[project86]

I suspect most Concero owners primarily use the USB input. The SPDIF input is nice to have and makes for a more versatile DAC, but I still consider Concero a USB DAC first and foremost. 

 

[gurus]

Looks like I might have to get one on a 30 day trial to see how it works in my system.
 
Is the USB on the Concero "galvanically isolated" to reduce power noise and artifacts?

 

[mcullinan]

Yes. I believe it is.
Definitely check it out...

 

[Nick Dangerous]

Quote:

Yes. I believe it is.
Definitely check it out...

 
I've read the specifications and can verify that it is well isolated from overrated budget-DAC syndrome.

 

[greyhorse]

Quote:

Is the USB on the Concero "galvanically isolated" to reduce power noise and artifacts?

 
I've read the specifications too, and it does not say anything about the USB on the Concero being galvanically isolated.  Since Concero is USB powered, there really is no benefit to galvanically isolate the USB anyway.  Any power supply hash will enter Concero directly from the power lines, so about the most you would achieve is to bandwidth limit the USB signal. 
 
It's a shame if most people are not using Concero using the S/PDIF input.  I personally find it to sound far better than USB input.  If anything, I'd love it for Resonessence to come out with an upgraded wall adaptor using a large capacity linear power supply with uber low output inpedance.  This might add more oompf to this diminutive and rather light sounding DAC.  Maybe it's the amp I'm pairing it with, but Concero sounds lacking in dynamics.
 
What kind of input impedances do everyone's amplifiers have?  I've tried 100K (too high when combined with the Concero's 300Ohm output impedance causing high frequency roll-off), and 10K (much better, but sound lacking in dynamics).  Maybe I should try 50K?

 

[mcullinan]

Galvanic isolation technology creates perfect silence in the background: not a hint of any artificial ambiance.
From..
http://resonessencelabs.com/concero-main/

 

[MoonUnit]

It uses galvanic isolation between the digital and analog sections of the board, not between the computer (USB) and the digital section. This arrangement actually makes a lot of sense. You can see the PE65812NL pulse transformer on the board in various pictures that are floating around online.
 

 

[gurus]

Quote:

It uses galvanic isolation between the digital and analog sections of the board, not between the computer (USB) and the digital section. This arrangement actually makes a lot of sense. You can see the PE65812NL pulse transformer on the board in various pictures that are floating around online.
 

That is the answer I was looking for.

 

[greyhorse]

 
Quote:

It uses galvanic isolation between the digital and analog sections of the board, not between the computer (USB) and the digital section. This arrangement actually makes a lot of sense. You can see the PE65812NL pulse transformer on the board in various pictures that are floating around online.
 

Wow, that is interesting technology.
 
Yes, I can see the pulse transformer, but as you can see on the attached picture, that is only isolating the S/PDIF input.  I have been out of the DIY DAC design thing for a while, but I have yet to hear of any way of completely isolating digital and analog sections of the DAC.  The only way to do this is if that technology is built into the DAC chip itself somehow.  Since a DAC chip is both an analog and digital device, the two supplies always have to meet at the DAC chip.  You are free to isolate various sections of either the analog or digital sections of a DAC, but not at the DAC itself.

 

[MoonUnit]

Quote:

Wow, that is interesting technology.
 
Yes, I can see the pulse transformer, but as you can see on the attached picture, that is only isolating the S/PDIF input.  I have been out of the DIY DAC design thing for a while, but I have yet to hear of any way of completely isolating digital and analog sections of the DAC.  The only way to do this is if that technology is built into the DAC chip itself somehow.  Since a DAC chip is both an analog and digital device, the two supplies always have to meet at the DAC chip.  You are free to isolate various sections of either the analog or digital sections of a DAC, but not at the DAC itself.

 
You're right... that was a brain fart. I was looking at the picture on my cell phone.
 
(You can fully isolate the analog and digital sections using a digital isolator. See Figure 11 here, where they use ISO150: shpat.com/docs/texas/df1706.pdf )

 

[bjh00]

Quote:

 
I've read the specifications too, and it does not say anything about the USB on the Concero being galvanically isolated.  Since Concero is USB powered, there really is no benefit to galvanically isolate the USB anyway.  Any power supply hash will enter Concero directly from the power lines, so about the most you would achieve is to bandwidth limit the USB signal. 
 
It's a shame if most people are not using Concero using the S/PDIF input.  I personally find it to sound far better than USB input.  If anything, I'd love it for Resonessence to come out with an upgraded wall adaptor using a large capacity linear power supply with uber low output inpedance.  This might add more oompf to this diminutive and rather light sounding DAC.  Maybe it's the amp I'm pairing it with, but Concero sounds lacking in dynamics.
 
What kind of input impedances do everyone's amplifiers have?  I've tried 100K (too high when combined with the Concero's 300Ohm output impedance causing high frequency roll-off), and 10K (much better, but sound lacking in dynamics).  Maybe I should try 50K?

 
While I have not heard the Concero I am currently auditioning the Chord Electronics Chordette Qute HD in my home system. It is powered by a tiny wall wart so safe to say it does not have a "large capacity linear power supply". Despite that it has a very obvious prominent low-end that gives it an unmistakable full bodied sound. ... good well defined bass at that!
 
I had the Wadia 121 at home immediately prior to the Cute HD. The 121 has an off-board power supply that looks at lot like the sort of thing you get with laptop computer,  and is obviously bigger/heavier that the Cute HD's little wall wart. The 121 has great bass, goes very low and is very articulate, but it certainly not nearly as ripe/powerful as the Cute HD's.
 
That's not to say that these DACs, Concero included, wouldn't benefit for a big stiff linear power supply, I suspect they *all* would, yet clearly there are other factors at play.

 

[project86]

The galvanic isolation on USB might be my error - I swear I read it on the Resonessence Labs site, but know that I look... it just ain't there. The 6moons article does explicitly mention it though. Either way, it's not an issue as has already been clarified above.
 
I've been using Concero a lot with my Analog Design Labs tube amp. It has a 50K input impedance and makes for a great pairing. But I've also used the Violectric V200 which is 10K and I don't perceive an issue with crushed dynamics. What amps are you using?

 

[mcullinan]

My amp a Parasound HCA 1500 is 33k input. the bass is great. I think it's accurate and really follows the recording. But it doesn't supplement music with more bass. My previous Dac, an old theta chroma 396 was known for its bass and definitely had more but also took up the mids a bit. Find a bass heavy track like young jeezy.
I was having a brightness issue, at least I thought. It seemed solved once I switched the Audirvana volume control to Dac and software. I have it set to -3db. It gives a little more room to use volume on my preamp. The brightness may be attributed to the pre too. I'm not sure but it's resolved.

 

[greyhorse]

Quote:

 
You're right... that was a brain fart. I was looking at the picture on my cell phone.
 
(You can fully isolate the analog and digital sections using a digital isolator. See Figure 11 here, where they use ISO150: shpat.com/docs/texas/df1706.pdf )

MoonUnit,
 
My statement still holds; you cannot completely isolate digital and analog sections of a DAC unless this is a built-in feature of some future DAC.  I have read through the application sheets for the DF1704, ISO150 and PCM1704, and you will notice the digital section of the PCM1704 is powered by Vcc.  TI is welcome to name things "analog" all they want, but the moment you are running any kind of digital circuitry off the analog supply, this still counts as both existing on the same power supply, regardless of how small that digital section might be.  One of the things the ISO150 allows a designer to do is minimize the digital "foot print" of the digital section of a DAC on the analog supplies.  Minimize, but not completely remove.
 
Project86,
 
I am currently using a just completed EHHA rev. A as the headphone amp, which is why I am able to change input impedances so easily.  Based on what I am hearing so far, I think I need a better headphone amp...  I am sure Concero can sound better than what I am hearing at the moment.  Next on the build list was a Bijou, but I am not sure Bijou and Concero will play nice with each other as they are both on the smooth side.  Maybe something solid state would work better.

 

[crisco]

Great thread everyone.  I've been reading with interest.  I'm in the process of upgrading my system and adding a computer-based capability.  I'm researching DACs in the sub $750 range and have stumbled upon this Concero as an interesting option.  I'm acutely aware of good system matching - but am by no means an expert.  My setup won't be including a headphone rig for now, but instead has an EL34 tube integrated and some tube-friendly tower speakers.  The speakers are fairly neutral across the frequency range - with perhaps a slight bump after 5kHz, but it's very minor.

So, with all this in mind - What would be the "better" match - the Concero or something like the Yulong D18? From what I've been reading (and I haven't heard either at this point), the Concero is more neutral, while the D18 is warmer.  Now,  I enjoy the warmth of the tubes....but don't want to overdo it, and lose too much detail etc.  On the other hand, I don't want something that will over-brighten the system either.  Any help would be greatly appreciated.
 
Cheers.