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Improving on a Nexus S and Sennheiser HD205s
db579
post Aug 1 2012, 15:35
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I currently use a (rooted) Nexus S as my media player using Voodoo sound to take advantage of the Wolfson WM8994 DAC and Sennheiser HD205 headphones. My files are either flac files stored on the phone or 320kbps mp3s streamed from Google Music via Wifi or 3g. If I wanted to improve on this what is the best way to do so?
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pdq
post Aug 1 2012, 15:51
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Better headphones? Anything else is probably a waste of money.
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xTobix
post Aug 1 2012, 19:16
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Hi db579,

QUOTE
I currently use a (rooted) Nexus S as my media player using Voodoo sound to take advantage of the Wolfson WM8994 DAC and Sennheiser HD205 headphones. My files are either flac files stored on the phone or 320kbps mp3s streamed from Google Music via Wifi or 3g


Reading on the specs of your headphone I guess you have made a very decent selection:
Sennheiser HD205 home
Nominal impedance 32 Ω,
Jack plug 3,5,
Transducer principle dynamic,
closed, Weight w/o cable: 206 g
Frequency response (headphones) 14 - 20000 Hz,
Sound pressure level (SPL) 112 dB(SPL),
THD, total harmonic distortion < 0,5 %

For most non-audiophile mobile devices it is probably good advice to keep the nominal impedance in the lower 10-50 Ω. The reason is that they are OK in delivering some current but start to clip fairly soon if higher voltages are required (what one needs to drive a higher impedance) since there are limited by their battery voltages. Hence a good balance or to use the right term "impedance matching" between driver (source) and headphones (sink) is key to use the full potential of your combo.

The two things I would recon if you really want to purchase new headphones would be to get the THD down to something 0.1% or even better. And the thing that would hold me back from purchasing the 205 is the fact that it sits on top of your ear (supraaural ear coupling). I always prefer circumaural since it works more natural since it uses the shape of your ear as you hear just without HP and also for longer hearing my eras get irritated with supraaural wearing style. (but that is a very personal thing)

I am using a Sennheiser HD 280 PRO home which has a little bit a high impedance but is till fine with my Samsung Galaxy first generation!

Some good advice: You really have to go to some place where you can actually test different headphones and also compare it to some decent driver (your phone connected via RCA to a dedicated headphone driver). This will allow to tailer HP to you and your driver. But I have to warn you - most likely you will be very disappointed from then on with your phones driver. (Good new however, there is cure in the pipe with Jelly Bean v4.1 since the finally implemented a USB-Audio protocol allowing one to stream the digital signal to an external DAC!)

In addition to that, I found the player to make the biggest difference of all. I am using after lots of testing powerampapp and several of my friends came to the same conclusion on their Android devices.

However, I was never able to distinguish between decent mp3 file and flac on my phone or computer output. You have to switch to a very decent driver and DAC to make out the differences between max mp3 (lame 3.98/3.99 320 insane mode) and loos less wave/flac.

I have no idea about your Voodoo sound but Wolfson WM8994 DAC sounds like a decent one. I would appreciate if you could provide some link to this to give me the chance to read the specs.

Cheers!
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saratoga
post Aug 1 2012, 19:26
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QUOTE (xTobix @ Aug 1 2012, 14:16) *
For most non-audiophile mobile devices it is probably good advice to keep the nominal impedance in the lower 10-50 Ω. The reason is that they are OK in delivering some current but start to clip fairly soon if higher voltages are required (what one needs to drive a higher impedance) since there are limited by their battery voltages. Hence a good balance or to use the right term "impedance matching" between driver (source) and headphones (sink) is key to use the full potential of your combo.


Generally speaking, devices like this will never clip, as the software does not allow you to set the volume that high. Instead, they will simply get (marginally) quieter as the impedance is increased. However, the effect is not particularly significant, as doubling the impedance only costs you 3 dB. Instead, I would recommend sticking to the higher end of that range, as virtually all portable electronic devices are not limited by the voltage available, but rather the current (since they have finite output impedance). Generally, you will get the best results on phones and mp3 players above 32 ohms (there are exceptions, players like the Clip series).

QUOTE (xTobix @ Aug 1 2012, 14:16) *
The two things I would recon if you really want to purchase new headphones would be to get the THD down to something 0.1% or even better.


Those THD numbers are essentially meaningless, so you should not pay attention to them. Even if they were not, THD depends on the dampening factor used to drive the headphones, so without specifying it, you can't know if the numbers are particularly good or bad.

QUOTE (xTobix @ Aug 1 2012, 14:16) *
In addition to that, I found the player to make the biggest difference of all.


No, the player makes almost no difference, beyond allow EQ and similar DSP style effects. Indeed, when using lossless files like flac, if two players have any difference at all (with EQ off), one of them is probably doing something questionable.

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xTobix
post Aug 1 2012, 19:54
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Hi Saratoga,

QUOTE
No, the player makes almost no difference, beyond allow EQ and similar DSP style effects. Indeed, when using lossless files like flac, if two players have any difference at all (with EQ off), one of them is probably doing something questionable.
or both ;-)

That is true only for a systems where ASIO drivers or some soft ASIO wrapper or WASAPI (exclusive ) is used as the output options. Phone manufacturers and in particular Samsung have their fingers in the audio path way before anyone else can do something. For example the build-in equalizer settings depending on the load where for the Galaxy first generation this threshold was about 200 Ω where the internal “optimizes” the audio output accordingly. The only way to completely circumvent this is to use the new usb audio protocol and us an external DAC - not even rooting will cure all the problems since this is hardware specific.

Now what Poweramp does is it has Brand/Device/OS-version specific settings to partially circumvent those settings and overwrite them (the PA-EQ is able to modify those internal EQ settings). Don't ask me to match since I was just using my ears.
But one thing for sure, your audio signal will be modified through any of these smartphone players since the phone has this default build in and customer demand this since bass is all people care about and is there way to evaluate the quality of audio is seems ;-) !

QUOTE
Those THD numbers are essentially meaningless, so you should not pay attention to them. Even if they were not, THD depends on the dampening factor used to drive the headphones, so without specifying it, you can't know if the numbers are particularly good or bad.

This statement and the one before of you are (partially) true (and the reason I have recommended it and personally would never buy any audio gear without) testing it truly in your setup! Although it is good to close in by comparing them on paper first otherwise you will be lost to the sales person which can be a very dangerous situation ;-)

And I have just discovered this Sennhiser HD 380 Pro which seems on paper to be a decent alternative since I am almost through my second set of ear pads on my HD 280.

Good luck to all!
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saratoga
post Aug 1 2012, 20:58
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QUOTE (xTobix @ Aug 1 2012, 14:54) *
That is true only for a systems where ASIO drivers or some soft ASIO wrapper or WASAPI (exclusive ) is used as the output options.


No it generally doesn't matter.

QUOTE (xTobix @ Aug 1 2012, 14:54) *
For example the build-in equalizer settings depending on the load where for the Galaxy first generation this threshold was about 200 Ω where the internal “optimizes” the audio output accordingly. The only way to completely circumvent this is to use the new usb audio protocol and us an external DAC - not even rooting will cure all the problems since this is hardware specific.


This is nonsense. The software has no way to know what the impedance is, so it certainly can't "optimize" for it. Furthermore, RMAA tests confirm that no EQ is applied at all on the Galaxy S:

http://www.gsmarena.com/samsung_i9000_gala...eview-500p6.php

My guess is that you're confusing the high output impedance of the S with equalization.

QUOTE (xTobix @ Aug 1 2012, 14:54) *
But one thing for sure, your audio signal will be modified through any of these smartphone players since the phone has this default build in and customer demand this since bass is all people care about and is there way to evaluate the quality of audio is seems ;-) !


This is certainly not true. Plenty of phones have been tested by RMAA, and virtually all have flat frequency response.

QUOTE (xTobix @ Aug 1 2012, 14:54) *
Although it is good to close in by comparing them on paper first otherwise you will be lost to the sales person which can be a very dangerous situation ;-)


No, like I said, they don't mean anything. No sense even reading them. Its just a waste of time.
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xTobix
post Aug 1 2012, 22:03
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hi saratoga,

thanks for the link to the S1 audio test. I had very different resources at the time and concluded on them.
So I have learned something today, indeed! Browsing across test results provides a good overview to what a modern phone is actually capable off!
I am impressed!

QUOTE
No, like I said, they don't mean anything. No sense even reading them. Its just a waste of time.

Despite the fact that you have just used exactly these values to show me that my arguments were wrong I am respecting your opinion. Anyway, I am not going to comment any further on this, what so ever.

Enjoy!
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saratoga
post Aug 1 2012, 22:34
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QUOTE (xTobix @ Aug 1 2012, 17:03) *
QUOTE
No, like I said, they don't mean anything. No sense even reading them. Its just a waste of time.

Despite the fact that you have just used exactly these values to show me that my arguments were wrong


I suspect you do not understand what those numbers mean if you believe this. The fictional THD values for a pair of headphones have a very different meaning then the measured frequency response of a DAC/amplifier tested under specific conditions. Specifically the ones for the headphones are meaningless numbers unconnected to reality, while the measured amplifier frequency response can tell you if EQ is being used.

QUOTE (xTobix @ Aug 1 2012, 17:03) *
I am respecting your opinion.


I haven't told you my opinion.
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markanini
post Aug 2 2012, 10:54
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QUOTE (xTobix @ Aug 1 2012, 20:54) *
Don't ask me to match since I was just using my ears.

No wonder you're saying that...

QUOTE (xTobix @ Aug 1 2012, 20:54) *
But one thing for sure, your audio signal will be modified through any of these smartphone players since the phone has this default build in and customer demand this since bass is all people care about and is there way to evaluate the quality of audio is seems ;-) !

...When it's obvious that you are commiting the fallacy of incredulity. Using ASIO or WASAPI exclusive won't change the output impedance, that's just silly.
Go read up on Headphone impedance before you make a further fool of yourself.
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db579
post Aug 2 2012, 15:04
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Thanks for the input guys.

@markanini Great blog thanks for posting that

@xTobix I have Jellybean 4.1, haven't had a chance to test the USB audio for myself yet but I've heard (on here amongst others) the USB port tends to not be as good for audio as it's used for so many things at once noise tends to get introduced more easily than a pure digital out.

http://www.wolfsonmicro.com/products/audio_hubs/WM8996/ That's the Wolfson DAC in the nexus S and the Galaxy S I and some version of III. Voodoo sound is an app to make better use of it since the standard Samsung software apparently doesn't do much with it. Needs root access though.
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kiit
post Aug 2 2012, 15:19
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QUOTE (db579 @ Aug 2 2012, 06:04) *
That's the Wolfson DAC in the nexus S and the Galaxy S I and some version of III. Voodoo sound is an app to make better use of it since the standard Samsung software apparently doesn't do much with it. Needs root access though.


Voodoo sound gives you direct access to the internal equalizer of the wolfson DAC in Samsung Phones. You can SEE that it is not bass boosted from the factory. Hope supercurio can get it working for the U.S. version of the S-III which does not come with a wolfson sad.gif

However, xTobis has a reason for his fears. Apparently the automotive industry does ship cars with heavy EQ baked into the hardware of car audio players, and there is no way out of it other than workarounds as he described in his post because of hardware DRM. But as far as I know this is untrue for smartphones so far. Probably due to Apple's influence on audio quality in that market with their amazing iPhone.

edit: I just looked it up. The S-III U.S.A. version by not using wolfson DAC (which has open-source drivers available for supercurio to modify) can never use Voodoo sound.

This post has been edited by kiit: Aug 2 2012, 15:40
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saratoga
post Aug 2 2012, 16:14
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QUOTE (db579 @ Aug 2 2012, 10:04) *
@xTobix I have Jellybean 4.1, haven't had a chance to test the USB audio for myself yet but I've heard (on here amongst others) the USB port tends to not be as good for audio as it's used for so many things at once noise tends to get introduced more easily than a pure digital out.


USB is a digital out. And no, it doesn't introduce noise.

QUOTE (kiit @ Aug 2 2012, 10:19) *
QUOTE (db579 @ Aug 2 2012, 06:04) *
That's the Wolfson DAC in the nexus S and the Galaxy S I and some version of III. Voodoo sound is an app to make better use of it since the standard Samsung software apparently doesn't do much with it. Needs root access though.


Voodoo sound gives you direct access to the internal equalizer of the wolfson DAC in Samsung Phones. You can SEE that it is not bass boosted from the factory. Hope supercurio can get it working for the U.S. version of the S-III which does not come with a wolfson sad.gif


Since the EQ is off anyway, why would you even want that? Its just some crappy EQ, you can easily install software with much better EQ without need for root access. Does it actually do anything useful?

QUOTE (kiit @ Aug 2 2012, 10:19) *
However, xTobis has a reason for his fears. Apparently the automotive industry does ship cars with heavy EQ baked into the hardware of car audio players,


Which is needed because the inside of a car is a small resonant space that will require EQ.

QUOTE (kiit @ Aug 2 2012, 10:19) *
But as far as I know this is untrue for smartphones so far. Probably due to Apple's influence on audio quality in that market with their amazing iPhone.


This has nothing to do with Apple. Having a fixed EQ makes no sense...
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db579
post Aug 2 2012, 17:31
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Yes I'm aware USB is a digital out. What I'm saying is that is not the port's only function regardless of whether it is being used for that or not (the port also powers the device while playing in some configurations for example). I have not tested this but several other members on this forum seem to think that USB is rarely well isolated whereas S/PDIF typically is.

Voodoo is not an EQ it is a driver for the Wolfson codec. As I understand it it replaces the driver written by Samsung.

This post has been edited by db579: Aug 2 2012, 17:31
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greynol
post Aug 2 2012, 17:44
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No one said it was an EQ. Saratoga was talking about the EQ function inside the DAC.

FWIW, after reading the disussion I'm under the impression that this app is not providing you any audible benefit.

This post has been edited by greynol: Aug 2 2012, 17:56


--------------------
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db579
post Aug 2 2012, 19:11
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Ah sorry I misunderstood.

I see, well it is entirely possible I've been conned here. This is the app I'm talking about http://project-voodoo.org/android-apps . Curious what others think?
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saratoga
post Aug 2 2012, 21:02
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QUOTE (db579 @ Aug 2 2012, 12:31) *
Yes I'm aware USB is a digital out. What I'm saying is that is not the port's only function regardless of whether it is being used for that or not (the port also powers the device while playing in some configurations for example). I have not tested this but several other members on this forum seem to think that USB is rarely well isolated whereas S/PDIF typically is.


Are you aware that the degree of "isolation" is completely irrelevant for a digital out?

QUOTE (db579 @ Aug 2 2012, 12:31) *
This is the app I'm talking about http://project-voodoo.org/android-apps . Curious what others think?


I think that page has basically no useful information. Is there any actual explanation of what that hack does?
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db579
post Aug 2 2012, 21:23
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QUOTE (saratoga @ Aug 2 2012, 21:02) *
Are you aware that the degree of "isolation" is completely irrelevant for a digital out?


To be honest no not really. I asked a question based involving this in this thread: http://www.hydrogenaudio.org/forums/index....showtopic=96272

and from that and this forum http://www.hifi-forum.de/viewthread-211-338.html (also posted in previous thread) I had largely gotten the impression that USB does not perform as well as S/PDIF due to poor "isolation" (suggested) or some other reason. If this is wrong I'd be grateful if you could tell me how/why? Thanks

As for voodoo sound yes I'm starting to see that now. Googling it brings up all sorts of blogs and forums raving about the improvement it makes but now that you've encouraged me to dig a little deeper I am struggling to find anything very concrete... Not sure if that's propriety but hmm...

This post has been edited by db579: Aug 2 2012, 21:28
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saratoga
post Aug 2 2012, 21:34
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QUOTE (db579 @ Aug 2 2012, 16:23) *
QUOTE (saratoga @ Aug 2 2012, 21:02) *
Are you aware that the degree of "isolation" is completely irrelevant for a digital out?


To be honest no not really. I asked a question based involving this in this thread: http://www.hydrogenaudio.org/forums/index....showtopic=96272


I don't think a ground loop is too likely with a battery powered device. More generally, if we're talking about a phone where the only connection is the USB port, I doubt this is an issue. I suppose more generally if you're talking about a PC it could (rarely) be a problem depending on how things are wired. But if a device is the only connection to a phone, and somehow it needs more "isolation" I think by definition its a broken device.

QUOTE (db579 @ Aug 2 2012, 16:23) *
and from that and this forum http://www.hifi-forum.de/viewthread-211-338.html (also posted in previous thread)


I don't speak german, and all I see is a bunch of nearly identical RMAA plots.

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db579
post Aug 2 2012, 21:47
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Okay, I guess I was just getting confused by what seemed to me like conflicting information. (The german thread seems quite speculative on second reading so probably not worth going into again).
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stephan_g
post Aug 4 2012, 13:31
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To clarify, USB can be problematic in a loopback measurement setup since it offers no galvanic isolation; the resulting ground loop can introduce all kinds of unwanted noises that screw up the results. Basically this also applies to internal soundcards, it's just a matter of loop area. (Balanced interconnections are used for good reason.) Toslink uses an optical connection, hence no ground loop there. Manufacturers of audio measurement interfaces go to great lengths to provide "floating" inputs and outputs.

If you're sticking to "full-grown" headphones, the subtleties of output impedance won't matter much to you. Anything with 10 ohms or less is usually fine for them, and less critical models won't show any appreciable coloration below 47 or 100 ohms (those, however, also tend to be less sensitive so you're more likely to run into artificial or technical volume limits more easily). The 330..470 ohm outputs found on many integrated amps and receivers may still be a problem.

Triple.fi 10 Pros, by contrast, are extremely critical since their impedance response makes a fine rollercoaster ride. As it is fairly well documented, you can obtain a reasonably accurate estimate for output impedance from measured FR deviation.

AFAIK, HD205s are fairly decent cans for the price but make some nice ear smashers. I wouldn't use these for comfy home listening. Assuming that the Galaxy S is not significantly quieter than, say, a Clip+, you shouldn't have a problem driving the usual suspects (HD600, HD650, HD800, DT880 250 ohm).
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db579
post Aug 4 2012, 16:23
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@stephan_g I appreciate you trying to clarify but some of that has gone a little over my head. Why does USB have a ground loop and toslink doesn't. When you say galvanic isolation you mean preventing current from flowing from the audio producing parts to other parts of the system and vice versa?

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stephan_g
post Aug 4 2012, 17:34
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Toslink (optical S/P-DIF) only establishes an optical connection. Electrical current cannot flow, hence it cannot complete a ground loop. Ground loops appear when two distinct points sharing a common ground are electrically connected via an additional second path.

In case of coaxial S/P-DIF, galvanic isolation is usually established by using transformers, but output ground apparently is electrically connected to some other ground in some cases, partly or entirely negating the benefits.

In audio measurements systems, sets of outputs and inputs are floating with respect to each other as well as the host computer. How exactly they are doing it without losing performance, I'm not sure.
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saratoga
post Aug 4 2012, 20:06
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QUOTE (db579 @ Aug 4 2012, 11:23) *
@stephan_g I appreciate you trying to clarify but some of that has gone a little over my head. Why does USB have a ground loop and toslink doesn't. When you say galvanic isolation you mean preventing current from flowing from the audio producing parts to other parts of the system and vice versa?


Plastic optical cable == no electrical contact.

With a phone you'll have something nearly as good, where the phone is running off of its internal battery, or else the power supply whatever DAC its hooked up to. In this case, you have electrical contact between the two systems, but no loop since there is just one point of contact. With a PC and a stereo hooked over USB, that won't be the case, since each will have their own power supply, thus a loop exists.
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