Jump to content

Rate this topic

Recommended Posts

Folks, it's that time of a year, you know... eggs and all that jazz. Hence please allow us to leave our critter here:

 

5abd69ce95d97_iFiEasterEgg.thumb.png.f3831a69e2603521cc2eb3c33c0aa372.png

 

... aaaaand that's it! Right? RIGHT?!?

 

Well, nope.

 

We have something very special to share with you tomorrow. Very, very special.

 

Stay tuned!

 

Share this post


Link to post
Share on other sites
Extra Ordinary MQA Easter Egg

[IMG]

Introduction

With Easter just around the corner, iFi audio has delivered an eagerly anticipated upgrade option as a very special Easter gift.

iFi first introduced MQA into its product mix with the nano iDSD Black Label in November 2017. Since then, iFi customers across the globe have been asking when this option would be available in other iFi products. The good news is that the latest improvements to the nano Black Label firmware version 5.30, ‘Cookies & Cream’, does just that.

Mqa for all

This latest firmware flavour not only adds the latest scoop to the nano iDSD Black Label sundae but it also dishes out MQA (Master Quality Authenticated) audio to the full range* of iFi audio products going back to 2013!

[IMG]

This ‘legacy’ update means that you can now download the MQA upgrade (PC and Mac) straight from the Support section of iFi’s website at no extra cost.

Mqa optimised

Firmware version 5.30 will optimise your device for MQA and can handle up to DSD256 and PCM384. Enjoy the MQA magic like never before.



And Finally…

None of the above would have been possible without the MQA software engineers who worked tirelessly alongside the iFi software team to make this unique opportunity happen. Thank you.

Go to https://ifi-audio.com/audio_blog/mqa-firmware/ to enjoy your upgrade.

This firmware provides MQA rendering as this is the ideal solution for portable products and those with power considerations. This means the workload is shared between the host (the computer) and the client (the DAC). The listener will still enjoy full MQA experience.

For more information on MQA, go to http://www.mqa.co.uk/customer/how-it-works

Legacy

*The only exception is the original iDAC.
 

Share this post


Link to post
Share on other sites

Very pleased to see this update, but I have a question:  how can you tell if MQA decoding is working?

 

I have updated my iFi Micro iDSD to 5.30, but when sending MQA content from Tidal, Roon, Audirvana, etc., the LED always stays Green (i.e, indicating up to 96k), so it seems there's no visible distinction between a MQA file coming across at 48k (i.e., no decoding) or an MQA file coming across at 48k and later being decoded to 96k, 192k, etc.

 

Pretty sure I've set the players properly (Roon = direct, no DSP, Audirvana = MQA decoder selected, Tidal = software upsampling disabled).


John Walker - IT Executive

Headphone - MacMini running Roon Server > Netgear Orbi wireless > Blue Jeans Cable Ethernet > mRendu Roon endpoint > iFi Audio xDSD > Focal Elegia

Home Theater - Mac Mini running Roon Server > Blue Jeans Cable HDMI > Pioneer Elite SC-81 > MartinLogan Motion series home theater speakers + M&K subwoofer

Share this post


Link to post
Share on other sites

Roon wouldn't work currently as this is a render implementation and they still have no first unfold. I only mention this because I'm not familiar with Audirvana or Tidal app jargon so I can't tell whether you are using the first unfold with these. 

Share this post


Link to post
Share on other sites
6 minutes ago, arglebargle said:

Roon wouldn't work currently as this is a render implementation and they still have no first unfold. I only mention this because I'm not familiar with Audirvana or Tidal app jargon so I can't tell whether you are using the first unfold with these. 

 

Ah, OK.  I didn't see anywhere they documented it's a renderer vs. decoder implementation, so I was ASSUMING decoder :/

 

Now I know what to do - thanks!


John Walker - IT Executive

Headphone - MacMini running Roon Server > Netgear Orbi wireless > Blue Jeans Cable Ethernet > mRendu Roon endpoint > iFi Audio xDSD > Focal Elegia

Home Theater - Mac Mini running Roon Server > Blue Jeans Cable HDMI > Pioneer Elite SC-81 > MartinLogan Motion series home theater speakers + M&K subwoofer

Share this post


Link to post
Share on other sites

Easter ‘Bug Bounty’ Hunt

Hunt 'em, wherever they are...

 

bounty1.thumb.jpg.38271577092d083f8f1a7d6ae00a63f6.jpg

 

Introduction

Our just announced firmware v5.30 is MQA capable and in one fell swoop, elevates legacy iFi products* with MQA capability for even more sonic enjoyment.

 

The MQA integration was a little difficult. It involved:

  • Totally replacing the customised core code
  • Re-apply tuning/core loading and
  • Further fine tuning the firmware for even more precise allocated resource use in order to allow us to support MQA and384kHz.

 

To bring all this to fruition required the combined efforts of the MQA and iFi software developers or a total of +1,000 programming hours to deliver firmware v5.30 (excluding testing on all iFi legacy units).

 

Notwithstanding, there may still be one or two software bugs we have not quashed – hence we would like to involveyou, the customer  in the Easter Bug Hunt.

 

More details are to be found in this thread:

Share this post


Link to post
Share on other sites

The NeXt Generation of Portable Audio

iFi Audio xDSD - The Official Launch

1.thumb.png.df928e06c4660f8822c4cbb0c523108b.png

Introduction

When iFi audio launched its original micro iDSD headphone amp, preamp, and DAC back in 2014, it raised the bar for small, portable, high-performing DACs. It’s been lifting it higher ever since. Last November saw the introduction of the nano iDSD Black Label, with a host of new features including support for MQA (Master Quality Authenticated) audio. Now, iFi has excelled itself again with the launch of xDSD – the first in the company’s next generation of portable DACs.

 

A sonic step up

With a pure analogue volume control retaining full-resolution at all volume levels, the xDSD is a major sonic step up for all smartphones, digital audio players and computers. Its selectable 3D+ and XBass+ functions bring both sensitivity and power to the careful listener. The artist appears in the room with music and lyrics flowing all around.

 

The xDSD has pulled off the task of being ultra-portable and wireless while supporting high-resolution formats, including MQA, and delivering 500mW of power per channel. By means of aptX HD and AAC, it brings hi-res streaming to Bluetooth.

 

Feature laden

In terms of attributes, the xDSD is similar to the micro iDSD, though it’s more advanced:

  • Burr-Brown Hi-Res True Native DSD DAC chipset for discerning listeners
  • Dual-mono headphone amplifier with 500mW of power per channel, which can unleash the full potential of both 32ohm and 600ohm headphones
  • High-resolution audio up to PCM768kHz and DSD512
  • MQA ready for playing back all high-res MQA encoded files
  • Wireless Bluetooth (aptX and AAC) for CD-quality wireless sound
  • S-Balanced compatible 3.5mm headphone output brings the benefits of the balanced connection to single-ended headphones
  • Advanced Analogue Signal Process (ASP), 3D+® and XBass+® headphone optimisation circuits
  • Pure analogue volume control retaining full-resolution at all volume levels
  • Audiophile Digital Filter 'Measure/Listen' selectable
  • Large 2200mAh Lithium-Polymer battery providing six-to-eight hours of playing time

Small is beautiful

All these features have been packed into a rugged magnesium-aluminium body measuring just 95x66.5x19mm and weighing 127g.  Though it has some similarities with the micro iDSD, it’s control layout is very different because of its Bluetooth wireless capability.

 

Take a look at the front panel controls (left to right) below:

2.thumb.png.3f8f6d7e2a3e348d28c75578434e5e31.png

  1. 3.5mm HP Jack (TRRS balanced compatible, no microphone support, switchable to line out).
  2. Right of the jack, two separate RGB LEDs indicate sample rate and input selection.
  3. Volume (Rotary with ‘push’ button) with translucent centre and volume indication backlight.
  4. Right of the 3D+/XBass+ button are two separate white LEDs to indicate 3D+ and XBass+.
  5. The 3D+/XBass+ button push button cycles between all off, 3D+, XBass+ and both.

3.thumb.png.3246f5f8098af26296a4fdbcf7f3e1eb.png

Rear panel controls (left to right)

  1. 3.5mm SPDIF (Coax/Optical combo, 192kHz supported).
  2. USB A-type OTG Input mounted centrally.
  3. Filter switch that slides between ‘measure’ and ‘listen’.
  4. Micro USB connection for charging (power input only, full charger detection for fast charge).
  5. Below the micro USB port, an RGB LED indicates battery status.

 

Time flies by when the listener is immersed in the music played by the xDSD. Guitars sound real and a Steinway piano sounds ‘woody’ instead of ‘glassy’ like an electronic keyboard. Musicality overflows.

 

The retail price of the xDSD is US$399 (ex-tax) or €449/£399 (incl VAT).

Share this post


Link to post
Share on other sites
5 hours ago, Samuel T Cogley said:

Hello @AMR/iFi audio

 

Can you tell us about DoP support for this unit?  Since it's capable of 768kHz, DoP256 should be supported, yes?

 

Thanks in advance

 

It is, yes. xDSD handles DSD up to 512 if firmware 5.2 (non-MQA) is loaded. 

Share this post


Link to post
Share on other sites
15 hours ago, AMR/iFi audio said:

 

It is, yes. xDSD handles DSD up to 512 if firmware 5.2 (non-MQA) is loaded. 

 

Thanks for the response, but this is confusing.  To the best of my knowledge, no iFI products are capable of DoP512 as this requires a PCM rate of 1411200 Hz.  Also, the "A" version of the firmware (like 5.2A) is what enabled DoP256.

 

I've noticed that the 5.2A firmware is no longer available for download (5.1A is available).  What happened to the "A" version of "Limoncello"?

Share this post


Link to post
Share on other sites
On 18.04.2018 at 6:08 PM, Samuel T Cogley said:

@AMR/iFi audio, I found 5.2A firmware on the xDSD download page.  It's missing from the iDAC2 download page.

 

We are working on 5.2 firmware at the moment, it should be online soon.

Share this post


Link to post
Share on other sites

xDSD – Premium. Pocket-portable. Perfection.

1.thumb.png.c7e30b747a9ee80553eefd2ca98d127c.png 

 

We are buzzed about the xDSD and our customers will be too. The xDSD is a ultra portable solution for everyday music lovers and high-end connoisseurs alike, and the wild child of the flagship Pro iDSD and high-end micro iDSD Black Label.

 

The xDSD shines both inside and out – from its AAC/aptX Bluetooth connectivity to its luxurious magnesium-alloy construction. From Spotify to MQA/DSD512, everyone will enjoy rediscovering their favorite playlists.

 

NeXt Gen Premium Portable Audio

So, what is the xDSD? It is an ultra-portable product designed to be used with headphones/IEMs/CIEMs and mobile digital sources such as smartphones and DAPs as well as stationary devices like computers, TVs and game consoles.

 

The xDSD can be operated either in wireless or wired mode via aptX/AAC Bluetooth (wireless) or USB and S/PDIF inputs (wired). It supports high-resolution formats (MQA and DSD) and includes the iFi S-Balanced 3.5mm TRRS headphone circuit, which delivers 500mW of power per chachannel. In short, the xDSD is a major game-changer for portable high-fidelity.

 

Part 1 – The Guided Tour

 

Hi-Res Wireless On-The-Go

 

4.thumb.png.eca0ccf677566931b187eb3a21c98c50.png

 

High-quality wireless is a major tool in its armoury. With Bluetooth, the xDSD can be wirelessly paired with smartphones or DAPs, so there’s no longer any need to stack several units together.

 

Picture this: Your xDSD stays in your pocket driving your headphones whilst the phone is in your hand, texting or browsing the web.

 

This ease of use transforms the user experience both on-the-go and at home.

 

New Aesthetics

When you first set your eyes on the xDSD, it is instantly obvious that it does not resemble any other portable audio product on the market.

 

The xDSD exudes luxury and style. The enclosure is tactile, compact and made of rugged, ridged magnesium-aluminium alloy. The moulded plastic means unrestricted BT transmission.

 

All the switches and connections previously seen on iFi products have been optimised to match the new chassis, yet they still provide easy access to all the xDSD’s standout features. This product is a stunning object in its own right with its visuals and user interface merely part of a far grander design.

 

2.thumb.png.dc572236b86a6e0cb63e903edd2a6c76.png 

 

At the front of the machine, from left to right:

 

-          the 3.5mm input.

-          LEDs for kHz and input

-          Centre rotary for on/off, volume control (mute) and input selection

-          LEDs for 3D+ and XBass+ (user-selectable)

-          Settings button 

 

3.thumb.png.cc85a31c729b562034c826cf8d5c4322.png

 

At the rear:

 

-          S/PDIF input (for DAPs)

-          USB type ‘A’ male (perfect for CCK/OTG)

-          Listen/Measure filter switch

-          Micro USB charging port (with status LED)

 

Stay tuned, there's more!

 

 

Share this post


Link to post
Share on other sites

xDSD – Premium. Pocket-portable. Perfection.

 

Part 2 – Loaded with Technology

 

We are our own sternest critics when we develop new products. Partly because of customer input and sometimes just because we can, for the sheer heck of it, we like to see how far we can push the technology envelope.

 

The xDSD epitomises this. This section provides an in-depth explanation of its technology and features – and why we’ve done what we’ve done so that it is both easy to use AND sonically stunning, as is the AMR/iFi way.

 

Multibit Digital Engine with Amr Global Master Timing

 

1.thumb.png.732c6f41b7756e11579869fa4cddbbc9.png

 

The xDSD is very much akin to the micro iDSD Black Label for a perfectly valid reason. Both products are based on the Burr-Brown DSD1793 D/A converter chip and share extremely similar digital and analogue stages.

 

The digital section of the xDSD is drawn from the micro iDSD Black Label with DSD512/PCM 768 compatibility with DSD via DoP, native DSD playback, USB type A and S/PDIF inputs, XMOS-based USB circuitry and clocks derived from the micro iDSD Black Label with zero-jitter operation courtesy of the AMR Global Master Timing (GMT) clock, re-clocking and data management.

2.thumb.png.b0b17ee7e95db809f4c24ccd29f3045c.png

 

The Bluetooth section inside xDSD is derived from our Retro Stereo50 and is also subject to the AMR GMT clock system that operates with femto precision. In the xDSD, the clock domain not only covers USB, S/PDIF and Bluetooth, but also synchronises the MCU (Master Control Unit) – effectively, the entire digital functionality of xDSD is slaved to the GMT clock system. It is global by name and by nature.

 

Remap – Optimise for Mqa or Non-Mqa Formats

We do not do things by halves. We write our own software code so the xDSD will launch with two specialised XMOS firmware versions.

 

  • v5.30 – pre-installed and optimised for MQA
  • v5.20 – is optimised for music file formats up to DSD512/PCM768 (non-MQA)

 

Each firmware version squeezes that last ounce of performance from the xDSD to suit each customer.

 

3.thumb.jpg.4d1788992e454d71bdc242c3eb74ea55.jpg

 

Just as car enthusiasts load different ‘remaps’ into the ECU (Electronic Control Unit) for their preferred driving experience, we let our customers load their preferred ‘file format remap’ for their own music torque curve.

 

S-Balanced Optimised for Balanced IEMs

 

Our exclusive S-Balanced technology extracts the maximum performance from single-ended and balanced headphones alike:

 

  1. With TRRS, the benefit is full dual-mono with grounds separated all the way to amplifiers. Just like audiophile hi-fi systems.
  2. With TRS, you lose the full separation of the grounds, however, by having two contacts on the ground crosstalk is reduced by 50% over a standard single contact socket.

4.thumb.jpg.16e3695d09aeeb362fee0f2df73a54d4.jpg

 

With S-Balanced, a dedicated negative wire per channel all the way to the star-ground of each channel’s amplifier to ensure there is no crosstalk between the channels.

 

Plugging in unbalanced headphones with a TRS connector instead of TRRS will cause zero issues and, in fact, there is only upside as crosstalk is cut by 50%, compared to using a TRS socket.

5.thumb.png.ed6c83f2355cd72401c65beaf96bd8f4.png

All the benefits of balanced, with none of the drawbacks.

 

And for those who wish to connect the xDSD to a home system, the xDSD can be set to line out mode. Its 3.5mm headphone jack is converted into a fixed 2V level 3.5mm line output. Needless to say, the xDSD remembers its settings as you left them so you can turn it on and pick up from where you left off.

 

Stay tuned, there's more!

Share this post


Link to post
Share on other sites

Has anyone gotten firmware to update on this form a USB-C Mac?  I couldn't get two different Macs and two different iFi Nano's to update and they all use the same firmware now.

IFi technical support was zero help and basically stopped even answering e-mails.

Share this post


Link to post
Share on other sites

Hi @AMR/iFi audio

 

I read something interesting about the bluetooth transmission with the xDSD.

 

So only the data streams from the bluetooth source to the xDSD?

 

So Hi-Res is supported with no compression?

 

Is the bluetooth input limited to PCM192kHz and DSD64 (DoP) sample rates?

 

I haven't seen this implementation of bluetooth for lossless audio streaming before, not between mobile devices for real time streaming.

 

And regarding clocking - does it work like SPDIF so the blueooth source is the master clock? Or works like iso/asynch USB ?

 

Can you share more info on this

 

Cheers!

 

 

Share this post


Link to post
Share on other sites
On 1.05.2018 at 1:33 AM, Em2016 said:

Hi @AMR/iFi audio

 

I read something interesting about the bluetooth transmission with the xDSD.

 

So only the data streams from the bluetooth source to the xDSD?

 

So Hi-Res is supported with no compression?

 

Is the bluetooth input limited to PCM192kHz and DSD64 (DoP) sample rates?

 

I haven't seen this implementation of bluetooth for lossless audio streaming before, not between mobile devices for real time streaming.

 

And regarding clocking - does it work like SPDIF so the blueooth source is the master clock? Or works like iso/asynch USB ?

 

Can you share more info on this

 

Cheers!

 

 

 

It's interesting that you ask about Bluetooth. Here goes then...

Share this post


Link to post
Share on other sites

Let's talk Bluetooth!

Some comments on X-Series Bluetooth. First, Bluetooth implementations vary widely. Just looking at BT revision level or codec support is not useful to understand sound quality potential of a given Bluetooth device.

Yes, Sub Band Codec (SBC) is seriously hobbled and should not be used for music. A very extensive comparison of Bluetooth codecs (sadly excluding AAC) is found here:

 

With aptX/aptX HD and AAC, optional codecs are available that perform better than SBC, however codec support is a fairly small issue.

By default, most certified Bluetooth modules only offer analogue outputs, directly from the System On a Chip aka. SOC (CSR/Qualcomm in the upper end devices, others in the rest). To get a digital output for SOCs with that option available, a firmware needs to be changed (which is not trivial) and - because is changed in the process - any agency certification needs to be applied yet again, which costs a nice stack of cash.

So most Bluetooth products rely on a DAC in a chip, to:

  • save money for an extra DAC
  • save money for firmware changes
  • save money for recertification process

The problem is that a DAC/headphone amplifier inside Bluetooth chipsets is usually worse than DAC/headphone amps used in most headphones. For example, let's compare top rated CSR chipset's specs to audio test results of last iPhone with a headphone jack or Apple's lightning to 3.5mm adapter.

With only 96dB dynamic range, aptX HD is wasted in such devices as these only support 16 bit audio on a DAC level and both objective and subjective audio performance from the SOC DAC/headphone amplifier is poor.

 

1.thumb.png.1759b75a37fa1538c5ed4435cffdd510.png


To move on, in order to have higher quality Bluetooth audio, we need to bite the bullet and pay developers to enable digital outputs and THEN pay for the recertification of the module according to CE/EMC (European Union) FCC (USA), Giteki (JP) and KCC (Korea) etc. Now we can add an external DAC chip of higher grade.

But hold it, we have another problem. Clocks. The typical Bluetooth SOC chip creates all clocks (those for audio as well) from a single 26MHz crystal via multiple PLLs of 'adequate' quality. The datasheet for the current 'Top of the Line' CSR chip (the only one that supports aptX HD) lists audio clock jitter as a maximum of 21,000pS in 'high quality' mode (more in power saving)!

In order to deliver 16 bit audio without degradation, jitter must be below 243pS!

So the jitter in the audio clocks actually precludes even 16 bit performance by being almost 100 times as large as the 16 bit limit as long as an external DAC (not the one in a Bluetooth chipset) includes means to clean up this jitter. The real performance will be degraded to only around 10 bit worth of actual audio performance.

If a 'high end' version of a given system produces 100x the jitter permissible for 16 bit audio, effectively limits audio to 10 bit and barely manages 16 bit equivalent SNR with volume control maxed out (even where external higher grade DAC's are used, then Bluetooth associated with poor audio quality is a reputation well deserved.

Noise and jitter levels in standard Bluetooth SOCs are comparable to the worst and darkest day of early digital audio, time when the understanding of what caused 'digital/artificial sound' was poor. The best external DAC will not solve this without extra effort spent on clocks.

Let's get real now: the extra bits from aptX HD over aptX are not going help here, even aptX and AAC are probably mostly a wasted effort.

In the xDSD we have the ultimate jitter fighting weapon on-board, in addition to our high quality DAC and a headphone amp, a super precise clock and memory buffer already applied to wired connections.

 2.thumb.png.f36e4cdc45e230e087368a8d04f08d8a.png

All in all, squeezing the last drop of quality out of Bluetooth is not hard. After dealing with the wireless side, we simply take digital data from a system associated with it in the same way we treat USB and S/PDIF. And finally we get to a point where we can tell the different codecs apart (and aptX wins).

3.thumb.png.4bd37f7ae5f394b32c83254df674adad.png 

In the xCAN it was more challenging to get a subsystem to get excellent sound from Bluetooth. We naturally can't fit a full xDSD level circuitry and that's why we cherry-picked ESS Sabre instead of Burr-Brown.

We feel that using the ESS Time Domain Jitter Eliminator to kill the jitter from the Bluetooth SOC is decisive in getting excellent sound quality. The reference clock for the ESS DAC is produced from a discrete oscillator with its own low noise power regulator.

4.thumb.png.f1a9bc856dea832ab7e3d844357e532c.png 

Swap in Burr-Brown (as excellent as it is in our xDSD), run it on Bluetooth clocks and the sound quality suffers severely.

The result of these efforts is a level of sound quality from Bluetooth for both xDSD and xCAN that is not comparable to the majority of Bluetooth products.

And yes, adding aptX HD and even LDAC more than aptX HD (as the extra bits of aptX HD are not very useful whereas the 96kHz maximum supported sample rate of LDAC is) would make sense for xDSD and xCAN. However, it requires a substantial R&D time and was not possible for this year's release cycle.

And lastly, slides used in this post were extracted from the Tokyo Headphone Festival presentation by iFi audio, already published by headpie.net at:

Share this post


Link to post
Share on other sites
6 minutes ago, AMR/iFi audio said:

Let's talk Bluetooth!

Some comments on X-Series Bluetooth. First, Bluetooth implementations vary widely. Just looking at BT revision level or codec support is not useful to understand sound quality potential of a given Bluetooth device.

Yes, Sub Band Codec (SBC) is seriously hobbled and should not be used for music. A very extensive comparison of Bluetooth codecs (sadly excluding AAC) is found here:

 

With aptX/aptX HD and AAC, optional codecs are available that perform better than SBC, however codec support is a fairly small issue.

By default, most certified Bluetooth modules only offer analogue outputs, directly from the System On a Chip aka. SOC (CSR/Qualcomm in the upper end devices, others in the rest). To get a digital output for SOCs with that option available, a firmware needs to be changed (which is not trivial) and - because is changed in the process - any agency certification needs to be applied yet again, which costs a nice stack of cash.

So most Bluetooth products rely on a DAC in a chip, to:

  • save money for an extra DAC
  • save money for firmware changes
  • save money for recertification process

The problem is that a DAC/headphone amplifier inside Bluetooth chipsets is usually worse than DAC/headphone amps used in most headphones. For example, let's compare top rated CSR chipset's specs to audio test results of last iPhone with a headphone jack or Apple's lightning to 3.5mm adapter.

With only 96dB dynamic range, aptX HD is wasted in such devices as these only support 16 bit audio on a DAC level and both objective and subjective audio performance from the SOC DAC/headphone amplifier is poor.

 

1.thumb.png.1759b75a37fa1538c5ed4435cffdd510.png


To move on, in order to have higher quality Bluetooth audio, we need to bite the bullet and pay developers to enable digital outputs and THEN pay for the recertification of the module according to CE/EMC (European Union) FCC (USA), Giteki (JP) and KCC (Korea) etc. Now we can add an external DAC chip of higher grade.

But hold it, we have another problem. Clocks. The typical Bluetooth SOC chip creates all clocks (those for audio as well) from a single 26MHz crystal via multiple PLLs of 'adequate' quality. The datasheet for the current 'Top of the Line' CSR chip (the only one that supports aptX HD) lists audio clock jitter as a maximum of 21,000pS in 'high quality' mode (more in power saving)!

In order to deliver 16 bit audio without degradation, jitter must be below 243pS!

So the jitter in the audio clocks actually precludes even 16 bit performance by being almost 100 times as large as the 16 bit limit as long as an external DAC (not the one in a Bluetooth chipset) includes means to clean up this jitter. The real performance will be degraded to only around 10 bit worth of actual audio performance.

If a 'high end' version of a given system produces 100x the jitter permissible for 16 bit audio, effectively limits audio to 10 bit and barely manages 16 bit equivalent SNR with volume control maxed out (even where external higher grade DAC's are used, then Bluetooth associated with poor audio quality is a reputation well deserved.

Noise and jitter levels in standard Bluetooth SOCs are comparable to the worst and darkest day of early digital audio, time when the understanding of what caused 'digital/artificial sound' was poor. The best external DAC will not solve this without extra effort spent on clocks.

Let's get real now: the extra bits from aptX HD over aptX are not going help here, even aptX and AAC are probably mostly a wasted effort.

In the xDSD we have the ultimate jitter fighting weapon on-board, in addition to our high quality DAC and a headphone amp, a super precise clock and memory buffer already applied to wired connections.

 2.thumb.png.f36e4cdc45e230e087368a8d04f08d8a.png

All in all, squeezing the last drop of quality out of Bluetooth is not hard. After dealing with the wireless side, we simply take digital data from a system associated with it in the same way we treat USB and S/PDIF. And finally we get to a point where we can tell the different codecs apart (and aptX wins).

3.thumb.png.4bd37f7ae5f394b32c83254df674adad.png 

In the xCAN it was more challenging to get a subsystem to get excellent sound from Bluetooth. We naturally can't fit a full xDSD level circuitry and that's why we cherry-picked ESS Sabre instead of Burr-Brown.

We feel that using the ESS Time Domain Jitter Eliminator to kill the jitter from the Bluetooth SOC is decisive in getting excellent sound quality. The reference clock for the ESS DAC is produced from a discrete oscillator with its own low noise power regulator.

4.thumb.png.f1a9bc856dea832ab7e3d844357e532c.png 

Swap in Burr-Brown (as excellent as it is in our xDSD), run it on Bluetooth clocks and the sound quality suffers severely.

The result of these efforts is a level of sound quality from Bluetooth for both xDSD and xCAN that is not comparable to the majority of Bluetooth products.

And yes, adding aptX HD and even LDAC more than aptX HD (as the extra bits of aptX HD are not very useful whereas the 96kHz maximum supported sample rate of LDAC is) would make sense for xDSD and xCAN. However, it requires a substantial R&D time and was not possible for this year's release cycle.

And lastly, slides used in this post were extracted from the Tokyo Headphone Festival presentation by iFi audio, already published by headpie.net at:

 

Wowza, I certainly got the full monty, in answers to my questions - and then some. I like it !

 

Great work and thank you !

 

 

Share this post


Link to post
Share on other sites
On 1.05.2018 at 1:33 AM, Em2016 said:

So Hi-Res is supported with no compression?

 

Currently Blutooth only supports 48kHz maximum sample rate. With aptX HD the wordlength is 24bit, with standard aptX  it is 16Bit. 

Sony's LDAC system uses 990k stream bandwidth and supports 24bit/96kHz, however it is still a bit from being widely supported in smartphones and even LDAC compresses.

 

On 1.05.2018 at 1:33 AM, Em2016 said:

Is the bluetooth input limited to PCM192kHz and DSD64 (DoP) sample rates?

 

Bluetooth on the xDSD is limited to 48kHz/16Bit. High res can still be played, via a software player with high grade sample rate conversion the result is quite good. For example, playing a 44.1kHz Flac version of a 352.8kHz recording and the full version leaves audible differences.

 

On 1.05.2018 at 1:33 AM, Em2016 said:

And regarding clocking - does it work like SPDIF so the blueooth source is the master clock? Or works like iso/asynch USB ?

 

It works like our S/PDIF implementation, namely audio data is sent into a memory buffer, clocked out and re-clocked by a separate adjustable clock (aka. GMT Clock system) which is synchronized to the long term average of the source clock, be it S/PDIF or BT.

 

In effect the results for S/PDIF and BT are the same as for USB, even though technically speaking S/PDIF and BT are clock masters. Jitter from either source does not transfer to the DAC.

 

You can find more on this in the Bluetooth discussion as well in the thread for the iPurifier S/PDIF, including measured results, as the tech inside the xDSD is exactly that of the iPurifier S/PDIF, but obviously with I2S out and I2S in for the BT system.

Share this post


Link to post
Share on other sites

Hot damn! According to Kakaku.com, our xDSD sits on the very top in Japan in two rankings, portable amps and amplifiers in general:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...