Worlds Greatest DAC and what it does differently

[pkane2001]

1 hour ago, beerandmusic said:

 

And just for reference purposes, does anyone know what a 1khz signal would look like digitally?

say 1/10 of one second recorded at 44.1K and assume "cleanest" with no attenuation....or in layman's terms, the "most simple".

 

If you are looking at the differences in the human-audible range, these "VAST" differences would be a VAST exaggeration. A 1kHz sine wave reproduced by most competently designed DACs (possibly excluding some NOS R2R types) will look like a 1kHz analog sine wave. You'll need to zoom in with a magnification of 10,000x times or more to start to see some minor differences, and that would be with some of the poorer performing DACs.

[pkane2001]

2 minutes ago, beerandmusic said:

 

Thank you sir!  I have always known that you are well respected for your knowledge but have been a bit of a pain in the past, so this type of response to a layman such as myself that is just seeking to gain knowledge to make a knowledgeable purchase is well received and appreciated.

 

Compliment received and acknowledged 😜

 

[pkane2001]

6 hours ago, fas42 said:

 

My point is that I very much doubt you will ever measure anything significant by what happens to a 1kHz waveform - only by setting up quite a sophisticated test layout - and, no, I don't know what that would be - would one have a chance of understanding what is the nature of the underlying distortions, etc ... In the meantime, I use my ears, with music ... 😉.

 

It can be significant, but usually not enough to fully characterize a DAC. A 1kHz signal can show significant distortions and noise. If it does, it points to problems with the analog, and possibly the digital section. If 1kHz looks good, it doesn't mean the DAC is perfect. There are more tests that can reveal other issues, including measuring distortions at other frequencies, timing/jitter, signal level linearity, filter type and shape, etc.

 

[pkane2001]

To give you an idea of the scale of the error, here's a 1kHz sinewave captured from a non-audiophile DAC (purchased for $20 used).

 

There are two overlapping waveforms here. Pink is the measured, captured digital waveform, while blue is the original, mathematically constructed sinewave:

 

The DAC isn't great as far as measurements are concerned. Here's that same 1kHz capture in the frequency domain, showing distortions (all peaks that are not at 1kHz are distortion), fairly high noise floor, and some stray noise signals. No doubt some of these are responsible for the tiny difference above.

 

[pkane2001]

1 hour ago, Miska said:

 

Given that the other DAC here is running 16-bit R2R at 192k sample rate, you don't need to zoom much to see stair steps on it. Or in frequency domain to see images at multiples of 192k sampling rate...

 

Vastly different, to a well performing DAC, the difference in image levels is in several tens of dB, even close to 100 dB.

 

 

True, and that's why I said 'excluding some NOS R2R types'. I wasn't aware that we were discussing a specific DAC here, but DACs in general. Maybe I missed this part. 

[pkane2001]

19 minutes ago, beerandmusic said:

so to clarify pkane, are you saying and confirming with MISKA that schiit bifrost mb DAC does have problems and that there are audible differences at the analog output (even with a 1k sine wave)?

 

Audible or not, I'm not going to say since that depends on you, what you listen to and what you can and cannot hear. Suffice it to say that I think it should be audible. To me, a 1kHz that looks like an obvious staircase isn't a proper reproduction of a sinewave. 

[pkane2001]

13 hours ago, beerandmusic said:

Just out of curiosity, you said vast differences would be a vast exaggeration except for certain pcm dacs....What pcm dacs would be more accurate?  I really don't want to have to build a fancy computer with fancy power supply to handle high rate dsd if pcm 192k would be sufficient...is there a PCM dac that would do better at accuracy that you could recommend or are you in the DSD camp?

 

I find DSD and PCM pretty much interchangeable, although PCM is much simpler to use in my application since I use various plugins and convolution filters as part of my audio chain. R2R NOS DACs with no software oversampling/filtering are not the correct (mathematically) way to reproduce sound. They introduce significant distortions and a stair-case waveforms, especially at lower levels, that look nothing like the original signal. This can all be fixed with proper filtering and oversampling in the DAC or in software, such as HQP. Of course, there are those who find the poorly reproduced R2R NOS audio to sound better. But it's not because it's more 'natural' or more 'accurate', quite the opposite.

[pkane2001]

1 hour ago, beerandmusic said:

Don't schiit multibit oversample/upsample? Or they just don't upsample high enough?  I was wondering if you had a recommendation for a "non-diy" PCM dac....or DSD dac that does both PCM and DSD equally well? Many seem to like RME adi-2 and Topping D90?  Would it possibly be beneficial to get an older higher end used pcm dac like ayre or emm?  As you know, it seems everyone on ASR believe all dacs that measure well sound exactly the same...do you fall in that same camp?

 

No idea. Haven't seen a Schiit DAC in person or ever considered one. Measurements I've seen have been OK/average recently, mediocre in the past. As I said, I'm using PCM almost exclusively these days. And while I have a few DACs that are DSD capable, I don't find DSD to be as convenient. And if I were you, I wouldn't take someone else's recommendation on what sounds best, including mine, no matter how many adjectives they use in their description. As far as measurements, RME has some very excellent devices out there, although they are not cheap.

 

An overall better-measuring DAC will be more transparent. I prefer not to make pronouncements on what someone will hear or not, but a DAC that adds a lot of distortion will be less transparent than one that doesn't, by definition. And within measurements I include my own DeltaWave null-type comparison that allows me to judge how close the reproduced musical waveform is to the original source. One of the main reasons I wrote DW was that I wanted an unbiased way to judge things like DACs, DDCs, amps, power supplies, software, and even cables. 

[pkane2001]

13 hours ago, Miska said:

 

Challenge is always to find a suitable capture device that has enough bandwidth and resolution and doesn't have analog + digital anti-alias filters that would complete otherwise incomplete reconstruction of the analog waveform...

 

So far I need to use three different measurement devices for complete set of measurements.

 

 

It's a challenge, but not a major one. There are excellent ADC devices out there, and some are inexpensive if you look at the Pro market. I rarely need one to go beyond 192kHz/24 bits, but when I do, I use a 100MHz DSO for that. 

[pkane2001]

15 hours ago, beerandmusic said:

So what have you discovered using this DW software regarding what dacs came close to reproducing to the original source?

Also, any surprises in all your testing?

 

 

I found that some inexpensive devices are often not very good, while others are really excellent. I've also found that pro devices are often a much better quality than some high-end audiophile ones, and at a lower price. Lately, I've been buying most audio equipment on the used pro market.

 

I found no obvious differences between audiophile and generic USB cables. I found very little difference between interconnects. I found some of the audiophile power-supplies to generate more noise than non-audiophile, stock versions. I found some of my older (high-end) DACs to be OK, but not anywhere near the performance of many modern, inexpensive DACs.

 

One finding that I didn't expect: I found many ground loops between devices. In my testing, ground loops are the norm. Rarely do I see a device that's fully immune to them, even with balanced interconnects, etc. It's really important to make sure these do not exist in your system before deciding to upgrade any of the components. Sometimes these manifest themselves in a low-level noise, sometimes rise to an audible hum. This is also an area where pro equipment seems to perform better.

 

 

[pkane2001]

2 hours ago, Miska said:

 

Yes, but I'm not talking about source files. I'm talking about checking DAC's reconstruction performance, and thus that needs enough bandwidth and dynamic range to capture all the output until it falls into the analog noise floor.

 

Remember that 192k 24-bit file contains a very long series of images until the zero-order-hold function falls into -144 dB at very high frequencies. When you want to reconstruct things, you need to remove all images and leave just the base band. Otherwise you are not getting the original analog waveform but something else.

 

I have 200 MHz DSO, but it has only 8-bit resolution, although it has 1M point FFT it still lacks a lot of dynamic range. So that's only the third instrument I use to do some basic checks about EMI/RFI output.

 

 

My testing usually focuses on the audible range. I let DAC do what it would normally do to reproduce the source file, then do a null-compare of the recorded result to the original file. DeltaWave allows me to apply an arbitrary low pass filter, so I usually do that to limit the result of the comparison to, say, under 20kHz. 

[pkane2001]

1 hour ago, beerandmusic said:

I personally would rather have a solution that recreates as accurately as possible than one that just focuses on what is percieved as the "audible range" if it can be done relatively inexpensively. 

 

With DeltaWave you decide what upper frequency is good enough. I know my hearing is diminished above 15kHz, so no reason for me to keep looking much above 20kHz.

 

1 hour ago, beerandmusic said:

Can you provide some examples models, especially if they isolate well?

 

Didn't keep track of this. I just found that I needed to fix ground loops nearly every time I tested by using separate power supplies (one being battery powered) or by using Toslink.

 

1 hour ago, beerandmusic said:

 I am surprised there would be any difference in interconnects unless they were just "loose"? 

 

Measurable differences well below -100dB, so nothing to get excited about. But yes, there were measurable differences.

 

1 hour ago, beerandmusic said:

What inexpensive modern dacs do you have first hand knowledge with that you are comfortable making this statement?

 

Nearly every one that's been measured on Gearslutz, since most posted a captured audio file that I could run through DeltaWave. At one point, I was planning to construct my own measurements list for all of these captures, so I downloaded and processed them all through DW. Had a recent disk crash and lost the files and the results. Maybe when I have a little more free time in the future, I'll try to do this again. Oh, and about 15 or so DACs that I have in my physical possession, from cheap SoundBlaster and Behringer interfaces to higher-end but still inexpensive Focusrite, UAD, and Apogee models.

 

[pkane2001]

33 minutes ago, beerandmusic said:

I routinely use toslink as it always sounds better than USB "to me", so perhaps i have ground loops (but i don't hear any hum or constant noise, that is typically suggested regarding them, but maybe it is above my hearing level but still affects the overall sound).

Since toslink isn't an option if i want to play native DSD files, i continue to look for different usb solutions.  When you say you use differeent power supplies, do you use them with the source or the dac? And are there any inexpensive power supplies that you have found that consistently improve this issue?

ground loops can be just a slightly elevated set of noise spikes, easy to see in a measurement but not obvious when listening. When measuring a device, I just make sure that the devices are not connected to the same power line. For example, use a laptop running off a battery while the DAC is running off AC power.

[pkane2001]

32 minutes ago, beerandmusic said:

PKANE>>

 

 

 

WHen you use one of those models on Gearslutz, did you still have to use a "better" power supply?

I have no control over how these were recorded, since these were done by others. Since a lot of these were recorded using an audio interface (the DAC and the ADC are both in the same unit) the chance of ground loop being formed between them is much smaller.