iFi Audio Pro iDSD discussion thread
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Franatic
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Thanks Brainfood. I hope that comes about but it would be nice to get confirmation it is still on that track. ifi has been very quiet and the idsd has been delayed before.
Yes, much has changed. It is fairly obvious that ifi is in some sort of redesign of the idsd pro. They were very active on this thread up until around May, when a release seemed imminent. Since then they have become very passive and guarded in their interactions with their prospective customers on this thread. I have no idea now when the idsd pro might be released or where the current development is at.
I don't know of anyone has seen a current prototype of the unit.
Thx Franatic, information much appreciated. In the beginning seemed it was the perfect fit for me but then, it was explained why the balanced out (4-pin) would not be included which was a good reason, none the least. So for me lack of HP balanced out certainly is not a deal breaker but the lack of remote volume would be that's why I was inquiring to see if that was still in the mix with all the changes, thx again.
DougD
1000+ Head-Fier
I could be misreading the tea leaves, but I think the double-punch of Gumby and Yggy have really pushed the boundaries of quality and value for everybody, and finding a viable product space suddenly became a lot harder.
Maconi
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So do we have any hints to a price-point? Is it going to be slightly more than the iDSD Micro or are we talking double the price?
gr8soundz
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More like triple the Micro's price. iFi stated (weeks/months ago) price would be $1500-2000.
Maconi
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gr8soundz
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Ouch, good to know. Guess it's the Micro or bust for me lol.
Yeah, the Micro is still great (keeping mine) plus it will have some advantages even over the Pro model.
The iDSD Pro won't have XBass and 3D like the Micro and it will still lack balanced headphone out just like the Micro. Both have dual internal dac chips as well.
Biggest upgrades (afaik) with the Pro are the built in vacuum tube and balanced in/out (in the rear). Not sure if that will make it worth 3x the price of the Micro.
I'm more impressed with the iCan Pro so far. Too bad iFi won't put a usb dac inside it.
Franatic
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Read this:
http://www.computeraudiophile.com/content/670-schiit-audio-yggdrasil-multibit-dac-review/
Evidently this Yggy has raised the bar higher. I had looked at Schiit devices and had to reject them because they used C-Media drivers which would not work with Windows Server 2012 R2. That killed usage in my system. That is when I found ifi and have been very happy with this choice.
This Yggy sounds very intriguing. However, it does not play dsd, which is a red flag for me. I want a dac that plays everything.....and is future proof.....and costs less than $2299. C'mon ifi, I believe you will slay this Schiit Yggy monster and Gumby too dammit, with your increased capabilities...... AND lower price.....AND superior sound quality. Bring it!!!
The Schiity vs iffy war is on.
EVOLVIST
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But I think you're missing a great deal of what the iDSD Pro will be about by stating it just has tubes and balanced IOs. In fact, we can take this quite a ways back, so let me distill what we know, and what should carry over into the final product.
[quote="iFi]
Originally Posted by iFi audio
Hi,
In a word "yes".
We do apologise for the later launch date but some things have happened that are bigger and better than what we had anticipated and led to our decision to make it a full re-design. We gotta feed our OCD!
Only the Burr-Brown native DSD/PCM chipset and some of the digital section remains.
Therefore, one can deduce that the analogue section in particular, is getting an "extreme makeover".
Even this flagship series is no longer called the mini...very radical indeed
[/quote]
On 12-19-2014 we get this. It's no longer the "mini," and a total redesign was in order.
[quote="iFi]
Originally Posted by iFi audio
(can the original poster change the title from "mini" to "Pro" desktop? :wink_face: )
Okay, okay - here you guys go.
To answer the above questions, (except for the casework), the micro is not a "super-size" of the nano, neither will the
Originally the iDSD
But this the iFi flagship. Following on from the discussions with distributors, customers and professionals in the recording industry, we will instead use the iDSD Pro to develop the Generation 2 version of the platform. This includes a few, but significant adjustments in usability and a number of features targeted at the professional market, though they do have uses in domestic audio as well.
Key changes are:
1) External Clock Synchronisation
The iDSD Pro will allow the use of external clocks for USB and AES/EBU modes.
Options available are the use of the BNC socket as 10MHz atomic clock input (this affects all clocks and inputs).
For external sync either Wordclock via BNC or AES3 on the XLR input are supported. Finally the BNC can be configured as wordclock out (to make one iDSD Pro the "master" in a multi channel playback setup).
The wordclock synchronisation is mainly for professional use, but will also allow the iDSD to be used in multichannel playback at home, as for this all DACs MUST be synchronised.
The ability to add an external atomic (or other low-jitter) clock will cater to those who like to tweak their setups to the limit, as it replaces the internal crystal clock reference directly.
2) USB linked Volume Control
The iDSD mini will use a fully balanced (4-deck) Alps motorised Potentiometer as volume control. This volume control will be linked into the Master Volume control for the USB Device with a full feedback loop, meaning if you move the slider in Windows/Mac, the actual potentiometer rotates to match this and in reverse, adjust the volume and the slider moves. The adjustment will be highly precise so it matches across multiple units and is absolute - that is set several to -10dB and what you get is precisely -10dB.
The volume setting system used here is a derivation of the "flying faders" system used in Pro-Audio to automate mixes, but obviously has many uses outside pro-audio, especially if linked with the replay gain function, if replay-gain is applied to this volume control.
Of course, there will also be a handset to remote control the volume. And being able to set the Potentiometer explicitly to any position, we will include separate memories for volume settings for Headphone and Line out mode. So plug in your Headphones and the Volume returns to the last volume setting used when a headphone was connected, unplug it and the volume returns to that set for the line out. So an analogue Volume control with all the precision and comfort of a digital one. But none of the drawbacks such as losing Bits which the truncating signal etc.
3) DSD decoding from SPDIF
This is probably the most requested feature, simply put, the iDSD Pro will be able to receive DoP encoded DSD over the SPDIF [/quote]
On 01-06-2015 the beast changes to the "Pro." a special point of emphasis we should look at here, is that at this point iFi has not only redesigned, but also shifted focus to the pro audio arena. This does not exclude Hi-Fi heads, but it expands the horizons quite a bit. Read what they are doing here. Really read it.
[quote="iFi].
Originally Posted by iFi audio
Hi,
As promised....please bear in mind that we can only discuss so much as we have to walk a fine line between informing our customers and not giving away our secret recipes. :wink_face:
Kind regards
iFi Skunkworks.
To filter actively or to filter passively, this is the question (part 1)
Some interesting questions have been raised around the subject of the filter circuitry for the iDSD Pro and the amplification stages. It is a complex subject.
So please bear with us as we do our best to inform you on the course we have taken and the reasons behind.
There is a whole lotta tech speak to crunch through - and it may seem heavy going. So if you suffer from insomnia, you may wish to bookmark this.
Without further ado…
Why filter the signal at all?
First, we must understand that a DAC-Chip will produce substantial supra-sonic output (which we justly may call “digital distortion”) in addition to the Audio signal we want. Just how this looks like depends on many factors. Rather than looking all options, let's focus on the BB DSD chip we use in iFi products.
It has a core that runs normally at a speed of around 11.3MHz to 12.3MHz. This is a very high speed. This is the speed at which the elements in the core switch. As the process is switching, it creates higher frequency components reaching much higher than main switching frequency.
This switching is one of the processes that produces this noise outside the audio band, the others are related to sample theory and produces what is often called “images”. Simply said, the actual audio signal is “mirrored” around the sample rate in a frequency plot, hence the name mirror images.
Source: [COLOR=000080]http://defenseelectronicsmag.com/site-files/defenseelectronicsmag.com/files/archive/rfdesign.com/images/digitalpll-Figure03.jpg[/COLOR]
Most audio circuitry cannot handle such supra-sonic signals, they are too fast and cause distortion to our audio signal. So what we require with any DAC is a filter that so to speak “strains out” the unwanted noise and leaves the audio signal. And ideally it gets all the noise and leaves the audio totally untouched.
In the real world ideal filters do not exist. A filter that removes the supra-sonic noise will have impact on the audio range and will introduce either phase-response variation, transient-response variation or both.
Source: [COLOR=000080]http://www.electronics-tutorials.ws/filter/fil82.gif[/COLOR]
We have to sail between the Scylla of insufficient filter selectivity (too much noise gets through) and the Charybdis of excessive filter impact on the audio (we filter out most noise and pad a lot of distortion the music). But filter to some degree we must, so we must chart a course that will hopefully take through instead being wrecked on rocks of Charybdis or sucked into the chaotic whirlpool of the Scylla.
Next time: Part 2: How to filter Digital Audio
[/quote]
on 02-13-2015 we get a little more insight on the thought process behind the iDSD Pro
[quote="iFi].
Originally Posted by iFi audio
To filter actively or to filter passively, this is the question (part 2)
How to filter digital audio
If we exclude digital filters (which are a whole other can of worms), to create filters, we require electronic parts that change with frequency in predictable ways.
1. Simple Filter - goes so far
The simplest filters combine just a single resistor and either an inductor or a capacitor. The problem is that such simple filters are not very selective. They impact the signal little, but also do not do much for the noise.
Source: [COLOR=000080]http://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/1st_Order_Lowpass_Filter_RC.svg/2000px-1st_Order_Lowpass_Filter_RC.svg.png[/COLOR]
(see also: [COLOR=000080]http://en.wikipedia.org/wiki/Electronic_filter#Passive_filters[/COLOR])
We normally need better selectivity than we can get that way.
2. Passive Filter - good in theory, not easy in practice
One way is to use combinations of multiple resistors with inductors and capacitors. This is called a passive filter.
With real capacitors and inductors such a filter can remain effective to as high as 100MHz. So it can very effectively filter not just the images but also the switching noise.
Source: [COLOR=000080]http://upload.wikimedia.org/wikipedia/commons/thumb/0/0e/Lumped_elements_ladder_filter_order_4.svg/450px-Lumped_elements_ladder_filter_order_4.svg.png[/COLOR]
Quality inductors take space and cost money and it is often difficult to find inductors that do not cause substantial distortion themselves. This is why this method is rarely seen today, even though it approaches an ideal filter quite closely and of course was used in early generation digital equipment.
3. Active Filter - another way to skin a cat
The other way is to use an active filter. Here we only use resistors and capacitors and “simulate” inductors using amplification. This means we rely on the amplification function of the active element to shape the filtering.
- one key advantage other than getting rid of inductors is that active filters allow the designer much, much freedom in trade-offs between selectivity and filter impact on the signal.
- another advantage is that these filters are widely documented and are easily calculated and modelled.
Source: [COLOR=000080]http://www.sussex.ac.uk/Users/pjly20/ras100_clip_image002_0000.jpg[/COLOR]
(see also: [COLOR=000080]http://en.wikipedia.org/wiki/Active_filter[/COLOR] )
There is a downside. Most of the common amplifier elements loose amplification as frequencies rise. Many audio Op-Amps will have no remaining gain at frequencies above a few MHz. So at very high frequencies the filter no longer filters as it should.
So such active filters are easier and cheaper to implement than adequate passive filters and can filter the so-called images well. But they struggle to filter the switching noise from the DAC as well, or indeed often at all.
Decisions decisions, what is one to do?
In the end it is the choice of the designer how to make sure all the different requirements are met and how trade-offs between mutually exclusive requirements are arranged.
In the iDSD nano we rely only on passive filtering, but the filter selectivity is not as extreme as with other iFi DACs.
In the iDSD micro, iDAC2 micro and the DAC in the Retro Stereo 50 we use a combination of passive and active filtering, using very wide bandwidth Op-Amps.
In the iDSD Pro, budget/size constraints are less of an issue and thus we can implement a fully-passive filter.
Think of the nano iDSD as BMW M1, micro iDSD/iDAC2 as M3 and Pro iDSD as the M5.
Each has its own price and engine/performance characteristics to suit different users.
(As a small side note, as we develop our code in-house, we "remap" the onboard XMOS (among other things) to push them beyond the theoretical read: datasheet specs. As is evident from the Quad-DSD256 and Octa-DSD512 on the iFi platform. So our M-line is beyond the factory version.)
Before you ask, for those car buffs among you, the BMW i8 is the reserve of AMR.
[/quote]
Then on 02-17-2015, even more insight.
[quote="iFi].
Originally Posted by iFi audio
To Filter or to not Filter: Part 3
An Op-Amp digression
In our previous part 2 article, we mentioned the “O-Word” already, so let's digress a little.
The Op-Amp is represented by the Triangle with the + and – sign inside in the triangle in the active filter above.
When you read some advertising copy in high-end audio you may believe that Op-Amps are the latest and best thing since sliced bread and one might even believe some of the fellas using them invented them. But Op-Amp's are really old.
The first functional design is normally attributed to Karl D. Swartzel Jr. of Bell Labs in 1941 and was used in a Radar assisted Artillery director during World War 2.
The word “Operational Amplifier” for the type of amplifier circuit it embodies is documented in 1947 and the first “integrated op-amp” using tubes was introduced in 1953
Historical timeline
1941: A vacuum tube op-amp. An op-amp, defined as a general-purpose, DC-coupled, high gain, inverting feedback [COLOR=000080]amplifier[/COLOR], is first found in [COLOR=000080]U.S. Patent 2,401,779[/COLOR] "Summing Amplifier" filed by Karl D. Swartzel Jr. of Bell Labs in 1941. This design used three [COLOR=000080]vacuum tubes[/COLOR] to achieve a gain of 90 dB and operated on voltage rails of ±350 V. It had a single inverting input rather than differential inverting and non-inverting inputs, as are common in today's op-amps. Throughout [COLOR=000080]World War II[/COLOR], Swartzel's design proved its value by being liberally used in the M9 [COLOR=000080]artillery director[/COLOR] designed at Bell Labs. This artillery director worked with the SCR584 [COLOR=000080]radar[/COLOR] system to achieve extraordinary hit rates (near 90%) that would not have been possible otherwise.[COLOR=000080][14][/COLOR]
All the way through to:
1972: Single sided supply op-amps being produced. A single sided supply op-amp is one where the input and output voltages can be as low as the negative power supply voltage instead of needing to be at least two volts above it. The result is that it can operate in many applications with the negative supply pin on the op-amp being connected to the signal ground, thus eliminating the need for a separate negative power supply.
The LM324 (released in 1972) was one such op-amp that came in a quad package (four separate op-amps in one package) and became an industry standard. In addition to packaging multiple op-amps in a single package, the 1970s also saw the birth of op-amps in hybrid packages. These op-amps were generally improved versions of existing monolithic op-amps. As the properties of monolithic op-amps improved, the more complex hybrid ICs were quickly relegated to systems that are required to have extremely long service lives or other specialty systems.
Recent trends. Recently supply voltages in analog circuits have decreased (as they have in digital logic) and low-voltage op-amps have been introduced reflecting this. Supplies of ±5 V and increasingly 3.3 V (sometimes as low as 1.8 V) are common. To maximize the signal range modern op-amps commonly have rail-to-rail output (the output signal can range from the lowest supply voltage to the highest) and sometimes rail-to-rail inputs.
(source wikipedia: [COLOR=000080]http://en.wikipedia.org/wiki/Operational_amplifier#Historical_timeline[/COLOR]).
Over the years the Op-Amp has slowly become the default building block for Amplifiers, both discrete and integrated and for the last few decades Op-Amps have been the dominant choice when it comes to “general purpose” Audio amplifiers (and outside audio).
They are manufactured in a huge variety at all price levels and with a massive array of different specifications and optimisations for specific jobs. Some are even sold as being optimal for audio.
Unfortunately, this ubiquity has also led to a lack of understanding of what happens inside these Op-Amp's. There are circuit structures that are common to almost all Op-Amps, there are inherent limitations that are too.
These days we pick up the Datasheet for an Op-Amp and we read:
“The XXX Op-Amp is a JFET-input, ultralow distortion, low-noise operational amplifier fully specified for audio applications. Features include 5.1nV/√Hz noise and low THD+N (0.00005%).”
Surely it ticks all boxes?
Come on, zero point how many zeros THD?
Noise in Nanovolts?
It even says “J-Fet” there and “J-Fets” are in fashion this year we hear.
It's even a special audio grade part. So let's just use that one, okay?
Actually, at iFi WE DO USE THAT ONE.
But not because of these numbers. Or the J-Fets. Or the “Soundplus” moniker.
Sorry to disappoint but our reason is more prosaic. Correctly implemented it sounds as good as anything we have tried and much better than most.
There are some other numbers for that chip that are not headlined. They have more to do with what happens in the real world.
For example, the bandwidth is only 11MHz at no gain and gets substantially less wide as gain is increased. And while the distortion is low at 1kHz and under ideal conditions, there are many things that make it worse, not the least raising the frequency so at 20kHz we have wipe off one zero of that very low distortion figure and at several MHz three to four of the zeros.
It also is not so great with low impedance loads, without adding buffers distortion goes up, so strike another zero if we drive 600 ohm. Actually, the gain is very load dependent!
Now it is not such a low distortion device anymore, is it?
One thing we do not really want to do is to make this Op-Amp filter signals in the region of several MHz or have it driving headphones. We have to take that over by different means if we want to use this Op-Amp for it's undeniable qualities.
If we understand the limitations and possible problems we can design our circuits accordingly and avoid the pitfalls of the limitations and take best advantage of the exceptional audio performance.
If we are simply members of the “Op-Amp of the month” club, we may get all sorts of results, maybe good, maybe bad, maybe indifferent.
Having Op-Amps or not is not a reliable indicator of quality.
Even the best Op-Amp's in the world can be implemented so ham-fisted that the result is poor, using Op-Amps that seem rather old and pedestrian correctly can give surprisingly good results in the real world.
[/quote]
Again on 02-25-2015
[quote="iFi]
Originally Posted by iFi audio
Many designers when implementing Op-Amps (or DAC Chips for that) never really look what is going on inside.
They just take a "datasheet" circuit, cookiecutter style and then swap Op-Amps around (or not) until it more or less sounds like they want (which may or may not be what others want or like).
Also, one thing that differs with AMR/iFi is that we have a team of lead designers - each with their own strengths and experience. If there is only one lead designer, that product tends to go down a certain path based upon the strengths/weaknesses of that one person.
More in the next part...
[/quote]
[quote="iFi].
Originally Posted by iFi audio
To Filter or Not Filter (Part 4)
Go Discrete
Often the use of discrete circuits is touted as the ultimate expression of the audio design craft. Certainly, going discrete does free us from the shackles of the Op-Amp data-sheet and from the limitations of the manufacturers catalogs, which despite offering 100's of parts usually seem to lack the one with the precise combination of spec's we want. Whatever we want, we design it in.
BUT often discrete designs are not as good as the best modern Op-Amps. With discrete circuitry we can never be as complex modern integrated circuits and this complexity can be used to improve performance.
If we try to imitate integrated circuit Op-Amps in discrete form – we are often ending up with something performing worse, bigger and more expensive than a good and inexpensive Op-Amp chip used right.
Additionally, we can always add discrete parts to extend a good Op-Amp chip that lacks some specific feature we want. Be it an ultra-low noise input stage or a big class A output stage, we can often add these to an otherwise suitable chip and in the process make a hybrid that keeps all the good stuff of the integrated Op-Amp and adds our own desired features with much less complexity and of course cost than a fully discrete design.
At iFi you can find an example of this in the iPhono and its added super low noise MC stage and the added Class A Buffer, that deliver a performance that no single Op-Amp chip could and that would be, if at all possible in purely discrete circuitry, neither small nor particularly affordable.
The iPHONO
(Incidentally, one of the few "objective audio tests" when auditioning a phono stage is to 1) play music as loud as you normally listen at. 2) Then lift the needle. 3) Then listen for the "noise" from the phono section. A good phono stage amplifies only the signal so you should not hear "it" from the normal listening position. A normal phono stage amplifiers the signal AND the noise).
So, realistically, there is just one reason to go fully discrete. To get something that does away completely with the fundamental Op-Amp circuit structure and instead does things radically different, something that allows us to step outside the triangle with its + [/quote]
[quote="iFi].
Originally Posted by iFi audio
Pro series – working on something stellar
We have been ‘off the grid’ of late on the Pro series.
First the bad news – we apologise but the Pro iDSD and Pro iCAN will not make it in time for the Munich Show. Both models have been delayed until the summer, circa June/July.
This does not best please us but there are two reasons. The upshot is that we don’t like to make things just to sell (though that is nice), we also like to ensure that you are getting something that is truly special that has a serious amount of performance and longevity built-in.
Special parts are nice and all but the Pro series like the micro iDSD we feel can be truly ‘interstellar’. Without giving too much away as we are still sometime off and things can change, there are 2 developments that explain the decision to push the launch date back:
1. Going All Discrete and Tubes – Instead of the proven TI current mode Headphone Buffers we have used in other iFi products, for the Pro-series we taken the decision to apply discrete Class A output buffers directly into the circuit design. This is a complete and fundamental re-design of both the iCAN and iDSD. The first and critical input stage of the single amplification stage (Unistage) can be selected to be either a very low noise J-Fet (< 4nV|/Hz) or a military grade General Electric NOS 5670 Tube.
2. Pro Chassis – some of you contacted us to remark that you would like the Pro chassis to be more appealing. It was not the final, final version but a prototype. Nonetheless, we acknowledge your comments and we took a look at it and thought ‘in for a penny…’. The final chassis will be different but not wholesale, but it should be nice.
All things told, the delay to the Pro iDSD and iCAN launch is from mid-May to mid-July, of some 2 months.
As we wish to keep some of the best bits under wraps, we shall keep further disclosures to the bare minimum, until the launch date is in sight. Thorsten and his gang would like to pass on their apologies and thank you all for your patience.
The micro iDSD was a full Crowd-Design project. The Pro series is not but we still acknowledge your input and try to take out the best bits.
[COLOR=00000A]Thank you for your continued patience. It is very much appreciated[/COLOR]
[/quote]
[COLOR=00000A].[/COLOR]
Then on 05-13-2015 iFi breaks a bit of silence to give us some more good bits.
[quote="iFi]
Originally Posted by iFi audio
Hi,
1) Will both the tube and J-Fet stages be built in to the unit and selected via a switch setting?
Yes.
2) Will the 5670 tube be singular and socket mounted for swapping?
As the units are balanced, there will be two tubes and yes, they are mounted in sockets. But we do not recommend downgrading to the 6922 family. You can start the hunt for WE396A - but genuine ones will not be cheap.
3) Will the usb input be a "usb B" type that the gemini cable connects to?
This is being finalised, but there is likely to be a B-Type USB 3 Socket.
Cheers.
[/quote]
Further clarification.
[quote="iFi]
Originally Posted by iFi audio
Hi,
To answer this and the previous question posed.
For the iDSD Pro we really went back to the drawing board after the first version. As a result its basic topology is very purist; which literally means just a passive lowpass filter, Volume Control and an Output Amplifier that could drive Headphones or Line Outputs with equal quality. This ultra simple signal path is one of the reasons that allowed the iDSD nano to offer such good sound quality on such modest budget. Its giant slayer status is largely attributed to this approach and we are adopting the same for the Pro iDSD.
Of course, for the iDSD Pro we have improved the quality and performance of these basic blocks massively. And we mean massively.
The passive low-pass filter incorporates inductors to form a LCRC filter with better filtering of unwanted digital noise while offering a wider audio bandwidth free of analogue phase-shift.
The Volume control is no longer a Chip, instead a balanced Alps Potentiometer (16mm Alps Black) is used. There is more to this Volume control which will be revealed at a later time. :wink_face: For fixed level line outputs the volume control is fully bypassed via relays (just like you find on the AMR DP-777) for the purest possible sound, connect a headphone and the Volume Control is restored.
The Output Amplifier is our new all discrete “Pro-Stage” which does away not only with Op-Amp Chips themselves but even with traditional Op-Amp like structures implemented discretely (e.g. like all these “discrete Op-Amp replacements”. It should be quite unique. Instead the circuitry owes much to the discrete designs of both Neumann and TAB-Telefunken for the West-German radio [/quote]
08-10-2015. We're getting a closer look at something truly special and unique.
[quote="iFi].
Originally Posted by iFi audio
Hi,
A Short History of Chipset Euphoria (nod to JK Galbraith readers :wink_face: )
Very fitting in the current economic climate:
In our book, firstly, R2R done properly takes a LOTTA work. Secondly, the statement 'Bit-Perfect Digital Filters' is a contradiction in terms; it only exists in sci-fi as it is a 'true oxymoron'1.
Multi-Bit CAN be Bit-Perfect, but often oversampling and digital filtering is used, that cannot be defeated by the user. To us this not something we would implement.
Further, while the mainstay of CD standard Audio, neither Multi-Bit nor Delta Sigma on their own are great for wider dynamic range coupled with higher sample rates.
Multi-Bit systems struggle with distortion at low signal levels. The TDA1543 from Philips which is found in many Non-Oversampling Multi-Bit DACs for example is show to have at best 14.5 Bit linearity at low levels with worst case less than 13 Bit linearity. This is not even really good enough for CD.
By comparison, Delta Sigma DACs can have essentially distortion at low levels that are equal to the noise (read no extra distortion). But Delta Sigma has its own limitations due to supersonic noise, slew limiting and lack of resolution to handle large dynamic steps.
We feel that splitting the job between Muti-Bit for the high-level parts (where it is most capable) and Delta Sigma for low-levels is the best choice when attempting to go past the CD-Limit of dynamic range. If we need to play back CD, well, the TDA1541A or UDA1305T are still our preferred choice, but they are limited to 16 Bit performance.
Cheers.
1A 'true oxymoron' (as opposed to an 'oxymoron') - is "something that is surprisingly true, a paradox2."
2 A paradox - the Greek roots translate to “contrary opinion,” and when two different opinions collide in one statement or action, that's paradoxical.
[/quote]
On 08-25-2015 we see what looks like taking the best of both world from delta-sigma and R2R, if I'm reading this right.
[quote="iFi]
Originally Posted by iFi audio
Hi,
Interesting points raised but we respectfully beg to differ, albeit slightly.
- I think that if the iDSD Pro is to be a flagship product, the functionality of the iUSB3.0 must be built in.
What kind of flagship product requires the addition of a $400 widget to make it sound like a flagship?
Please bear with us but adding the "iUSB 3 Technology" makes only sense for DACs that are:
1) USB Powered (for any function) - which includes many notionally self-powered, high-end DACs even ones that cost US$10k (see upcoming RMAF for ones that use the iUSB3.0).
2) Lack galvanic isolation (so noise from the USB circuitry can enter the actual DAC/Clock DAC) - which is most DACs out there
3) Have the clock system for Audio on the "dirty USB Side" rather than the "clean DAC Side" in terms of PCB Layout - again, most DACs out there are affected as USB Chip application notes invariably show the audio clocks on the same sheet as the USB Chip.
We hope this sheds more light on what/who the micro iUSB3.0 is aimed at.
This does not apply to the Pro iDSD. The iDSD Pro will have galvanic isolation and is fully self-powered. So the iUSB3.0 will not help much if any. Few DACs do this at any price. And to answer the next likely question, we have not snipped a trace to get galvanic isolation. :wink_face:
- People who bought the Retro Stereo 50 must already be mildly annoyed at the idea that it can be improved by adding an external widget. It's supposed to be an all-in-one so basically it's out of date already.
Its priorites are in a different direction for a different customer base. The Retro has tube amp, DAC, phono stage and headamp all under one chassis and comes with speakers. And the fact that it handles DSD512 means it is quite future-prooofed.
The $400 iUSB Power* is for all iFi and non-iFi products. It improves the sound of US$10k DACs that use a USB connection see at RMAF for example. So yes it wll improve the Retro too.
- Very soon now most other DAC manufacturers will be adding this new USB technology to their products, just as they all added 'asynchronous' operation to replace the greatly inferior 'adaptive' mode.
We accept other manufactures will cotton on - such is life and the nature of free-markets. But fear not. As we originally designed this stuff, we will continue to push the envelope while at the same time, trying to maintain the same backwards and forwards modularity for iFi and non-iFi products. eg ANC was developed by AMR for its future products - but it has been trickled-down to the iDAC2 and iUSB3.0.
However, if you are referring specifically to "re-driving USB Inputs," this normally does not make much sense for inclusion in a DAC, as it does not remove the problem from inside the DAC.
If you place these electronics inside the DAC and power them on the same groundplane and with the same PSU as the USB Chip you have put the whole problem back into the DAC.
If you then start separating power supplies etc. et al until you have a situation similar to the iUSB 3 you are looking at major effort, which can be completely avoided by providing galvanic isolation and placing the clocks and other noise sensitive items on the "qiuet side."
Because Bits are truly just Bits. As long as the USB circuitry spits out the right bits and cannot effect any clocks, power supplies etc. and as long as correct impedance USB Cables are used the USB System is quite "tweak proof" which is what we have done as much as we can across the board.
Cheers.
Edited by iFi audio - 9/25/15 at 5:00am
09-25-2015 - among other things galvanic isolation mentioned first
[/quote]
DougD
1000+ Head-Fier
Received the new Music Direct catalog on Wed.
It shows a big picture of the iFi iCAN Pro Headphone Amplifier, and gives a short description, concluding with "Read more on our Web site." Price listed as $1,695. Says "NEW" (but does not say "arriving soon.")
The web site as of 5 minutes ago says "Availability: Usually ships in 2 - 3 weeks*"
So ... the Pro could be close.
OTOH, making a catalog of this size probably takes a long time, so this may be an estimate of availability from a few months ago. But this is the first time I have seen an actual price in black & white.
It shows a big picture of the iFi iCAN Pro Headphone Amplifier, and gives a short description, concluding with "Read more on our Web site." Price listed as $1,695. Says "NEW" (but does not say "arriving soon.")
The web site as of 5 minutes ago says "Availability: Usually ships in 2 - 3 weeks*"
So ... the Pro could be close.
OTOH, making a catalog of this size probably takes a long time, so this may be an estimate of availability from a few months ago. But this is the first time I have seen an actual price in black & white.
EVOLVIST
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What page of the catalog? I'm not seeing it. The one with Grace Slick and Janis on the cover?
I saw it on Music Direct's website. I'll be sure to give them a call tomorrow and see what's going on.
Thanks for the heads up!
EVOLVIST
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Ah, thanks! I was looking in the amp section, and didn't even think of going off the grid to find it.
Fascinating. Wow.
Fascinating. Wow.
EVOLVIST
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So, I called up Music Direct and they claimed it could be longer than 2 or 3 weeks, that he believes he hasn't gotten them from the importer yet.
It's still good news. That means the iDSD Pro can't be too far behind.
This also probably accounts for iFi's silence.
It's still good news. That means the iDSD Pro can't be too far behind.
This also probably accounts for iFi's silence.
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