Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Asus Zonar U5 DAC - setting headphone impedance? (Read 10677 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Asus Zonar U5 DAC - setting headphone impedance?

hi all

the Asus Xonar U5 DAC has an option to set the impedance for headphones, which is great i suppose, except i don't know what the hell i'm doing

i've read some stuff on 'impedance' and i may as well be reading chinese (http://www.head-fi.org/a/headphone-impedance)

the phones are the QPAD QH-85 - spec tells me: Nominal impedance: 60 Ω per system

the DAC has a setting for 'low', 'medium' and ... you guessed it; 'high'

the Xonar can apparently drive phones up to 150 OHM impedance - if the QH-85's are 60, that tells me they're not "low" impedance, but they're quite far from 150, so i'm guessing i should set the Xonar impedance to 'medium'

Quote
Xonar U5 includes a headphone amplifier that supports headphones all the way up to 150ohm impedance


1) am i guessing correctly?

2) what happens if i drive them at 'high'?

TIA

---

full phone specs...
http://qpad.com/products/headsets/QH-85-Black/

Asus Zonar U5 DAC - setting headphone impedance?

Reply #1 –
Quote from: hydro.driver on
the Asus Xonar U5 DAC has an option to set the impedance for headphones, which is great i suppose, except i don't know what the hell i'm doing

i've read some stuff on 'impedance' and i may as well be reading chinese (http://www.head-fi.org/a/headphone-impedance)


That link is about the impedance of headphones, which is not the same thing.

These might be more useful:

https://en.wikipedia.org/wiki/Headphones#El...characteristics
https://en.wikipedia.org/wiki/Headphone_amp...utput_Impedance

Quote from: hydro.driver on
the DAC has a setting for 'low', 'medium' and ... you guessed it; 'high'


Probably you want the "low" setting.  I'm actually not sure why you would ever want to use any other setting.  Although without knowing what those settings correspond to its hard to say.

Quote from: hydro.driver on
the Xonar can apparently drive phones up to 150 OHM impedance


It can go a lot higher than that.  Probably whoever said that didn't know what impedance meant, or just meant that this was the highest they had tried. 

Quote from: hydro.driver on
- if the QH-85's are 60, that tells me they're not "low" impedance, but they're quite far from 150, so i'm guessing i should set the Xonar impedance to 'medium'


No, you're confusing the impedance of the headphones with the impedance of the source. 

Quote from: hydro.driver on
1) am i guessing correctly?


No.

Quote from: hydro.driver on
2) what happens if i drive them at 'high'?


Depends what the setting actually does, but probably they get a little more quiet and distortion goes up while bass might roll off or at least shift some. 

Asus Zonar U5 DAC - setting headphone impedance?

Reply #2 –
@saratoga - thanks for the reply, but i'm not sure i'm any less confused

actually, when i drive the phones with the Xonar impedance set to 'high', the volume is louder - it sort of seems the detail might be better also, but i think that is very likely a perceived difference rather than real

if i drive them at low, i lose a lot of top-end volume to the point where they are barely sufficient when you want to listen at a volume that brings out enough detail without killing your hearing

as far as who wrote that the Xonar can drive up to 150 ohm impedance phones, that comes straight from Asus

Asus Zonar U5 DAC - setting headphone impedance?

Reply #3 –
Sound cards have very strange specs these days.  I hope they don't actually have 600ohm outputs, because that would be terrible. 

It sounds like you want the "high" setting, as my guess would be it corresponds to gain.  Higher volume will definitely increase the perception of detail.  If you can somehow find the actual output of your sound card, you can calculate the maximum volume with your headphones.

Asus Zonar U5 DAC - setting headphone impedance?

Reply #4 –
Quote
actually, when i drive the phones with the Xonar impedance set to 'high', the volume is louder
I'd guess the signal is simply higher (louder).  Higher impedance headphones tend to be less sensitive, but it's just a tendency and it's not always true.

Quote
- it sort of seems the detail might be better also, but i think that is very likely a perceived difference rather than real
We do hear more detail (and more bass) at higher levels.

Quote
as far as who wrote that the Xonar can drive up to 150 ohm impedance phones, that comes straight from Asus
That's not very meaningful except for the tendency of high impedance headphones to be less sensitive (less loud with the same voltage).

Higher impedance is actually easier  on the amplifier/source.  That same output can drive powered speakers (typically 10K to 100K Ohms) but it can't directly drive a 4-Ohm or 8-Ohm speaker.

Asus Zonar U5 DAC - setting headphone impedance?

Reply #5 –
i appreciate the help guys, but i'm no nearer my goal of figuring out how to set the impedance of the Xonar - low, med. or high - for the QPAD phones, or does it even matter?  can i damage the DAC or phones if it is set wrong?

Asus Zonar U5 DAC - setting headphone impedance?

Reply #6 –
Quote from: hydro.driver on
i appreciate the help guys, but i'm no nearer my goal of figuring out how to set the impedance of the Xonar - low, med. or high - for the QPAD phones, or does it even matter?  can i damage the DAC or phones if it is set wrong?


No, you won't damage anything.  Asus lists the maximum output of their sound card as 1.3Vrms, but the QPAD headphones do not give a sensitivity rating.  They do list a maximum input of 250mw, and I think the U5 can only deliver 28mw into 60 ohms, but I just learned that from Google, so YMMV.

Use whichever setting gives you the most useful volume range.

Asus Zonar U5 DAC - setting headphone impedance?

Reply #7 –
thanks

sorry if i seemed impatient, but i really don't understand all the tech in the audio scene

Asus Zonar U5 DAC - setting headphone impedance?

Reply #8 –
Quote from: hydro.driver on
thanks

sorry if i seemed impatient, but i really don't understand all the tech in the audio scene


Poor documentation and confusing marketing makes it a lot worse, unfortunately. ;/

Asus Zonar U5 DAC - setting headphone impedance?

Reply #9 –
Quote from: hydro.driver on
actually, when i drive the phones with the Xonar impedance set to 'high', the volume is louder - it sort of seems the detail might be better also, but i think that is very likely a perceived difference rather than real


What is this setting and how are you actually changing it?

Asus Zonar U5 DAC - setting headphone impedance?

Reply #10 –

Asus Zonar U5 DAC - setting headphone impedance?

Reply #11 –
From what you've said, its unclear what that setting really does.  Unless theres some documentation, pick a random setting that sounds ok to you?

Asus Zonar U5 DAC - setting headphone impedance?

Reply #12 –
I doubt the switch changes the output impedance of the amplifier. I have a similar HW SW switch on my U7 and as far as I can tell, it only changes the output voltage at the maximum volume (maybe it's just a simple voltage divider on the amplifier's input). In case you have 16 Ohm headphones and you would set the card to the highest gain, you would have problems with OS mixer (e.g. one notch would be too quiet and a notch up would be too loud).

I have this problem on my Sound Blaster Omni which has a powerful amp and the volume control in Windows 7 is not fine enough to set a reasonable volume when driving 16 Ohm headphones. So I need to resort to SW volume control (scaling the digital signal).

Asus Zonar U5 DAC - setting headphone impedance?

Reply #13 –
@Martel - the QPAD QH-85 lists the impedance @60 ohms

Specification QPAD QH-85
Transducer type: Dynamic Ø53mm
Operating principle: Open
Frequency response: 15Hz-25KHz
Nominal impedance: 60 ohms per system
Nominal SPL: 92±3dB
T.H.D: < 2%
Power handling capacity: 250mW
Sound coupling to the ear: Circumaural
Ambient noise attenuation: approx. 10 dBA
Headband pressure: 5 N
Weight with microphone and cable: 350g
Cable length and type:  1m + 2m extension + 10cm iphone
Connection: Mini stereo jack plug(3.5MM)

i would guess that spec must mean something very different than the example 16 ohm spec you're talking about since i have no problem with volume control regardless of what impedance i set the Xonar to

@saratoga - yes, the documentation is horrible - the entire Sound Studio user manual consists primarily of 3 or 4 pages, mostly screen-shots, and doesn't even 'impedance' at all, much less HOW to set it

i just opened a support request to QPAD since they seem to be the most approachable (vs Asus or Sonic Studio), so hopefully that will result in better detail as to how to set the impedance in the Xonar

Asus Zonar U5 DAC - setting headphone impedance?

Reply #14 –
Quote from: hydro.driver on
@Martel - the QPAD QH-85 lists the impedance @60 ohms

Specification QPAD QH-85
Transducer type: Dynamic Ø53mm
Operating principle: Open
Frequency response: 15Hz-25KHz
Nominal impedance: 60 ohms per system
Nominal SPL: 92±3dB
T.H.D: < 2%
Power handling capacity: 250mW
Sound coupling to the ear: Circumaural
Ambient noise attenuation: approx. 10 dBA
Headband pressure: 5 N
Weight with microphone and cable: 350g
Cable length and type:  1m + 2m extension + 10cm iphone
Connection: Mini stereo jack plug(3.5MM)

i would guess that spec must mean something very different than the example 16 ohm spec you're talking about since i have no problem with volume control regardless of what impedance i set the Xonar to

@saratoga - yes, the documentation is horrible - the entire Sound Studio user manual consists primarily of 3 or 4 pages, mostly screen-shots, and doesn't even 'impedance' at all, much less HOW to set it

i just opened a support request to QPAD since they seem to be the most approachable (vs Asus or Sonic Studio), so hopefully that will result in better detail as to how to set the impedance in the Xonar


Huh?  You mentioned problems with volume control in your second post in this thread.  As I said, "Use whichever setting gives you the most useful volume range."

Asus Zonar U5 DAC - setting headphone impedance?

Reply #15 –
Quote from: Martel on
I doubt the switch changes the output impedance of the amplifier. I have a similar HW SW switch on my U7 and as far as I can tell, it only changes the output voltage at the maximum volume (maybe it's just a simple voltage divider on the amplifier's input). In case you have 16 Ohm headphones and you would set the card to the highest gain, you would have problems with OS mixer (e.g. one notch would be too quiet and a notch up would be too loud).

While we don't know exactly how this works without detailed tech notes or schematics, it is likely that the switch changes the easiest to change thing that relates, which would be gain.  Hihg impedance headphones tend to have less sensitivity to voltage, so increase it, no? ;-)

Asus Zonar U5 DAC - setting headphone impedance?

Reply #16 –
Quote from: Arnold B. Krueger on
Quote from: Martel on
I doubt the switch changes the output impedance of the amplifier. I have a similar HW SW switch on my U7 and as far as I can tell, it only changes the output voltage at the maximum volume (maybe it's just a simple voltage divider on the amplifier's input). In case you have 16 Ohm headphones and you would set the card to the highest gain, you would have problems with OS mixer (e.g. one notch would be too quiet and a notch up would be too loud).

While we don't know exactly how this works without detailed tech notes or schematics, it is likely that the switch changes the easiest to change thing that relates, which would be gain.  Hihg impedance headphones tend to have less sensitivity to voltage, so increase it, no? ;-)

What about the 50 ohm 83.5dB/mW Hifiman HE6?

Asus Zonar U5 DAC - setting headphone impedance?

Reply #17 –
This setting is probably similar to STX's one. Here's a description by Stereopile:
Quote
The maximum output level [...] depended on the setting chosen: 885mV (0dB, for headphones with impedances below 64 ohms), 3.52V (+12dB for headphones with impedances of 64–300 ohms), and 7.03V (+18dB for headphones with impedances of >300 ohms).


Now the U5 and U7 output 1.3Vrms max, so there is no risk of damaging your 60ohm/250mW headphones even at max volume.
"I hear it when I see it."

Asus Zonar U5 DAC - setting headphone impedance?

Reply #18 –
And BTW, I am under the impression that it is not even controlling amplifier gain but in fact is nothing but driver-side digital attenuation for the lower-settings. These cards are also supposed to be running at full blast with no volume control when using ASIO output (I don't remember whether that was using native ASIO or ASIO4All though). It's not surprising actually, they tend to measure very well and that's easiest to accomplish with a straightforward fixed-gain output stage with no PGA anywhere in sight, i.e. a "brute force" concept relying on high DAC performance.

That being said, the U5 uses a TPA6130A2 headphone amp, which does feature volume control via I2C. Maybe this is also being used since the CM9882 DAC used doesn't feature super-duper levels of SNR yet.

(Ironically, the '6130A2 could mean that the U5 is better suited for headphone driving than the U7 with its thrifty but somewhat load-averse LME49726.)

Asus Zonar U5 DAC - setting headphone impedance?

Reply #19 –
Quote from: theriverlethe on
Quote from: Arnold B. Krueger on
Quote from: Martel on
I doubt the switch changes the output impedance of the amplifier. I have a similar HW SW switch on my U7 and as far as I can tell, it only changes the output voltage at the maximum volume (maybe it's just a simple voltage divider on the amplifier's input). In case you have 16 Ohm headphones and you would set the card to the highest gain, you would have problems with OS mixer (e.g. one notch would be too quiet and a notch up would be too loud).

While we don't know exactly how this works without detailed tech notes or schematics, it is likely that the switch changes the easiest to change thing that relates, which would be gain.  Hihg impedance headphones tend to have less sensitivity to voltage, so increase it, no? ;-)

What about the 50 ohm 83.5dB/mW Hifiman HE6?

The exception does not disprove the rule. ;-)

The hifiman is legendary for what it doesn't have, which is efficiency. Probably well matched to many of the better pro headphone amps.