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A week with the iFi Micro iDSD

206.190.136.245
Posted on November 20, 2014 at 08:59:51
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 A good friend of mine who bought $499 iFi Micro iDSD for business trips lent it to me to give it a listen.

I used it mostly in fixed output mode in 2 channel system, and briefly on my desk at work with Audirvana and Vanatoo powered monitors in variable output mode.

First, the good news. It really does sound great. Very high resolution and spacious presentation. DSD sounds amazing on it, as good as much more expensive DACs I have had in the system.

The negatives are as follows:

-In variable mode, the channel tracking is poor at low volumes. I lost the right channel when I brought the volume almost all the way down.

-Again, in variable mode, when there are no sounds going through the DAC for a while and you wake it up by playing music or watching a video, there is a very loud pop through the speakers.

-Same pop happens when you switch from DSD to PCM and back..not every time but often.

Overall, just based on sound, it really is one of the best budget DACs I have heard.

 

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RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 10:22:03
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Hi,

> The negatives are as follows:
>
> -In variable mode, the channel tracking is poor at low volumes.

This suggests you have too much gain in your system. Reduce the gain after the iDSD micro until comfortable listening volumes are attained at around 11-12 O'Clock position for the volume control. Tracking for most traditional potentiometers goes to heck below around -40dB (8-9 O'Clock).

When set to "normal" mode the preamp out produces 5.5V at full scale and with the volume turned up nearly full. You need to match this level in the rest of the system as well to get the best Signal/Noise ratio.

The variable mode is mainly meant for active (studio) monitors in a desktop setup, which usually have input level controls but lack an easy volume control and like high (studio style) line levels.

> -Again, in variable mode, when there are no sounds going through
> the DAC for a while and you wake it up by playing music or watching
> a video, there is a very loud pop through the speakers.

Same as above. Dial the gain down and the pop becomes much softer.

It is because the iDSD micro is mainly aimed at battery/mobile operation and thus tries to save battery power and/or maximise available charging current when not in use. The pop during go-asleep/wakeup is normally quite soft.

You could have contacted iFi's tech support and gotten suitable advise.

> -Same pop happens when you switch from DSD to PCM and back..not
> every time but often.

It is not the same pop. Please use the ASIO (native DSD) interface to send audio and the pop goes away. It also goes away if you use J-River on Windows and you set some obscure settings correctly.

It is actually down to limitations in the DoP DSD format and in playback software.

We have been nevertheless working on resolving this issue in our USB Firmware, we recently issued a firmware update which improves the situation, though it does not eliminate this 100%. It is still being worked at and we do expect a new firmware that solves this in our hardware, rather the relying on the playback software "soon".

Our tech support people can advise you in detail, also regarding the updated firmware and how to apply it. They are really quite on the Ball, we have more tech support people than I have in the engineering team!

Finally thank you for having a listen and sharing your impressions.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 10:59:48
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 First, thanks for your reply and supplied information.

To clarify, when I used it on the desktop I was using it with a MAC/Audirvana combo. Drivers not an issue.

-"Wake Up Pop" occurs even when volume control all the way down. I am using it in hub power mode, so I am not even sure why there would be battery circuit engaged.

-I got one thing wrong..it was in FIXED mode that the DSD/PCM pop would occur, and this was with a SOtM mini server, again no drivers required. I did not notice it on desk top.

-To address your other notes, I do not believe it is a system issue for the following reason. I was sufficiently impressed with the Micro that I purchased a Nano, which I just got.

Channel tracking is perfect, even at low volumes. This applies to a competitors product with a variable volume control as well. I have not changed anything, same USB cable, same computer, same software, powered monitors are set to 50% of available gain.

Secondly, there is no wake up pop on the Nano.

Again, sonics were beyond reproach. If I was going to buy a Micro, which I may very well do, it would used in fixed mode for my needs.

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 11:17:51
Bob_C
Audiophile

Posts: 2667
Location: NY
Joined: July 31, 2000
 "I purchased a Nano, which I just got."

Looking forward to your impressions.

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 11:38:06
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Hi,

> To clarify, when I used it on the desktop I was using it with a
> MAC/Audirvana combo. Drivers not an issue.

MAC/Audirvana is limited to using the DoP protocol for DSD. The problems with pops and clicks when changing from DSD to PCM or reverse with DoP are well documented and not specific to iFi products.

In fact only products that use a DAC Chip that not only auto-selects between PCM and DSD material but internally converts DSD to (a form of) PCM are reliably free from this problem, as they in effect never actually change from PCM to DSD.

> -"Wake Up Pop" occurs even when volume control all the way down.

Of course.

I was referring to the gain AFTER the iDSD (Amplifier/Active Speaker), both in order to get the correct volume control range and a normal (quiet) level of pop during enter/exit power save.

You will find that if you turn the gain controls on your active speakers / amplifiers down enough to have a sensible volume control range the standby clicks are much reduced.

As said, both the problems with tacking at low volume and the loud clicks are a direct result of excessive gain AFTER the iDSD micro, Just turn things down and there is no substantive problem.

> I am using it in hub power mode, so I am not even sure why there
> would be battery circuit engaged.

Power save is applied in USB power mode after 15 minutes without signal. The reason is that standard USB ports (at 500mA maximum current) lack sufficient power to power the iDSD micro in normal and turbo mode. Especially Turbo mode will eventually deplete the battery even without signal on standard 500mA USB ports.

Hence the iDSD micro will switch off the DAC, analogue stages and headphone amplifier (which account for most of the power consumed) when no music is playing to allow the battery charger to charge the battery if needed.

Like the iDSD nano, the iDSD micro is in effect always on "Battery Power".

> -I got one thing wrong..it was in FIXED mode that the DSD/PCM pop
> would occur, and this was with a SOtM mini server, again no drivers
> required. I did not notice it on desk top.

The pop will happen if the playback software does not gracefully exit DSD playback but stops DSD playback via DoP hard. Fixed or variable has nothing to do with it.

It is a fundamental weakness of the DoP protocol combined with DSD.

If you had applied the Version 4.06 Firmware revision to the iDSD micro you may have found the problem much less noticeable. The 4.06 Version of the firmware has been out since September.

> -To address your other notes, I do not believe it is a system issue
> for the following reason.

It is a system issue.

> I was sufficiently impressed with the Micro that I purchased a Nano,
> which I just got. Channel tracking is perfect, even at low volumes.

The nano uses an electronic stepped attenuator controlled by the microprocessor. The potentiometer in the nano controls this electronic attenuator indirectly via an AD converter that reads out the position of the potentiometer. So tracking is as perfect as this stepped attenuator allows.

The micro uses the potentiometer directly to control the audio signal.

We feel that the iDSD nano attenuator/output chip offers high sonic quality, however it is not we feel as good as using the potentiometer directly for audio, as it is done in the micro.

> Secondly, there is no wake up pop on the Nano.

Because the nano has a much smaller battery and a much lower power consumption, so it happily lives on a 500mA USB Port and has plenty of power left for charging in this case. So there is no "sleep" mode and no wakeup.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 12:03:12
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 Thanks for all the additional information. Well laid out and informative.

I will ask my friend to check his firmware version.

I believe it only is upgradable via windows machines so I may have to do it for him on a laptop, since he only owns MACs.

One side question, what was the thinking behind using an OTG USB input?

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 12:04:21
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 It is very good. Not quite as spacious as the Micro, but a real steal at $189. Absolutely wipes the floor with the Dragonfly.

 

RE: "Absolutely wipes the floor with the Dragonfly", posted on November 20, 2014 at 12:50:25
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 On what types of program material? Good old 16/44.1 from a laptop USB port?




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: "Absolutely wipes the floor with the Dragonfly", posted on November 20, 2014 at 13:22:00
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 Mac Mini. Everything from mp3/aac to 192 Khx PCM. Even YouTube.

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 14:31:23
audioengr
Manufacturer

Posts: 6017
Location: Oregon
Joined: April 12, 2001
 DACs should mute when switching from DSD to PCM and back.

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 17:09:34
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 Yes, they should.

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 18:43:20
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 ..Firmware update completed..thanks.

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 22:30:23
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Steve,

> DACs should mute when switching from DSD to PCM and back.

The iDSD micro does mute when switching, the problem is DoP.

If ONE DoP marker is missing (read one sample) the system switches back to outputting PCM.

What this means to a DAC that processes DSD natively (without conversion into intermediate formats) is that the DAC becomes in effect stuck at one rail. When it has been switched to PCM this full scale DC offset is suddenly cleared.

The problem is that all happens within one sample. Even with interrupt and fast MCU it is often not possible to catch this stream change before it has put a full-scale pulse through the system, as the this pulse happens at the instant the stream changes.

This is just too short to engage analogue mute and digital mute will not help, as the DAC needs to be reconfigured between PCM and DSD. J-River on Windows (not sure about Mac) implements a suitable mechanism to make DoP stream changes do not cause big clicks as well.

When using DSD via ASIO this does not happen as there is a better management of how the stream change is indicated. one might say that when the Spec for DoP was written it never considered the situation where a DAC has to be reconfigured. At any extent, it being dealt with in firmware and will resolved as soon as we can.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: A week with the iFi Micro iDSD, posted on November 20, 2014 at 22:30:47
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Hi,

> what was the thinking behind using an OTG USB input?





Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

DoP is a bad kludge, posted on November 21, 2014 at 07:29:08
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 This is a design flaw with DoP. This is why I previously characterized DoP as a kluge. Perhaps a better assessment is that DoP is a bad kluge.

This is not your fault. Other DACs have the same problem. Good luck at coming up with a workaround that minimizes this problem, but I doubt that there is a real solution to it other than the best solution: don't use DoP.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: DoP is a bad kludge, posted on November 21, 2014 at 07:39:36
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Tony,

I agree, DoP is a cludge.

But if it can be made to work like on ESS DAC without resorting to broad spectrum re-sampling, async sample rate conversion etc., it is not a problem.

As we found playback software other than J-River not very open to help fix it on the playback side we put our software team on this.

Right now we have the problem 60-70% licked already. We know how to fix the rest, it just means re-writing/restructuring many lines of code which tend to have knock on effects and then testing the heck out of the code.

And yes, the fixes will be available to all DSD capable iFi devices.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: DoP is a bad kludge, posted on November 21, 2014 at 11:12:44
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 Good luck with the software updates, I hope you don't run into a "squeezing a balloon in a suitcase" situation where fixing one part of the problem pops out another part that was previously OK.

The problem you mentioned concerned robustness of the coding in the face of data errors. There really is no excuse for data errors on a USB connection, but there are still opportunities for problems, e.g. unwanted mode switches due to buffer underruns at the computer. These errors depend on the size of device driver buffers, etc... Some years ago when I was playing with DoP on my Mytek I was able to cause these problems by deliberately overloading the computer and causing buffering errors. The results seemed to depend on buffer sizes. I didn't investigate further, since I normally use ASIO and the driver allows native DSD over USB. Early versions of the Mytek driver and firmware had horrible pop problems on wanted and unwanted mode switches, but later revisions cured this. (The only pops that I get now come if I turn off the DAC without powering down my powered monitors.)



Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: DoP is a bad kludge, posted on November 21, 2014 at 11:57:35
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 Why can't you use native DSD?. DSD to PCM at 352.8k is not bad either.

 

RE: DoP is a bad kludge, posted on November 21, 2014 at 14:03:43
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 "Why can't you use native DSD?. DSD to PCM at 352.8k is not bad either."

I use native DSD. I tested DoP and found that it didn't work so well. I agree that downsampling DSD to PCM at 352.8 is not bad, but I wouldn't call it good.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: A week with the iFi Micro iDSD, posted on November 21, 2014 at 14:22:50
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 In a two channel system, in your opinion would you get a better result from using the supplied blue OTG cable or a standard, high quality USB cable and the supplied adapter?

 

Thanks, looks like exactly what I need..., posted on November 21, 2014 at 16:40:23
Ivan303
Audiophile

Posts: 48887
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
 in the office for listening to Lossless FLAC streaming QOBUZ from my laptop to my headphones.


First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

 

RE: A week with the iFi Micro iDSD, posted on November 21, 2014 at 21:44:41
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Hi,

> In a two channel system, in your opinion would you get a better
> result from using the supplied blue OTG cable or a standard,
> high quality USB cable and the supplied adapter?

This is a question along the lines of "how long is a piece of string?".

How do we define "high quality USB Cable"?

I have seen "audiophile USB Cables which are any funloving impedance other than 90 Ohm and unlikely anywhere near the seam along any section of the length.

Such a cable would likely be a much worse option than the supplied USB 3 Cable. Other audiophile USB Cables are quite well made and should work at least as well, or better.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

DSD to PCM at 352.8 is not bad, posted on November 22, 2014 at 02:33:34
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 Sounds fine in my system; may be it's your player. See this

http://www.audioasylum.com/forums/pcaudio/messages/14/140707.html

 

RE: DSD to PCM at 352.8 is not bad, posted on November 22, 2014 at 13:54:38
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 My DAC doesn't play 352.8. So I had to reconvert to DSD. It is possible that most of the degradation that I heard came on the reconversion to DSD rather than the downconversion to 352.8.

I do know that conversion from DSD to 352.8 and back to DSD is not transparent, as can be determined by playing the two files. Also, this is known by recording engineers such as the people at Channel Classics. As a result they try to do all the mixing in the analog console connected to the microphone preamplifiers so they can issue pure DSD recordings. Sometimes, however, it is necessary to remix and this involves the trip through 352.8.






Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: DSD to PCM at 352.8 is not bad, posted on November 23, 2014 at 00:42:15
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Tony,

I commented on this elsewhere (in a "popular science" level article attached to an interview in Audiostreams).

If we convert DSD to PCM and back, no matter what rate and bitdepth (and no matter where the conversion takes place) we incur losses. In effect we get the worst of both formats and best of non, same for the PCM->DSD->PCM case.

A in my experience A SINGLE conversion is acceptable if done at high enough level of quality.

Example 1 - Convert DSD to PCM at 176.4KHz and 24 Bit and play this back using a pure PCM DAC (read multibit) without additional digital filtering and result is very good, not identical but I have no DAC that can make this comparison truly fair, so I suspect it is more DAC differences than anything else.

In my system I have so far preferred this to any "DSD DAC" playing it as DSD, but as said this may be down to the DAC's than the format. I have BTW not preferred it to native 176.4/24 PCM recordings (that is multibit SAR type ADC sourced) made without digital filter though (there are a few).

But once you introduce digital filters (especially brickwall type) or other manipulation the sound reverts to generic PCM for either source.

Example 2 - Convert PCM (say 176.4/24) to DSD256 or DSD512 (I find DSD and DSD 128 insufficient) and play this using a DAC that leaves DSD in native, unmanipulated format and the results are very good.

Using DSD(64) especially introduces that distinct DSD sound, which to me is an acquired taste. At DSD256 (11.3MHz) I find it hard to tell if I am listening to the DSD256 converted version or the original PCM played back without digital filter, at DSD512 (22.6MHz) I am not betting a red penny either way.

But using double conversion in either case (so to PCM to DSD512 and back to PCM or DSD to PCM and then back) is always readily audible to me, regardless of other preferences.

Bottom line, ideally play DSD as DSD and PCM as PCM, with no domain conversion. If you must convert (e.g. because your DAC does not support DSD and it plays PCM which is > 80% of your music collection better than anything else for your taste or because your DAC is DSD only etc.) keep the conversion singly and as high quality as possible.

There are large differences in the possible algorithms DSD->PCM or PCM->DSD between for example Weiss Saracon, J-River MC and ASIO-Proxy (PCM->DSD only).

ASIO-Proxy is notionally for foobar but applicable to any ASIO capable player and DAC on Windows

Of course, anyone who took Information Theory 101 or has one of the least common of all senses will hardly be surprised by this.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: DSD to PCM at 352.8 is not bad, posted on November 23, 2014 at 07:47:57
Sprezza Tura
Audiophile

Posts: 4585
Location: New York City
Joined: August 24, 2012
 While in general I agree with you about PCM/DSD conversions and vice versa, it is a bit different at the production level.

Analog tapes captured to DSD or native DSD recordings produced as Redbook CDs can sound quite good.

Case in point: The pricey Japanese SHM CDs which are made from flat transfers from master tapes, converted to 176.4 for mastering, then finalized as a CD. They are using SOTA SRC and the end results are superb. Those SHM discs sound very analog.

One of Sony's original papers on DSD noted that it was an excellent capture tool from which other digital formats could be commercially produced and even hints at the fact that this what it may have originally been intended for.

 

RE: DSD to PCM at 352.8 is not bad, posted on November 26, 2014 at 03:44:17
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
 Hi,

I would not agree consider DSD "an excellent capture tool for other digital formats".

What Sony got right was to store the modulator output as master, not the converted version decimated to PCM, especially given the available filter technology in the 90's.

What they got wrong though was to use a 2-Level modulator at 2.8MHz.

Even with 1990's tech a capture at 8-Bit/11.3MHz would have been possible. A capture at 24-Bit/176.4kHz without digital filtering was commercially possible back then.

Either would have been a hugely better choice...

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: A week with the iFi Micro iDSD, posted on November 27, 2014 at 13:27:07
Bob_C
Audiophile

Posts: 2667
Location: NY
Joined: July 31, 2000
 Yes IFI hit a homerun with these DACs. I use the Nano in my not so portable headphone setup driving a Stax amp and vintage Stax phones.

I am looking forward to the 3rd installment of Mr. T's trilogy... the Mini which will a desktop DAC.

 

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