MQN testing/experimentation thread

[jkeny]

the playerextreme.exe in the test folder could be used, just rename it to mqncontrol.exe. It uses the original memcpy, no optimisations, no memory play - reads straight from the hdd, presumably is bit perfect.

Is this the worst sounding?
I was thinking more about putting in do-nothing loops in the render loop or somehow delaying it's operation to the extent that it affected the sound?

[LowOrbit]

One of of differences that MQn produces is in stereo presentation it can be wide, narrow, compressed, tall or 3d. Is there no measurement that can be used to measure the effect on stereo presentation ? The same on pitch, some versions have an enhanced treble, some the bass is enhanced, can a tone be played and then checked to see if it has changed pitch ? Don't know if that is the correct attribute, but am looking at a way to measure the audible differences.

My take on this is that there are only two variables in the reproduction of sound. Amplitude and time. Frequency derives from the modulation of amplitude over time (although it is obviously not a simple relationship in a complex sound such as music, which is why we use 44100 samples a second to get a decent quality reproduction of a complex sound wave).

Every aspect of music can be represented by a complex analysis of those two factors (Fourier analysis does just that by breaking a complex sound down into simple sine waves that vary in amplitude over time). When you make changes in MQn perhaps you are changing the way samples aggregate through the dac and filter. One change produces an effect that impacts on high frequencies so you get something bright (but which is actually a distorted version of the truth), another change causes bass frequencies to distort which results in a fuller, bassier sound (that is again distortion but not in a simple enharmonic manner). These effects (because they probably affect small, cyclical groups of samples) are relatively subtle so do not manifest as great big, bad sounding distortion. In effect there is a smearing which is generated by the way the code executes or the way the cpu shares its time between the many concurrent processes it needs to run.

The less smearing, the cleaner, more tonally accurate the music is portayed the and less "noise" there is masking the very low level cues in the signal, which manifests as perceived changed in soundstage, or opening up the detail in the recording (so that, for instance, I can suddenly here the tiny tambourine bell hits in a Grace Jones track).

Certainly the interactions between buffers, event triggers, cpu availability and so on are complex.

My experience of listening to MQn is similar to John Kenny's description above, and I think is a part of the above mechanism I've outlined (probably poorly and a massive oversimplification). I hear tighter timing, better organisation of sounds, richer, more palpable instrument tones (analog synths which suddenly really hit home but in previous player didn't, a real sense of the twang of nylon guitar strings). And the host of low level details and cues that separate instruments in the mix and open up layers of texture and complex percussion.

[erin]

One of of differences that MQn produces is in stereo presentation it can be wide, narrow, compressed, tall or 3d. Is there no measurement that can be used to measure the effect on stereo presentation ? The same on pitch, some versions have an enhanced treble, some the bass is enhanced, can a tone be played and then checked to see if it has changed pitch ? Don't know if that is the correct attribute, but am looking at a way to measure the audible differences.

I think you could measure this in room, using either one or two fixed position microphone(s) and software such as smaart

[jkeny]

One of of differences that MQn produces is in stereo presentation it can be wide, narrow, compressed, tall or 3d. Is there no measurement that can be used to measure the effect on stereo presentation ? The same on pitch, some versions have an enhanced treble, some the bass is enhanced, can a tone be played and then checked to see if it has changed pitch ? Don't know if that is the correct attribute, but am looking at a way to measure the audible differences.

That's the problem - these effects are due to perceptions so the psychoacoustics of this need to be known in order to begin to direct the measurement.
Sound stage size, instrument timbre are all related to timings within the music. I forget the actual figures on this but timbre is mostly determined by the first ? mS of the audio envelope. Sound stage is determined by the timing & level of the signals reaching each ear.

Before MQN arrived, we all experienced better reproduction when hardware tweaks such as linear supplies/batteries were used. The same sort of improvements that MQN continued to enhance - better body to the sound, better more stable sound stage, etc.

Could be noise reduction or could be timing issues/stability - could be both

[nige2000]

sbgk, idea: after you have finished MQn you could try writing some code for ripping CD's as a background service.....

By the time MQn is finished CDs will no longer exist. What is missing from existing rippers that you want another one ?

my turn

bits are bits:)
lol

[LowOrbit]

One of of differences that MQn produces is in stereo presentation it can be wide, narrow, compressed, tall or 3d. Is there no measurement that can be used to measure the effect on stereo presentation ? The same on pitch, some versions have an enhanced treble, some the bass is enhanced, can a tone be played and then checked to see if it has changed pitch ? Don't know if that is the correct attribute, but am looking at a way to measure the audible differences.

That's the problem - these effects are due to perceptions so the psychoacoustics of this need to be known in order to begin to direct the measurement.
Sound stage size, instrument timbre are all related to timings within the music. I forget the actual figures on this but timbre is mostly determined by the first ? mS of the audio envelope. Sound stage is determined by the timing & level of the signals reaching each ear.

Before MQN arrived, we all experienced better reproduction when hardware tweaks such as linear supplies/batteries were used. The same sort of improvements that MQN continued to enhance - better body to the sound, better more stable sound stage, etc.

Could be noise reduction or could be timing issues/stability - could be both

This would be very difficult to do in a domestic environment due to the generally unknown mix of direct/reflected sound at different frequencies. You'd probably need to do this in an anechoic environment to make a meaningful measurement.

[erin]

One of of differences that MQn produces is in stereo presentation it can be wide, narrow, compressed, tall or 3d. Is there no measurement that can be used to measure the effect on stereo presentation ? The same on pitch, some versions have an enhanced treble, some the bass is enhanced, can a tone be played and then checked to see if it has changed pitch ? Don't know if that is the correct attribute, but am looking at a way to measure the audible differences.

That's the problem - these effects are due to perceptions so the psychoacoustics of this need to be known in order to begin to direct the measurement.
Sound stage size, instrument timbre are all related to timings within the music. I forget the actual figures on this but timbre is mostly determined by the first ? mS of the audio envelope. Sound stage is determined by the timing & level of the signals reaching each ear.

Before MQN arrived, we all experienced better reproduction when hardware tweaks such as linear supplies/batteries were used. The same sort of improvements that MQN continued to enhance - better body to the sound, better more stable sound stage, etc.

Could be noise reduction or could be timing issues/stability - could be both

This would be very difficult to do in a domestic environment due to the generally unknown mix of direct/reflected sound at different frequencies. You'd probably need to do this in an anechoic environment to make a meaningful measurement.

I disagree, using a fixed position microphone it will capture any differences if they are there to be measured. Im talking about taking measurements off axis. This might explain the wider or narrower sound stage that we experience

[erin]

Absolutely agree, Erin, the measurements have to be taken at the analogue out of the DAC, at least initially to prove the case. At a later stage further & deeper measurements of the digital signal going into the DAC would be of interest but not just bits measurements but actually electrical signal measurements.

Both are important and interesting but the analog domain stuff is easier to measure.

Question 1: Why record analogue to tape? Why not directly into a good digital recorder? This has to be sufficiently accurate for the proposed level of measurement required.

You could be right about that. Testing both ways should deliver similar results. If not, we would have to look at why not...

Question 2: What level of null is acceptable or is it just that we want to compare the MQN null value to other player null value? What value null is achieved by playing the same track through the same player twice & nulling the inverted against the original ? Remember there is never a perfect null. The nulls for MQN have to be consistently & significantly different to other players but what does significant mean? If we are talking about noise being reduced & subtle audio cues being now heard - what level does this imply -70dB, -80dB, -90dB, what do you reckon?

That is a good question :) I guess someone just has to do a few tests and see what they come up with.

Maybe we should branch off this discussion to another thread about measurements of MQN?

Fair call, it is a bit OT

[LowOrbit]

Absolutely agree, Erin, the measurements have to be taken at the analogue out of the DAC, at least initially to prove the case. At a later stage further & deeper measurements of the digital signal going into the DAC would be of interest but not just bits measurements but actually electrical signal measurements.

Both are important and interesting but the analog domain stuff is easier to measure.

Question 1: Why record analogue to tape? Why not directly into a good digital recorder? This has to be sufficiently accurate for the proposed level of measurement required.

You could be right about that. Testing both ways should deliver similar results. If not, we would have to look at why not...

Question 2: What level of null is acceptable or is it just that we want to compare the MQN null value to other player null value? What value null is achieved by playing the same track through the same player twice & nulling the inverted against the original ? Remember there is never a perfect null. The nulls for MQN have to be consistently & significantly different to other players but what does significant mean? If we are talking about noise being reduced & subtle audio cues being now heard - what level does this imply -70dB, -80dB, -90dB, what do you reckon?

That is a good question :) I guess someone just has to do a few tests and see what they come up with.

Maybe we should branch off this discussion to another thread about measurements of MQN?

Fair call, it is a bit OT

The easiest way would be to add a test tone to the start and end of whatever file you used for the testing. That way you could ensure sample level alignment when lining up the files for null comparison. It's probably easier with a simple tone than identifying the absolute start of a track otherwise.

[LowOrbit]

I disagree, using a fixed position microphone it will capture any differences if they are there to be measured. Im talking about taking measurements off axis. This might explain the wider or narrower sound stage that we experience

Probably the earlier suggestion to take the output directly from the analogue stage of the DAC is better. Otherwise you are measuring the interaction with the room which is complex.