tokengesture said:

I think the balanced cable talk comes more from optimising the Ponoplayer rather than the PM3

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Is that simply so people don't have to switch the Pono between balanced / single mode? The PM-3s only take 30mW / 0.88 Vrms to get them up to 115dB.
 
I guess my point is to reassure people coming to this thread that you don't need to re-wire these cans to get them loud, even on portable sources.

miceblue said:

Mhmm, I think metallicy could describe the PM-3 a bit. For me, shouty or bright would be more in line for my impressions. Evidently from Innerfidelity's measurements, the PM-3 seems to have varied performance in the upper-mids and lower treble based on the placement of the headphones on the dummy head.

As for the test with the PM-3, I don't know if it was because of the higher output impedance of the Pono, but I did hear a little more bass with it compared to the iPhone. If I recall correctly though, the iPhone 4S has around a 3-ohm output impedance too. Some day when I get a spare male 3.5 mm jack, I'd like to measure its output impedance. Maybe I'll make a balanced cable for the PM-3 while I'm at it too since I need to make female balanced TRRS to XLR and female balanced TRRS to unbalanced TRS adaptors anyway for a different earphone.

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Again, the output impedance is not having any effect on the frequency response of the planar magnetic PM-3.

I can relate to 'slightly metallic' as a descriptor for the PM-3 sound. That kinda captures shouty and bright in one word for me.

LH Labs designed their Pulse X and Wave X to be fully balanced and they have been far more transparent about their design topology. Both the Pulse X and Wave X use dual mono DACs, differential signaling for the I/V amplification and differential/balanced outputs. The single-ended mode just branches out from the balanced outputs of the amp section and a summer is used, so the fidelity of the signal is preserved for both outputs. I'd expect the two outputs to sound similar in this case.

Supposedly, at least from what Innerfidelity quoted from Ayre, the Pono is designed to be fully balanced from the DAC to the amp.

I have no idea what the Pono does between single ended and balanced outputs, but at about the same listening volume level, there was definitely a difference in sound to me and I'd like to hear it again with the PM-3 in the future.

I suspect most of what it does different between the two outputs is put double the power into each channel in balanced mode, which is likely to produce a better sound out of planar magnetic like the PM-3, sensitive though it be.

nztechfreak said:

I suspect most of what it does different between the two outputs is put double the power into each channel in balanced mode, which is likely to produce a better sound out of planar magnetic like the PM-3, sensitive though it be.

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Why would that produce a better sound than turning the volume up in single-ended mode? Even with really dynamic material, I never need more than my old iPod classic can provide with these cans.

rrod said:

 
Why would that produce a better sound than turning the volume up in single-ended mode? Even with really dynamic material, I never need more than my old iPod classic can provide with these cans.

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hypothetically an amplifier with a truly balanced interface (not referring to a bridged amplifier as balanced which is common in the audiophile world) will common-mode noise rejection, which means that it will only amplify the difference between the two inputs and can remove noise as noise tends to impinge on each line equally in magnitude and phase.
 
however, from my understanding, pono simply bridges together a pair of single-ended amplifier channels, so it does not have that benefit and is a bridged amplifier rather having balanced interface.
 
...though my understanding on this topic is not perfect, so perhaps more knowledgeable members can chime in.
 
some discussions on this topic:
http://www.head-fi.org/t/757435/no-balanced-why
http://www.head-fi.org/t/753012/balanced-cable-what-is-it-and-why-would-i-want-it

money4me247 said:

  hypothetically an amplifier with a truly balanced interface (not referring to a bridged amplifier as balanced which is common in the audiophile world) will common-mode noise rejection, which means that it will only amplify the difference between the two inputs and can remove noise as noise tends to impinge on each line equally in magnitude and phase.
 
however, from my understanding, pono simply bridges together a pair of single-ended amplifier channels, so it does not have that benefit and is a bridged amplifier rather having balanced interface.
 
...though my understanding on this topic is not perfect, so perhaps more knowledgeable members can chime in.
 
some discussions on this topic:
http://www.head-fi.org/t/757435/no-balanced-why
http://www.head-fi.org/t/753012/balanced-cable-what-is-it-and-why-would-i-want-it

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I was one of the people ticking off SE in that second thread ^_^ The conclusion always seems to be that it (bridged connection) doesn't matter a whit for headphones, since it should be possible to do whatever you want single-ended anyway. Here's another thread, just to get info out there:
http://www.head-fi.org/t/539458/why-balanced-headphone-amps
 
No doubt you can run fussier cans to better volumes with the Pono, but it seems the PM-3 is not mean to be fussy.

rrod said:

I was one of the people ticking off SE in that second thread ^_^ The conclusion always seems to be that it (bridged connection) doesn't matter a whit for headphones, since it should be possible to do whatever you want single-ended anyway. Here's another thread, just to get info out there:
http://www.head-fi.org/t/539458/why-balanced-headphone-amps

No doubt you can run fussier cans to better volumes with the Pono, but it seems the PM-3 is not mean to be fussy.

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PM-3 is one of the least fussy cans I've owned over the years. I use my iPhone when I'm on the go, and SE on my HA-1 at bedside, just because I can. The difference between phone and HA-1 is not really significant to me.

The only thing I have had the opportunity to run in "balanced" mode with the PONO is the Earsonics Velvets, clearly a difference whether in volume, power or whatever.

rrod said:

   
Why would that produce a better sound than turning the volume up in single-ended mode? Even with really dynamic material, I never need more than my old iPod classic can provide with these cans.

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There are several differences between single ended and differential systems:
 
Differential, if the same amplifier as single ended and ignoring losses, has twice the voltage and four times the power output into the same load
 
Because of the above, each amplifier in differential is loaded with half the impedance of single ended.
 
The signal in differential no longer touches the ground, which can make design easier.  The relatively high currents from a headphone can disrupt the signal integrity of the around low current parts of the circuit if the layout isn't perfect.
 
The above point also means the left and right do not share a return path in differential, either in the cable or the active circuitry.
 
The output impedance, unless specially increased in single ended, is often double in differential. 
 
Any even order distortions in single ended can be cancelled in differential, while odd order remain similar.
 
However as some distortions can be load dependant, as the load in differential is half, those distortions can rise.
 
Most high end DACs have differential outputs, and is has benefits staying differential all the way to the transducer.
 
Differential is more noisy, but not double due to some noise being cancelled, and others being uncorrelated. 
 
Differential costs more.
 
I could go on, but it is a mixed bag of features, which are more involved than a bit of output impedance and fancy cable.

jagwap said:

 

Spoiler: There are several differences between single ended and differential systems:

 
Differential, if the same amplifier as single ended and ignoring losses, has twice the voltage and four times the power output into the same load
 
Because of the above, each amplifier in differential is loaded with half the impedance of single ended.
 
The signal in differential no longer touches the ground, which can make design easier.  The relatively high currents from a headphone can disrupt the signal integrity of the around low current parts of the circuit if the layout isn't perfect.
 
The above point also means the left and right do not share a return path in differential, either in the cable or the active circuitry.
 
The output impedance, unless specially increased in single ended, is often double in differential. 
 
Any even order distortions in single ended can be cancelled in differential, while odd order remain similar.
 
However as some distortions can be load dependant, as the load in differential is half, those distortions can rise.
 
Most high end DACs have differential outputs, and is has benefits staying differential all the way to the transducer.
 
Differential is more noisy, but not double due to some noise being cancelled, and others being uncorrelated. 
 
Differential costs more.
 
I could go on, but it is a mixed bag of features, which are more involved than a bit of output impedance and fancy cable.

 

Click to expand...

 
Thanks for the info!  I don't want this to become a de-rail into amplifier design, so I'll just repeat to anyone considering these cans that they sound great on everything I've used them on with the good old stock cable.

lol
All of this balanced stuff made me realise that I built my K 701's balanced cable incorrectly in the strictest sense. I used a star quad microphone cable and I did the wiring with adjacent cables instead of non-adjacent ones.
http://en.wikipedia.org/wiki/Transmission_line#Star_quad

Ah well, I guess it's a good learning experience. I'll know that for next time though (PM-3 maybe).

Not sure this is relevant but I wanted to include:
 
Excerpt from  A letter to the editor of Stereophile from Charles Hansen...
 
 
The bottom line is that a set of high impedance cans will be driven by a relatively low output impedance in the range of 3 ohms or so, which is far more than adequate. And if the user connects lower-impedance headphones and/or drives them at higher and higher levels, the output impedance drops further. It becomes a self-correcting situation so that the Pono Player can drive even the lowest impedance loads without difficulty.
 
What’s more, connecting to the Pono-Player with balanced cables will connect two separate amplifiers to each transducer, each driven 180° out of phase with the other. This will double the available voltage swing, thus quadrupling the output power (as well as canceling all of the even harmonics and rejecting imperfections in the power supply).
 
The end result is that the Pono Player is the only portable player to date that will drive virtually any headphone to satisfying levels, regardless of impedance or sensitivity, without the need for an external headphone amplifier, especially when used in balanced mode.

The Oppo guys at Axpona told me they changed their mind and they will not be offering a balanced cable for the PM-3 so the only option is an aftermarket cable if you want to go balanced.

Speaking of Axpona, whats the deal with the red and blue PM-3s?