DAC-AH - fixing the phase

[schapman]

So i got my DAC-AH from eddie last week. He told me for ideal sound (I thought it sounded great compared to my xfi already), i should invert the pos/neg because the phase is backwards.

Seeing as I go xfi->coax->DAC-AH->M^3->Headphones, is there any way to do this without re-cabling my 650s?

 

[Mrjabba]

Quote:

Originally Posted by schapman /img/forum/go_quote.gif So i got my DAC-AH from eddie last week. He told me for ideal sound (I thought it sounded great compared to my xfi already), i should invert the pos/neg because the phase is backwards. Seeing as I go xfi->coax->DAC-AH->M^3->Headphones, is there any way to do this without re-cabling my 650s?

there is software to invert phase, done digitally i guess??
something like this i guess:
http://www.redsofts.com/soft/493/13881/Stereoizer.html

you can also perform modifications to the op-amp circuit, which i assume is more difficult then recabling your headphones.

 

[regal]

Changing the pos neg on the DAC-AH will not work because the ground is shared. The phase on headphones makes no difference. It only matters if you are integrating front stereo speakers to a sub or rear/center channels.
With 2 speakers like a headphone and phase makes no difference.

 

[d-cee]

i've been told that if you do the passive bypass it is no longer a problem

if you're using your speakers solely with the DAC you could just reverse the phase on your speakers by wiring one of the speakers backwards (i think this will cancel out the phase in the DAC, someone please confirm)

 

[Mrjabba]

Quote:

Originally Posted by regal /img/forum/go_quote.gif Changing the pos neg on the DAC-AH will not work because the ground is shared. The phase on headphones makes no difference. It only matters if you are integrating front stereo speakers to a sub or rear/center channels. With 2 speakers like a headphone and phase makes no difference.

you don't change the pos and neg on the dac, it has to be done at the amps output.

not sure if phase makes a difference on headphones, but it's definitely noticeable on a 2-channel speaker setup. *no subs or rear speakers involved*

 

[schapman]

Quote:

Originally Posted by d-cee /img/forum/go_quote.gif i've been told that if you do the passive bypass it is no longer a problem if you're using your speakers solely with the DAC you could just reverse the phase on your speakers by wiring one of the speakers backwards (i think this will cancel out the phase in the DAC, someone please confirm)

That is what Eddy told me. I'm only using the headphones with the DAC though, and to my ears it sounds great so I'll probably just stick with it.

Maybe I'll start modding in the future and see what I can do about it

 

[regal]

Quote:

Originally Posted by Mrjabba /img/forum/go_quote.gif you don't change the pos and neg on the dac, it has to be done at the amps output. *

That's what I said.

Quote:

Originally Posted by Mrjabba /img/forum/go_quote.gif not sure if phase makes a difference on headphones, but it's definitely noticeable on a 2-channel speaker setup. *no subs or rear speakers involved *

Only if the two speakers have a different phase, not if they are both 180 or 0.

 

[Herandu]

Hmmm, changing the phase? I would love to know why Eddy thinks that's a good idea for headphones. It ain't a good idea for speakers as it is. Various frequencies get canceled or reduced in strength, whilst others are amplified. I did have the misfortune or spending several years in the anechoic chamber of my uni when I was a student. Unless the rules of physics have changed since then I would consider changing the phase nothing short of a cheat in order to make the sound appear better as it is. But that would only apply at certain frequencies. It would not resemble the actual signal that the audio engineer would have heard and mixed for when the final track mix was carried out.

 

[Mrjabba]

Quote:

Originally Posted by Herandu /img/forum/go_quote.gif Hmmm, changing the phase? I would love to know why Eddy thinks that's a good idea for headphones. It ain't a good idea for speakers as it is. Various frequencies get canceled or reduced in strength, whilst others are amplified. I did have the misfortune or spending several years in the anechoic chamber of my uni when I was a student. Unless the rules of physics have changed since then I would consider changing the phase nothing short of a cheat in order to make the sound appear better as it is. But that would only apply at certain frequencies. It would not resemble the actual signal that the audio engineer would have heard and mixed for when the final track mix was carried out.

i've read about people changing the polarity of their speakers to invert the phase all the time. they enjoy the sound too

i actually have a test track on one my cds that demonstrates phase, it plays a voice in phase and everything is in focus and precise imaging. then the second part of the test track the same voice is out of phase and everything thing is wide and scattered.

this track helps you position your speakers, so that when the music is out of phase everything should sound wide and you can't pinpoint the person, but when in-phase the imaging is precise. i can upload this if anyone is interested

anyway, i've also read that engineers sometimes also record music out of phase? is there in truth in this?

 

[bowraboy]

I was under the impression that the phase is wrong & this is a fix.

 

[Herandu]

Quote:

Originally Posted by Mrjabba /img/forum/go_quote.gif i've read about people changing the polarity of their speakers to invert the phase all the time. they enjoy the sound too i actually have a test track on one my cds that demonstrates phase, it plays a voice in phase and everything is in focus and precise imaging. then the second part of the test track the same voice is out of phase and everything thing is wide and scattered. this track helps you position your speakers, so that when the music is out of phase everything should sound wide and you can't pinpoint the person, but when in-phase the imaging is precise. i can upload this if anyone is interested anyway, i've also read that engineers sometimes also record music out of phase? is there in truth in this?

There is a difference between recording something out of phase (as in the case of your CD for instance) and wiring your system out of phase. The room acoustic problem with signals canceling or amplifying each other at certain frequencies due to reflection off the various surfaces etc in the room is well known. Boomy bass is one example, or a carpeted versus wooden floor is another. There are discs that have test signals that allow you to reduce this as much as possible by repositioning your speakers until you get an acceptable result.
But when you start swapping over the + and - leads you are making adjustments to the audio spectrum in a dramatic way. A 180 degrees in fact. Bass is one frequency that is most affected by this. i.e. you are going to hear less bass if you stand in between the speakers. That is because the one speaker cone is going out, whist the other is going in. So you get a cancellation as a net result. On headphone it can be felt as an uneven feeling on your eardrums.

I did some technical work on this when designing a noise canceling set of headphones with a Hong Kong company called Archief. The noise canceling headphones are a good example of how phase change can affect sound.

In the case of this DAC: if both L&R output signal circuits are the same in design, then the earth path and signal path would be the same. There is no way on earth the phase can be wrong then. A positive signal sent along the input of both L&R will have to come out positive at the output as well. If you swap one over in terms of phase then the positive signal on the input will be positive on one output and negative on the other. So if you wired up the outputs to an oscilloscope you are going to observe signal cancellation on the display.

And that makes me question what Eddy is saying. Unless he can show up or send me a PM to explain to me his technical take on this I shall have to mark it as snake oil.

 

[bowraboy]

This is off a website that sells the DAC-AH -

" Correcting output phase, this involves changing the Op-Amp circuit so that the output is in-phase. Music will have more focus and imaging will be tighter and precise."

What do you think?

 

[Mrjabba]

Quote:

Originally Posted by Herandu /img/forum/go_quote.gif That is because the one speaker cone is going out, whist the other is going in. So you get a cancellation as a net result.

when you reverse the polarity on both speakers, why is that only one speaker cone is going out while the other is going in?

i'm no expert in the matter, just curious.


Quote:

Originally Posted by bowraboy /img/forum/go_quote.gif This is off a website that sells the DAC-AH - " Correcting output phase, this involves changing the Op-Amp circuit so that the output is in-phase. Music will have more focus and imaging will be tighter and precise." What do you think?

did a little reading about opamps and from what my brain can understand opamps can be run in either inverted or non-inverted operation?



while reading up on the trends ta-10 amp, that i know own, there was some talk about phase.
i didn't quite get it all but here it is:

Quote:

Is inverted phase/polarity a big issue? (They are actually two different things but a phase invert button on a DAC or preamp offers a quick fix for both.) Because of all the variables and uncontrollable factors (recordings could be mixing tracks of normal and inverted phase for example), this is almost a non or so-what issue. There's a 50/50 chance that a CD is recorded in inverted phase. And the likelihood that you can tell one from the other is close to zero unless you have the right tools. Through this exercise, I realized that the NuForce amps too are inverted. Their designer Jason Lim confirmed it and stated that their amps sound better that way. I've owned his Reference 9 and Reference 9 SE for almost a year. The 9 has been connected to a Deltec DAC with a phase inversion switch which has been unknowingly switched to inverted and therefore should sound normal. The 9 SE has been connected to normal phase gear and should theoretically produce inverted-phase music all the time. You know what? I didn't know a thing until now and even now that I know, the musical enjoyment I've been getting from my NuForce amps has not diminished one wit. For my own peace of mind though, I reconnected all my TA-10s and NuForce amps in absolute polarity by either reversing the speaker cables or by means of the DAC's phase inverter, just so that whenever I play that one Accardo/Philips label of Rossini's Sonatas for Strings, the image won't shift. (A word of warning to those who are particularly bothered by inverted phase: Never try to open your TA-10 or NuForce amps and reverse the internal speaker connecting wires. You might reverse the whole circuitry and ground wiring and damage the amplification chip.)

http://www.6moons.com/audioreviews/trends/ta10_3.html

 

[regal]

Mr Jabba, you are absolutely correct and don't let swindlers try to convince you otherwise.


Your test tracks are demonstrating one speaker out of phase not both channels of the source!

This is what people are confusing.

Mr. Wu's "fix" only matters if you have three or more speakers! Not for 2 channels like headphones.

In a stereo system (2 speakers) it doesn't matter if the DAC is 180 or 0 phase. A 180 phase DAC is not going to make one driver opposite the other. Music is AC !