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Audible Performance Differences in HiFiBerry Digi+ and Digi+ Pro/Digi2

I just so happen to have a Hifiberry Digi+ I/O, the one with only one 27 MHz oscillator (oh no, the horror!) and no isolation transformer.

I made some quick measurements of it at 88.2 kHz and 96 kHz sample rates using the optical input of a MOTU Ultralite Mk5, looks text book perfect to me for 24 bit data. Tests were done with the REW signal generator on the Pi with the MOTU connected to Mac mini running another instance of REW as REW in Linux would not recognize any inputs beyond the first 2 (TOSLINK is input 13/14).

When I have some free time tomorrow I can run some measurements of the DAC output with a Cosmos ADC to see if there is any difference between USB input and TOSLINK from the Digi+ I/O.

88.2 kHz, 1 kHz tone, 0 dBFS, -145 dB THD+N
View attachment 189849

88.2 kHz, J Test
View attachment 189850

96 kHz, 1 kHz tone, 0 dBFS, -145 dB THD+N
View attachment 189851

96 kHz, J TestView attachment 189852

Maybe the DAC output tests will show something different but this is about as excellent as it can be from a digital transport standpoint.

Michael
Ok, so youre biased having the HAT that sounds worst regarding to changer.

Interesting nevertheless - but I would personally never use a digital transport with a compromised , single clock if using spdif. This clock is gonna be optimized for 44,1 or 48 kHz sampling frequency, not both.
This is my experience after listening ( and having ) a bunch of digital transports thru the years.

The extra cost for the HAT with two crystals is small. Why do you think the ingeneers at hifiberry have two better clocks in the more expensive card , one for each sampling frequency ? Because there is no difference in sound quality ?

The 27 mhz clock used in digi+ seems to be optimized for 48 kHz, which is fine if youre watching tv or movies.
Read more here :
 
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Excellent it may be, this is not investigating difference in sound presentation.
 
Ok, so youre biased having the HAT that sounds worst regarding to changer.
Worse is too big a word in this regard. The Digi+ Transformer serves me well at the moment, much better than my focusrite 2i2 did. The Digi2/Digi+ Pro is simply producing a deeper sound, the lower frequencies being more compact, the higher freer standing, combining together in a more open presentation. I cannot hear any flaws with the Digi+, but I could note the layer which is occluding the details in HF and LF when comparing. Against BDWoody’s school book remark, that this is a result of sighted listening, I must insist he cannot know because he is barely in a position of knowledge in this regard, has he not even listened to both devices at all. The different signature is perceptible, I regard the new version as superior, but the Digi+ is probably not a bad device.
 
Why do you think the ingeneers at hifiberry have two better clocks in the more expensive card , one for each sampling frequency ? Because there is no difference in sound quality ?

Not that has been shown so far.

They've convinced you it matters, which is all that matters to them.

Still no evidence the units chosen sound different.
 
Ok, so youre biased having the HAT that sounds worst regarding to changer.

Interesting nevertheless - but I would personally never use a digital transport with a compromised , single clock if using spdif. This clock is gonna be optimized for 44,1 or 48 kHz sampling frequency, not both.
This is my experience after listening ( and having ) a bunch of digital transports thru the years.

The extra cost for the HAT with two crystals is small. Why do you think the ingeneers at hifiberry have two better clocks in the more expensive card , one for each sampling frequency ? Because there is no difference in sound quality ?

The 27 mhz clock used in digi+ seems to be optimized for 48 kHz, which is fine if youre watching tv or movies.
Read more here :

Who says I don't also have a Hifiberry Digi2 Pro (and also an Allo Digione)? I purchased the Digi+ I/O because other folks on the forum were interested in using it with CamillaDSP and I like to tinker, it is a great way to add SPDIF to a USB multichannel DAC like the MOTU M4 or the DIYINHK ES9016/9038 boards. I purchased the Digione as I wanted a BNC output to mate with a BNC to AES transformer and it has a really nice aluminum case.

If you think a 27 MHz clock is "optimized" for 48 kHz you are pretty clueless. Clocks optimized for the 48 kHz family will be integer divisible by 48 kHz (6.144 MHz, 12.288 MHz, 24.576 MHz, 49.152 MHz, etc).

Why would they use two crystals? Because people like you pay more for them? Seems easy enough.

You may not believe this but I've done a lots of controlled listening with a variety of clocks. I have a Ian Canada McFIFO / McDualXO which allows for a multichannel I2S stream to be buffered and re-clocked. I originally purchased it to act as a multichannel clock buffer but eventually got in to a bit of clock rolling. For the longest time I swore in sighted swapping that the Crystek 575 sounded the best, but after I had my wife swap out and listen blind I was unable to tell a difference, it was humbling.

See below for both Hifiberry boards along with a variety of clocks I tried in the McFIFO / McDual, from left to right: Crystek 957, generic DIP-14 clock, NDK SDA, Connor Winfield OH6410LF, Crystek 575.

IMG_7517.jpg


Michael
 
Excellent it may be, this is not investigating difference in sound presentation.

Agreed, but it shows that Tangband's point about flawed digital output devices is not the reason for audible differences here.

Hmm...if only there was a way to test whether a difference was actually audible in a controlled way, I'm sure some day someone will think of a way to do it :).

Michael
 
Agreed, but it shows that Tangband's point about flawed digital output devices is not the reason for audible differences here.

Hmm...if only there was a way to test whether a difference was actually audible in a controlled way, I'm sure some day someone will think of a way to do it :).

Michael
Interesting !:)
For me its very simple - always keep the unit that makes you listen to music the most enjoyable way.
If there is no long therm difference - always buy the cheapest one.

You listen to with your ears and life is to short for boring hifi.

This has made me ditch my Yamaha wxc50 playing flac from a NAS , and also AirPlay with a lot of different units - its not good enough, for me.
 
Agreed, but it shows that Tangband's point about flawed digital output devices is not the reason for audible differences here.

Hmm...if only there was a way to test whether a difference was actually audible in a controlled way, I'm sure some day someone will think of a way to do it :).

Michael

Agreed, but we had sorted this out tens of posts before: I am not burdened with doubt.

I kept switching the units until the digital coax showed signs of wear and I could barely return it. I am sure about my judgement, it is on the behalf of others here that this issue is rolling. Btw, I am interested in an explanation, no doubt. Despite this the extra mileage of organizing a double-blind is not my concern, my blind testing was rejected, probably with good reasons, and I am confident with my choices.
 
The people insisting on measurements usually behave as if the person who shares his experience owes the audience a set of data. This is messed up. If they want data, they must provide the means, send the technical equipment which is necessary and if the process is complex, a well structured manual. Also, if it is a lot of work to acquire data, they must think about some reimbursement. Despite that there are guys around with formal training in i. e. engineering, there is also many who have not worked with advanced measuring tools. This means it is a project on its own to comply. I probably wouldn’t do it, it is a lot of work and one must be knowledgeable to make the measurements correctly, so that the data can show something. I have other things to do besides my hobby.
I’m sorry, but I feel like you’re missing the point here. If someone comes onto a science-based forum and makes claims, they need something other than anecdote to back up those claims. Without some verifiable evidence using established methods, subjective claims are nearly meaningless and add little to the conversation. At home, of course, we’re all free to believe whatever we want.
 
Last little bit of data to add to the discussion, here are measurements of the Ultralite Mk5 DAC output with USB and the Hifiberry Digi+ I/O TOSLINK, they are absolutely identical. Only somewhat interesting thing here is that 96 kHz is ~1 dB better than 88.2 kHz from a THD+N perspective with both inputs.

Frequency response, 4V DAC output level, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode. Results are the same across all inputs, it may not look like it here because they are identical but there are four measurements in the plot.
FR.jpg


88.2 kHz sample rate, USB, 1 kHz @ 4 V, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode, -107 dB THD+N
usb_mk5_88.2_thd+n.jpg


88.2 kHz sample rate, Digi+ I/O TOSLINK, 1 kHz @ 4 V, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode, -107 dB THD+N
digi_mk5_88.2_thd+n.jpg


88.2 kHz sample rate, USB, J Test, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode
usb_mk5_88.2_jtest.jpg


88.2 kHz sample rate, Digi+ I/O TOSLINK, J Test, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode
digi_mk5_88.2_jtest.jpg


96 kHz sample rate, USB, 1 kHz @ 4 V, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode, -108 dB THD+N
usb_mk5_96_thd+n.jpg


96 kHz sample rate, Digi+ I/O TOSLINK, 1 kHz @ 4 V, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode, -108 dB THD+N
digi_mk5_96_thd+n.jpg


96 kHz sample rate, USB, J Test, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode
usb_mk5_96_jtest.jpg


96 kHz sample rate, Digi+ I/O TOSLINK, J Test, 6.7 V input level on Cosmos ADC, Cosmos ADC in stereo mode
digi_mk5_96_jtest.jpg


Michael
 
I’m sorry, but I feel like you’re missing the point here. If someone comes onto a science-based forum and makes claims, they need something other than anecdote to back up those claims. Without some verifiable evidence using established methods, subjective claims are nearly meaningless and add little to the conversation. At home, of course, we’re all free to believe whatever we want.
You are getting it all wrong. I have started this thread in which you have placed your injection, to solve a practical question, not to produce measurements. Some guys came around, picked up interest and quickly applied their models to the case. Subsequently turning this into the discussion which you retrospectively normalize as the model discussion of this forum, an ideal not even realized in a fraction of its threads. The wording „claim“ is also wildly off: It suggests an intention, while what I was doing is sharing my experience only. And when someone across the internet tells me this cannot be true, because his model does not allow, I feel inclined not only to chuckle, I will also repeat my experience. This is primary experience, without double-blind testing, but at least not a dude who read a scientific model and tells me this is the world. It is not me not sufficing a standard, but people who are longing to see their set of beliefs out in the world.

Again, you can pay for measurements with my local HiFi guy, I will ask him for an invoice and leave it here. When it is covered, I will bring it to the measurement bench.

Regards
 
You are getting it all wrong. I have started this thread in which you have placed your injection, to solve a practical question, not to produce measurements. Some guys came around, picked up interest and quickly applied their models to the case. Subsequently turning this into the discussion which you retrospectively normalize as the model discussion of this forum, an ideal not even realized in a fraction of its threads. The wording „claim“ is also wildly off: It suggests an intention, while what I was doing is sharing my experience only. And when someone across the internet tells me this cannot be true, because his model does not allow, I feel inclined not only to chuckle, I will also repeat my experience. This is primary experience, without double-blind testing, but at least not a dude who read a scientific model and tells me this is the world. It is not me not sufficing a standard, but people who are longing to see their set of beliefs out in the world.

Again, you can pay for measurements with my local HiFi guy, I will ask him for an invoice and leave it here. When it is covered, I will bring it to the measurement bench.

Regards
Have you done any reading on expectation bias? Believe it or not, people are trying to help you see that our ears can't be trusted due to the influence of this bias, which is an inherent part of being human. I spent many years and lots of money chasing audio ghosts before I realized I needed to verify what I was hearing with objective tests to counter this bias.


Anyway, I'm done now. Have fun!
 
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Have you done any reading on expectation bias? Believe it or not, people are trying to help you see that our ears can't be trusted due to the influence of this bias, …
My dear, I am reading in this place for two years, there is barely a thread which does not explain this and I find it plausible. Believe it or not.

It does not change a thing in this regards. I have no intention to spend my time on a double-blind (only have one board atm anyway) and have found the one S/PDIF board to be better. I have created filters for my speaker which I thought where marvelous before I learned they where junk. I have had a intimate relationship with speaker linear distortion measurements over the last year and learned my lessons. But I stand with what I said, despite all the people who read the smart book. And I cannot help you with your scientific vision, only tell some ‚anecdotes‘.
 
My dear, I am reading in this place for two years, there is barely a thread which does not explain this and I find it plausible. Believe it or not.

It does not change a thing in this regards. I have no intention to spend my time on a double-blind (only have one board atm anyway) and have found the one S/PDIF board to be better. I have created filters for my speaker which I thought where marvelous before I learned they where junk. I have had a intimate relationship with speaker linear distortion measurements over the last year and learned my lessons. But I stand with what I said, despite all the people who read the smart book. And I cannot help you with your scientific vision, only tell some ‚anecdotes‘.
This was an interesting thread. :)
In another thread, someone recently tested the Douk U2. A USB bridge with spdif that measured very well, infact like ”state of the art” equipment in hifi. The interesting thing is- I own a Douk U2 and there is still a slight difference in soundquality with my Genelec 8340 compared to my sky song xmos208 driven on batteries. The latter sounds better. Both does it measure better than Douk U2 ? I doubt it .

This is during long term listening - its more fun and the music sounds slightly more natural with one of the USB bridges.

 
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