. More turns or loops creates a larger field (area of magnetic influence), in lay mans terms bigger magnetic area for the coil to move more efficiently.
   
  3.) It also allows SS amps to work more efficiently with lesser distortion have a look at data sheets and a graph of distortion vs output impedance for most audio op-amps and you'll get the idea.
   
*Problems with high impedance*
  1.) Difficult to drive for low powered devices which are configured with lower gains.
  2.) Most need an amp with a different gain (most headphone amps are more geared towards current rather than voltage i.e low impedance than hi impedance)
   
*Do high impedance headphones sound better than low impedance ones?*
  Actually, in headphones "sound stage" or "airiness" or simply the experience depends upon the following,
         1.) *Frequency response*, the curvy graph shows that volume decreases or increases with change in frequency this is actually the complex magnetic field pulling and pushing with different amount of force at different frequencies, impedance affects this in complex ways but to make life easy, it makes it more somewhat "straight" or linear.
          2.) *Distortion*, represents the amount of "change" from the actual signal to the real signal (input signal to output signal) the reason why this is measured by a square wave is because square waives are difficult to drive as they have a "part" DC in them which in theory does not generate flux. Impedance does not a large effect on this.
          3.) Build and design, (to long i cant type so much  )
   
  So to conclude,
  High Impedance is only a d*different approach in energy delivery* in basic terms its relative to *rather faster flowing electrons (hi impedance)* or *MORE but slower electrons (low impedance) *how they effect sound is *dependent on the magnetic filed generated and diaphragm construction* (physical response of diaphragm).
   
  Hope this clears the air.
   
  Rohan


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## jmkarthi

that was a nice explanation.. thanks Rohan575
   
  Quote: 





rohan575 said:


> Hello, i am Rohan an audio engineer and i have just joined head fi so a HI! to all,
> 
> Regarding Impedance
> 
> ...


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## caol ila

High impedance headphones are for classic tube circuitry that had high voltage but low current delivery.
   
  The transmission line standards in studio settings calls for 600 ohms, and 600 ohm headphones had the maximum power delivery since max power occurs when supply and load impedances are matched. High damping rates were not an issue back then.
   
  Low impedance headphones are for low voltage sources with higher current delivery. In other words, modern portable battery operated units.
   
  Just match the right type of headphone with the right source. The DT880 can be had in 32, 250 and 600 ohm versions. Some of the old Sennheiser headphones were 2000 ohm.
   
  There are also other things to consider, such as sensitivity and the impedance curve. Headphopnes with a resistive impedance curve do NOT need a low output impedance amp, but those with a highly reactive impedance curve should be driven by an amp of much lower output impedance. Otherwise, the impedance fluctuations form a highly variable voltage divider network.


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## rohan575

please note:
   
  I stated it in terms of speed of electrons, it is not! speed of electrons in a conductor is constant, rather the potential that they are accelerated under changes


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## Chris J

Quote: 





caol ila said:


> High impedance headphones are for classic tube circuitry that had high voltage but low current delivery.
> 
> The transmission line standards in studio settings calls for 600 ohms, and 600 ohm headphones had the maximum power delivery since max power occurs when supply and load impedances are matched. High damping rates were not an issue back then.
> 
> ...


 

 Hi,  I agree with most what you are saying expect the part about 600 ohm transmission lines.
  600 ohm transmission lines have no application to driving headphones. Neither does maximum power delivery. You do not want to match supply and load impedances.
  If you drive a 600 ohm headphone with a 600 ohm output impedance headphone amp you will have very poor efficiency in the amp/headphone interface and a damping factor of 1.


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## Tribbs

If high impedance makes for _better sound _why are all speakers (at least those I am aware) spec'd between 4-8 Z and not, say, 600-1200 Z? 
   
  Also, impedance is the voltage–current ratio at a particular frequency.  The impedance varies across the frequency spectrum.
   
  For further consideration is this interesting post by tomb:
   
_There is a hypothesis that hasn't been proven with extended testing, but can be one explanation for why Grados sound better with tubes. It has to do with the over-emphasis toward zero output impedance that exists with many solid-state amps. Contrary to conventional wisdom around here, Grados at 32 ohms do not necessarily prefer amps with low output impedance. Dsavitsk has postulated that the higher damping factors resulting from low output impedance may actually contribute to Grados sounding harsh. He's designed/built enough amps to test this out on a real basis. From my limited experience, I would agree. Grados will sing with certain types of tube amps, but border on unlistenable harshness with ultra-low output impedance solid state amps._


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## rosgr63

Great summary Rohan, Thanks


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## Chris J

Quote: 





tribbs said:


> If high impedance makes for _better sound _why are all speakers (at least those I am aware) spec'd between 4-8 Z and not, say, 600-1200 Z?
> 
> Also, impedance is the voltage–current ratio at a particular frequency.  The impedance varies across the frequency spectrum.
> 
> ...


 


 Hi,
  Please refer to this:
  Go to "Head Fi" Home page
  scroll to bottom of page
  you will see a list of articles
  click on "all articles"
  then go to page 3 of "all articles"
  on page three you will find a link to an article called "Headphone Impedance"
  this may go some way to answer your question
   
  I agree with your comment about the low Z headphones and high Z headphones, there are lots of good low Z designs and lots of good high Z designs.
  As for Grados, the textbook answer is "use a very low output Z headphone amp"...............OTOH if you like the sound of a hi output Z tube amp, then go for it!
  I have a pair of Q701 which I enjoy using with my relatively high output Z OTL tube amp. It goes against the rules but I still like it!


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## nikongod

Quote: 





tribbs said:


> If high impedance makes for _better sound _why are all speakers (at least those I am aware) spec'd between 4-8 Z and not, say, 600-1200 Z?


 

 You can currently buy 16 ohm speakers off the shelf from a variety of sources (speakers for guitar amps, hi-fi, and automotive) and historically speakers were made in a VERY VERY wide variety of impedances, with some going as high as several hundred ohms. 
   
  Regarding SS amps: none of that mattered when everything was transformer coupled. You just got the transformer wound for the speaker you had. When speakers were almost only sold in big integrated boxes (you know the old style tube radios) this was not difficult or even prohibitive. 
   
  Regarding why we dont have other impedances TODAY I'l ask you a question, and tell you the answer. 
  Are 4 and 8ohms better, or is that just what non-technical users are familiar and comfortable with? Its the later. The best item for the job depends on the job. Period. Anyone who gives you a default answer on BEST is a fool. People default to 4&8ohms because that is what they are familiar with.


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## Chris J

Quote: 





nikongod said:


> You can currently buy 16 ohm speakers off the shelf from a variety of sources (speakers for guitar amps, hi-fi, and automotive) and historically speakers were made in a VERY VERY wide variety of impedances, with some going as high as several hundred ohms.
> 
> Regarding SS amps: none of that mattered when everything was transformer coupled. You just got the transformer wound for the speaker you had. When speakers were almost only sold in big integrated boxes (you know the old style tube radios) this was not difficult or even prohibitive.
> 
> ...


 


 I would argue that 8 ohm speaker are standard because most audio power amplifiers are optimized to work best into 8 ohm speakers.
   
*BTW, this has nothing to do with impedance matching or Maximum Power Transfer.*


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## nikongod

Quote: 





chris j said:


> I would argue that 8 ohm speaker are standard because most audio power amplifiers are optimized to work best into 8 ohm speakers.
> 
> *BTW, this has nothing to do with impedance matching or Maximum Power Transfer.*


 
   
  Based on what if not maximum power transfer?


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## Chris J

Quote: 





nikongod said:


> Based on what if not maximum power transfer?


 

 OK
  Deep breath.
  Not too sure what you know and what you don't know...........so forgive me if this sounds like a lecture
	

	
	
		
		

		
			





 or if I sound like Mr. Spock.
  Maximum Power Transfer means (as you probably know) the Source Impedance = the Load Impedance.
  In our case this would mean the headphone impedance would be equal to the headphone amplifier output impedance.
  The voltage divider principle would apply here.
  As you know no doubt know:
  If headphone impedance = Amp output impedance then you would have poor damping factor AND poor efficiency in the headphone/amp interface.
  In a loudspeaker system most loudspeakers have an average impedance of approx. 8 ohms (just stating the obvious) and the power amplifier has an output impedance in the range of 0.1 ohm or less. 
  When the audio power amplifier manufacturers design a 100 Watt amp to work with an 8 ohm speaker they use a power supply with enough voltage and current to provide 100 watts (for example) and select output transistors to deliver enough current.
   In addition, Audiophile amplifier manufacturers usually design in enough capacity to also support a 4 ohm load or even lower.
  How do I know this? I'm an EE.
  Regards, C
      
  .......any thoughts on the Nikon D90? I'm thinking about getting one.


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## nikongod

Quote: 





chris j said:


> OK
> Deep breath.
> Not too sure what you know and what you don't know...........so forgive me if this sounds like a lecture
> 
> ...


 

 In a crop-sensor Id lean towards the D7000 or maybe 5100 unless you need a feature that you can only get on the D90. The high ISO performance and dynamic range of the newer bodies totally dominates the older digital cams. 
   
  I thought we weren't talking about maximum power transfer, specifically ignoring it per your post at the top of the page. 
   
  Skipping that, and the next bit about the same thing with headphones we get to the part about a hypothetical SS amplifier with a 100watt power rating, and a 0.1ohm output impedance. 
  What about this amplifier would not work better with a 16ohm speaker than an 8ohm one? 
  The electrical damping factor would be better with the 16ohm speaker than the 8ohm speaker. 
  You stated that the transistors are selected to supply enough current into 8ohms, so why wouldn't they supply adequate current for 16ohms? 
  The absolute max power would probably (although there are conditions where this does not apply) be lower with the 16ohm speaker than the 8ohm one, but if the amp had decent overhead/safety factor in its power rating this should not be a problem. 
  So whats left? Various distortions? Crosstalk? You can find pretty solid numbers for both in chip-amp data sheets, and from a few manufacturers who specify the performance of their amplifiers into 16ohms. 
   
  Why 8ohms:
   
  8ohm speakers became the default choice for a few reasons, none of which have really anything to do with being better, and most have to do with being cheaper. 
   
  One of the reasons was that on less expensive consumer grade transformer coupled tube amps a popular place to save a few bucks was in the transformer. Aside from poor quality in general, the various output taps seen on better amps were dropped. The designers of this cheap gear were faced with a decision of what 1 tap to use. 8 ohms was the most common choice between the also common 4 and 16 ohms, so that's what they picked. A few dollars less sells amps all day long... people quickly realized that their new amps only had taps for 8ohm speakers so that's what people bought. 
   
  Tube amps with multi tapped output transformers dont have these problems, and work GREAT into any load they have a tap for, but the extra taps add cost to the amp and most people just dont care. The few people who did care enough to spring for extra taps wanted all sorts of cool in their amps (McIntosh, Harmon-Cardon, Leak, and others) , which drove the cost even higher so aside from a fairly small niche the 4 and 16ohm speakers had a foot in the grave before SS even became the defacto-standard. 
   
  When SS amps hit the scene in force they really put the nail in the coffin for both the 4 and 16ohm speaker. 8ohm speakers generally play a bit louder on a given SS amp than a 16ohm one. It is a well known fact that a few db louder is perceived as better by the vast majority of people so that was the end of the 16ohm speaker. 4 ohm speakers generally go a little louder still on the same SS amp, but there weren't many 4-ohm stable SS amps until well after 8ohms became basically *the* standard. The lack of 4ohm stable amps killed the 4ohm speaker - once a speaker gets a rap for blowing up amps (even though its because the amp is crap) that reputation gets around, and sticks. After this point speaker designers had basically no choice but to build "8ohm" speakers. 
   
  What sucks about the whole thing is that speaker designers are forced to make "8" ohm speakers with extremely low reactance so that they dont anger the amplifier designers & builders. Building a speaker is a BUNCH harder than building an amp, the amp guys should bow humbly to the needs of the speaker builders, but it never happens.


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## Chris J

Quote: 





nikongod said:


> In a crop-sensor Id lean towards the D7000 or maybe 5100 unless you need a feature that you can only get on the D90. The high ISO performance and dynamic range of the newer bodies totally dominates the older digital cams.
> 
> I thought we weren't talking about maximum power transfer, specifically ignoring it per your post at the top of the page.
> 
> ...


 


 I'm looking for a Nikon which can use my old AF lenses. I'm talking about lenses which are approx. 7 years old. 24 mm, 50 mm and 105 mm. I understand that the the 5100 does not support old AF lenses?
   
  If an amplifier was designed to max out at 100 Watts into an 8 ohm load, it would max out at approx. 50 Watts into a 16 ohm load. In actual practice you would get slightly more than 50 Watts because you would get less voltage drop across the output transistors and the power supply would sag less.   So it would work fine into a 16 ohm load but draw less power because the 16 ohm speakers would draw less current.
  I agree, damping factor would be higher too.
  Poorly designed amplifiers can become unstable when driving a speaker system with too much reactance, for example QUAds.


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## Tribbs

Quote: 





chris j said:


> Hi,
> Please refer to this:
> Go to "Head Fi" Home page
> scroll to bottom of page
> ...


 
   
  Ah ha!  This article > http://www.head-fi.org/a/headphone-impedance
   
  Chris and others, thanks for your posts.  Not at all taken as lecturing.  It is discussions such as these that I enjoy the most.
   
  If I may, I would be most curious of your (and others) opinions about Dr. Gilmore's DynaLo design with Grados.


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## Chris J

Quote: 





tribbs said:


> Ah ha!  This article > http://www.head-fi.org/a/headphone-impedance
> 
> Chris and others, thanks for your posts.  Not at all taken as lecturing.  It is discussions such as these that I enjoy the most.
> 
> If I may, I would be most curious of your (and others) opinions about Dr. Gilmore's DynaLo design with Grados.


 

 Thanks for the link to the headphone amp.
  A very interesting design, he obviously knows what he is doing.
  The real short answer is:
  In some ways it is a fairly simple circuit, but very, very well thought out.
  I like his thinking: first create a good design, then add a little feedback.
  OTOH, it is a tremendous amount of voltage and current available to drive a headphone!
  I suspect 0.5 Watts would destory a pair of Grados, I guarantee it would deafen you!
 His suggestions for running a pair of SR-80s sounds a bit like overkill for a pair of $100 'phones!
   
  More later.........Chris


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## Tribbs

Speaking of overkill, here is a link to interesting measurements of a Kevin Gilmore designed "DynaHi".
_It is a follow-on design _based on Gilmore's "Dynalo".
http://www.ibiblio.org/tkan/audio/dynahi.html
   
  FYI - another DynaLo thread:
http://www.head-fi.org/t/461997/lost-link-to-a-dynalo-amp


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## Chris J

Quote: 





tribbs said:


> Speaking of overkill, here is a link to interesting measurements of a Kevin Gilmore designed "DynaHi".
> _It is a follow-on design _based on Gilmore's "Dynalo".
> http://www.ibiblio.org/tkan/audio/dynahi.html
> 
> ...


 


 Good lord!
  It "only" dissipates 70 Watts?
  Mindboggling...................it puts out a crazy amount of voltage and power!
  If this is a desk top amp, you better have a BIG desk.
   
  Thanks Tribbs, that is insane!
  C


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## nikongod

if it were a real amp it would dissipate 70W...... (wait for it)..... in the tube heaters.


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## Chris J

Quote: 





nikongod said:


> if it were a real amp it would dissipate 70W...... (wait for it)..... in the tube heaters.


 


   
  Tube amps get a special efficiency exemption!


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## rohan575

even class A amps waste more than 70% of the power just to keep them properly biased and in class A opertation. What matters is the actual power delivered to the headphone which is given by 
     E X I cos(x) where cos(x) is the power factor which makes life bad for EE guys.
   
  Long live tubes (with better,faster MOSFET's coming up i dont think they will)
  Rohan


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## bcschmerker4

This was a lively debate sometime before I joined Head-Fi™, and I consider many of its points still valid. 
	

	
	
		
		

		
		
	


	




 I actually think of headphones in the 600Ω range as _medium_-impedance.  For me, truly _high_-impedance headphones have voice-coil impedances of 2 - 10 kΩ inclusive, center-tapped, for direct feed from paired 6K6 or similar tubes in push-pull, and use 6- or 7-pin Cannon® or functionally-similar connectors to allow application of +Vpp to the taps, plus a dedicated protective ground. 
	

	
	
		
		

		
		
	


	




 Modern electrostatic headsets are a special case of the high-impedance headphone, as, being capacitive rather than inductive in nature, they are of infinite DC resistance and require one conductor for each diaphragm and two for the corresponding field grids, plus protective ground.


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## Redkitties

So Low impedance is good?


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## bcschmerker4

redkitties said:


> So Low impedance is good?


 

 Depends on your hardware.  Most portable devices are voltage-limited by their power supply and therefore require headphones of under 64Ω.  I'm after a medium-impedance set myself, for an Asus® CM1630-06 that packs a XONAR® Essence™ STX™, as its Texas Instruments® TPA6120A2 headphone amplifier (Zs = 10.7Ω) is spot-on for a 120 Ω headphone consistent with the design specification proposed in IEC 61938-1996.  And old tube hardware wants greater than 500Ω due to the inherent very-low-current characteristics of 6V6GT, EL84, and similar beam power tubes, even with output transformers.


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## jouyang3

In electrical engineering, if circuit is constructed for envelop detection, then it is reasonable to assume that it is a RC circuit.
  
 Generally modulated signals, music, especially those from AM radio come will be envelope detected. A modulated signal is usually the sound wave itself multiplied by a cosine of a different frequency. The resulting waveform is a wave that has an envelope resembling the original signal while encapsulating the cosine that the original signal multiplied. Envelop detection can now be used to detect the envelope of this resulting waveform so then it actually is able to reproduce the original signal.
  
 The circuit to construct this envelop detector is usually consisted of RC circuit in combination with diodes for rectification. RC circuits has two stages, 1. it charges the capacitor up. 2. it discharges the capacitor. When the modulated waveform passes through, any rising cosine component will quickly charge the capacitor up and when the cosine drops, the capacitor slowly drops. The capacitor will immediately be charging again when the cosine raises again. As a result, you will have an approximation of the original signal.
  
 Another info: parallel impedance/resistance can be computed with the following equation:
  
 Rout = 1/(1/R1 + 1/R2 + ... 1/Rn)
  
 Now, after the context, we can jump into the question: why do we use high impedance headphones?
  
 Two reasons: 1. RC circuit. If a low-impedance headset is hooked directly across the resistance of the RC circuit, the resulting impedance (resistance) drops, making the time constant be much smaller. This will result in the capacitor discharge much faster and hence the envelope detector will lower in accuracy.
  
 2. Parallel headset: every headset has its resistance/impedance value (just like any circuit). Generally speaking, audio systems require high output impedances for better quality. If you hook multiple headset together with low impedance, it will lower the output value. Even if you hook a couple high impedance headset and then in parallel with a low impedance headset, given the impedance of the "low impedance headset" is small enough, it can actually lower the overall output impedance of the circuit (refer to the equation above).
  
 I haven't been working in this field, I am merely a college student, correct me if I am wrong, but I hope this might answers your question.


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## eyeopen

Hi I read and am confused, what is better quality to listen to 16 or 33 Ohms?


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## Jnjy

eyeopen said:


> Hi I read and am confused, what is better quality to listen to 16 or 33 Ohms?




If it has a dynamic driver, probably 33 ohms sound better


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## eyeopen

ok thankx, I got the audiotecs now anyways, the better ones.


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