or Connect
Head-Fi.org › Forums › Summit-Fi (High-End Audio) › High-end Audio Forum › Audio-Gd Master 7 - Discrete Fully Balanced DAC (PCM1704)
New Posts  All Forums:Forum Nav:

Audio-Gd Master 7 - Discrete Fully Balanced DAC (PCM1704) - Page 101

post #1501 of 3492
Quote:
Originally Posted by hans030390 View Post

 

Even then, you can still get nearly perfect measurements for two devices and still hear a difference, especially when comparing R2R and sigma/delta chips. Some of this might have to do with the ultrasonic noise and filtering techniques as well that go beyond what your ADC's sampling rate might pick up, but this is starting to get outside of my limited knowledge area.

 

Most of this has to do with processing artifacts in your brain, you'll have to upgrade the wiring in your auditory cortex and install new supramarginal and angular gyri to be sure.

 

Make sure to use the right instrument.

 


Edited by anetode - 3/10/14 at 4:06am
post #1502 of 3492

Clearly those extra spikes in the OR5 measurements mean the OR5 needs to go in the garbage!

 

What can we infer from that? First, remember that these measurements can be a real PITA unless you know exactly what you're doing and have precision gear. Take these for what they are (i.e. likely very useful, but not guaranteed to be perfect or correct).

 

Even if it were the case that the OR5 were no better or even slightly worse with jitter, it certainly still produces good results (as I like to say, good enough to the point where I don't care as long as I like what I hear).

 

One thing I noticed is that the OR5 seems to do the best job producing "clean" results in the 11500-12500Hz band (and perhaps cleaner overall). That could be relevant, as a low, clean noise floor is very important for DACs, IMO. I would not be quick to overlook small details like these. I could be wrong.

 

It's also likely the OR5 affects more than just jitter, and that's fine, because jitter isn't everything. I'm sure if purrin did a wide variety of measurements, you'd be able to see more differences, though audible differences of these sorts sometimes aren't shown until you do uncommon or even new types of measurements.


Edited by hans030390 - 3/10/14 at 5:03am
post #1503 of 3492
Excellent post and I totally agree. It does help with noise and this is why he stressed to me to buy the new PSU.

I think they market it in away to give us we want to hear , not what we should know about.

The AP1/PP does the same thing and is marketed the same way. I think if we read it helps with noise we would not buy it so quickly.

Ps audio has just released a new DAC. And it does both PCM and dsd. But the marketing is towards a totally now level of sound reproduction and does point towards jitter. But as I use my pwd mkii now with my offramp it greatly improves what I have. Given it's not just jitter but like you say about other noise issues as well.

I also have a MSB DAC. The separate PSU,s are huge in size and they claim both jitter and power as the improvement over the sound of there's compared to others.

But what is perplexing to me. Is the backlash I get back when I mention how greatly it improves the sound.
I was called a prophet. Maybe it's my way of writing.

Al
post #1504 of 3492
PS.

Here is some other thoughts on this too. Kingwa does make good products and huge PSU,s . Why did he just not make something inside to isolate , or a separate product. He did make the the separate usb converter . So,it makes me wonder does he really know how to make it better or is it worth it.

Al
post #1505 of 3492

Nice graphs but what are we looking at with the coax and OR5 graphs?    Is it still no tone input (silence)?   What is the sampling rate of the inputs and bit depth (looks like 24 bit)?   The sharp peaks at 12Khz may imply an artifact with 48, 96 or 192Khz sampling rates.  I would think power supply noise would be uncorrelated with the sampling rates meaning its noise would be random and moving through the graphs (not locked).  The two small peaks on the OR5 could perhaps be beat clocks (sums and differences) of the two OR5 oscillators but mathematically doesn't seem to work out.  So still looking...  

post #1506 of 3492

ADC was running at 24/96. DAC was running at 16/48. The jitter test involves a 12kHz tone with intentional sidebands about -130db below (LSB toggle at Fs/192). Something very similar to below. Any modulation in the 12kHz due to jitter should be seen as symmetrical sidebands above the noise floor). We won't see the low level sidebands in the original signal. My equipment is too noisy.

 

post #1507 of 3492
Quote:
Originally Posted by aive View Post
 

 

Thanks for making the effort! Some really good data.

 

What do you infer from all that?

 

Doesn't seem like much difference - the OR5 seems to introduce a few harmonics with that fundamental signal but I can't spot anything else really. Also, the USB32 and coax actually measure very well in comparison.

 

I was starting to think that soundstage and instrument separation quality are heavily dependent on jitter - and that the reason why the OR5 improves on the stock M7 sound is because it improves upon the jitter performance.... I might have to rethink that philosophy..

 

I infer absolutely nothing from all that. There are a lot of strange things which go on. The subjective difference between OR5 and USB on the M7 is so obvious I know I could pick out which is which via blind AB. Generally, I find measurements not so useful if the differences are subtle.

 

Hansnums may have a point. Maybe I should zoom in 11000-13000kHz region. If anything it's fun trying to chase down measurements which may correlate to our subjective experiences.

post #1508 of 3492
I am glade you people are doing this
I did a post on 5 web sites about jitter
What we hear and what it sounds like when we
Remove it. I rec a host of a answers.
I can add two things to what you are looking for.
One post said it effects sounds from about 10k to 20 k
Another poster responded that jitter is not the major
Improvement in the USB converters
And that noise is the major contributor
Meaning psu and interference. So
As I do understand what you are doing
I figure this would help. One poster opened up
The AP1/Pp. And said what is inside is reclicking
But mostly voltage regulation and noise removal circuitry
Now given both the AP1 and offramp both proved there product
With clean plowed
Psu. I am just throwing it out there

Al
post #1509 of 3492
Quote:
Originally Posted by purrin View Post
 

 

 If anything it's fun trying to chase down measurements which may correlate to our subjective experiences.

 

Yah, this is what I enjoy, trying to identify the science behind all this subjectiveness :D There has to be a reason!

post #1510 of 3492

Thanks purrin.  I understand now.  The original Stereophile article link is below. Purrin is using 48Khz sampling and 12Khz where Stereophile used CD sampling rates of 44.1Kh and 11.025kHz tones (Fs/4).

 

So it appears in purrin's test setup that he is recording some artifact with about 1kHz sidebands regardless of stimulation.  This is seen in the his first graph with no tone and just the M7 with no signal input.   So can only assume these 1Khz sidebands are just there in all the other measurements.  In that case the USB tests look pretty good but the Fs/192 sidebands (250Hz) are showing up readily in the OR5 test.  Sorry to be dense but I had to re-read the Stereophile article a few times for it to sink in as it applies here.

 

Purrin, what is the USB device in the two test graphs - M7 USB32 input (latest V2 F/W)?   And is the OR5 driving the RJ45 I2S input on the M7?  Just making sure I understand what is going on.  Thanks! 

 

http://www.stereophile.com/content/case-jitters


Edited by DACLadder - 3/10/14 at 1:24pm
post #1511 of 3492

The USB is the latest 2014. OR5 is driving I2S via RJ45.

post #1512 of 3492
Dumb question. Is there anyway to convert one the outputs to USB. Weather it is a I2S or spidif . The reason is I have two dacs that do PCM and dsd but the dsd is only though the USB on both .

Al
post #1513 of 3492
Quote:
Originally Posted by blitzxgene View Post
 

This is per what dacladder pm'd me when I asked him a few weeks ago:

 

"...to use a standard Ethernet cable wired straight through (no crossover) you will need to modify the M7 5-pin ribbon cable.  Do this at the DSP board as that side is already wired funny.  

 

The M7 DSP board header has two notches for polarity so looking from the front of the M7 these notches are facing you.  Therefore the connector pins count left to right 1-2-3-4-5.    On the DSP board side remove connector pins 2-3-4 from the connector housing.  Pin 1 (GND) and 5 (MCLK) stay the same.   Move the loose cable from pin 4 to its new home on the connector housing pin 2.  Then reposition cable pin 2 to connector pin 3.  And finally cable pin 3 to connector pin 4.

 

So at the DSP board header lift pin 4 and move to pin 2. Then move the other two down one notch.  If you get confused an need to get back to square one the ribbon cable is currently wired RJ-45 board 1-2-3-4-5 go to DSP board header pins 2-4-3-5-1.  Take a picture of your unmodified cable for reference."

 

I have already rearranged the cable as specified and could post a picture after I leave work. That said, no OR5.... :(


great thanks, I will use a standard CAT7 cable and modify the 5-pin ribbon. It is easy? No soldering or unsoldering? Just reconnecting the internal wiring by hand? I have not opened my M7 yet.

post #1514 of 3492
Quote:
Originally Posted by seaice View Post
 


great thanks, I will use a standard CAT7 cable and modify the 5-pin ribbon. It is easy? No soldering or unsoldering? Just reconnecting the internal wiring by hand? I have not opened my M7 yet.

 

Only thing that's kinda tricky is putting enough pressure on the pins to release them from the header holding them. But no, no soldering needed.

post #1515 of 3492

Anyone using M7 with Audio-gd amp? I'm thinking about changing stock ACSS connectors/cables with Limo. Is it worth it?

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: High-end Audio Forum
Head-Fi.org › Forums › Summit-Fi (High-End Audio) › High-end Audio Forum › Audio-Gd Master 7 - Discrete Fully Balanced DAC (PCM1704)