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iFi Audio Nano iDSD discussion + impression - Page 13

post #181 of 1713
Quote:
Originally Posted by Dixter View Post
 

Interesting with all the back and forth banter here about the HO vs LO and how its controlled...    Just yesterday I looked up the Texas Instrument data sheet (BurrBrown) because I wanted to see how the device handle's DSD and the other formats and to look at the output power specs....     It takes a while to read but everything that is in the IDSD is covered in the spec sheet...  there isn't much more for the designers to add besides a good power supply and the interface to control this chip...and a housing...   

The DAC chip does it all....  including the output volume settings...     in other words... as nice as the iDSD is, its still just an implementation of an advanced off the shelf DAC...   

Now just enjoy what ifi has brought to us all..  :-)

+1. I remember seeing this DAC chip in one of the mails from TI not that long ago, wishing at the time somebody will use it in something that does not cost an arm and a leg.

 

Regardless how one feels regarding non fixed RCAs out , volume control, etc; there are numerous possibilities for potentiometers alone, some mentioned here http://www.audiokarma.org/forums/showthread.php?t=180948 ; some are priced above the ifi nano - and have yet to be built into a circuit of one sort or another...

 

Whatever defficiences nano might have - check the measurements of headphones and IEMs and weigh if an odd

0.000X % of distortion that might be creeping in here or there is going to be audible. For one thing, it does have VERY low output impedance; this is great as a headphone amp, but helps enormously not to act as a compressor

when driving power amplifiers. Best DACs have long ago (decades...) figured out really low output impedance is the only way to handle dynamic range of CD (96.X dB) - and it is even more important with higher resolutions that achieve 120 dB and above - all of which are supported by nano. Inserting an usual line preamp between these low output impedance DACs and power amps will ALWAYS degrade the sound, no matter how highly regarded might that line preamp be otherwise - by constricting dynamic range. Speaker systems likely to reveal this compression are of necessity large and $$$$ - better headphones/IEMs should not have such limitations and are affordable to much more people.  

 

My opinion ifi has done great in this case - it supports all the HiRez likely to be made gradually available during its lifetime, is really portable, drives anything you might use it with ( with the exception of the most difficult cans, such as AKG K 1000 and/or electrostatics ) with aplomb, works well at home, IF used correctly (on internal battery) avoids most of the powering issues of digital gear - and costs less than cable from A to B many users use - so, what is not to like ? Even equipment costing 100 times as much as nano still has to involve some compromise(s) ...

post #182 of 1713
Quote:
Originally Posted by StratocasterMan View Post
 

 

I'm not concerned about listening to headphones and speakers at the same time. That isn't the concern. From the response above, it does sound like iFi has put quite a bit of thought into the issue.

 

If I am understanding things correctly, it is necessary to set the volume control of the iDSD on maximum to get the proper output from the RCA outs. Apparently, this is 1.8V. That is a little less than what seems to be the accepted standard of 2.0V, although in reality, I don't think a standard really exists. That means that the user must have a more powerful speaker amplifier to obtain the same results than if the output was 2.0V, because the speaker amplifier is receiving a slightly weaker signal than what I would call normal.

 

It also means the user must constantly remember to unplug their headphones from the the iDSD when switching from headphones to speakers and vice versa. If one wishes to use their speakers, it will be necessary to turn the volume control on the iDSD to max to obtain 1.8V output through the RCA jacks, which is probably at best on the low side. Doing this without unplugging headphones (or while wearing headphones) means that the iDSD headphone amplifier will now be outputting the maximum headphone volume it can output.

 

Anyone who left their headphones plugged into the iDSD on their last listening session must not forget to unplug them before setting the iDSD volume to maximum in order to use their speakers.

 

Hi,

 

Drop us a PM regarding the dealer from whom you purchased the iDSD.

 

We do appreciate your using some very high-end IEMs with the iDSD - no guarantees but we may be able to arrange for an attenuator that suits your needs.

 

We can but try.

 

Thank you to others who chimed in - all this feedback is really appreciated.

post #183 of 1713
Quote:
Originally Posted by Dixter View Post
 

Interesting with all the back and forth banter here about the HO vs LO and how its controlled...    Just yesterday I looked up the Texas Instrument data sheet (BurrBrown) because I wanted to see how the device handle's DSD and the other formats and to look at the output power specs....     It takes a while to read but everything that is in the IDSD is covered in the spec sheet...  there isn't much more for the designers to add besides a good power supply and the interface to control this chip...and a housing...   

The DAC chip does it all....  including the output volume settings...     in other words... as nice as the iDSD is, its still just an implementation of an advanced off the shelf DAC...   

Now just enjoy what ifi has brought to us all..  :-)

Hi,

 

Nice work, close but some small misinterpretations:
 
Burr Brown + Analogue Vol = iFi's pain, customer's sonic gain
The Volume control in the DAC Chip only operates for PCM data up to 192KHz. Past that, at AMR/iFi we do not "like" digital volume controls, period. Despite the best marketing attempts to "talk up" Digital Volume Controls (which are "free" as in "free beer"! because its built into the chip  and so free to use to any designer), one cannot get past the fact that for each 6dB attenuation you lose 1-bit of resolution.
 
It does not matter if the volume control itself operates in 32-Bit or 64-Bit, in the playback software or in the DAC itself. In many cases even systems with optimal arrangement of gain run with 20dB or more attenuation for normal listening levels, a 16-Bit (CD-Standard) audio signal would be degraded to 12...13-Bit levels, which by comparison makes MP3 sound great. And High Resolution Files would suffer even greater degradation.
 
Therefore, in the iDSD, we make no use whatsoever of this digital volume control, as it would not work for 352.8/384KHz and DSD and because it would noticeably degrade the sound quality. In fact, our choice of the specific Burr-Brown Chip we use, is in a large degree because we wished to avoid DACs that convert DSD internally to PCM so that a digital filtering and volume control can be used (AKM, AD, Cirrus Logic, ESS, Wolfson Micro). Of course we also avoid the loss in resolution from digital volume controls to boot.
 
Instead the iDSD uses a balanced analogue stepped attenuator after the DAC and lowpass filter but before the output stage to control volume. Thus the full resolution from the DAC is preserved, no matter what the volume setting. Of course, the circuit's self-noise remains, which is another separate issue*, but is one of the reasons why we suggest to add an in-line attenuator for extremely sensitive headphones, instead of dialing down gain (which cannot reduce the circuit's self-noise)...this is a major issue that is oft overlooked.
 
It may also be worth mentioning that in addition to good power supplies** good clocks*** are needed. In order to handle DSD and DXD/384KHz on the Burr-Brown chip, a lot of custom design and software design is needed. The Burr-Brown chip has totally separate Digital signal paths (including clocks!) for DSD, DXD and PCM and needs much programming to work.
 
Equally the USB solution must decode DSD, DXD and PCM very differently, to feed the DAC the correct Data in each mode. This is one of the reasons why this excellent chip is often overlooked. It takes effort and higher costs.
 
ESS/XMOS is the easy "go to"
The stock XMOS solution (which is nowadays essentially the main "go-to" for USB Audio) only supports DACs that have the same Pins for PCM and DSD and automatically select between DSD and PCM. This generally means ESS Chips. These require no work whatsoever to get DSD and DXD to work with an XMOS USB Audio solution. 
 
It literally means take the stock XMOS schematic and copy/paste, then take the ESS reference design for the chip used and add the analogue stage of choice from the options ESS suggests and copy/paste again. The main "design" input becomes which particular Op-Amp-Chip to select (Burr Brown "SoundPlus", New Japan Radio "Muses" or whatever else is liked). The stock XMOS code incorporates a digital volume control that reacts to the PC's volume control and local pins connected to push-buttons, the only change needed is to change the Manufacturer name and to recompile the Firmware. Voila, you have just made a seemingly very advanced DAC.
 

This route was actually the first thing we tried (hey, it was fast 'n easy), but we did not find the sonic results too convincing and hence looked at other solutions for the iDSD, which resulted in greater complexity and cost and needed extra development time. As AMR were among the first companies to ship a customised XMOS USB Audio Solution in the AMR DP-777 (in May 2011) we have been quite intimate with the XMOS solutions, but even so the software development took over 6 months.

There you have it - a brief history of how and why we arrived at the tech specs behind the nano iDSD and why the iDSD is “quite different” from many of the current “cookie-cutter" XMOS/ESS designs.

 

 
 
*The iDSD’s self-noise levels are comparable possibly even better than the other very nice products in its product class, such as the Resonessence Labs Herus/Concero range or the Audioquest Dragonfly, Meridian Explorer, LH-labs Geek Out etc.
 
** We do a bit of cheating in the iDSD Nano by running DAC and Output stage directly from the LiPo Battery which is almost as quiet and has nearly as low output impedance as our iUSB Power in the micro range.
 
*** We again "cheat" here by avoiding so-called "Femto Clocks" (they are usually specified for Jitter/Phase noise from 12KHz - 1MHz, where any proper crystal oscillator also has "femto seconds" of phase noise). Instead we use proper crystal oscillators that offer much lower audio band (20Hz-20KHz) jitter/phase noise, which is what matters for audio (read: main audible band), compared to many "Femto Clocks".

Edited by iFi audio - 2/6/14 at 3:45am
post #184 of 1713

My order was shipped yesterday - less than 3 weeks after I ordered it from Music Direct - not bad,,,,,

post #185 of 1713

BTW - kudos to iFi for providing so much information about their kit! They must be quite confident in their design and specifically the custom programming etc, that their ideas will not be easily copied (stolen). For us hobbyists we drink up as much info as we can get to learn more about our passion.

post #186 of 1713

After a short exchange of emails with iFi technical support, my nano iDSD will be RMA'ed tomorrow.  I brought the device down to the shop where I had bought it.  30 secs of testing by the staff confirmed that there is an issue with my volume knob.

 

Someone asked me to compare it to my Fiio X3.  I will give a short comparison next week.

post #187 of 1713

I just got to know about the iFi Audio Nano iDSD from a friend, the other day.  What? A DAC with a Battery when paired with my iPhone5 will do PCM, DSD, and DXD.  Really?! For just 2 bills??!! Is it April Fools Day, Already???!!!

 

I phoned our local Audio Shop to check, and they did have the iDSD on DEMO. Out of curiosity, I dropped-by. 

 

Connection:

My iPhone5 with Onkyo HF Player  > Apple Camera Connection Kit > iFi Audio iDSD > a Custom Audio RCA to RSA Balanced cable> Ray Samuel Audio Intruder (balanced-in) > CUSTOM 20awg Pure Silver 7NUPOCC cable (balanced-out) > Audeze LCD-XC.  

 

Music Format: DSD.  Sample Rate 5.64MHz.  

 

Took just a few songs, before I caught myself smiling like a fool.  Took-out just 2 bills from my wallet, and left for home with a  Shiny New iFi Audio Nano iDSD. 

 

Reaching home, I unplugged the iPhone then connected the iDSD & RSA Intruder to my MAC with Media Center 19.  

 

Music Format: DSD/DXD  Sample Rate 384KHz/64bit   

 

For the next few days, my Conductor finally gets to take a short Break from Desktop duties.   My iFi Audio Nano iDSD and RSA Intruder will do double shifts: Portable-Daytime & Desktop-Evenings.    Thanks iFi!

post #188 of 1713

I have a question regarding it's abilities to bitstream from PC to receiver. So I'd like to plug this into my computer via USB and bitsream dolby digital or dts content to my receiver for it to do the processing. Will this device do that via the digital output? Sorry if noob question.

post #189 of 1713
Quote:
Originally Posted by techfish View Post

I have a question regarding it's abilities to bitstream from PC to receiver. So I'd like to plug this into my computer via USB and bitsream dolby digital or dts content to my receiver for it to do the processing. Will this device do that via the digital output? Sorry if noob question.
The coax out can push 24/192 to your DAC of choice...I don't think it will do multichannel, though. But the guys at ifi can give a better answer.
post #190 of 1713

So, even if I may not be able to play hi-res files, is it possible to use the iDSD without installing a driver. Have a very restrictive IT dept. at work and doubt they will go for letting me install a driver. Don't get me started on these guys...

post #191 of 1713
Quote:
Originally Posted by Roscoeiii View Post
 

So, even if I may not be able to play hi-res files, is it possible to use the iDSD without installing a driver. Have a very restrictive IT dept. at work and doubt they will go for letting me install a driver. Don't get me started on these guys...

Hi,

 

This is unrelated to the iDSD:

 

OS X and Linux are USB Audio Class 2.0 compliant with driver built-in = no driver required.

 

Win is needs driver to be USB Audio Class 2.0 compliant = need iFi driver.

 

Full info+driver here

 

http://ifi-audio.com/en/download.html

 

best regards

post #192 of 1713
Will I be able to use iDSD with USB 2.0 cable, i.e. can I connect iDSD to USB 2.0 port of my laptop?
Edited by koolas - 2/7/14 at 4:04pm
post #193 of 1713
Quote:
Originally Posted by Roscoeiii View Post
 

So, even if I may not be able to play hi-res files, is it possible to use the iDSD without installing a driver. Have a very restrictive IT dept. at work and doubt they will go for letting me install a driver. Don't get me started on these guys...

i'm guessing you're on a windows machine at work? if so, i'm not sure what to tell you.

 

if you're on a mac, you might need to install software that will play flac/DSD files if that's what you're going to listen to. if you're just going to use itunes, then plug and play with the idsd.

post #194 of 1713
Quote:
Originally Posted by koolas View Post

Will I be able to use iDSD with USB 2.0 cable, i.e. can I connect iDSD to USB 2.0 port of my laptop?

yes. that's what the idsd does.

post #195 of 1713

I think what he was getting at is that the USB on the iDSD is apparently 3.0. Yes they are all backward compatible with 2.0.

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