IPB

Welcome Guest ( Log In | Register )

DAC IV stages
Yahzi
post Feb 20 2013, 18:38
Post #1





Group: Members
Posts: 191
Joined: 21-November 12
Member No.: 104669



How important are DAC IV stages in the design of a DAC? I've heard they can cause audible differences. Is this true? I'm not a DAC designer, but I assume there are those who understand the technical merits. Is it a big deal?
Go to the top of the page
+Quote Post
 
Start new topic
Replies
John_Siau
post Feb 20 2013, 22:52
Post #2





Group: Members
Posts: 84
Joined: 28-July 09
From: Syracuse, NY USA
Member No.: 71848



Take a look at published specifications for D/A converters, DVD players, sound cards, iPod, etc. Many only have an 80 to 90 dB SNR. This means that the noise will be audible in an A/B/X test if the peak music levels exceed 80 to 90 dB SPL (easily achieved).

Worse yet, most D/A converters are preceded by a digital volume control. If 20 dB of digital attenuation is dialed in (very typical), the SNR will degrade by 20 dB. In many systems, the user will need to apply 20 dB of digital attenuation to achieve a playback level that peaks at 100 dB SPL. Under these conditions the converter noise may reach 30 to 40 dB SPL. It is not hard to hear the noise floor drop from 30 of 40 dB SPL to less than 0 dB SPL in an A/B/X test.

I have an ABX tester, and it is very easy to pick out D/A converters that have high noise floors.

If one wishes to use a digital volume control, the D/A converter will need an extra 20 dB SNR to keep noise inaudible at loud playback levels. If we want to achieve "CD" quality and use 20 dB of digital attenuation, then 116 dB SNR is required. Under these conditions, noise may still become audible if playback peaks exceed 96 dB SPL.

D/A converters with >116 dB SNR are few and far between. Noise alone is a dead giveaway when comparing D/A converters.

This post has been edited by John_Siau: Feb 20 2013, 22:57


--------------------
John Siau
Vice President
Benchmark Media Systems, Inc.
Go to the top of the page
+Quote Post
Arnold B. Kruege...
post Feb 21 2013, 16:00
Post #3





Group: Members
Posts: 4012
Joined: 29-October 08
From: USA, 48236
Member No.: 61311



QUOTE (John_Siau @ Feb 20 2013, 16:52) *
Take a look at published specifications for D/A converters, DVD players, sound cards, iPod, etc. Many only have an 80 to 90 dB SNR. This means that the noise will be audible in an A/B/X test if the peak music levels exceed 80 to 90 dB SPL (easily achieved).


That is far from being a universal truth. The actual answer depends on the test.

The answer given above probably presumes that we set up the system to play music at a desired high SPL, and then mute the music player. If we hear any noise even if that requires sticking our heads inside the loudspeaker, then the test is failed. That will demonstrate the need for a DAC whose SNR is equal to the peak SPL observed during the listening phase. This should be less than 120 dB or we are talking pretty severe ear damage.

The first step towards what I think is a more reasonable experiment would be to not allow the listener to stick his head inside the speaker cone, but rather constrain himself to a normal listening position. If then we presume a typical quiet room in a residence, then we can probably still do the same basic kind of test as above and get away with a DAC whose SNR is the peak SPL minus maybe 20-30 dB. If we cherry pick the room, maybe only 10-15 dB.

If we back off from a very high peak SPL to a more typical and comfortable SPL that is not the one we use with visiting firemen, then we may pick up another 10 dB or more.

The above rationalizing moves as I would categorize them with some personal bias, probably gets us below 100 dB.

The opposite extreme can be obtained by doing a different experiment that is IMO no less "real world". In this experiment, we set up the system to play music at a desired high SPL, and then wait for the music to stop playing, but continue to play the recording which would then contain the sound in the performance room that remains including the noises made by the people while they are trying to be quiet, the HVAC, etc. This test gets us below 90 dB, and may get us down as low as 60 or 70 dB. 75 dB is IME a 90% solution. 85 dB is a 99% solution.

As a practical matter, the vast majority of people find players and systems with 90 dB dynamic range to be highly satisfying, to say the very least.

Remember that allegedly picky listeners like vinyl, and a vinyl system with 75 dB "Needle Raised" dynamic range is about as good as that technology ever got.
Go to the top of the page
+Quote Post
John_Siau
post Feb 21 2013, 18:44
Post #4





Group: Members
Posts: 84
Joined: 28-July 09
From: Syracuse, NY USA
Member No.: 71848



QUOTE (John_Siau @ Feb 20 2013, 16:52) *
Take a look at published specifications for D/A converters, DVD players, sound cards, iPod, etc. Many only have an 80 to 90 dB SNR. This means that the noise will be audible in an A/B/X test if the peak music levels exceed 80 to 90 dB SPL (easily achieved).


QUOTE (Arnold B. Krueger @ Feb 21 2013, 10:00) *
That is far from being a universal truth. The actual answer depends on the test.


I agree, but the test conditions may be closer to typical applications than you describe below:

QUOTE (Arnold B. Krueger @ Feb 21 2013, 10:00) *
The answer given above probably presumes that we set up the system to play music at a desired high SPL, and then mute the music player...

If we back off from a very high peak SPL to a more typical and comfortable SPL that is not the one we use with visiting firemen ... probably gets us below 100 dB ...

As a practical matter, the vast majority of people find players and systems with 90 dB dynamic range to be highly satisfying, to say the very least.


Using your numbers:
100 dB SPL (slow)
90 dB SNR D/A converter

And adding the following assumptions:
10 to 20 dB music crest factor
30 to 40 dB SPL ambient (quiet room)
10 to 20 dB digital attenuation prior to D/A conversion


system output noise = (average SPL) + (crest factor) - ((D/A SNR) - (digital attenuation))

Worst case given the above assumptions:
(100 + 20) - (90 - 20) = 50 dB SPL

Worst case, the converter noise is 10 to 20 dB louder than the room noise. This should easily be noticeable between tracks, and may be audible in quiet passages of music, even if the noise is white.

Best case given the above assumptions:
(100 + 10) - (90 - 10) = 30 dB SPL

Best case, the converter noise is equal to the room noise, or 10 dB quiter than the room noise. It may be very hard to hear this noise between tracks IF the noise is white.

But, please notice the "IF"

The converter SNR may be limited by a single spurious tone and not by white noise. If so, the noise will be much more noticeable.

Our ears have the ability to hear a 3 kHz tone 30 dB lower in amplitude than the surrounding noise (I encourage the skeptical reader to try this test for themselves). The 30 dB at 3 kHz number can also be derived from masking theory.

If one of the converters under test has a noise floor that is limited by a single tone (AC hum, power supply switching frequencies, or crosstalk from other parts of the system), then this noise will be much more noticable (and much more objectionable than the above calculations would suggest).

Bottom line, it is quite reasonable to expect noticeable differences in a converter's noise floor in a moderately demanding application. It is unreasonable to assert that all converters are good enough to be indistinguishable.

This post has been edited by John_Siau: Feb 21 2013, 18:51


--------------------
John Siau
Vice President
Benchmark Media Systems, Inc.
Go to the top of the page
+Quote Post
[JAZ]
post Feb 21 2013, 20:36
Post #5





Group: Members
Posts: 1793
Joined: 24-June 02
From: Catalunya(Spain)
Member No.: 2383



QUOTE (John_Siau @ Feb 21 2013, 18:44) *
system output noise = (average SPL) + (crest factor) - ((D/A SNR) - (digital attenuation))


I have several doubts on what you say an definitely, that formula doesn't help.

The part that confuses me especially is why do you imply that lowering the volume digitally, increases the noise level.

What i mean is, decreasing the SNR does not increase the noise SPL.


Quiet room: 30dB SPL.
Let's take a reasonable device (you keep talking about consumer products after all), so output: 90dB SPL
Let's also say that the device has a SNR of -91dB ( 1, just to make it different than 90).

Now, decrease the volume by 20, so max is 70db SPL.
The SNR of the device also now increases from -91dB to -71dB
The difference between max and noise floor (the SNR on this playback situation) is 40db SPL.

Is the room noise floor hearable now, compared to the signal? Maybe.
Is the noise produced by the device audible? I still wonder how.


Let's take a setup with more SNR.
Let's take some in-ear phones. : 100db SPL
Now, since they are in-ear, the room noise floor is reduced, let's say 20db SPL.
Taking the same device that has SNR of -91dB

Let's attenuate by 20dB, so peak signal 80db SPL.
The SNR of the device increases from -91dB to -71dB
Difference between max and noise floor (SNR of playback situation) is now 60dB.

So... what is hearable, after all? The SNR of the device is still below the noise floor.

Go to the top of the page
+Quote Post
John_Siau
post Feb 21 2013, 22:49
Post #6





Group: Members
Posts: 84
Joined: 28-July 09
From: Syracuse, NY USA
Member No.: 71848



QUOTE ([JAZ] @ Feb 21 2013, 14:36) *

QUOTE (John_Siau @ Feb 21 2013, 18:44) *
system output noise = (average SPL) + (crest factor) - ((D/A SNR) - (digital attenuation))


I have several doubts on what you say an definitely, that formula doesn't help.

The part that confuses me especially is why do you imply that lowering the volume digitally, increases the noise level.


Decreasing the volume with the digital volume control is necessary to reduce the volume to a normal listening level. This decreases the signal, but does not decrease the noise level. Most systems are designed to provide "normal" listening levels at something less than full volume (often 20 dB less than full volume). If you use 20 dB of digital gain reduction, the SNR degrades by exactly 20 dB.

If you do the math, the noise floor of consumer D/A converters is often higher than the ambient noise level in a quiet room when audio is playing at "normal" levels.


--------------------
John Siau
Vice President
Benchmark Media Systems, Inc.
Go to the top of the page
+Quote Post
Arnold B. Kruege...
post Feb 22 2013, 16:27
Post #7





Group: Members
Posts: 4012
Joined: 29-October 08
From: USA, 48236
Member No.: 61311



QUOTE (John_Siau @ Feb 21 2013, 16:49) *
QUOTE ([JAZ] @ Feb 21 2013, 14:36) *

QUOTE (John_Siau @ Feb 21 2013, 18:44) *
system output noise = (average SPL) + (crest factor) - ((D/A SNR) - (digital attenuation))


I have several doubts on what you say an definitely, that formula doesn't help.

The part that confuses me especially is why do you imply that lowering the volume digitally, increases the noise level.


Decreasing the volume with the digital volume control is necessary to reduce the volume to a normal listening level. This decreases the signal, but does not decrease the noise level. Most systems are designed to provide "normal" listening levels at something less than full volume (often 20 dB less than full volume). If you use 20 dB of digital gain reduction, the SNR degrades by exactly 20 dB.

If you do the math, the noise floor of consumer D/A converters is often higher than the ambient noise level in a quiet room when audio is playing at "normal" levels.


That would be related to mathematical models whose relevance can and has been disputed for several decades, starting no later than Fielder's ca. 1995 AES paper.

Trouble is that in the real world, being disturbed by noise from the DACs is exceedingly rare. We've got ower 10 years experience with consumers playing video DVDs with 16 bit sound at high listening levels and no widespread complaints about background noise. We have fewer but still a significant number of years of experience with portable digital players with similar results.

When presented with 3 independent well-publicized opportunities to obtain recordings on media with > 16 bits all of the products failed in the mainstream marketplace. It was subsequently found that a very high proportion of those recordings were upsampled recordings that started out with 16 or fewer bits of dynamic range. There were no listener complaints based on just listening until the results of unfavorable technical tests were publicized.

I understand the need for high quality low volume product offerings with far greater capabilities than the minimum that is required for the mainstream market. If nothing else they facilitate the creation of media with the required quality levels since a product can't be better than the means used to create it. These products need not be justified based on the needs of the mainstream market but can make sense even when they vastly exceed the minimum need.
Go to the top of the page
+Quote Post
John_Siau
post Feb 22 2013, 18:17
Post #8





Group: Members
Posts: 84
Joined: 28-July 09
From: Syracuse, NY USA
Member No.: 71848



QUOTE (Arnold B. Krueger @ Feb 22 2013, 10:27) *
Trouble is that in the real world, being disturbed by noise from the DACs is exceedingly rare...

I understand the need for high quality low volume product offerings with far greater capabilities than the minimum that is required for the mainstream market. If nothing else they facilitate the creation of media with the required quality levels since a product can't be better than the means used to create it. These products need not be justified based on the needs of the mainstream market but can make sense even when they vastly exceed the minimum need.

Yes, and yes.

But let me bring this thread back to the question of detecting D/A converter differences in an ABX test. I believe the SNR performance of many common audio products, combined with the ubiquitous use of generous amounts of digital volume control is sufficient to expose detectable differences in an ABX test. This does not mean that the general public is dissatisfied with these devices, and it does not imply that the converter noise is objectionable, but it does indicate that converter differences should be detectable in an ABX test. In fact, this has been my experience.

In the past, I posted the results of 2 ABX tests I conducted here at Benchmark:

ABX test - DAC1 vs MacBookPro via headphones
ABX test - DAC1 vs MacBookPro via speakers

In the two above tests, truncation in the MacBook's digital volume control was a dead give-away and resulted in a perfect score in the ABX tests.

The calculations I have presented in this current thread suggest that converter noise floor differences can also be sufficient to give away the identity of "X" in an ABX test (when using typical amounts of digital attenuation). SNR reduction and truncation are two distinct issues that can be caused by digital volume controls.

When digital volume control is used, it takes more than 16 equivalent bits to reproduce a 16-bit noise floor (1 extra equivalent bit is required for every 6.02 dB of digital attenuation). Again this does not mean that the casual user will be dissatisfied with the audio performance. However, the casual user MAY be able to detect the difference between two D/A converters.

This post has been edited by John_Siau: Feb 22 2013, 18:17


--------------------
John Siau
Vice President
Benchmark Media Systems, Inc.
Go to the top of the page
+Quote Post
saratoga
post Feb 22 2013, 18:40
Post #9





Group: Members
Posts: 5054
Joined: 2-September 02
Member No.: 3264



QUOTE (John_Siau @ Feb 22 2013, 12:17) *
In the past, I posted the results of 2 ABX tests I conducted here at Benchmark:

ABX test - DAC1 vs MacBookPro via headphones
ABX test - DAC1 vs MacBookPro via speakers

In the two above tests, truncation in the MacBook's digital volume control was a dead give-away and resulted in a perfect score in the ABX tests.


I'm curious how you know that its digital volume control? Digital control introduces quantization noise, which is white. Analog volume control introduces thermal noise, which is also white. Short of plotting the noise power as a function of gain and checking the slope, how would you be sure you heard one or the other?

FWIW, most PCs use analog volume control (as the Intel onboard specifications use it). Obviously Apple can do whatever they want, but I'd be surprised if they did otherwise.
Go to the top of the page
+Quote Post

Posts in this topic
- Yahzi   DAC IV stages   Feb 20 2013, 18:38
- - John_Siau   The I-V (current to voltage) conversion stage of a...   Feb 20 2013, 20:48
|- - Soap   QUOTE (John_Siau @ Feb 20 2013, 14:48) Fo...   Feb 21 2013, 03:37
|- - John_Siau   QUOTE (Soap @ Feb 20 2013, 21:37) QUOTE (...   Feb 21 2013, 15:20
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 09:20) QU...   Feb 21 2013, 16:09
- - Yahzi   Thanks for the reply John. I'm getting a few p...   Feb 20 2013, 21:47
- - John_Siau   Designing an I-V converter with a 130 dB SNR is no...   Feb 20 2013, 22:02
|- - Yahzi   But it is largely irrelevant if it is competently ...   Feb 20 2013, 22:28
||- - benski   QUOTE (Yahzi @ Feb 20 2013, 16:28) But it...   Feb 20 2013, 22:44
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 20 2013, 16:02) De...   Feb 21 2013, 16:11
|- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 21 2013, 10...   Feb 21 2013, 16:47
- - John_Siau   Take a look at published specifications for D/A co...   Feb 20 2013, 22:52
|- - saratoga   QUOTE (John_Siau @ Feb 20 2013, 16:52) Ta...   Feb 20 2013, 23:51
||- - John_Siau   QUOTE (saratoga @ Feb 20 2013, 17:51) 80d...   Feb 21 2013, 14:57
||- - saratoga   QUOTE (John_Siau @ Feb 21 2013, 08:57) QU...   Feb 21 2013, 20:00
||- - John_Siau   QUOTE (saratoga @ Feb 21 2013, 14:00) All...   Feb 21 2013, 23:03
||- - saratoga   QUOTE (John_Siau @ Feb 21 2013, 17:03) QU...   Feb 21 2013, 23:23
|||- - John_Siau   QUOTE (saratoga @ Feb 21 2013, 17:23) QUO...   Feb 22 2013, 15:15
||||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 22 2013, 09:15) QU...   Feb 22 2013, 16:33
|||||- - saratoga   QUOTE (scuttle @ Feb 22 2013, 09:49) From...   Feb 22 2013, 17:58
|||||- - scuttle   QUOTE (saratoga @ Feb 22 2013, 16:58) QUO...   Feb 22 2013, 19:01
|||||- - saratoga   QUOTE (scuttle @ Feb 22 2013, 13:01) No. ...   Feb 22 2013, 19:39
||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 13:39) Wel...   Feb 22 2013, 20:13
||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 14:13) Bo...   Feb 22 2013, 20:36
||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 14:36) Lik...   Feb 22 2013, 20:46
||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 14:46) QU...   Feb 22 2013, 20:53
||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 14:53) Roc...   Feb 22 2013, 21:13
||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 15:13) QU...   Feb 22 2013, 21:38
|||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 15:38) The...   Feb 22 2013, 22:21
|||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 16:21) Bu...   Feb 22 2013, 22:24
|||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 16:24) QUO...   Feb 22 2013, 22:38
|||||||- - greynol   QUOTE (John_Siau @ Feb 22 2013, 13:38) So...   Feb 22 2013, 22:48
||||||||- - John_Siau   QUOTE (greynol @ Feb 22 2013, 16:48) Is t...   Feb 22 2013, 22:57
||||||||- - greynol   QUOTE (John_Siau @ Feb 22 2013, 13:57) Ye...   Feb 22 2013, 23:05
|||||||- - saratoga   QUOTE (Arnold B. Krueger @ Feb 22 2013, 17...   Feb 23 2013, 04:02
|||||||- - Arnold B. Krueger   QUOTE (saratoga @ Feb 22 2013, 22:02) Loo...   Feb 23 2013, 17:11
|||||||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 23 2013, 11...   Feb 27 2013, 15:10
|||||||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 27 2013, 09:10) In...   Feb 27 2013, 16:30
||||||||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 27 2013, 10...   Mar 4 2013, 17:28
||||||||- - Soap   QUOTE (John_Siau @ Mar 4 2013, 11:28) QUO...   Mar 5 2013, 01:11
|||||||- - Nessuno   QUOTE (John_Siau @ Feb 27 2013, 15:10) Wh...   Feb 28 2013, 13:57
||||||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 22 2013, 15:13) An...   Feb 22 2013, 22:56
||||||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 22 2013, 16...   Feb 22 2013, 23:06
|||||- - greynol   QUOTE (scuttle @ Feb 22 2013, 10:01) That...   Feb 22 2013, 19:42
|||||- - Arnold B. Krueger   QUOTE (greynol @ Feb 22 2013, 13:42) QUOT...   Feb 22 2013, 20:36
|||||- - greynol   QUOTE (Arnold B. Krueger @ Feb 22 2013, 11...   Feb 22 2013, 20:43
||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 09:15) Wr...   Feb 22 2013, 17:48
|||- - scuttle   QUOTE (saratoga @ Feb 21 2013, 22:23) QUO...   Feb 22 2013, 15:49
||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 17:03) QU...   Feb 22 2013, 16:10
||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 22 2013, 10...   Feb 22 2013, 19:41
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 20 2013, 16:52) Ta...   Feb 21 2013, 16:00
||- - John_Siau   QUOTE (John_Siau @ Feb 20 2013, 16:52) Ta...   Feb 21 2013, 18:44
|||- - [JAZ]   QUOTE (John_Siau @ Feb 21 2013, 18:44) sy...   Feb 21 2013, 20:36
|||- - John_Siau   QUOTE ([JAZ] @ Feb 21 2013, 14:36...   Feb 21 2013, 22:49
|||- - [JAZ]   That the usual listening volume of most electronic...   Feb 21 2013, 23:45
|||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 16:49) QU...   Feb 22 2013, 16:27
|||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 22 2013, 10...   Feb 22 2013, 18:17
|||- - John_Siau   The following quote from NwAvGuy's Sansa Clip+...   Feb 22 2013, 18:32
|||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 12:17) In...   Feb 22 2013, 18:40
||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 12:40) I...   Feb 22 2013, 19:10
||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 13:10) QU...   Feb 22 2013, 19:45
||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 13:45) I d...   Feb 22 2013, 20:38
||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 14:38) QU...   Feb 22 2013, 20:42
|||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 22 2013, 12:17) Bu...   Feb 22 2013, 20:58
|||- - saratoga   QUOTE (Arnold B. Krueger @ Feb 22 2013, 14...   Feb 22 2013, 21:07
|||- - Arnold B. Krueger   QUOTE (saratoga @ Feb 22 2013, 15:07) QUO...   Feb 22 2013, 23:01
||- - Ethan Winer   QUOTE (Arnold B. Krueger @ Feb 21 2013, 10...   Feb 21 2013, 20:43
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 20 2013, 16:52) D/...   Feb 21 2013, 16:04
|- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 21 2013, 10...   Feb 21 2013, 16:28
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 10:28) QU...   Feb 21 2013, 18:28
- - Yahzi   So your view is that it is a potential issue but i...   Feb 20 2013, 23:09
- - saratoga   I think SNR is probably not the best way to think ...   Feb 22 2013, 00:05
- - greynol   Since when has NwAvGuy been the ultimate arbiter o...   Feb 22 2013, 18:53
|- - scuttle   QUOTE (greynol @ Feb 22 2013, 17:53) Sinc...   Feb 22 2013, 19:08
|- - greynol   QUOTE (scuttle @ Feb 22 2013, 10:08) You...   Feb 22 2013, 19:18
- - greynol   So rockbox uses the analog volume control, which i...   Feb 22 2013, 20:27
- - greynol   1) 6 dB is not 20 dB 2) Downward scaling in order...   Feb 22 2013, 21:30
- - Mach-X   Rather ironic that everybody is rather correct. Th...   Mar 5 2013, 11:47


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 31st October 2014 - 07:12