[roamling]

So what Vincent said so far is that there will be a headphone amp (no standalone dac) and the unit wont have a AC power in but will be powered either by USB or an internal battery (which can be charged over USB I guess). The option to charge the battery while the amp is running might not be an option this way but that's something I wanted see implemented as well (hence this is why I asked if the unit would have an AC in)
 
I also want to see implemented that the iDSD micro will have a very powerful internal battery which will either be providing a high current to power a huge range of headphones or also be having a battery run time of 20 hours plus.
 
Based on the previous feedback it seems that unit should have the gain switch (which I think is essential if a headphone amp is part of the design) and the the 3D function (and Bass Boost?) implemented . 
 
Here is my concern, I would rather have the DAC side of the design prioritized (Filters, Up-Sampling of PCM files, Phase Invert Switch) but I also see potential for the headphone amp features being implemented at the same time. My suggestion would be to put more options at the bottom of the unit. The front of the unit should have 2 switches, 3D and Digital filter for example (things that need to be changed quit often or options that are fun to play around with while listening to music). All the other functions could be neatly placed on the bottom of the unit (like the DIP switches in the iPhono), including Gain, Phase Invert and even functions like running the unit from USB power or the battery. 

 

[KeesJan]

It is a very good thing to listen to customers before launching new products! We daily hear what customers want, what they like or dislike.
 
What would be nice on the upcoming Micro iDSD:
 
1. an optical and coaxial input (both would be nice, but because of the small size maybe impossible)
2. a USB input (which there will be)
3. analogue and headphone outputs on the back of the box
 
I'm very curious what the result is of this crowd-design!  

 
All the best,
 
Kees Jan Lankhaar

 

[ClieOS]

(1) Given it is the 'micro' series, which is more of a transportable and not of a portable line of products, I don't see the need for battery. I do like to see a robust USB power filter to keep out the noise from PC, or better yet a full USB isolator built into the Micro iDSD. But given the tall requirement on high speed USB isolation, I'll settle with just a good power filter to keep things quiet. Those who needs a portable DAC already has the Nano iDSD. No point of building two products that compete with each others.
 
(2) Talking about two products that compete with each others - I wonder if Micro iDSD is supposed to replace iDAC (as more of an all-in-one solution). If it is, then putting a similar headphone amp section inside makes sense to me. But if it isn't, I rather see a standalone DAC that can go hand in hand with iCAN. Trying to stuff a whole iCAN inside the Micro iDSD is probably not going to work well, so I rather see a more full featured iDSD than a half baked iDSD + iCAN hybrid. On one hand the idea of an all-in-one device does look more advertising; but on the other hand, it doesn't add much value to those who already own an iCAN or iTube.
 
(3) Gain adjustable line-out is a good idea, perhaps a selectable 2Vrms / 1Vrms output, since some amp (especially the portable one that built for iDevice) do clip with 2Vrms.
 
(4) Digital input will be nice, though I am not sure if DSD / DXD signal can be carried over S/PDIF. Not sure digital output is needed. I rather have the space used for relocating the RCA jack to the back instead of on the front like iDAC.
 
(5) The filter from Nano iDSD is of course a must.

 

[iFi audio]

Hi All.
 
Yes, this is the "micro" chassis.
 
In terms of size:
 
nano = cigarette packet
micro = cigar box
mini = shoe box
 
So as you can see, this micro iDSD is designed to be desktop/portable.
 
It will have the battery-power option as the user feedback has been that this is an integral part of the nano iDSD's commercial success.
 
thank you

 

[iFi audio]

  Are you intending to use an AC in and USB for charging the battery/powering the device or just the USB in for running the device?

Hi,
 
Based upon the unanimous feedback to the nano iDSD, it seems: USB powered OR battery-powered is the way to go. The micro chassis is twice the length of the nano chassis.
 
So the A/C input on this portable/desktop device is not needed.
 
thanks

 

[iFi audio]

Just to let you guys know, our senior software designer (not Thorsten BTW who has enough on his plate), after seeing the posts here, is sweating profusely.
 
Because whatever is agreed upon at the end, it means a lot of custom in-house software design is needed ... he has packed his sleeping bag and camp bed.
 
Am sure we'll all let him sleep as much as he likes once the unit is out in early June.
 
Keep your suggestions coming...

 

[tf1216]

I currently use the iLink so I have some familiarity with iFi-audio.  As far as the performance I couldn't be happier.  You guys have helped me troubleshoot a problem which was not the fault of the iLink.  Customer service goes a long way for me.  Keep doing what you do.
 
However, there are a few things that I do not like about the iLink that could be considered when designing the micro iDSD.  What I would not like to see on the micro iDSD is the toggle switch.  I find it too hard to switch its position because of the amount of force required.  I know we can't have it all in this world but maybe there could be an alternative that can serve the purpose for switching between features.  Also, the iLink is very light so certain USB cables cause the unit to lift off the table.  What would be neat is a weight that could be added to the top of the unit that would keep the micro iDSD flat to the table.  Maybe an upside down U-shaped piece that would rest on the device.
 
One other thing I was wondering is if a sleeve could be made for the iFi products.  I currently stack my DAC/Amp on top of the iLink and I wish I had a fitted sleeve to protect the housing from getting scratched.  Maybe the micro iDSD could be made to rest (snap) onto the other iFi devices as well. 
 
If a display is incorporated, the ultimate way to integrate it, in my opinion, is to mount it inside the chassis behind the panel similar to the Analog DAC from MSB Audio.  I think what they do is machine many tiny holes which allows the display to be seen and have it appear that the panel is lighting up.  That would look slick on an iFi product.

 

[iFi audio]

Tech Talk with Thorsten - part 1

Holy Cow! What a thread, what a lot of input already! Thank you all.

I have been testing our first prototype this week using Audio Precision 2 test-set, as well as other gear. Below is a photo of my area of the test laboratory.
 

 
Sorry for roached table, it has been there since around 2005 and seen a lot of gear come and go. And has scars from one or twenty soldering irons.
 
Everything works well (the software team did a good job, almost no bugs in the first code release!) and the results are what we had hoped and more for in a DAC worthy to complement the Stereophile Class B rated iDAC.

Too bad that as a result of the input in this thread the final product is going to be so different, that this will be merely a first step. I was going to confirm the specification today to our marketing people, instead I will include them here as a historical benchmark, so you can see what we ourselves intended to do and what results we got so far.

iDSD micro core specification:
Input:                                   
USB 3.0 type B Socket
compatible with iPhone,iPod, iPad and Android Devices,
camera kit or USB-OTG cable required
 
Outputs:
Audio RCA, fixed 2V
Audio 3.5mm Headphone variable, 3.3V maximum output
SPDIF RCA (up to192kHz PCM)
 
Powersupply:
2,800mAH Lithium Polymer battery and USB (selectable),
dual channel super-regulator for DAC
 
Indicator:
Single Multicolour LED to indicate Signal and Sample Rates
 
DAC:
Dual-Core DSD, PCM & DXD DAC by Burr Brown
bitperfect DSD processing, bitperfect PCM processing
(2-DAC Chip; 4-Channel; 8-Signals, custom interleaving for maximum SNR)
 
Audio Formats:
44.1/48/88.2/96/176.4/192/384KHz PCM                                                                          
2.8/3.1/5.6/6.2MHz DSD
DXD      
 
Filters
PCM: Bit-Perfect Processing and Minimum Phase/Standard digital filter selectable
DSD: Extreme/Extended/Standard Range analogue filters selectable
DXD: Bit-Perfect Processing, fixed analogue filter
 
HP Volume Control:
precision analogue volume control, < 2dB Tracking error
 
HP Amp Power:
> 150mW/15 Ohm
THD + N (line):
<0.005% @ 0dBFS
 
THD + N (HP):
<0.005% @ 0dBFS
 
SNR (Line):
117dB(A) @ 0dBFS
 
SNR (HP):
111dB(A) @ 2V out
 
Clock:                                   
Ultra low jitter Crystal Clock (rms jitter < 300 Femtoseconds)
 
Audio Path passives:
Tantalum Oxide Thin Film thin film surface mounted resistors,
TDK high stability C0G surface mounted capacitors
Panasonic PolyPhenylene Sulfide stacked film surface mounted capacitors
 
But that is now already ancient history, time to look forward.

Of course we will keep all the good stuff we were going to include as standard, yet after reading this thread so far, I think we can do even better.
 
I have been surprised both by the variety of input and by how much thought and effort some of you have put into this.
 
Thank you all very much. Posters alamakazam and roamling seem to be trying to put our industrial design team out of a job, truly awesome work.
 
To reiterate, the micro chassis is sized like a cigar box, just like this prototype model.
 

 
We are still working through the suggestions received so far, it will take time. A fair few items we can probably add-in quickly, borrowing technology from the shelves of our parent company AMR.
 
For others we have to conduct a feasibility study, which is happening as I write this.
 
Ciao,
 
Thorsten Loesch

 

[roamling]

Thank you for the kind words. It was a really awesome experience to brainstorm over a design and give input into this project. Sometimes I really think of changing my current way to boring day to day job... 

 

[wisnon]

I am biased towards the use of a Low Pass Filter for DSD, so you can have a bifurcated circuit where PCM goes one way via a chip (eg BB-1795) and DSD goes straight to the LPF. If possible, you can do a simplified version of Ted Smith's design and use an upsampling algorithm to move all DSD input to DSD128 and then LPF out. Now, I know there is no space to use transformer output, but you can use digital and analog LPF and output with discrete components, not opamps!
 
DSD via RCA or BNC spdif is desirable, not just by USB. Analog VC is also desirable. PCM filter needs to be very good...no pre and post ringing. it will have to beat Pono Player which uses good AYRE PCM filtering. Option to use a quality LPSU like Hynes to power the unit.
 
Femto clocking a must.

 

[exsomnis]

I love the sound signature of the nano iDSD so keeping with the same BB DAC chip is something I agree with.
 
I would like to see improved support for iDevices - without the need for a Apple CCK.  
 
This is the feature that I considered when choosing the nano iDSD - however, I was a bit disappointed with the need for a clunky CCK.  As a result, the nano iDSD isn't as comfortably portable as it could have been.  
 
In the same vein, I would also love to see implementation of the USB micro B port instead of USB B, as is the case with most portable DACs on the market.  
 
The last thing to improve - QC on volume control.  

 

[iFi audio]

  I love the sound signature of the nano iDSD so keeping with the same BB DAC chip is something I agree with.
 
I would like to see improved support for iDevices - without the need for a Apple CCK.  
 
This is the feature that I considered when choosing the nano iDSD - however, I was a bit disappointed with the need for a clunky CCK.  As a result, the nano iDSD isn't as comfortably portable as it could have been.  
 
In the same vein, I would also love to see implementation of the USB micro B port instead of USB B, as is the case with most portable DACs on the market.  
 
The last thing to improve - QC on volume control.  

 
Hi Exsomnis for the kind comments and for your nano iDSD review - we already had some people flag this to us already! The first of many!
 
The CCK is unavoidable - there is Apple hardware circuitry in there to extract the digital signal. Same for OTG for Android devices. No way around this one!
 
thank you

 

[exsomnis]

   
Hi Exsomnis for the kind comments and for your nano iDSD review - we already had some people flag this to us already! The first of many!
 
The CCK is unavoidable - there is Apple hardware circuitry in there to extract the digital signal. Same for OTG for Android devices. No way around this one!
 
thank you

 
No, thank you - it really is a gem of a product and having heard a full iCan-iTube-iDAC-iUSB setup (which was glorious, by the way), I can testify that there's high quality across the iFi line.  It's fantastic to know that you're listening to the users too - I'm looking forward to see how the micro iDSD turns out. 

 

[roamling]

   
To reiterate, the micro chassis is sized like a cigar box, just like this prototype model.
 

 
We are still working through the suggestions received so far, it will take time. A fair few items we can probably add-in quickly, borrowing technology from the shelves of our parent company AMR.
 
For others we have to conduct a feasibility study, which is happening as I write this.
 
Ciao,
 
Thorsten Loesch

 
 
Just to clarify, is the prototype set up in a way that the RCA out will be in the front like on the iDAC or is that still open to decide?
As you know I personally would prefer the RCA out at the back and the only out in the front would be the headphone out.

 

[Dixter]

I know this wont make it into the new micro idsd but I'd like to mention it just for future thought...     
I now own and use the nano idsd and I like it very much...  
the biggest issue for me and I'm sure lots of other people is the simple fact that you plug in the idsd or any other DAC for that matter and immediately you are tied down to your source/DAC by your headphone cable/source....
 
Not a problem if you just want to sit for hours listening to music and get nothing more done... 
 
So I decided I wanted to have the freedom to move about, get some things done around the house but at the same time be able to listen to some music on my choice of phones....
 
My solution was to couple the nano idsd with the Fiio W1 (2.4GHz Lossless transmitter)  and now I just cue up several albums in DSD using iriver media center 19 and couple my headphones to the W1 receiver and I get the same uncompressed music from the nano idsd that I like so much but now I'm able to move about while listening to the music...  
 
And whats really cool is that I can also get more than one of the W1 receivers and let other people listen to lossless music wireless at the same time... with their choice of phones...   
 
so wouldn't it be cool if you had a idsd that had native 2.4G lossless wireless transmit capabilities built in from the get go...  then you also would create the wireless receiver/amp so you could plug in your phones and be free of being strapped to your computer...