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Human-Audio "MUTO": LiFePO4 battery powered & fully discrete DAC: they did it again!

post #1 of 4
Thread Starter 

Hi guys, I thought it would a good idea to discuss about this very promising DAC from Human Audio that happens to be both battery powered and using a fully discrete output stage: http://www.human-audio.com/humanaudioeng_muto.html




It's very refreshing to see new ideas put into action, and not just yet another PCM179x opamp based clone, when you're even lucky if it's not using a high ripple SMPS.


Initially, a friend of mine went for their Tabla Pico, for which I had already posted a quick review at http://www.head-fi.org/t/598333/


He loved it so much that he was in the market for a new DAC because the coax input of his "Benchmark DAC-1" was going through a mandatory ASRC and that was drastically coloring the sound to his ears(he eventually got rid of it).


But he had so many DAC's to choose from, hah! These days, rage is still in 1) battery power 2) discrete output stage 3) natural sound à la R2R.


The nice thing with dealing with this manufacturer is that you get a 2 weeks cooling-off period, so this was mostly a risk-free trial.......the only risk being that he'd love it so much that he'd want to keep it tongue.gif


He's still undecided on the headamp and he will most like go tubey, so he left me the privilege of trying it...and I much obliged happy_face1.gif


So, what do we know about this DAC?


[:yann39] supports up to 24/192 through two user selectable coax inputs(one RCA and the other being a true 75Ω BNC).


[:yann39] two internal LiFePO4 batteries, offering up to 12 continuous hours operation time and the best ripple performance you could dream of.


[:yann39] the battery charging process is fully automated, just like in their Tabla Pico. It will start when the unit is switched off or if the battery loading level reaches its low state(with no audible glitch whatsoever of course).


The usual drawback of battery powered gear is that once the battery's flat, you're forced to recharge and wait for hours before being able to use it again.....the MUTO never gives up on ya, and I've tried really hard to hear a difference between pure battery power and its battery/wallwart hybrid mode and couldn't hear any change whatsoever...so this is as "plug and forget" as its gets!


[:yann39] fully discrete output stage using bipolar and J-FET transistors in "Class-A".


[:yann39] the wallwart is galvanically isolated from the DAC, so no AC induced noise today TYVM...you can put back your power conditioners back into their boxes and put them in the attic where they belong ^^


It also implies that if your coax transport provides a galvanically isolated output(and any transport >$30 does), the MUTO will only share its ground with your amp...no mains or computer induced interferences whatsoever!


Of course I did crack it open, its dimensions are 10 cm x 5.5 cm x 13 cm:


imagebam.com imagebam.com imagebam.com imagebam.com imagebam.com



So we have the two big batteries, the mainboard taking care of the inputs, battery charging, LED's etc...and then we have the DAC daughter board itself, that's soldered with the components on the inside so we couldn't identify them...anyway, they nail polished most of the chips in their Tabla Pico, I would presume that they don't want to endorse clone makers harvesting the fruits of their R&D.


I did plug it to the auxiliary input of my beloved "Stello Eximus DP-1":


imagebam.com imagebam.com imagebam.com imagebam.com imagebam.com imagebam.com


I plugged it to my friend's Tabla Pico USB transport using a male/male 75Ω BNC coupler, and used my collection of orthodynamic headphones in order to listen to this dynamic duo through the "wire a gain" headamp of the DP-1 smily_headphones1.gif


One good thing is that there is no audible glitch when switching sample rates, I really like that! It might seem like a detail but a lot of DAC's make nasty white noise when their S/PDIF receiver loses sync and needs to resync...fear not, this is not going to happen here.


Also, even though it runs in Class A the case never gets any warm.


I shoud also say that I've been listening to this combo for a little while, so I'm not quite posting "new toy syndrom"-ridden impressions and my much acclaimed "Eximus DP-1" is famous for its musical sounding sweet colored sound that makes everything so enjoyable to listen to, with a stunningly live sounding character....its output stage is based on opamps, though.


To be perfectly frank, the first second I heard the MUTO, it instantly reminded of the "Prodigy HD2" soundcard.....a wild guess about the DAC chip being used in the MUTO would be that it's either an AK4396 or one of its elder brothers.


This sigma-delta DAC chip was called the "miracle DAC" and took the market by storm because it was supposedly providing R2R performance.


Richard Kulavik of AKM Semiconductors explained it this way : "This DAC is a large departure from other delta-sigma DACs designed by us and others like BurrBrown, Analog Devices and Cirrus Logic. The AK4396 is an entirely new modulator, pioneered and patented by AKM. It achieves something unique. In the past, many of the old Phillips and BurrBrown parts were R-2R* based products. These older products were looked upon as some of the best. One of the reasons was high frequency noise. In older R-2R parts, HF noise was not present. In all delta-sigma parts prior to the AK4396, everyone has fought HF noise caused from the delta-sigma modulator with the insertion of large filters and other parts to attempt to solve a problem created by the delta-sigma design. The AK4396 today effectively does not suffer any modulator-induced HF noise and is over 60dB better than the nearest Cirrus and BB devices. All of this HF noise can cause many audible artifacts downstream. That is the 'miracle' we believe is making the difference today. This part gives you the performance and linearity of a delta-sigma device with the noise performance of an R-2R part, something that was never previously available."


So the best way to describe the MUTO would be an uncompromising Prodigy HD2 without the computer noise(the HD2 provides poor shielding from PCI/EMI/RFI interferences) but still with this very natural sound that would appear to match exactly everything I've read so far about the so-called "R2R sound".


This link explains who does what, even though those pictures were drawn in MSPaint for all we know: http://www.mother-of-tone.com/conversion.htm


I would presume that the output stage of the MUTO has been made as simple as can be because there is far less noise to deal with than in your usual PCM719x implementation.....and that's very audible to my ears.


I've been A/Bing the built-in DAC section of the Eximus DP-1 to the MUTO, and when the DP-1 can actually make youtube videos rather enjoyable, this is a major no-go on the MUTO...the MUTO is not sweet sounding, colored or anything like that. It's clearly an uncompromising HD sounding DAC and the GIGO principle never rang so true.


This said, I reconsidered and fired up a whole bunch of nearly perfectly mastered albums and 24/88.2 SACD digital rips and yeah baby! this is a no-joke sounding DAC once you provide it with worthy material bigsmile_face.gif


So yes, 3D sounding sound staging yada yada, but what struck me the most was not the usual depth/width impression I always get with the DP-1 when using a headphones crossfeed plugin, it was the impression of height! Yay, I never ever felt height so clearly...that's what I call a head spinning 3D SS, and even more so in bluray movies ph34r.gif


There is indeed a lot of spatial cues embedded inside most recordings, but it'll take some very finely engineered gear in order to extract it all successfully.


So all in all, this is a piece of gear that's using a never-seen-before approach, and this would make a perfect DAC for mastering purposes. My friend's goal was to find a transport and a DAC that would color the sound as little as possible, and then buy one or two completely different sounding headamps so he would never get bored of his rig(and not hear me nagging him that his DAC and his transport suck when he'd be complaining to me ^^). I think he made a perfect choice, and a nice high-end tube headamp will do wonders in order to amplify the sonic goodness of the MUTO even further regular_smile%20.gif


I will post more feedback in due time when my friend will have made up his mind on the headamppopcorn.gif

Edited by leeperry - 8/7/12 at 5:30am
post #2 of 4

This looks promising~ beerchug.gif

post #3 of 4
Thread Starter 

It is! The Human-audio peeps are majorly OCD'ed with clean battery power(we all how PSU's play a drastic role towards SQ) and they are the market leaders when it comes to glitch-free battery power management IMHO happy_face1.gif

Edited by leeperry - 8/29/12 at 7:39am
post #4 of 4

thx for the trouble you took to write yr impression, again another dac to consider,

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