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Audio-Gd Master 7 - Discrete Fully Balanced DAC (PCM1704) - Page 99

post #1471 of 3498
Quote:
Originally Posted by Clemmaster View Post
 

 

That's not the spectrum of a pink noise.

 

Yes it is. That's how pink noise appears when processed through an RTA type analyzer which does not use equal frequency bins but rather logarithmic bins. That's why pink noise (instead of white noise) is used to calibrate speakers, etc.

post #1472 of 3498
Quote:
Originally Posted by purrin View Post
 

 

Yes it is. That's how pink noise appears when processed through an RTA type analyzer which does not use equal frequency bins but rather logarithmic bins. That's why pink noise (instead of white noise) is used to calibrate speakers, etc.

Gotcha.

post #1473 of 3498

Purrin's plot look great for a quick test. The only thing that sticks out for me is the PWD2 rolls off on the highs earlier than the M7.  PWD2 crosses -40dB at 30Khz versus closer to 40Khz for the M7.  I know... dog whistle area.. but if we are nit picking plots that's about it. 

post #1474 of 3498

Master-7

 

 Frequency response

 

 

 

Frequency response swept swine

 

 

 

I'm lost here

 

 

Did a third pink noise test with audacity. With less gain now so I don't get so much distortion.


Edited by mowglycdb - 3/6/14 at 7:57pm
post #1475 of 3498
Quote:
Originally Posted by mowglycdb View Post

 

 

That sort of squiggly response and sharp drop off almost always means you're either setting your tests up incorrectly (sometimes as simple as a setting mismatch between devices) or you are using gear that is not really good enough to produce trustworthy DAC measurement results in nearly any context. Devices like Creative SB1240 or E-MU 0404 USB are inexpensive ways to get some surprisingly decent DAC measurements (keeping in mind their limitations), if you are interested in getting into this further. As someone that's still learning much about that subject myself, DAC measurements can be a real PITA to get right sometimes. Basically, really weird results like these are most likely not indicative of what the DAC is actually doing.

 

Until then, I'd just toss up differences to the fact that they're different DACs. Considering the M7 uses an R2R, PCM1704 chip and the other DAC uses, I believe, a Sabre chip, it follows from subjective impressions that the Sabre DAC is likely going to sound brighter overall. Whether that's more neutral or not comes down to personal preferences, though.

post #1476 of 3498
Quote:
Originally Posted by mowglycdb View Post

 

I'm lost here

Did a third pink noise test with audacity. With less gain now so I don't get so much distortion.

 

Comb effect where certain frequencies are out-of-phase. Looks like a processing deal. Possible artifact / interaction between the nature of the noise and how the analyzer is processing that noise. Can you use another spectrum analyzer?

post #1477 of 3498
Quote:
Originally Posted by purrin View Post
 

 

Comb effect where certain frequencies are out-of-phase. Looks like a processing deal. Possible artifact / interaction between the nature of the noise and how the analyzer is processing that noise. Can you use another spectrum analyzer?

 

The NFB-1 was fine, though.

post #1478 of 3498

OKay I'll use REW 5

 

What test do I use?  WhitePN  ?  Pink PN? 


Edited by mowglycdb - 3/7/14 at 1:41pm
post #1479 of 3498
Quote:
Originally Posted by Clemmaster View Post

 

The NFB-1 was fine, though.

 

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.

 

Quote:
Originally Posted by mowglycdb View Post
 

OKay I'll use REW 5

 

What test do I use?  WhitePN  ?  Pink PN? 

 

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


Edited by purrin - 3/7/14 at 4:06pm
post #1480 of 3498
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.

 

Sure.

 

I also thought of a DAC / ADC sampling rate miss-match, but even then, any ADC should have a anti-aliasing filter.

The best safe way is to do repeat the same 2 captures many times while ensuring the setup is the same (not necessarily a "correct" setup) to see if that deviates from the initial observation.

 

You also cannot discard the fact that the DAC itself could have a weird and random behavior. It is obviously more likely that this results of an operator's miss-usage.

post #1481 of 3498

Is the I2S out of the M2tech Hiface Evo compatible witht the I2S input of M7? I have already ordered the Off-Ramp 5 but found an opportunity to get the Evo locally. Does it make any sense to compare the IS2 transfer of these two devices feeding M7? Is there any I2S comparison of these two?

 

Evo data (M2tech site): I2S output voltage: LVCMOS (3.3V) with 25mA current capability on each line

Master 7 I2S in (Audio-GD site): 3.3V level
 

post #1482 of 3498
The one to ask would be dacladder. He would know.
I have the offramp 5 all,the goodies and the AP1/PP. AND they both are very good . I use my AP1/PP with my HDVD800 , UMPP6 and my jh3A/16fp combos,.it dramatically improves them. Now the AP1/PPdoes dsd . The others do not unless you enable dop in jriver. As in a dsd file in a 176 PCM file envelope. It's a shame the hdvd800 does dsd but only through USB. .

Al
post #1483 of 3498

The Evo looks to be electrically compatible with the M7 RJ45 input.   And is even pin-for-pin wired the same as the M7 input.

 

Not sure about their MCLK rates at various sampling rates.  On the Off Ramp 5 all I remember is the MCLK is 24.576Mhz at 192Khz and half of that at 96kHz (12.228Mhz).   The Evo MCLK output is 24.576Mhz and steady for 48, 96, and 192 KHz.   So MCLK compatibility is a Kingwa question. 

 

M2tech has a nice app note on I2S (below)...  Scott

http://www.m2tech.biz/public/pdf/App001%20Using%20hiFace%20Evo%20I2S%20Output%20-%20PrB.pdf


Edited by DACLadder - 3/8/14 at 6:21am
post #1484 of 3498

I have had the Master7 and Master 1 preamp on home loan for a couple of weeks now. The source is a HTPC (intel ion, Win7) with several audio interfaces optical, coax, USB.  In the other ende ATC SCM50 active speakers and the setup works ok, but not flawlessly.

I have tried different inputs on the Master 7 but using USB interface freezes my computer after a short while. I have installed the correct USB driver (USB32 V2.0 driver) for the unit with nstalled Firmware #9-3. After much fiddling back and forth with ASIO, VIA ASIO, WASAPI etc I have given up USB for now and are back on coax which works fine, but I percieve a kind of splashy or ringing sound effect to the music, so Im not sure I am 100% convinced of the Master 7 as a dac for me.

Im eager to try out I2S interface with Empirical audio OR5 but the unit is so f..ing expensive with upgrades, shipping and taxes... :-( 


But then I found out about the Teralink X2 USB to I2S rj-45 interface, costing below $70!

 

Anyone tried it ?  ?

post #1485 of 3498

Speaking of the OR5 with M7 - what's the best way to reconcile the different i2s pinouts of these two devices? Rereading over this thread I saw that purrin started making up a custom terminated CAT cable. Is there a better/easier way? I'd rather not reterminate RJ45s as I don't have the tools nor do I want to stuff it up and end up with a lossy termination >< Is it possible to change the i2s wiring to from the main board to the RJ45 socket within the Master 7 itself? Seems possible looking at photos but I can't find a photo where I can zoom in enough to confirm.

 

Thanks appreciate the info.


Edited by aive - 3/8/14 at 11:06am
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