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O2 AMP + ODAC - Page 189

post #2821 of 5248
Quote:
Originally Posted by adydula View Post


Try that with any other amp.

Try that with the vmoda driving the o2.
Well for one, I don't have another amplifier modeled after the "wire with gain" approach. Secondly, I don't have another amp with unity gain. Thus, any other test I do with another amp I have is not going to answer my questions.
post #2822 of 5248
Quote:
Originally Posted by miceblue View Post

Speaking of "transparency," the O2 is supposed to be transparent compared to the DAC1 PRE. People make the claim that it's supposed to follow a "wire with gain" kind of model, but in recent listening tests I haven't found that to be the case.

MacBook Pro (X volume level) -> V-MODA Crossfade M-100
versus
MacBook Pro (X volume level) -> O2 (maximum on the volume knob, unity gain, AC powered) -> V-MODA Crossfade M-100

Were the theory of a "wire with gain" true, I should hear no difference between the above setups, no? I find the MacBook Pro's headphone out to sound much more coherent and transparent than through the double amping. Through the double amping, the bass becomes woolier and more bloated, and the treble subdued a bit. Instrument separation becomes more blurred and it just sounds less transparent to me.


http://apple.stackexchange.com/questions/57186/what-is-the-impedance-of-the-line-headphone-jack-on-macbook-pro-retina

Impedence mismatch?

post #2823 of 5248
Can I ask a question of the gurus here?

If I stack the ODAC & O2 does it matter what goes on top? I know there should be no interference but I thought I'd see if there's an accepted wisdom on this.
post #2824 of 5248

No one in there right mind would do this in the real world.

 

But....with the volume control cranked up to max what do u think the maximum voltage RMS is ??

 

What do you think the vmoda's input would be designed to handle?

 

What happens if the latter amp is over driven or provided with distortion ?

 

What happens if clipping is occurring?

 

and yes how about impedance mismatching and all the above.

 

 

I think I will stick my finger in a hot cup of coffee and see if it affects the taste???

 

Sorry to be a bit condescending but this type if off the wall testing is probably better off in a thread about how to measure stuff etc....or a thread why not double amp????

 

Really..

 

Alex

post #2825 of 5248

Zorrofox...it shouldn't matter....jus don't stack them in a microwave! LOL.

 

Alex

post #2826 of 5248
Quote:
Originally Posted by adydula View Post

Zorrofox...it shouldn't matter....jus don't stack them in a microwave! LOL.

Alex

I just thought I'd ask, lol. I don't do microwaves anyway.
post #2827 of 5248
@miceblue: not a good idea. Google 'gain structuring'. At best you'll amp distortion and cause clipping, at worst something will go snap, crackle and pop.
post #2828 of 5248
Quote:
Were the theory of a "wire with gain" true, I should hear no difference between the above setups, no? I find the MacBook Pro's headphone out to sound much more coherent and transparent than through the double amping. Through the double amping, the bass becomes woolier and more bloated, and the treble subdued a bit. Instrument separation becomes more blurred and it just sounds less transparent to me.

 

There is your problem right there, headphone outputs and line outputs are not the same thing.  I would totally expect that setup to sound like garbage.

post #2829 of 5248
Quote:
Originally Posted by Zorrofox View Post

Can I ask a question of the gurus here?

If I stack the ODAC & O2 does it matter what goes on top? I know there should be no interference but I thought I'd see if there's an accepted wisdom on this.

 

Put the O2 on top or the volume control is more awkward to use. Seriously though it makes no difference whatsoever.

post #2830 of 5248
Quote:
Originally Posted by mcandmar View Post
 

 

There is your problem right there, headphone outputs and line outputs are not the same thing.  I would totally expect that setup to sound like garbage.

 

 

Quote:
Originally Posted by adydula View Post
 

No one in there right mind would do this in the real world.

 

But....with the volume control cranked up to max what do u think the maximum voltage RMS is ??

 

What do you think the vmoda's input would be designed to handle?

 

What happens if the latter amp is over driven or provided with distortion ?

 

What happens if clipping is occurring?

 

and yes how about impedance mismatching and all the above.

 

 

I think I will stick my finger in a hot cup of coffee and see if it affects the taste???

 

Sorry to be a bit condescending but this type if off the wall testing is probably better off in a thread about how to measure stuff etc....or a thread why not double amp????

 

Really..

 

Alex


Just saw that the o2 amp is turned to max vol...

I think I saw the HP in question is ~100 db/ mW. You shouldn't need that much volume really.

post #2831 of 5248
More than the O2, it's your ears which are gonna take a hammering. I have never dared to max the volume on most of my headphones.
post #2832 of 5248
T
Quote:
Originally Posted by mcandmar View Post

Put the O2 on top or the volume control is more awkward to use. Seriously though it makes no difference whatsoever.

Thats the way I have it right now but aye, I wasn't expecting it to matter since these boxes are so well laid out but what do I know smily_headphones1.gif
post #2833 of 5248
Quote:
Originally Posted by adydula View Post

No one in there right mind would do this in the real world.

But....with the volume control cranked up to max what do u think the maximum voltage RMS is ??

What do you think the vmoda's input would be designed to handle?

What happens if the latter amp is over driven or provided with distortion ?

What happens if clipping is occurring?

and yes how about impedance mismatching and all the above.

I think I will stick my finger in a hot cup of coffee and see if it affects the taste???

Sorry to be a bit condescending but this type if off the wall testing is probably better off in a thread about how to measure stuff etc....or a thread why not double amp????

Really..

Alex
Quote:
Originally Posted by Xenophon View Post

@miceblue: not a good idea. Google 'gain structuring'. At best you'll amp distortion and cause clipping, at worst something will go snap, crackle and pop.
Quote:
Originally Posted by anthk View Post

Quote:
Originally Posted by mcandmar View Post

There is your problem right there, headphone outputs and line outputs are not the same thing.  I would totally expect that setup to sound like garbage.
Just saw that the o2 amp is turned to max vol...
I think I saw the HP in question is ~100 db/ mW. You shouldn't need that much volume really.
Quote:
Originally Posted by gikigill View Post

More than the O2, it's your ears which are gonna take a hammering. I have never dared to max the volume on most of my headphones.

I just quoted people and will address all of them in 1 response.

I wasn't using maximum volume from the MacBook to the O2, just volume 1/16 for example, so the VRMS value going into the O2 and the volume going to the headphone shouldn't be a problem at all with the O2 at unity gain.
1/16 volume from MacBook -> 1.0x gain/no gain from O2 at maximum volume = 1/16 volume to ears assuming the O2 is just a "wire with gain"

A mismatch of impedance is probably a more likely thing to occur now that I think about it, but I'll have to look into the gain structure stuff too.


As for someone actually doing this in reality, it's definitely a legitimate situation. I like the sound out of ___ system, but the volume is too quiet and I would like to make it louder. A "wire with gain" would provide exactly this, no? And say it's a computer soundcard (MacBook in this example), you can't actually separate the DAC and amp components.
Edited by miceblue - 5/8/14 at 10:08am
post #2834 of 5248

Hi miceblue,

 

the Vmoda is 32 ohms and that's most probably way too low for the macbook. The usual rule of thumb is that the headphone impedance should be 8-10 times or higher than the output impedance of the amp. That would mean the output should have 3-4 ohms or less and apple seems to state less than 24 ohms...

 

http://apple.stackexchange.com/questions/57186/what-is-the-impedance-of-the-line-headphone-jack-on-macbook-pro-retina

 

So the sound of the Vmoda is probably a bit colored when directly connected to the macbook and will sound different when when the macbook just drives the O2 with >10k ohms input impedance.

 

Joachim

post #2835 of 5248

I cant even belive this is happening......OMG...

 

This is really well.....you know.....

 

Have fun....

 

A.

 

:deadhorse:


Edited by adydula - 5/8/14 at 1:26pm
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