iFi's Pro iDSD (official) - NEW Firmware - MQA and more.

[AMR/iFi audio]

Folks...

 

IFA 2018 
...it's almost here!

 

 

When?

• The 31st Aug - 5 Sept 2018!

The place?

• Berlin!

Where exactly?

• Hall 1.2, stand 206, WOD Audio (iFi's German distributor)

 

You'll have a chance to preview our EISA award winner - xDSD! Our two lovely girls - Victoria and Sarah - will be there supported by Thorsten Loesch himself.

 

If you'll attend, please visit us!

[AMR/iFi audio]

22 hours ago, austinpop said:

 

Proving again, that sometimes "Loesch" is more. 

 

 

In this specific case it is indeed 

[AMR/iFi audio]

On 8/20/2018 at 2:32 AM, Em2016 said:

1. I imagine there's a fair bit of RF generated by the DSD re-mastering FPGA.. I know the analogue filtering will probably help with RF filtering but are there any other steps? Is the FPGA 'dog-housed' for EMI/RFI shielding ?

 

In reality the FPGA is fairly quiet in term of radiated EMI and power supply noise.

 

On 8/20/2018 at 2:32 AM, Em2016 said:

Is the FPGA 'dog-housed' for EMI/RFI shielding ?

 

No, instead the FPGA and all other relatively "noisy" sections are on separate boards which feature a 4-layer design made to avoid any radiated EMI towards the main audio board. 

 

In addition, the whole digital section is galvanically isolated from the DAC/clock/audio board.

 

For external EMC regulation compliance the unit uses a metal case.

 

On 8/20/2018 at 2:32 AM, Em2016 said:

 How is intersample overs addressed, with the PCM digital filters and DSD re-mastering?

 

Bitperfect operation (no digital filter) and our GTO filter, due to being very "short", are free from this problem. As DSD signals are scaled to 0dBFS (PCM) = -6dB (DSD), the DSD Remastering system also doesn't have this issue regardless of a filter selected. 

 

Further, all "addressing inter-sample over's" does is dynamic range cutting in case of well-recorded music and digital data manipulation which precludes bitperfect playback.

 

Nicely recorded music does not feature heavy clipping which is a pre-requiste for "inter-sample overs" to occur outside testing with test signals to provoke them.

 

And if we are listing to a recording with heavy, sustained clipping, does some minor extra clipping on top of a flat line clipping matter?

 

Of course not, clipping on top of clipping is still a flat line, so the "intersamples overs" are "hidden" by the very problem that causes them in the first place and therefore they do not need to be addressed in the real world.

 

On 8/20/2018 at 2:32 AM, Em2016 said:

I know this can be address by the end user by applying headroom management in the software playback

 

We strongly recommend to not do that. Recordings which would provoke "intersample overs" will still be heavily clipped and sound poor anyway and those free from this problem will be degraded.

 

On 8/20/2018 at 2:32 AM, Em2016 said:

3. What is the power output of Pro iDSD driving flat 14 ohms headphones? 

 

This depends on headphones wired balanced or unbalanced. 

 

In balanced mode maximum output of 10V is available, while rated at 16 ohms it will also be available for 14 ohms loads with a minor increase in power over 16 ohms.

 

Generally speaking, power is a poor indicator of headphones' compatibility. Rating these in dB/mW (as is common) is extremely confusing. A better measure is to rate in dB/1V (similar to speaker sensitivity ratings that are nowadays dB/2.83V regardless of actual speaker impedance).

 

Alternatively the innerfidelity.com system of XXV @ 90dB is also useful and can be easily converted to dB/1V.

 

Our headphone calculator can help to normalise different ratings for sensitivity and to see if a combination can play sufficiently loud to meet the THX playback level recommendations, if it will be much louder (earbuddy or iEMatch should be added) or not loud enough. 

[AMR/iFi audio]

9 hours ago, MoWa said:

P.S. Hope, that the MQA update comes as advised. On the new website this functionality is not advertised anymore, or at least I haven’t found it. 

 

Please rest assured that very soon things will happen. MQA is going nicely and will be with you folks soon.

[AMR/iFi audio]

4 hours ago, jimdukey said:

Dsd upsampling with HQ is great!

From pcm and dsd files.

 

Ain't it ? ?

[AMR/iFi audio]

21 minutes ago, Em2016 said:

Hi @AMR/iFi audio

 

For long term health of Pro iDSD components, do you recommend leaving the unit on 24/7?

 

Or turning it to 'standby' when not in use?

 

And does this recommendation apply to solid state AND tube state? Or only solid state?

 

Some designers like Rob Watts of Chord recommend leaving their gear on 24/7 - fewer power cycles, less stress cycles on certain components.

 

Thanks!

 

 

 

It's possible to leave the unit on, but we don't recommend it because we want to save the polar bears.

 

Pro iDSD doesn't have a standby more, it's either on or off. 

 

We will leave other companies to speak for themselves about leaving gear on  ?

[AMR/iFi audio]

On 8/25/2018 at 5:17 PM, Em2016 said:

 

Noted, thanks!

 

Is it the XMOS USB interface that does PCM filtering/up-sampling?

Or does the FPGA handle both the PCM up-sampling AND DSD re-mastering?

 

And what is underneath the big heat sink in the pic below?

 

Crysopeia FPGA is the reason why you can upsample every incoming data up to DSD1024 but we'll leave to ourselves which chip does what exactly. 

 

There are J-FETs and MOSFETs under that radiator.

[AMR/iFi audio]

Folks, we have something interesting to share...

 

iFi audio - The GTO filter 
Part 1/4 - The TL;DR

 

What iFi GTO^TM is?

Based on AMR’s ‘Organic’ mode, the further refined iFi GTO^TM Digital Filter resolves a number of audible problems associated with both classic digital filters AND non-oversampling systems, sounds on par (or better in optimal systems) to the latter and its transient optimised performance is similar.

 

How iFi GTO^TM does it?

Our GTO^TM filter tuned to fit inside the ‘ringing envelope’ of our own hearing makes ultrasonic ringing objectively measurable yet not perceived. It essentially ‘masks’ this time-domain distortion to make it inaudible.

 

Why do I want iFi GTO^TM?

Because it provides natural sound free from audible time domain distortion!

[AMR/iFi audio]

28 minutes ago, applesnowleo said:

I am having some strange issues with SOTM and ROON and also iFi iDSD Pro.

 

And this issue happens more frequently than I hopped, a video of the issue could be seen on the link below.

 

When changing the format on a playlist from PCM to DSD and DSD to PCM this happens sometimes, the only way of stopping it is change to another sample rate, or turn off the DAC and again ON.

 

Is something that has been present for sometime, and not only ROON related, anyone has had this issue?

 

https://youtu.be/iNyhjnLg2iA

 

It's highly likely that your settings are the culprit. You can shoot us a message here: http://www.amr-audio.co.uk/index.html

 

Our tech team will do their best to sort you out, though there's a third-party software involved, which Pro iDSD doesn't support.

[AMR/iFi audio]

On 8/25/2018 at 4:24 PM, Em2016 said:

Hi @AMR/iFi audio

 

For long term health of Pro iDSD components, do you recommend leaving the unit on 24/7?

 

Or turning it to 'standby' when not in use?

 

And does this recommendation apply to solid state AND tube state? Or only solid state?

 

Some designers like Rob Watts of Chord recommend leaving their gear on 24/7 - fewer power cycles, less stress cycles on certain components.

 

Thanks!

 

 

 

It's possible to leave the unit on, but we don't recommend it because we want to save the polar bears.

 

Pro iDSD doesn't have a standby more, it's either on or off. 

 

We will leave other companies to speak for themselves about leaving gear on  ?

[AMR/iFi audio]

This happened several days ago, enjoy!

 

 

[AMR/iFi audio]

15 hours ago, Stings said:

Oh, i figured out how to upsample. You press the Filter knob to switch between passthrough, DSD512 and DSD1024.

 

Yup, filter knob needs to be pressed and DSD remaster mode (1 press = DSD512, 2 presses = DSD1024) is engaged.

[AMR/iFi audio]

15 hours ago, Stings said:

How do you access, play and share your music library on USB3 hard drive? Is there a web GUI that we log into to manage and share our music library? I want to be able to access my library from multiple computer devices and locations on my network. How do we do it? I plugged a 512gb USB flash drive into the pro idsd but how do i play from it and how do i connect to it from other computers or stereo systems?

 

Thanks

 

Stings

 

Please use MUZO app to do this. 

 

Our Pro iDSD review is at www.6moons.com and it's a good one! 

 

http://6moons.com/audioreviews2/ifi/1.html

 

Enjoy!

[AMR/iFi audio]

Folks, our latest XMOS firmware 5.3C is alive! It adds one VERY SPECIAL thing: The GTO filter. What is it, you might ask. Well...

 

iFi audio - The GTO filter 
Part 1/4 - The TL;DR

 

What iFi GTOTM is?

 

Based on AMR’s ‘Organic’ mode, the further refined iFi GTOTM Digital Filter resolves a number of audible problems associated with both classic digital filters AND non-oversampling systems, sounds on par (or better in optimal systems) to the latter and its transient optimised performance is similar.

 

How iFi GTOTM does it?

 

Our GTOTM filter tuned to fit inside the ‘ringing envelope’ of our own hearing makes ultrasonic ringing objectively measurable yet not perceived. It essentially ‘masks’ this time-domain distortion to make it inaudible.

 

Why do I want iFi GTOTM?

 

Because it provides natural sound free from audible time domain distortion!

 

Stay tuned folks! We have a lot of filter related goodies to come!

[AMR/iFi audio]

iFi audio - The GTO filter 

Part 2/4 - Introducing the iFi GTO™ Digital Filter

 

ALL DIGITAL FILTERS FOR AUDIO ARE WRONG.

ALL OF THEM, INCLUDING THE 'NO FILTER' OPTION.

THIS IS WHY WE NEED YET ANOTHER FILTER!

 

All digital filters (including no filter) differ in how they are wrong and how this influences objective measured performance as well as subjective listening performance with music and indeed, specific types of music. All digital filters add specific distortion signatures in either time vs. amplitude domain or frequency vs. amplitude domain. These distortions become all the more relevant the lower the sample rate. So, the most abundant digital music source -CD quality - is most impacted with greater possible audible consequences than High-Res content.

 

Wherever there is a difference, there is also a preference. Subjective listening preference may be informed by a range of factors including a learned or acquired response to recorded sound (e.g. what sounds ‘right’ or ‘hifi’ is not what sounds natural in comparison to a live performance), including direct referencing acoustic music performances.

 

However, with sufficient data from extensive listening tests and some inductive thinking, one should be able to propose and implement a digital filter that offers substantial improvements in removing ultrasonic noise over the ‘no filter’ (non-oversampling) case while avoiding as much as possible erring too far in the other direction with excessive and audible ringing.

 

So here it is - the ever so musical iFi GTO^™ Digital Filter in the Pro iDSD which is the first ever seen in any DAC. In due course, technological hurdles permitting, we will try to implement it as a firmware upgrade for just about all[1] iFi audio digital products.

 

What is the iFi GTO^™ Digital Filter?

The Gibbs Transient Optimised filter (GTO) is named after the ‘Gibbs phenomenon (2)’ in mathematics. 

 

Wikipedia referred to the Gibbs phenomenon as “the peculiar manner in which the Fourier series of a piecewise continuously differentiable periodic function behaves at a jump discontinuity. The nth partial sum of the Fourier series has large oscillations near the jump, which might increase the maximum of the partial sum above that of the function itself. The overshoot does not die out as n increases, but approaches a finite limit.”

 

Most crucially, this is one cause of ringing artefacts’ in signal processing which the GTO addresses.

 

Way back in May 2011, the parent company of iFi audio, AMR, pioneered an earlier version of this filter in the DP-777 digital processor where it was available as an ‘Organic’ filter. Since 2011, more time has been invested into producing a filter that offered both better compatibility and technical performance than non-oversampling, while delivering a transient optimised performance that differs as little from non-oversampling as possible, delivering the new GTO™ filter.

Non-oversampling Transient response vs Organic- Digital Filter AMR DP-777

 

No doubt there will be extended debate if our GTO^™ digital filter offers the right trade-off, compared to others. To us the two key qualities we sought was to shape of the unavoidable transient or time domain distortion so that is free of any ‘pre-ringing’ and that completes its impulse response within a fraction of the Haas (precedence effect) window; to remain in effect, inaudible to the human ear.

 

What we really refer to when we are talking about ringing in digital filters is actually a form of ‘Echo’ or ‘Reverb’ where, in addition to the actual transient time-shifted lower amplitude, copies of the impulse are generated using delay lines (see also the transients and digital filters section later on).

 

The human hearing itself is subject to an inherent transient post (impulse) ringing that completely decays within around 0.7mS[1] (see also the transients and the human hearing section later on).

 

The GTO filter’s transient post-ringing decays completely within 0.72mS for a 44.kHz source, ensuring that the unavoidable blurring of the transient response cannot be heard, but is integrated by the human hearing into the original transient.

 

This is in stark contrast to some alternative filter concepts. For example, the ‘Transient Aligned’ filter seeks a maximum number of taps, leading to an impulse response that falls well outside the Haas window. ie. its ‘ringing’ is very audible, in part because there is a pre-ringing (or pre-echo) present and in part through the sheer length of the delay line used.

 

For example, the 16k tap Transient Aligned filter in the Pro iDSD has an impulse response with equal pre- and post-ringing trail of around 186mS @ 44.1kHz sample rates, or a total 386mS worth of ringing. This is certainly sufficient time delay to be perceived as reverb. Using an even larger number of taps lengthens this impulse response even more.

 

 

Transient Aligned Digital Filter Transient response vs GTO™ Digital Filter iFi iDSD Pro

 

It may be of course, that some will prefer the sound of a very long filter, with large amounts of ringing/reverb/echo as the result is often perceived as extra added spaciousness, however, to anyone seeking to be close to the original musical performance such additives are usually unwanted.

 

In the end, with the iFi GTO filter, by keeping the filter short and without pre-ringing, the filter response is inaudible because it is masked by the limits of the human hearing system. At the same time this filter still permits significant attenuation of unwanted ultrasonic images, compared to non-oversampling and also other attempts at “low tap number digital filter”.

 

Analogy: if a 20million mega pixel camera was used to take a picture of a straight line, the naked eye would see only a straight line. As the resolution is ‘beyond’ that of the human eye, any ultra-fine imperfections are not ‘seen’. This is the same as with the GTO filter with human hearing.

 

If the GTO™ digital filter is so ‘perfect’, why include the other filters with the Pro iDSD? As remarked before, individual listeners may have different listening preferences and rather than imposing one option, even if we feel this option is not the best, we prefer to leave the choice down to the individual.

1) The original iDAC micro cannot receive this upgrade
2) https://en.wikipedia.org/wiki/Gibbs_phenomenon

3) “Response of the human tympanic membrane to transient acoustic and mechanical stimuli: Preliminary results” Payam Razavi, Michael E. Ravicz et al - Hear Res. 2016 Oct; 340: 15–24.

[AMR/iFi audio]

21 hours ago, Stings said:

okay. I figured out what the USB-B connector was and why i looks different then my normal audio cables. The connector on the ifi Pro iDSD is a USB-B 3.0 connectior not a USB-B 2.0 connector. That is what the extra piece on top of the USB-B connector is. I’m not sure what it does but at least I know how to find and order a cable now. I’m guessing the top portion of the connector is a isolated power connector. That would make sense, to keep the power signal from infecting the data signal. But again this is just my speculation. Does anyone know? And, is USB 3.0 quieter then 2.0?

 

  Is it better to stay with your old USB 2.0 cable or to buy and use a new USB 3.0 cable? Witch has a lower sound floor?

 

Yes, we use USB3.0 interface in our products. As far as this standard goes, please take a look here:

 

https://en.wikipedia.org/wiki/USB_3.0

[AMR/iFi audio]

iFi audio - The GTO filter 

Part 3/4 - Introducing the iFi GTO™ Digital Filter

 

How taps relates to what is heard

So far, we have identified that we prefer the GTO filter because it has few taps.

Because:

 

More taps = more reverberation.

Few taps = minimal reverberation

 

Reverberation[1] is artificial. Sound engineers add reverb to make recordings more spacious, artificially so. Digital filters introduce reverb by the nature of their operation. In fact, a digital reverb unit operates precisely like a digital filter in principle – as depicted in this diagram.

 

Within digital filters are Digital Delay Lines which is defined by Wikipedia:

 

"A digital delay line is a discrete element in digital filter theory, which allows a signal to be delayed by a number of samples.

Delays of N samples is notated as {z} ^{-N} motivated by the role the z-transform plays in describing digital filter structures.

Digital delay lines are widely used building blocks in methods to simulate room acoustics, musical instruments and digital audio effects."

 

To our ears, the GTO filter simply sounds ‘right’ without any hint of artefacts or exceptional detail that feels ‘processed’, by avoiding large number of tap’s that add excessive reverb.

 

 

 

Transients and the human hearing

The human ear is a marvelous system with an incredible dynamic range (~135dB in middle frequencies) huge bandwidth (almost 1:1000) and a transient resolving ability that exceeds the upper limit of hearing steady state tones. Yet it is also subject to limiting factors which result in, so to speak, “blind spots” in its behavior that do not exist in purely mechanical systems (e.g. microphone). These “blind spots” can mask some behavior which objectively is distortion to be inaudible. For example, harmonic distortion masking has been well documented since the at least the 1950s if not earlier and it is reasonable to consider that ‘ringing’ on transients is also masked to a certain degree.  

 

If we wish to produce audio gear that is capable of operating in a way that subjectively sounds undistorted to the human hearing (the most logical preference), we must understand its limitations and capabilities. Here, we focus on the time-domain capabilities.

 

It has been shown that the human hearing’s time domain resolution for the initial transient may be as small as 5μs. Some debate remains as to the exact limits, though work done by Dr Peter Lennox of Derby University suggests a median between 13…18μs, or a location accuracy of less than 2 degrees.

 

 

Additionally, the transient response of the human hearing includes 500...700uS ringing caused by the ear’s mechanical system (Tympanic Membrane, Malleus / Incus / Stapes).

 

 

This ringing occurs after a transient event, there is no pre-ringing. The ringing in the ear’s system will mask any similar external ringing, which will instead be integrated into the transient, so it is inaudible.

 

Any pre-ringing is not masked by the human hearing, nor is any ringing that continues substantially beyond 500...700uS.

 

 

---

[1] https://en.wikipedia.org/wiki/Reverberation#Digital_reverberators and https://en.wikipedia.org/wiki/Digital_delay_line

[AMR/iFi audio]

8 hours ago, MoWa said:

 

Hi ifi,

 

any news regarding the firmware upgrade of the Pro iDSD, to enable MQA ?

 

It is a brave statement of you regarding the GTO filter in a forum, where people are going to painful lengths, in order to run the HQPlayer at full capability.

 

However just my short point of view: I did only use the GTO once I got the Pro iDSD, however after sneaking here into this forum and one guy recommending to try upsampling to DSD with the HQPlayer I became curious...Now I even changed my roon core to a wintel machine, so I can run native  DSD512, which the Mac cannot.

 

I do not know how they do it, but some of the filters in HQPlayer do sound really fantastic and better to my ears, as coming out of the computer in 44,1kHz (or upsampled) and then upsampling only in the Pro iDSD with the GTO filter (or other filters of the iDSD) applied.

 

The different filters in the HQPlayer do sound different and very much like briefly described by the developper. I can distinguish this on my set-up in a reproducable way.

 

What is the truth and what is not: I think it shall be allowed, what makes it good for yourself, but since we are naming us audiophiles it should be within some practical tolerance window, in order to ensure quality reproduction, which I believe there will be a wide range of opinions for. 

 

I was also thinking about a suitable analogy: How about processing pictures or video content with suitable software. Is it closer to reality thereafter or just better for us to see, recognize details and enjoy ?

 

You put tubes into the DAC, which is very nice for getting a relaxed sound - and we can choose it, if we like it -, but after switching onto these you do not need to discuss any longer about differences coming from the different upsampling filters, the sound alterations coming from the tubes are bigger than that.

 

The Pro iDSD is also a super DAC when fed with native DSD512, without any further processing before conversion, and we do also have the GTO and the conversion to DSD1024 inside, so we can choose - perfect.

 

Now we are waiting for the MQA support.

 

....

 

Thanks for your input. Let's put it this way:

 

1. We like Jussi's work a lot and we respect the man.

2. MQA is still in the works but we're getting closer every day.

3. We do all these things (filters, transistors, tubes etc.) because we think this is the way to go, we like it this way and we are always about providing people many options to choose from.  

[AMR/iFi audio]

Also folks, AMR will be demoing two machines in the Colorado Audio Society Hospitality Suite at RMAF. Room 6007.

 

 

Yup, we're giving away Fast Blow fuses for Magnepan speakers! 2.5A for Magnepan 3.6/3.7 and 4A for other Magnepan machines.

[AMR/iFi audio]

Folks, RMAF!

 

Amazing show, amazing vibe, amazing visitors, amazing hardware! And we're there!

 

 

Many of our products are to be found at our place, including the full Pro stack (Pro iESL + Pro iCAN + Pro iDSD) and a number of fabulous headphones; Focal Utopia, Final D8000 etc.

 

 

And we have something very special in there too! The latest AMR DAC. For now we'll just put these pictures here, but in upcoming weeks we'll reveal more nfo about this machine!

 

[AMR/iFi audio]

On 10/7/2018 at 12:22 AM, Stings said:

Hi,

  I have the iDSD Pro and bought some extra tubes to try on it, but found out that is is not exactly tube roll friendly. It is a real pain to get to the tubes. I am still not able to get to them. 

  What wrench is needed to remove the set screw on the second knob, so I can open the case to change tubes? The other knob set screws are T6 and the back of the case screws are T15 but the second knob screw is different. What wrench do i use?
 

Thank you

 

Stings

 

You don't have to do anything with knobs. Just remove screws at the product's rear, apply some pressure and the whole PCB (still attached to front) will slide off. It's a bit tricky, but perfectly doable.

[AMR/iFi audio]

4 hours ago, datasyd said:

 

My ifi Micro iDSD BL sounds beautiful playing Tidal MQA files and that is despite it still pending a GTO-filter firmware upgrade for MAC users.

 

I believe my ifi Micro iDSD BL presently sounds better than my Pro iDSD, specifically for Tidal MQA files [assuming both devices are running through my Pro iCAN to either my headphones or home stereo].

 

The Micro is still awaiting the GTO filter, but it is fair to say the initial MQA firmware upgrade made to my Micro iDSD made for a significant difference so I'm expecting the Pro iDSD MQA firmware upgrade to 'restore order'.  Either way, I'm very keen for both products to fully deliver on the promise.

 

We're happy if you're happy! We'll deliver as promised.

[AMR/iFi audio]

On 10/26/2018 at 6:41 PM, The Computer Audiophile said:

New review is up!

 

 

 

Yup, we've seen this masterpiece, thanks!

[AMR/iFi audio]

On 10/26/2018 at 12:39 PM, danielet80 said:

Hi, I have a question to ask: the tubes installed can be replaced with the same model or is possible test other types of tubes? There are tests already performed with other types of tubes?

 

You can try, but we believe that besting tubes on-board is $$$ and improvement will be mild at best.

[AMR/iFi audio]

10 hours ago, Xin said:

 

 

 

News from AMR?!? ?????

 

Yup! But we're not saying anything specific yet!