Serious Question: How can DAC's have a SOUND SIGNATURE if they measure as transparent? Are that many confused?

[Reynaldo]

From my perspective IFI have some way to go before I would consider them even remotely credible.

I'm glad I don't take these reviews into account.

 

[Reynaldo]

So this was not your idea/push to support higher sample rate DSD and stick with DSD1793 chip ?

And even the DSD512 and DSD1024 upsampler in the Pro iDSD?

I think he was referring to another DAC I have from Musical Fidelity that is PCM only.

 

[Music1969]

I think he was referring to another DAC I have from Musical Fidelity that is PCM only.

Not but I have some question anyway regarding iFi sticking with DSD1793 chip anyway

And Pro iDSD upsampling to DSD1024

 

[Reynaldo]

Not but I have some question anyway regarding iFi sticking with DSD1793 chip anyway

And Pro iDSD upsampling to DSD1024

I had already asked him about this chip, because two DACs I have here use this chip.
Unfortunately several answers have been removed to another place changing the entire sequence.

 

[Thorsten Loesch]

iFi Audio NEO iDSD

Note, I did the electronics design, but not the PCB layout.

U400 - Power supply SOC - this takes in 5V DC and produces 1V, 3.3V, 5.7V (Audio PSU Bus) & 12V for the OLED Display using switchers and low noise 3.3V linear regulated for the clock synthesizer

U100 - XMOS 16 Core Transputer - handles SPDIF Receiver, USB Audio Device etc. duties

U200 - Clock Synthesiser (private label)
U201/2 Reclocking
U203 - TPS71750 regulator for DAC
U204 - single DS1793 DAC
U206 - Quad Op-Amp (private label) - note how the chinese "engineer" who designed the PCB placed it a long distance from the DAC, the opposite of recommended practice)

U300 - Switched Ladder Digipot (private label) - note hoe this is placed close to the Op-Amp, where we have a low impedance node resilient to interference
U301 - Quad Op-Amp (private label) - note how there relatively long lines from the Digi-pot this Op-Amp
U302 - FET Switch 74HC4053 for gain switching
U303/4/5/6 - MAX97220 used as power buffer - note how they are placed far away from the driving Op-Amp - this caused stability issues with the feedback loop of the multi-loop design

U307...318 - dual Mosfets used for line & Headphone switching.

Observe the RVT marked Electrolytic capacitors. They are "basic quality", upgrades to Sanyo Os-Con or Elna Silmic depending on position would likely offer some benefit. In a 800 USD device there is certainly enough budget for such upgrades.

There is no isolator between the XMOS Chip and the DAC/Analogue Circuit. This feature had already been developed and deployed for the iDSD Pro, in a 300 USD it's omission was justifiable, not however in a much more expensive product.

The fet based signal switching was appropriate for a 300 USD product, for a much more expensive product a total of five signal relays would have not broken the bank.

There are a number subideal choices in PCB layout that, together with the use of an OLED display cause interference from the OLED Display to leak into the Audio circuit. THis is not the case on the iDSD Pro and unacceptable even for a 300 USD produced IMHO.

Thor

 

[Thorsten Loesch]

So this was not your idea/push to support higher sample rate DSD and stick with DSD1793 chip ?

High Sample rates can be supported on many different DAC Chip's, including ESS,CS, AKM et al.

The market has been pushing high sample rates and high resolution even though 99% digital audio available are Redbook CD standard recordings, or in the case of many officially "high resolution" recordings are "upconverted" from Redbook sources.

It was partially my decision to stick with DSD1793. I was not the only party setting the design requirements for products.

And even the DSD512 and DSD1024 upsampler in the Pro iDSD?

As we were designing an FPGA based digital filtering engine and had the ability top do it AND as there was customer demand, DSD Upsampling was included.

In listening, I found I preferred the DSD conversion of PCM while not using any digital filtering over playing it back as PCM, something I had not observed with using J-River DSD "upsampling".

On most DAC's I own I replay DSD converted to PCM176.4/24Bit.

Thor

 

[Reynaldo]

On most DAC's I own I replay DSD converted to PCM176.4/24Bit.

I use a Mac Mini with Audirvana.
I have installed v3.5 and the new version of Audirvana Origin.
That's exactly what it does when I'm using the M1SDAC which only plays PCM, it converts DSD to PCM176.4/24Bit.
I don't know if it does the same thing with other DACs, but it does exactly that with the Musical Fidelity M1SDAC.

 

[Reynaldo]

Here the internal image of the Musical Fidelity M1SDAC.
The image quality is not good, but you get the idea.

 

[NikJi]

But there can't be an "if" the differences exist according to your own experience, what those differences are is not apparent and you presume that if I had the time and frankly gave a damn those same differences would be apparent to me in the same way they are apparent to you. What if I can't hear those differences at all, or hear a differences completely different to your experience.

How can you be sure the rest of your system is just not up to snuff and creating those differences in the DAC's performance?

Nope, "if" is not an option.

It is not “if”. It is “if you”. I heard a difference. Question is will you? If not, what will you be measuring for?

 

[NikJi]

How many people here have any experience in manufacturing, process engineering and recipes?

 

[Thorsten Loesch]

From my perspective IFI have some way to go before I would consider them even remotely credible.

From my perspective iFi products perform as designed and intended. I could have designed them differently, the way everyone else and emphasised SINAD & SNR like most others do, but I did not for my own reasons.

If you believe that high SINAD and SNR translate into "good sound" or you purchase equipment to measure it on AP2 and then take to the printouts to the gents to do whatever, don't buy these products. Simple as that.

Actually the latest generation of products that are no designed like every other chinese company and use ESS should suit you. They are the cheapest too.

Thor

 

[Thorsten Loesch]

Not but I have some question anyway regarding iFi sticking with DSD1793 chip anyway

And Pro iDSD upsampling to DSD1024

Do ask.

Thor

 

[SIY]

How many people here have any experience in manufacturing, process engineering and recipes?

What would you like to know?

 

[Music1969]

As we were designing an FPGA based digital filtering engine and had the ability top do it AND as there was customer demand, DSD Upsampling was included.

In listening, I found I preferred the DSD conversion of PCM while not using any digital filtering over playing it back as PCM, something I had not observed with using J-River DSD "upsampling".

Have you someone with you at AMR/iFi used HQPlayer?

The developer showed many years ago on Computer Audiophile forum that the micro iDSD measured better in numerous measurements when PCM44.1 was upsampled to DSD512

And iFi products then became really popular with the HQPlayer world because it performed well and was very affordable

Did you ever catch wind of this discussion and see the measurements?

Some from 2014:

iFi iDSD Micro measurements

Here are my standard set of measurements, this time with iFi iDSD Micro. First sweep 0 - 22.05 kHz. Source is 44.1 kHz 32-bit PCM file. Filter "Bitperfect" (NOS): Filter "Standard": Filter "Minimum(phase)": Upsampled to 768/24 PCM in HQPlayer: Upsampled to DSD256 in HQPlayer: Upsampled to DSD512 ...

audiophilestyle.com

 

[Blumlein 88]

Ahhhh… thanks for the advice. I wish I had the means to record and post what the Audioquest Dragon and the THX Onyx sounded like on the Sony MDR7506. That said, it is a simple experiment anyone of you can try. All you need is to go to amazon.com and purchase the 3 items (with free returns), hear them and post your feedback. It is so much simpler than someone like me attempting to convey it to you in words.

I've recorded some AQ vs other interconnects. There wasn't any discernible difference. Ran them thru Deltawave and they nulled out down around the thermal noise floor vs some regular RG6 coax interconnect. So I wonder if you could hear them if you didn't know which was which?

 

[Thorsten Loesch]

Have you someone with you at AMR/iFi used HQPlayer?

Yes.

The developer showed many years ago on Computer Audiophile forum that the micro
iDSD measured better in numerous measurements when PCM44.1 was upsampled to DSD512

Well, "BETTER" is one of those "how long is a piece of string" things.

The iDSD micro also measures better if PCM44.1 is "upsampled" to DXD, which he did not show.

In both cases the main difference was the digital filter used.

And iFi products then became really popular with the HQPlayer world because it performed well and was very affordable

Did you ever catch wind of this discussion and see the measurements?

Yes.

Nobody at iFi minded that he promoted our products in the same posts where he promoted his software.

The upsampling engine is very flexible (too flexible?) and performs - well as expected from the settings.

Objectively speaking, the typical BB/TI "advanced segment" DAC, be they voltage or current output versions have the same basic core but used differently.

There are normally 66 unitary weighted current sources (unitary means they all have the same current). For PCM they are used as a 64 level (6 Bit) Thermometer DAC that works traditional for the 6 MSB (most significant bit's) and a 3rd order Delta Sigma Modulator at 128 * FS (typical, this can actually be configured via software for devices with software control) for the bit's below the 6 MSB.

As each of the 66 current sources may have a small error relatively to the nominal value, the actual current sources are selected randomly from the pool, for each of the bit clock cycles the internal logic selects the correct number of current sources (say 33 out of 66) but which actual current source is activated is selected randomly.

You might say that a 6 bit multi bit DAC (though not R2R) is used for the top 36 dB of the dynamic range while a single bit DAC with a single bit switch is used for the 77.....93dB of the dynamic Range. There is no other DAC range from other manufacturers currently around that works like this. The relevant Patent only expired recently and all other "hybrid" DAC's use a different approach.

In DSD mode the current sources are used to form instead a 8 cells long analogue FIR Filter with non unitary weights. This is a very similar structure to the discrete DIY DSD DAC the developer of HQPlayer published. The use of only 8 cells with non-unitary weights creates a different filter characteristic from Jussi's 32 cell unitary weighted analogue fir filter and better time domain behaviour.

Anyway, feeding the DAC Chip a 352.8kHz/32 Bit PCM Stream derived from 44.1kHz PCM uses a different process to create an analogue output from feeding it 44.1kHz PCM and sending it instead 22.5792MHz DSD uses still another process.

Certainly digital filters and modulators are different, with different result in the analogue domain, which I have reason to consider audible via a process that is not clear to me, other than that all processing is subtractive in nature and introduces deviations from the original signal. And where is a difference, there is often a preference.

In the iDSD Pro I basically constructed our own DSD -> PCM and PCM -> DSD engine using a FPGA (It can actually do a lot more than we have exposed to the user in the iDSD Pro) so I had control over the functions, filters etc. and selected what I felt to be likely to come closest to a "fair" DSD domain representation of the PCM. With this objective measured differences were minimised. I also designed the analog stages to compensate the 6dB gain loss of DSD.

I found that in listening I preferred the DSD512 rendering to DSD1024 and to any of the PCM Modes, in all cases using the "no digital filter" filter option.

Thor

 

[Music1969]

Anyway, feeding the DAC Chip a 352.8kHz/32 Bit PCM Stream derived from 44.1kHz PCM uses a different process to create an analogue output from feeding it 44.1kHz PCM and sending it instead 22.5792MHz DSD uses still another process.

Yes DSD is more "direct" pathway to analogue right ?

 

[antcollinet]

It is not “if”. It is “if you”. I heard a difference. Question is will you? If not, what will you be measuring for?

How do you know the difference you heard is actually in the signal reaching your ears, and not due to one of the many cognitive biases from sighted listening?

How do you know there is anything for "if you" to hear?

 

[Killingbeans]

How many people here have any experience in manufacturing, process engineering and recipes?

*raises hand*

Not audio though. Slot machines and motion controlled stage equipment for the most part.

Don't know about recipes. I have a few in my kitchen. Or maybe you mean "recipes for disaster". I've seen quite a lot of those during my time in manufacturing

 

[Palladium]

Naaaah, my personal intellectual honesty couldn't possibly be wrong, it's everything else that is.