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REVIEW: Ross Martin PCM 1794 DAC- $250 Overachiever - Page 2

post #16 of 61

I have a DAC/AMP unit, it is wider but looks almost exactly like the one bixby has. The RCAs are output. It even came with fully balanced output (mine has TRS instead of XLRs though) which I didnt even care as I was not expecting balanced rig anytime soon.  

post #17 of 61
Thread Starter 
Originally Posted by genclaymore View Post

Is the RCA plugs on it output's or Inputs. Also how is it usb connection.

My model had both RCA and XLR outputs.  As for USB see my comments above in the review.  

post #18 of 61

Now I got really curious about this Ross Martin DAC: How does it fares against good soundcards? As Claro Halo or Xonar Essence?

post #19 of 61

I also wondering about that too.

post #20 of 61
Thread Starter 

The only soundcards I have used were the pci cards form E-mu the 0404 and the 1212m.  Both of these cards were outclassed by the Ross Martin Dac.  The pro audio TC Electronic BMC-2 also got beat by the Ross Martin dac.  

post #21 of 61

EDIT: I apologize for getting the DAC chip numbers confused... The Ross Martin PCM 1794 DAC is NOT an R2R style DAC, like the PCM 1704 chip is. I goofed on that big time. I'm sorry for all the confusion that may have caused. I'm leaving the information lingering in this post just for the information and links available. Just to clarify, the Ross Martin PCM 1794 DAC discussed in this thread does NOT use an R2R style DAC chip.







The most important thing about computer audio cards, other than decent build and parts, are the clocks used to run them, are they "true" clocks or not. At least this is the gist of what I've learned in the past decade. Getting your audio away from the electrical noise of the innards of a computer is generally a good idea, and piping it into a DAC that has higher quality design and isolation, and parts, also a good idea.



Long story short: Good Sound Card --> Digital Out ---> DAC = :-)




Short story long:




Here's some helpful info on the topic:



Explanation of PCM aka CD-DA format: http://www.mother-of-tone.com/cd.htm <-- has nice graphs and is an interesting primer on understanding how an analog waveform gets "interpereted" into a ladder of steps in a digital interperetation of a sine wave.


The same site, whose author is the creator of the Altmann Tera Player, on Computer Audio: http://www.mother-of-tone.com/computer_audio.htm


A very revealing post and thread on "regular" 16 bit "Redbook" format digital audio and "HiRes 24bit" and higher sampling rate Digital Audio. From Head-Fi's Sound Science forum: http://www.head-fi.org/t/415361/24bit-vs-16bit-the-myth-exploded


Great article on understanding how a master clock works and what in the heck it is and why it is important to digital audio, including jitter: http://www.soundonsound.com/sos/jun10/articles/masterclocks.htm


EDIT: just found the page I was looking for that explains WHY the "old fashioned" R2R style "NOS" DAC chips, like the PCM-1704 (and some other chips like those Philips TDA135x chips, etc) are "better" than the newer type of Sigma-Delta DAC chip designs, and why Sigma-Delta chips need "higher resolutions" to sound as detailed and clear as R2R chips: http://www.mother-of-tone.com/conversion.htm



In any case, about soundcards, I've typically had Creative "xyz" version cards, occasionally a builtin, which lets face it, AC'97 implementations bite, and although the newer "post AC'97 / HD Audio" built-in solutions are better than those, a real soundcard with a good design and good master clocks are important. The card should have 2 master clock oscillator crystals, since there are two different frequency multipliers scaling up to 192KHz: See below:


From: "http://www.mother-of-tone.com/computer_audio.htm":


Master Clocks:


"22.579 MHz is a multiple of the 44100 / 88200 / 176400 Hz sample rates.

24.576 MHz is a multiple of the 48000 / 96000 / 192000 Hz sample rates."




A nice feature on a soundcard as a source is SPDIF, either TOSLINK (optical) whose electrical isolation (when implemented with good jitter control at both ends of the route) are what some think is best), or COAXIAL at a specified proper ohm rating, built to standards, has a better jitter profile than TOSLINK. Either are digital out, and unless your equipment is (probalby really expensive) and can handle AES/BNC (another (some say superior) digital out) then SPDIF to an outboard DAC is probably best.


Sorry for the complex post and hopefully it wasn't too dense or straying (let alone veering) into too many esoteric directions... It was intended as a quick batch of articles to get familiar with digital audio concerns, and whats important in a soundcard, so you could think about having a good one to begin with, and then getting a good signal out to an external DAC like the Ross Martin. Or any other DAC you use in the future.


This also culminates the last year of my research into digital audio, soundcards, DAC's etc, and since faverodefavero and genclaymore asked how the Ross Martin fared against decent soundcards, I guess I went on a bit of a soapbox tear of info sharing. The ASUS Xonar uses the same DSP (the C-Media CMI8788 Oxygen) as the Auzen X-Meridian 7.1 (First Gen) I am using, and those two are of the nicer non-pro soundcards out there. The plus side to them are audiophile design, good grounding, good capacitors, good noise & feedback rejection, and DIP-8 sockets for some (not sure about the Xonar) but the X-Meridian (1 & 2 G) both allow all channels to have their opamps rolled by the user.


In my personal experience, running just my X-Meridian's L/R out to my headphones, with an upgraded opamp (OPA627AU's) sounded nice, but optical SPDIF TOSLINK to an iBasso D10 DAC/Amp to my headphones sounded cleaner, higher resolution, and overall better.




Long post, I know, but I hope it answers some questions and is helpful.


If anyone has anything to add or improve on what I said, feel free. If it's off topic you can just PM.



Back to the Ross Martin DAC please, I wasn't trying to thread-jack.




EDIT: I found the sampling rate frequencies necessary for proper master clocks.

Edited by AnAnalogSpirit - 7/23/12 at 10:05am
post #22 of 61

^^^Woah, that was amazing! Thanks for the links.

post #23 of 61

try out Mytek digital 32 Bit DAC

post #24 of 61

The only Mytek 32 bit dac i could find is $1595 how is that relevant to this thread, or did i miss one ?

post #25 of 61
Wow. Thanks so much for the info, flacvest, it's great and with good links as well!

Now, about the HT Omega Claro Halo, can anyone coment on it's toslink output please? I mean, how good is it? Can't find much info on HT Omega's website...

Again, thank you!
post #26 of 61
Thread Starter 

While I have not heard the Claro, I have used E-Mu cards and their Toslink out was quite good as Toslink goes.  Most all Toslink transmitter circuits are a $2 chip and can do a good job of getting the data out of the computer and to the target dac.  At least the E-Mu cards were about the same with Toslink and spdif coax.  And they did a good quiet job of feeding the outboard dac.


hope this helps.

post #27 of 61

Could you compare the Ross Martin to the internal Touch DAC?

post #28 of 61
Thread Starter 

Assume you mean the Logitech Touch, since you cannot get a digital out of the ipod Touch.


The Touch has a pretty decent dac in it but sounds a bit thin without as much low end and body in the mids when compared to the Ross MArtin.  Highs also seem a bit more effortless on the RM.  Depth and black background are a bit more apparent with the RM.  If you have not heard the RM, the Touch internal dac is quite a good dac on it's own.  

post #29 of 61

Yes, the logitec.  Thanks for posing.

post #30 of 61
Originally Posted by bixby View Post

Here are some pics of the Ross Martin Dac.  As for comparing the bifrost to the Ross Martin.  I am sure I could if they would like to send me a demo.  I heard the bifrost hooked up to one of their amps with their computer at RMAF.  I could not get a handle on how the Dac sounds by itself obviously.  Sorry.





You should email these to him and suggest him put them up
Edited by kskwerl - 4/5/12 at 8:36pm
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