iFi Audio Pro iDSD discussion thread

[labjr]

  Hi all,

Major case of feature creep - so we are going to aim for prototype for CES and then launch in Mar.


 
When we have anything close to soup, we'll put it up here.


 
The next new product is the Retro and that is coming in November.


 
Okay, not fully soup, but here you go as we're in a good mood today!






 

iDSD mini
Formats:	44.1/48/88.2/96/176.4/192/352.8/384/705.6/768KHz PCM
	2.8/3.1/5.6/6.2/11.2/12.4/22.4/24.8MHz DSD
	DXD
Filter:
	DSD: Standard/Extended Range/Minimal analogue, selectable
	DXD: Bitperfect Processing, fixed analogue filter
DAC:
Clock:	Ultra low jitter Crystal Clock (rms jitter < 300 Femtoseconds)
Analogue Stages:
Volume Control:
Audio Path passives:	Tantalum Oxide Thin Film thin film surface mounted resistors,
	TDK high stability C0G surface mounted capacitors
	Elna Silmic II Electrolytic Capacitors
Input: (selectable)	USB 3.0
	compatible with iPhone,iPod, iPad and Android Devices USB-OTG#
	AES-EBU Balanced
	BNC SPDIF Unbalanced
	Bluetooth with aptX
Audio System Support:	PC - ASIO 2.2, WASAPI, Kernel Streaming (KS), Directsound
	Mac - Core Audio
Output
	Audio RCA (2V/5V @ 0dBFS)
	6.3mm Headphone 4V/10V maximum output
	Headphone Output Power 4,000mW/16R max.
Dynamic Range:	TBD
THD &N (Line)	TBD
THD &N (HP 100mW)	TBD
Output Power (16R):	> 4000mW
PowerSource:	External DC 14V (compatible with 12V Battery systems)
Power Consumption:	< 15W
Size:

[td=colspan:2] Fully-Balanced DAC (USB/SPDIF/AES-EBU/Bluetooth) [/td] [td=colspan:2]PCM: Standard/Minimum Phase digital, Bitperfect 1, Bitperfect 2; selectable[/td] [td=colspan:4]Quad Core Dual Mono Bit Perfect DSD, PCM & DXD DAC by Burr Brown in current output mode (4-DAC Chip; 8-Channel; 16-Signals)[/td] [td=colspan:4]Balanced fully discrete Class A - Non-Feedback I/V conversion by single BISS Supertransistor[/td] [td=colspan:4]Balanced fully discrete Class A - Non-Feedback Line output buffer using J-Fets and BISS Supertransistors[/td] [td=colspan:4]High Speed current mode Class A Headphone Buffer with balanced fully discrete Class A - Non-Feedback input buffer using J-Fets and BISS Supertransistors[/td] [td=colspan:4]Balanced 4-Way precision analogue by ALPS, Remote Control, can be bypassed for Line Outs[/td] [td=colspan:2]Panasonic PolyPhenylene Sulfide stacked film surface mounted capacitors[/td] [td=colspan:2]SPDIF RCA/Optical (only PCM up to 192KHz)[/td] [td=colspan:2]XLR True Balanced Audio (Output adjustable 4/10V @ 0dBFS [+14dBu/+22dBu])[/td] [td=colspan:2]220mm x 62mm X 210mm (W X H X D including feet, knobs and connectors)[/td]

Cheers.

Hello ifi,
 
Is there any reason not to do a bipolar supply and get rid of the electrolytic capacitors in the signal path?

 

[iFi audio]

Hello ifi,

Is there any reason not to do a bipolar supply and get rid of the electrolytic capacitors in the signal path?

Hi,

 
Apologies for the slightly delay as we had to ask Thorsten & co but also, there we are not able to divulge all at this moment in time.

 
But here you go:

 

SmartPower – does what it says on the tin

Short Answer
It has bipolar power supplies, just like the iDSD micro. There are no electrolytic cap's in the signal path.


Long Answer
It also does away with any chip or discrete Op-Amp's. The analogue stages are fully discrete, using a circuit that is "NOPA" (Not an OP-Amp) but pure single ended Class-A, of course doubled up for balanced operation.

 
The actual iDSD mini will have a TWO bipolar power supplies;
- a lower voltage one for the headphone and line drivers, to limit how much power is burned up and
- a higher voltage one for the analogue stages to maximise dynamic range.

 
Nice to have dedicated power supplies optimised for each section!

 
We use modern very high speed "Stealth" DC-DC converters, as in the micro. These provide a much cleaner power than any linear power supply (audiophile LPSs included), as any noise they produce is in the MHz range, where correct PCB Layout and simple LC filtering can eliminate such noise well. These "Stealth" converters are characterised by low noise and output impedance in the audio band (20Hz-20kHz) same as the best low noise regulators and they switch at frequencies exceeding 1MHz.

 
This is a very different approach from classic switchers that normally operate somewhere from 30k to 100kHz (read: close to the audible range), have regulation bandwidth of usually only a few 100Hz and have significant impact on audio circuitry together with problems of getting enough filtering. Common switching DC-DC converters are usually designed to have 10-100mV noise on the output at the switching frequency and tend to have many high harmonics, creating the RFI/EMI problems commonly associated with them.

 
In a power supply for an audio device we ideally do not have the LC filter acting in the audio band as the changes of impedance will cause audible effects. So if we use a 20KHz LC filter, it will only attenuate 40KHz by 12dB and 100kHz by around 30dB. This is insufficient to keep smps noise away from audio circuitry, 10mV at 100kHz will still leave 0.3mV 100kHz noise, 100mV of 40kHz noise will leave 25mV!

 
On the other hand our Stealth DC-DC converters are usually designed to have <= 10mV noise on the output at the switching frequency with few high harmonics. For a 1.28MHz frequency DC-DC converter and the same LC filter as before with a cutoff above 20Khz, noise is attenuated 72dB, so 10mV noise (as much as we ever allow) will become 2.5 microvolt, or 0.0025mV or 0.0000025V. Yes this is 118dB below a 2V signal! So the power supply plus first filter has noise levels at frequencies below 1MHz that is low enough for > 19-Bit resolution (the powersupply, not the complete DAC itself)!
And we never use only a single layer of filtering, instead we use additional highly advanced zero feedback discrete regulators with a bandwidth of several MHz, which remove another 40dB -60dB (100 to 1,000 times) of the noise. So in our actual designs any noise left from the DC-DC conversion is below the measurement limits of any but the most extreme test gear.

 
This kind of performance is very difficult to attain with ANY form of LPS or SMPS and of course, it requires rigorous and extreme design in all areas, at the very cutting edge of technology.

 
It is also worth mentioning that as we implemented bipolar PSU on the iDSD micro, this was one of the key problems we faced, how to make this work well enough for prime time... this was documented over on the Crowd-Designed thread.
Using such advanced technology allows us to take one incoming DC Voltage (which may even be from a battery but can also be from a fairly noisy SMPS) and to generate as many bipolar and single polarity rails as our design requires, with noise levels that approach our iUSB Power or indeed many a battery.

 

[labjr]

Very interesting! Thank you for the thorough explanation!

 

[Abra]

Ifi, thank you for the information. But ...
I have got a micro iDSD + iUSB + GEMINI for a five day trial period. And I have to say, I was not very impressed by the iDSD as a stand-alone DAC in my home stereo system. It was not especially bad, but replacing it's preamp with my system's pre, and adding the iUSB to it, I liked it much more. Annoying noises removed from the highs, clean but not lean sounding, good balance beetween detailed and meaty sound, excellent rithm, floating with the music etc., I liked the micro iDSD + iUSB set much more, than the iDSD dac alone. 
There was only one serious objection on the micro iDSD + IUSB voice. While it lively follows every vibration of the music, a bit to swiftly. Slightly lacks the calm of power, stability . But at this price, this can be easily forgiven. 
Because the micro is not specially designed to a home stereo system (I had problems with the "phd" power supply handling), I decided to wait for the mini.
I think to target something similar PS for the mini as the micro has is not a good idea. Instead of approaching the iUSB, exceed it please. The mini is a higher positioned device than the micro set, isn't it? A better PS, with the stability of the big boy DACs?

 

[tf1216]

Hi Abra, what DAC do you currently use?

 

[Abra]

Currently I'm rather in the analogue domain. I have Kuzma Stabi turntable with Van Den Hul Colibri pickup, Clearadio disc washing machine. I also have a Marantz 10B tuner.
The only digital souerce I have is an old Philips CD-304 cd player. Modified with Bendix 6900 and RCA Nuvistor tubes, Black Gates, tantal resistors, Van den Hul internal wireing and in many other way I don't remember.
Now it's the time to change to computer audio. Tired of turning discs, cleaning pickup, washing vinyl. It's hard, but not impossible to find an appropriate DAC matching my taste. 
After testing more than a dozen of different DACs, I found two of them would be appropriate. The iDSD is the second. Musiically at least. In functionality and price it's a clear winner. I hope the mini will outperform both of them.

 

[john57]

Tired of turning discs, cleaning pickup, washing vinyl
 
Also tired of hearing the vinyl slowly deteriorate each time I play it. Scratches, click and pops no more.  Have one turntable but have not used it for quite some time.
We will see how the mini iDSD will turn out.

 

[iFi audio]

  Currently I'm rather in the analogue domain. I have Kuzma Stabi turntable with Van Den Hul Colibri pickup, Clearadio disc washing machine. I also have a Marantz 10B tuner.
The only digital souerce I have is an old Philips CD-304 cd player. Modified with Bendix 6900 and RCA Nuvistor tubes, Black Gates, tantal resistors, Van den Hul internal wireing and in many other way I don't remember.
Now it's the time to change to computer audio. Tired of turning discs, cleaning pickup, washing vinyl. It's hard, but not impossible to find an appropriate DAC matching my taste.
After testing more than a dozen of different DACs, I found two of them would be appropriate. The iDSD is the second. Musiically at least. In functionality and price it's a clear winner. I hope the mini will outperform both of them.

Hi,
 
Understood.
 
We like vinyl a lot too and have the iPhono+iTube.
 
For sure, the micro iDSD setup will not usurp the Kuzma setup which is pretty high-flying. We use Garrard 301, Linn LP12 among others.
 
Maybe the Mini iDSD or the AMR DP-777 SE - best try them in your system and see how they fit.
 
Thanks.

 

[Abra]

You can do it surely, if you want. I wish you to develop an even better product than the micro iDSD. Thanks.

 

[iFi audio]

  You can do it surely, if you want. I wish you to develop an even better product than the micro iDSD. Thanks.

Hi,
 
Google AMR DP-777...

 
There is a Head-Fi thread on here somewhere...

 

[diamondears]

Mike,

Hi,

Google AMR DP-777...

There is a Head-Fi thread on here somewhere...

Mike, do you have existing desktops with HP outs?

When are the minis coming out?

Cheers.

 

[diamondears]

DP-777 + micro iCAN = mini iDSD?

 

[iFi audio]

DP-777 + micro iCAN = mini iDSD?

Hi,
 
No desktop components as yet.
 
This is where the mini line will come in.
 
The mini iDSD is the first of this.
 
It will be really neat.

 

[BillsonChang007]

Hi,

No desktop components as yet.

This is where the mini line will come in.

The mini iDSD is the first of this.

It will be really neat.

Something I learn: when iFi says that it is going to be really neat, it is really going to be something impressive

 

[bjas406]

Will the mini idsd include the built in iPurifier just as the micro does?