MQN testing/experimentation thread

[Diapason]

...that poses further questions worthy of exploration! :P

[jrling]

Have just listened to 2.71 v2 [Atom in my case]. Sublime.
Then moved to 2.71 Raw. Only had to listen for one minute to be clear that is was different and clearly inferior to 2.71 v2. Focus lost and everything just less clear.

What is so continuously surprising to me is that the difference in the coding between the two is small but the output quality is so different.
No doubt SBGK can explain what are the coding differences to enlighten those who know about such things.

Jonathan

[wushuliu]

Thought I'd move my posts from the main MQN thread:


wushuliu wrote:
Anyone tried AMD Ramdisk yet? First 2GB are free...

http://www.amd.com/us/products/desktop/ ... rview.aspx

Hm, after doing some more reading this looks *very* cool:

Tutorial 1

http://youtu.be/xhtfMGUTLEA

Tutorial 2:

http://youtu.be/8xYSvmP_tUU

Unfortunately my amp is out of commission for a few days so I can't test. But I bet it will be great for audio playback.

********************

I've just installed AMD Ramdisk and so far results are very promising. It's AMD software that is usable on AMD and Intel platforms. It creates a ram drive for you to place files. First 4Gb are free. I have just placed some audio files to compare. There is a definite audible change in presentation and I believe for the better - music is smoother, more digititis is removed. I think there is potential here with MQN.

Follow up: There is definitely an audible difference in presentation. I'll keep the rest of my thoughts on it to myself for now. Hopefully someone else will try this. It's easy to install and configure and again is usable on both AMD and Intel platforms.

[jesuscheung]

that AMD ramdisk looks the same as RAMDisk 4.3.0 RC 1. even the version number is identical.

maybe AMD bought it.

AMD ramdisk doesn't allow install on my R1.

so i installed the original RAMDisk.

it works!! thx

need more testing

[jkeny]

Yes, it makes an audible difference to the sound that I can hear on my laptop headphones. Haven't tried it on my main system.
Not sure if the difference is a good one as it seems to take away the "presence" of the sound & push it further back. So some HF energy is reduced or tamed?
Might have other better characteristics on my main speaker-based system?

But in terms of testing - it is a conundrum to SBGK, how this could affect the sound!

[wushuliu]

Yes, it makes an audible difference to the sound that I can hear on my laptop headphones. Haven't tried it on my main system.
Not sure if the difference is a good one as it seems to take away the "presence" of the sound & push it further back. So some HF energy is reduced or tamed?
Might have other better characteristics on my main speaker-based system?

But in terms of testing - it is a conundrum to SBGK, how this could affect the sound!

Agreed, I'm torn on the presentation. One one hand the yes the presence is reduced on the other hand I hear other things I did not catch before. Like listening to a song with a tabla I can hear the skin of the hands slapping the drum. Vocals lack the same presence but on the other hand have more 'intimacy' and again a certain tactility as though I can see the person at the mic. Sibilance is reduced and there is an analog wamth due to the HF taming. It's kind of like dolby noise reduction.

At the least it makes an interesting alternative, especially for those who still find their playback too 'digital'.

Also be sure to format the Ramdisk to NTFS, not FAT. NTFS sounds more open.

[markvandepas]

Thought I'd move my posts from the main MQN thread:


wushuliu wrote:
Anyone tried AMD Ramdisk yet? First 2GB are free...

http://www.amd.com/us/products/desktop/ ... rview.aspx

Hm, after doing some more reading this looks *very* cool:

Tutorial 1

http://youtu.be/xhtfMGUTLEA

Tutorial 2:

http://youtu.be/8xYSvmP_tUU

Unfortunately my amp is out of commission for a few days so I can't test. But I bet it will be great for audio playback.

********************

I've just installed AMD Ramdisk and so far results are very promising. It's AMD software that is usable on AMD and Intel platforms. It creates a ram drive for you to place files. First 4Gb are free. I have just placed some audio files to compare. There is a definite audible change in presentation and I believe for the better - music is smoother, more digititis is removed. I think there is potential here with MQN.

Follow up: There is definitely an audible difference in presentation. I'll keep the rest of my thoughts on it to myself for now. Hopefully someone else will try this. It's easy to install and configure and again is usable on both AMD and Intel platforms.

Thankx for the tip !

Besides possible sound quality improvement, I would like too know if using a RAMdisk could help reducing SSD wear out on my server 2012 setup.
In my setup Server 2012 writes too my Kingstone 60 Gb SSD every 45 seconds (!!) or so.

I don’t like this high disk write activity because:
* The less OS (disk write) activity there is, the better sound quality there will be (theoretically).
On my cMP-cPlay setup, XP did not do any disk writing at all !
* Preventing SSD wear out.

-> How too stop this constant writing and reading too my litlle SSD?
* Has anybody successfully stopped (or greatly reduced) this constant disk activity in server 2012?

* Secondly: if it can’t be stopped: can it somehow be re-direct too RAMdisk?
For that I changed the environment-variables.
But I doubt it too be effective.
I don’t see any files in Ramdisk:\temp
Are there any inmates who successfully re-directed this activity?
My geuss is that server 2012 does al lot of logging.
But don’t know how too stop that logging.
Any Ideas?

-> Tip for inmates who want too try RAMdisk on server 2012:
Because Radeon RAMdisk will not install on windows server-versions, I installed Dataram RAMdisk on my server 2012 setup (as suggested by the Radeon RAMdisk installer)
Dataram RAMdisk can be downloaded here:
http://memory.dataram.com/products-and- ... re/ramdisk

-> On sound quality:
I installed a 1024 MB RAMdisk on a 4GB RAM win server2012.
However not using this 1024 Mb RAMdisk (!) at all, installing this 1024 ram-disk changed sound quality the way Wushuliu describes.
(BTW: I think I like the change in Sound Quality.)
So Just the fact that it’s there on my machine, changes sound quality.
Strange.....

[wushuliu]

Yes I believe one of the benefits of the Ramdisk is to reduce wear on your drive.

[jkeny]

OK, I've being doing some measurements using the IQ_test I mentioned before & I may have a handle on what's going on but it is tentative & needs to be analysed/discussed/teased out.

The IQ_test allows a measure of the timing differences that may occur when a specially generated audio file is played & recorded. This audio file is a stereo one with mathematically known timing differences between channels. This is an important point that I'll come back to later but any timing differences found in the plots are because there is a difference between the timing of the signal in the two channels.

Firstly we should look at what a plot of a perfect reproduction of the file would look like:



So this graph needs some explanation. The X-axis is the frequency range from 0Hz to 22KHz. The Y axis is the timing slip in microseconds. In other words any timing differences at all frequencies will be shown. So this graph shows a predominantly flat line at zero i.e no timing slips at any frequency. The spikes at 6KHz, 12KHz & 19KHz are some anomalies of the software which I haven't been able to track down but they can be ignored in the following plots. The real point is to show what a perfect playback would look like - a flat line across all the frequencies. How I generated this plot was to feed the generated file directly into the analysis software without going through any playback & recording steps.

I firstly decided to do these measurements through the analogue out of the laptop as I hoped that it might exaggerate any differences between playback software & maybe give some hints of what differences to look for in the plots. The timing errors in these plots will be a result of a number of things, not just the playback software:
- the computer being used for playback
- the DAC converting it to analogue
- the recording device being used for recording
- the playback software itself.
So by only varying the playback software it is hoped that we can see some changes in the plots if they are not swamped by the timing issues of the rest of the playback & recording chain.


So first a look at playback through Foobar directly out of the analogue out of the laptop & recorded onto a Zoom H2 recorder


You can see that the timing slippage gets worse (the rising slope) as the frequency rises. Also that there are mis-timing fluctuations (i.e it's not a straight clean line but a fuzzy up & down line) at all frequencies. And that these fluctuations increase (more fuzziness) as the frequency increases.

Now for MQN through laptop.

As you can see it looks very similar to the Foobar plot with no glaring differences.

OK, but this is a very high level plot across the full frequency spectrum which shows timing delays rising to 90 milliseconds at the higher frequencies.

So I said the channel timing differences are important & here's why - in the real world we localise sound by the timing differences we can perceive in the same signal that reaches each ear. We are very sensitive to this timing difference as it is a necessary survival mechanism. There are psychoacoustic tests that have shown in the right circumstances a timing difference of 1.5microseconds can be sensed. This seems very low & probably 5 microseconds is a reasonable figure. What this means is that at 10 feet away we can sense a sound source movied 3 inches left or right.

Anyway, what this means is that we perceive the sound stage of our audio playback mostly (inter-aural intensity differences are also important - IID) through these timing differences arriving at our ears. These timing differences have been captured by the recording engineer with whatever mic pattern he used & also later by panning sounds to the left or right.

To perceive a solid sound stage the recording has to be done properly & the inter-channel timings that whatever mic configuration picks up have to be preserved.

I have seen it stated by researchers that the main frequency range which is used in this way is the range 300 to 5KHz so here's a plot of 300 to 1KHz for starters (Edit Actually I think it may be 500 or 700 upwards? So another graph is needed to zoom in on this area)

Firstly Foobar


And MQN


With this zoomed in view I believe we can see that MQN shows a slope that is lower than Foobar - in other words it has lower timing errors at each point in this frequency range.

This may be one of the clues to what we are hearing - it results from lower timing errors when played back through MQN.
I have further plots which are done playing back through an external DAC (Ciunas) rather than the laptop's analogue outs & this again shows a generally lower slope than the laptops plots. So, my tentative conclusion is that we don't have perfect playback timing but we have improved timing. This timing varies according to frequency - rising towards higher frequencies & this timing variation interferes with the sound stage solidity. If the plot showed a fixed timing across all frequencies i.e a flat horizontal plot then we would have no issue, I believe - it would produce the best sound stage.

BTW, if anyone is interested, I can supply the analysis files which can be plotted, zoomed in or out & changed in various ways to get different views into the results

Of course all this could be rationalisation of the results? That's why getting a body of results together would give a better handle on the trend that we are looking for.


Oops, I see my dropbox links don't show as images? Too late to do anything with them now - maybe one of the mods can help to host these? Here's the dropbox folder for the files https://www.dropbox.com/sh/6v25r8woxupbesb/DGmKOJQnjK

[jesuscheung]

interesting.

do a test to compare between latest MQn versions. see if differences are noticeable.