Raspberry Pi I2S to SPDIF Hat

I see. I didn't realize the unit in your pictures was the P2. Thanks.

 

Sound good re: the digital side.

Think you mean ~1ps or ~0.001ns jitter, can't possibly be as high as 1ns!

 

got mine!

hello scott, did you noticed improve in these boards using them with a pi zero?

 

I may have missed this before, but what are people using for linear power supplies?

 

No I do mean 1ns. You're thinking of the clocks themselves which measure down into the pico seconds. But the carrier where the digital data is encoded on and then the clock is recovered from has a different requirement. 1ns is actually very good. For example, the S/PDIF spec for BNC, 24-bits@ 96Khz allows for 80ns.

Cheers,
Michael

It might very well be lower, but the 1ns is the limit of our test equipment

 

Cool, that makes sense. Thanks!

 

Since the audible results of all your guys testings for the digital side seems to be very positive, I think we can assume that the jitter is likely to be very good. But I do need to find a way to test it more accurately. Both the Dscope and the Audio Precision units are only good to one nano second.

Now you've got me thinking about it! It is definitely gonna cost me some money to resolve my curiosity.

Cheers,
Michael

 

@drfindley
using this one from the bay :

supposedly a LT3042, cabled it between the HifiBerry standard PSU and the Pi, removed the R3 on my Digi+ pro so as to have only the onboard 3.3V LDO do its work and it seems to be an improvement! (just removing R3 seemed also to be an improvement while still usind standard wallwart)
(had to solder the wallwart directly on the big cap as this board should be used with AC voltage in, hence the 4 diodes)
Pi3 with PiCorePlayer is lean enough that the radiator on the mosfet is just reaching a couple degrees (°C) above room temperature.
I'll be using this same setup when my 502 reach home! (and report back of course)

 

At last, somebody making the distinction between phase jitter (down to the ps levels) and transport jitter!

Do you have a measure of pulse distortion, too?

 

Phase jitter is also very difficult to measure. What we rely on are the clock sources that we use. The NDK SD2025 series are rated very close to the Crystek 900 family. Much less expensive and smaller.

At some point cost becomes prohibitive to improve that jitter. Our feeling is that in the digital domain any further improvement would be pointless. Because you are creating a transport stream and sending it down a cable there's going to be far bigger factors that will impact the sound quality than the clock jitter. It's still really important, but I think we have an extremely good set of clocks.

For something like a saber DAC you might want to use a little bit better clock because they use an ASRC with a fixed frequency clock to push the samples out. There the Crystek clock is possibly worth the money (which is over $20 USD).

Cheers,
Michael's

 

Yes please do post your results. Also please compare your results to the 502DAC built in regulator which is also an LT3042. You may find the results a dead heat.

Cheers,
Michael

 

I'm using a Wyrd

 

Nice! We mentioned that a bit earlier, just fyi--

http://www.superbestaudiofriends.or...-pi-i2s-to-spdif-hat.1990/page-39#post-117222

Like referring to it as the "carrier" (or "transport") -- I seem to always use "the overall spdif clock" to refer to that... for example:

http://superbestaudiofriends.org/in...t-that-made-me-happier.1970/page-9#post-89021

 

You have the Wyrd hooked up to a 502DAC?

 

I ended up buying the IFi ipower 5v power supply. It is a switching power supply, but from all the research I have done it compares very favorably to linear power supplies costing multiple times more, and it is filtered so not to dirty up the power line like most cheap switching power supplies do. It is also very efficient and doesn't waste watts like some of those big linear power supplies do (if you are worried about such things). I was thinking about buying a cheap power supply (Condor or the like) off of Ebay for $30> That would have worked and been an improvement over a cheap 5V phone charger, but it is very DIY to put together.
The IFi seems like the best bang for buck without going DIY. Cost $49 on Amazon or BHphoto shipped.

 

I do. It powers the pi and hat

 

Thanks for the discount, Michael. I've been watching this unfold for some time now & have just ordered a 502DAC. The clincher for me is the AES interface. I currently use a Digi+Pro, so comparisons will be interesting.

 

Order placed.

Thanks Michael

 

@Michael: Order placed too! In the end you just managed to have some boards done way before the date we were thinking about, that's great!

 

What are peeps using for a case? Any off the shelf cheapo cases?