Author Topic: Need advice/help with I2S Project  (Read 1078 times)

Offline Nidri

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Need advice/help with I2S Project
« on: March 03, 2018, 08:07:34 PM »
So I have this DAC called Aqua la Voce S2.
Like PS Audio, Sonore, GD Audio, Empirical and others, Aqua have included an I2S Interface.
Of course just about everyone implements I2S differently*, with the PS Audio I2S-over-HDMI approach perhaps being closest to a standard.
My DAC's I2S input is via RJ45 (also used by Empirical and others, but with different pin configurations - of course).

This is the Aqua Pin Configuration:


Currently this RJ45 input can be fed by only two products that I know of:
- The Aqua CD Transport (La Diva)
- Pink Faun can supply a PCIe card with an HDMI-to-RJ45 cable specifically wired for Aqua products

I'm really interested in testing the capabilities of this input so am considering two possibilities (the two above are not suitable):

1. Direct USB-to-I2S Adapter

Probably the simpler approach. I would need something like this:
(http://jlsounds.com/i2soverusb.html)
SPECS: (http://jlsounds.com/uploads/Specifications.pdf)
or
(https://amanero.com)

2. Networked I2S Roon Endpoint

Here I would use an RPi or Odroid with separate module/HAT that would provide I2S output points.
The Allo Boss DAC, for example, seems to include I2S connections on the board so an RPi/Boss could form the basis for this approach.
I'm not familiar with Odroid at all though, there must be other options here I'm sure.

Obviously regardless of which approach I take I'll also need to add a case, transformer, cabling, socketry, etc., for example:

RJ45 Plug:
(https://www.audiophonics.fr/en/diy-interfaces/digital-interface-selector-i2s-x2-to-rj45-p-11570.html)
OR
(https://www.audiophonics.fr/en/diy-interfaces/unbalanced-i2s-to-balanced-rj45-ouput-module-board-p-11387.html)

Internal I2S Cabling:
M/F(https://www.audiophonics.fr/fr/connecteurs-circuit-imprime/cavaliers-i2s-flexible-plaque-argent-male-femelle-254mm-15cm-awg-22-set-x5-p-11888.html)
F/F(https://www.audiophonics.fr/en/connectors-for-pcb/i2s-connectors-female-female-silver-plated-254mm-15cm-awg-22-set-x5-p-11717.html)

I2SoverUSB even sell specialised PS boards for their solution:
(http://jlsounds.com/power.html)

Etc. Etc.

So, what do you guys think? I'm aware I might be chasing a very small performance difference here, but you never know unless you try.

1. Which of the two approaches is best? I would prefer an I2S Roon Endpoint (for maximum separation from my Mac), but if it's too complex, then the USB/I2S will also work.
2. Is there someone in Joburg with the required Knowledge/Background/Engineering degree/etc. to help me build this thing? For a fee obviously.

Thanks for reading.
Yes I am a little crazy.

Mods please move this to the DIY section if you feel it's more appropriate.
I just thought that the digital guru's are more likely to hang out here.

* I2S Config Database:
(https://docs.google.com/spreadsheets/d/1h5PMUBkldkpt1rCnAR4ZHYGZNeCe-vwIFyKWYMZWsX0/edit#gid=0)

Offline 2wice

Re: Need advice/help with I2S Project
« Reply #1 on: March 03, 2018, 11:04:11 PM »
I run 2 Amanero and love them to bits.
I also ran i2s straight from RPi and I won't do that again. Day and night difference. I suspect there is a power/clock issue on the RPi's i2s lines.
15cm is too long for i2s I think. Try keep that as short as possible.
It's possible to have 3cm ribbon cable with the Amanero if planned nicely.
Next week I'll have some i2s isolators for Amanero for you for free if you are going that route.
Good luck.

Offline CAD

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Re: Need advice/help with I2S Project
« Reply #2 on: March 04, 2018, 06:27:20 AM »
This is my I2S plankie

Odroid C2
ESS9028QM DAC
30VA R-core TRF
Dietpi-Roon



Sounds ok so far.
Linux Kernel support for I2s seems to be a lot more common for RPI than Odroid

2wice is correct : keep the ribbon cable as short as possible

I also cant help wondering if Xmos/Amenero would be the better way to go

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Offline Nidri

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Re: Need advice/help with I2S Project
« Reply #3 on: March 04, 2018, 12:13:33 PM »
Thanks for the input and advice guys.
I will formulate my plan around an Amanero or XMOS USB-to-I2S design then.
Much simpler.
Also, I didn't realise I2S signals were so sensitive.
Will have to reconsider cabling and enclosure.
n

Offline Rotten Johnny

Re: Need advice/help with I2S Project
« Reply #4 on: March 04, 2018, 03:06:22 PM »
Interesting thread, what makes I2S so sensitive to cable length?
I like beautiful melodies telling me terrible things -- Tom Waits

Free your mind...and your ass will follow.

Offline 2wice

Re: Need advice/help with I2S Project
« Reply #5 on: March 04, 2018, 03:15:48 PM »
This is hearsay by I think they are susceptible to picking up crosstalk and EMI

Offline CAD

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Re: Need advice/help with I2S Project
« Reply #6 on: March 04, 2018, 03:27:48 PM »
Yebo as above from what I have read up.
Perhaps I2s would require special shielding  :nfi:
The way of the warrior is NO match for the way of the wife.
Light travels faster than sound. This is why some people appear bright until you hear them speak.

Offline Rotten Johnny

Re: Need advice/help with I2S Project
« Reply #7 on: March 04, 2018, 03:35:51 PM »
Ethernet cable should then be perfect, no?
I like beautiful melodies telling me terrible things -- Tom Waits

Free your mind...and your ass will follow.

Offline Air

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Re: Need advice/help with I2S Project
« Reply #8 on: March 04, 2018, 04:24:10 PM »

Offline pwatts

Re: Need advice/help with I2S Project
« Reply #9 on: March 04, 2018, 04:26:35 PM »
That pinout is shite. Shielding may help but not for the reasons you think. Change the pinout or the cabling to a proper differential impedance-matched setup (like Ethernet).

Offline pwatts

Re: Need advice/help with I2S Project
« Reply #10 on: March 04, 2018, 04:51:21 PM »
Also, think twice before adding isolators (either on the USB or I2S side). They may provide isolation but it comes at a cost of substantial jitter. In my experience, and what I've read from others who did more in-depth research, designing so that isolation is not necessary trumps adding isolators with substantial margin.

Offline gavinbirss

Re: Need advice/help with I2S Project
« Reply #11 on: March 04, 2018, 08:23:13 PM »
isolation will require separate 5/3.3V power and this may drive need for "cleaner" power to DAC side. 

Be sure to check out DIYINHK for XMOS based chipsets.

A reclocker, like the KALI if DAC is in SLAVE mode may also yield better sonic results.

Pink Fauhn has differential balanced I2S output and HDMI may be the more logical connector here.

Cable length may be less of an issue when balanced.

If forced with RJ45, try CAT7 cable. There are some RJ45 recepticacles that have 8 adjacent pins (2.5mm) for easier hookup.

Offline pwatts

Re: Need advice/help with I2S Project
« Reply #12 on: March 04, 2018, 09:28:28 PM »
Reclocking could help (or not, depending on the quality of the source clock) but it's a band-aid.
If you're stuck with the RJ45 pinout, make sure the cable is kept as short as absolutely possible and experiment with grounding. A regular CAT5 cable will not have shielding. A CAT6 cable may help a bit but not much since it provides improved bundle separation (which may even make matters worse in this case) but lower DCR of the wiring. STP cables may help, but also introduce ground loops since your precious non-isolated single-ended digital ground will now travel with both the internal cables as well as the shield.

So, being limited by the DAC input it's worth to limit the length as much as possible and experiment with cables and grounding.

Offline gavinbirss

Re: Need advice/help with I2S Project
« Reply #13 on: March 04, 2018, 09:59:22 PM »
Quote
Reclocking could help (or not, depending on the quality of the source clock) but it's a band-aid.

Not to split hairs unnecessarily this is in context with using a RPi or Odroid C2 (SBC), a reclocker like a Kali, will have a superior clock. A RPi has a terrible reputation and it is said that it can not even generate a 44.1Khz clock accurately.  Going USB on a RPi will be reliant on a poor performance, especially when trying high "bandwidth" bit rates. Horsepower also limits the DSD-to-PCM capabilities.

Offline Cam

Re: Need advice/help with I2S Project
« Reply #14 on: March 14, 2018, 07:05:27 PM »
This is my I2S plankie

Odroid C2
ESS9028QM DAC
30VA R-core TRF
Dietpi-Roon



Sounds ok so far.
Linux Kernel support for I2s seems to be a lot more common for RPI than Odroid

2wice is correct : keep the ribbon cable as short as possible

I also cant help wondering if Xmos/Amenero would be the better way to go

Nice setup there cad, Im looking at building a similiar but I would like to install into an old cd player. Where did you get your transformer from? An do you think its possible to hook up an i2s dac to a cd player that has coax and spdif outputs?
Also can you comment on the performance of your ess9028 dac? I cant decide whether an ess dac or ak4495 dac would be better..