[HamilcarBarca]

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Doesn't that mean that it wouldn't pair well with Denon cans? I believe they need 1 or less if i'm not mistaken.

 
I've read multiple times, but can't verify personally from theory or practice, that the ideal output impedance of an amp is 1/10 or less of the input impedance of the headphone.
 
Edit: I just read another technical discussion of headphone amps. Some few engineering details with which I'm familiar were correct. He (or she) says the guideline is 1/8 (not 1/10) and this guideline becomes less important as the ability of the amp to deliver clean power at higher volumes increases.
 
There's a lot of uninformed regurgitation of engineering terms among some 'audiophiles'. I have 10 hours of (undergraduate) EE, which is enough to recognize some obvious nonsense, but I'll never be an engineer. However, some people are convinced of the 1/10 guideline, so I wrote that a 5-Ohm output impedance is a negative. It might have been better to say "possible negative".
 
Until I buy another set, I'll be using the M-Stage with 32-Ohm headphones. Maybe I'll be disappointed.

 

[Mad Max]

The M-Stage is anything but a disappointment with 32-ohm Grados, awww yeah!

 

[HamilcarBarca]

Quote:

The M-Stage is anything but a disappoint with 32-ohm Grados, awww yeah!

 
Glad to hear it!
 

 

[Chris J]

Quote:

 
I've read multiple times, but can't verify personally from theory or practice, that the ideal output impedance of an amp is 1/10 or less of the input impedance of the headphone.
 
Edit: I just read another technical discussion of headphone amps. Some few engineering details with which I'm familiar were correct. He (or she) says the guideline is 1/8 (not 1/10) and this guideline becomes less important as the ability of the amp to deliver clean power at higher volumes increases.
 
There's a lot of uninformed regurgitation of engineering terms among some 'audiophiles'. I have 10 hours of (undergraduate) EE, which is enough to recognize some obvious nonsense, but I'll never be an engineer. However, some people are convinced of the 1/10 guideline, so I wrote that a 5-Ohm output impedance is a negative. It might have been better to say "possible negative".

 
The general guideline is and output impedance of 1/8 (or 1/10) OR LESS.
A headphone amp is typically a voltage source, an ideal voltage source will have zero output impedance.
In practice depends on how inductively and/or capacitive reactive the headphone is, and subjectively, what sound do you like.
Other people will claim that some headphones are designed to work with high output impedances, for example, some of the Beyers.

 

[JosephsART]

I've read multiple times, but can't verify personally from theory or practice, that the ideal output impedance of an amp is 1/10 or less of the input impedance of the headphone.

The general guideline is and output impedance of 1/8 (or 1/10) OR LESS.

 
The way I read this; the output of your amplifier should be 1/8, 1/10, 1/20+ that of your headphone. Your headphone impedance should not be less than a minimum of 8 times your amplifier impedance.
 
This is known as the damping factor?
 
If the amplifier output impedance is lower than 8 times your headphone impedance, your amplifier fails to control movement in your sensitive headphones.
 
So if the Matrix M-Stage outputs 5ohms, the minimum impedance your headphones should have are 40ohms. Preferably, 50ohms or higher (like most headphones which aren't designed to be portable).
 
I'd imagine amplifiers which amplify at exceptional voltage have difficulty managing their output impedance; so technically, a quality amplifier with 0 output impedance is highly desirable if you wish to amplify any kind of headphone. Ideally, an amplifier output of 4ohms or less for 32ohm headphones.

 

[Chris J]

Quote:

 
The way I read this; the output of your amplifier should be 1/8, 1/10, 1/20+ that of your headphone. Your headphone impedance should not be less than a minimum of 8 times your amplifier impedance.
 
This is known as the damping factor?
 
If the amplifier output impedance is lower than 8 times your headphone impedance, your amplifier fails to control movement in your sensitive headphones.
 
So if the Matrix M-Stage outputs 5ohms, the minimum impedance your headphones should have are 40ohms. Preferably, 50ohms or higher (like most headphones which aren't designed to be portable).
 
I'd imagine amplifiers which amplify at exceptional voltage have difficulty managing their output impedance; so technically, a quality amplifier with 0 output impedance is highly desirable if you wish to amplify any kind of headphone. Ideally, an amplifier output of 4ohms or less for 32ohm headphones.

 
 
Yes, lower output impedance gives you a higher damping factor.
 
The vintage receiver guys will go nuts over this, typically a vintage receiver drives the headphone jack off the power amp output, but the receiver manufacturers put a 100 to 330 Ohm resistor in series, so the output impedance of the headphone jack is actually 100 to 330 Ohms and the damping factor, well, it kinda sucks!  But the vintage receiver guys love their vintage receivers.....

 
If a Grado owner says the Grado headphones work fine with a Matrix M, then I will go with what he says.
The output impedance is not terrible for a Grado, it may actually make the Grado 'phone sound fuller.
1/8 or 1/10 is only a guideline.
 
Not too sure what your last paragraph means: 
But I woulld basically agree, the lower the output impedance, the better.
A power amplifier for driving speakers will have an output impedance in the range of 0.5 Ohms to 0.05 Ohms or even less, and those power amps may output 20 or 30 or 40 or more Volts.
Output impedance is a function of the characteristics of the output transistors and how much feedback the amp uses.

 

[geetarman49]

Quote:

 
 
Yes, lower output impedance gives you a higher damping factor.
 
The vintage receiver guys will go nuts over this, typically a vintage receiver drives the headphone jack off the power amp output, but the receiver manufacturers put a 100 to 330 Ohm resistor in series, so the output impedance of the headphone jack is actually 100 to 330 Ohms and the damping factor, well, it kinda sucks!  But the vintage receiver guys love their vintage receivers.....

...

true, but some perspective helps ... most vintage receiver (amp) owners have been extolling their use with headphones that happen to like a lot of 'juice' - from k70x to various hifimans/lcd's

 

[Chris J]

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true, but some perspective helps ... most vintage receiver (amp) owners have been extolling their use with headphones that happen to like a lot of 'juice' - from k70x to various hifimans/lcd's

Very true, thankings for pointing that out!
They don't output as much power as everyone thinks, the voltage and current is limited by the high ouput impedance of the headphone jack.
I once calculated how much power, voltage and current you can get out of a power amp with a 330 Ohm output impedance and posted it on the Vintage receivers thread.  I think I made someone cry that day!

 
My main point was the output impedance of these vintage receivers is reeely freeeking high.
 
I'm not a big fan of them, they weigh a ton, take up a lot of space and have the potential for problems (some of this stuff is from the late '70s!) just to drive an itty bitty pair of 'phones which need 100 or 200 milliWatts??? I don't geddit.

 

[dogwan]

Quote:

 
 
Yes, lower output impedance gives you a higher damping factor.
 
The vintage receiver guys will go nuts over this, typically a vintage receiver drives the headphone jack off the power amp output, but the receiver manufacturers put a 100 to 330 Ohm resistor in series, so the output impedance of the headphone jack is actually 100 to 330 Ohms and the damping factor, well, it kinda sucks!  But the vintage receiver guys love their vintage receivers.....

 
If a Grado owner says the Grado headphones work fine with a Matrix M, then I will go with what he says.
The output impedance is not terrible for a Grado, it may actually make the Grado 'phone sound fuller.
1/8 or 1/10 is only a guideline.
 
Not too sure what your last paragraph means: 
But I woulld basically agree, the lower the output impedance, the better.
A power amplifier for driving speakers will have an output impedance in the range of 0.5 Ohms to 0.05 Ohms or even less, and those power amps may output 20 or 30 or 40 or more Volts.
Output impedance is a function of the characteristics of the output transistors and how much feedback the amp uses.

 
I actually can't stand my Grado's on the Matrix. Find the combo to be kind of shrill. (disclosure-using the LME49720HA op-amp). I am a fan of the Grado house sound and find they work great with my Mini^3 portable amp.
 
For me the sweet spot with the Matrix is with the 150 ohm Yamaha HP-2's. Also  Fostex T50rp's which are 50 ohm and the Senn HD600's at 300 ohm are equally enjoyable. Not sure the why's or wherefor's, but that's my experience.
 
RE: vintage receivers, I have a 1972 Hitachi integrated that is fantastic sounding on speakers. But not so great with any phones except my 600 ohm AKG 240m's. I know the amp is capacitor coupled and uses 220ohm resistors for the headphone out. What Chris J wrote makes sense based on that experience. However, I do follow the vintage receiver thread because I just love the old beasts. Just not for dedicated headphone amp duty.
 
-Dogwan

 

[Chris J]

Quote:

 
I actually can't stand my Grado's on the Matrix. Find the combo to be kind of shrill. (disclosure-using the LME49720HA op-amp). I am a fan of the Grado house sound and find they work great with my Mini^3 portable amp.
 
For me the sweet spot with the Matrix is with the 150 ohm Yamaha HP-2's. Also  Fostex T50rp's which are 50 ohm and the Senn HD600's at 300 ohm are equally enjoyable. Not sure the why's or wherefor's, but that's my experience.
 
RE: vintage receivers, I have a 1972 Hitachi integrated that is fantastic sounding on speakers. But not so great with any phones except my 600 ohm AKG 240m's. I know the amp is capacitor coupled and uses 220ohm resistors for the headphone out. What Chris J wrote makes sense based on that experience. However, I do follow the vintage receiver thread because I just love the old beasts. Just not for dedicated headphone amp duty.
 
-Dogwan

 
Ouch!
I have my eye on a pair of Grado RS-2i, sounds like they may not get along with my Matrix M.
Back up plan is to use my iBasso D12 as a DAC and headphone amp for the Grados.
 
Lots of us AKG Q701 fan boys love the M Stage & Q701 combo. I'm sure everyone knows the Qs have an impedance of 62 Ohms. I have no technical explanation or rationale for this, I just know what I like.
 
I don't follow the Vintage Receiver forum thread thing too closely.......maybe all these Vintage receiver fans use high impedance headphones?

 

[derbigpr]

Quote:

 
Ouch!
I have my eye on a pair of Grado RS-2i, sounds like they may not get along with my Matrix M.
Back up plan is to use my iBasso D12 as a DAC and headphone amp for the Grados.
 
Lots of us AKG Q701 fan boys love the M Stage & Q701 combo. I'm sure everyone knows the Qs have an impedance of 62 Ohms. I have no technical explanation or rationale for this, I just know what I like.
 
I don't follow the Vintage Receiver forum thread thing too closely.......maybe all these Vintage receiver fans use high impedance headphones?

 
 
A vintage receiver is not necessary....a new receiver or speaker amp that sounds good with speakers will be equally good with headphones. Even low impedance ones.

 

[HamilcarBarca]

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A vintage receiver is not necessary....a new receiver or speaker amp that sounds good with speakers will be equally good with headphones. Even low impedance ones.

 
A new receiver or speaker amp that sounds good may be equally good with headphones.

 

[derbigpr]

Quote:

 
A new receiver or speaker amp that sounds good may be equally good with headphones.

 
Well, as you wish, but I have yet to find one that has a bad headphone output and doesn't do mid end (up too DT880/HD650 league) headphones justice.  I have lately tried A LOT of receivers and integrated speaker amps (from entry level to very expensive Denons, Marantz, Onkyos, Yamahas, Nads, Rotels, CA's) even some cd players. Basically what I did was take my DT880 600's and HFI2400's with me when I went into the hi-fi stores to audition speakers and amp,  and just pluged my headphones into everything that was on the counters, and haven't found a single unit that would sound anything short of great or would lack power. In fact, I sold all my headphone amps in the last 2 weeks because of my findings.   I think that it makes no sense to own a dedicated headphone amp if for the same money I can have a speaker amp AND an equally good headphone output. Unless I buy some high end headphones, or need something for portable use, I will never buy a head amp again.

 

[geetarman49]

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A new receiver or speaker amp that sounds good may be equally good with headphones.

yes ... vintage receivers are appreciated because in most cases their headphone output is derived from the speaker output; most modern day receivers use an independent cct comprised of a single opamp for the headphone output, so good spkr output is no guarantee for good headphone output.

 

[derbigpr]

Quote:

yes ... vintage receivers are appreciated because in most cases their headphone output is derived from the speaker output; most modern day receivers use an independent cct comprised of a single opamp for the headphone output, so good spkr output is no guarantee for good headphone output.

Actually, virtually ALL new receivers or integrated amps have headphone outputs that are derived from the speaker outputs. They don't have separate cheap headphone out circuits like many people think. Some more expensive ones do have separate high quality headphone circuits, but virtually every unit up to 1000-1500$ doesn't.