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Audio-Gd Master 7 - Discrete Fully Balanced DAC (PCM1704) - Page 100

post #1486 of 3589

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.... :(

post #1487 of 3589

Awesome, thanks for the advice!

 

How come no OR5? Have you got it on order? What's the waiting time like for one of these babies?

post #1488 of 3589
Quote:
Originally Posted by aive View Post
 

Awesome, thanks for the advice!

 

How come no OR5? Have you got it on order? What's the waiting time like for one of these babies?

Other financial responsibilities/i'm poor.

post #1489 of 3589
Take one for the team and buy the 70 one. Just kidding it may make a difference but I do not think it is in the league of good ones.

Al
post #1490 of 3589
Quote:
Originally Posted by purrin View Post
 

 

Yes. These things happen. Point goes back to what I initially said. Use the right tool for the job. It's like what Hans says. Measuring DACs is not like any noob can pick up whatever random tools and start pressing random buttons and running random tests. Even if you know what you are doing, weird stuff happens. For all we know, it could be interactions between upsampling / oversampling / digital filters on the two DACs and the ADC converter running at different sampling rates. It's important to be able to recognize when results are erroneous due to improper setup or measurement artifacts and stop chasing ghosts. I have a few measurements where the M7 FR looks right and the PWD2 FR is affected with comb filter effects.

 

 

What you are trying to do? Use the right tool for the job.

 

You sujested using another tool than audacity. I'm not sure what type of noise I should use because the REW 5 gives a lot of options. I'm trying to check if my Master-7 is neutral across the frequency spectrum.

post #1491 of 3589

Use sweeps in REW. Noise isn't a good way to measure DAC frequency response.

post #1492 of 3589
Quote:
Originally Posted by mowglycdb View Post
 

I'm trying to check if my Master-7 is neutral across the frequency spectrum.

 

Why? You already did. I know your RightMark FR results were weird looking, but that sort of wiggly response is exactly what you'll get with mismatched settings or other inconsistencies in your setup. Fix those, and you should see a fairly flat response (source: I've done a lot of tests with RightMark). Even then, purrin has already shown a couple measurements indicating the DAC is flat across the spectrum with maybe a tiny, tiny bit of droop in the very upper frequencies (normal for many DACs).

 

Aside from NOS DACs, the frequency spectrum of a DAC is usually not a place you'll get a ton of information about the DAC (i.e. they all measure about flat, unless you have a NOS DAC or another DAC with heavy top-end roll-off).

 

First, you'll want something with a clean, low noise floor and the ability to decently resolve low-level details (again, SB1240 is a great, cheap option). You'll want to look at things like the noise floor, THD, IMD, jitter, crosstalk, low-level resolution (-90dB 1KHz tests), etc.

 

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.

post #1493 of 3589

Purrin, I noticed that you've previously released a jitter measurement for the Master 7 with coax input. Would you (or anyone else) be able to do the same for the i2s input with your OR5? And possibly, if you have time, do a jitter test with the integral USB32 for comparison?

 

I'm interested to see if the improvement people are experiencing with the OR5 over the in-built USB32 is due to reduced jitter.

 

Thanks :)

post #1494 of 3589

Yeah. I'll give this a shot again. I hate taking jitter or other low level measurements without precision gear. I'll get different results depending upon the time of day, if the laptop is charging, where the gear is plugged in, the orientation of the moon, sunspots, etc. But I guess I can do as long as everyone understands to take the measurements with a grain of salt.

post #1495 of 3589

hehe, awesome, thanks :) I'm just curious in observing the relative differences between the two (OR5 and USB32) so won't be making any comments re absolute measurements that may be spurious :P


Edited by aive - 3/9/14 at 1:21pm
post #1496 of 3589

It is time for a shout-out for the Master 7.  I have had mine now for 700+ hours. 

 

Always a little hesitant to buy something without listening to it first, especially when the dealer is thousands of miles across the ocean. 

 

Made my choice because I loved my Reference 5.32, respect for Audio-gd, and from all the feedback and comments on head-fi from you guys and elsewhere.

 

John Darko's review of the Reference 7.1 mirrors my thoughts and feelings about the M7; check it out if you have not already done so and are considering this dac.

 

I'm just loving it, and loving the music through my headphones even more.  The highpoint for me is the incredibly tight taut bass and the smoothest high frequencies.  The feeling of being in a live venue, which I didn't think could be captured by a microphone, is found by the M7.  Even studio recordings are presented so that you get a chance to be there during a recording done many years ago.  Electronic and techno music are even more mind-bending.  Very happy with this gear.

post #1497 of 3589

Kingwa confirmed that the I2S out of M2tech hiface Evo is compatible with the I2S input of Master 7.

post #1498 of 3589
Quote:
Originally Posted by aive View Post
 

hehe, awesome, thanks :) I'm just curious in observing the relative differences between the two (OR5 and USB32) so won't be making any comments re absolute measurements that may be spurious :P

 

no signal - just M7 outs into ADC with nothing playing

 

coax from PC mobo

 

usb (ASIO)

 

or5

post #1499 of 3589
Quote:
Originally Posted by purrin 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..

post #1500 of 3589
I can add this.
I put up a post on several forums
Regarding the AP1/PP. And the offramp 5
I ear marked as jitter being the item to be clarified
The results I got back were some what surprising
As these devices are marketed to reduce jitter
And I am sure they do , it seems they more Likely
Improve noise than jitter.
I did a simple test with my AP1/PP with my
HDVD800. I did the test using a surface pro
In was using it's own internal memory card slot
So no external anything. And no charging either
The results were amazing and very easy to hear
On red book. 16/44

Al
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