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Introducing DIY fiber optical i2s send/receive boards

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vortecjr

vortecjr

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Joined 2009
sonore.us
derekr said:
I like it and, depending on price of course, am in. A few questions:

From the PCB image it looks like you’re using an SFP cage. Will there be an option for an open SFP cage and my choice of transceiver? I already run 1Gbase LC fiber to a Roon server.

Which leads to the next question - will it be Roon Ready?

I am assuming that if, like me, the primary source is a server with fiber out to an SFP-equipped switch then all I need do is come out of a second SFP port on the switch with my choice of transceiver to your SFP-cage equipped board and then into the DAC via i2s?

How are you handling the clocking?

The two similar existing offerings I can find don’t tick all the ‘audiophile’ boxes - the Engineered-DOCK ticks all the boxes except it’s too pricey, isn’t Roon Ready and it’s using RJ45 (I exchanged emails with Alexandre re an SFP-equipped backplane but he didn’t seem too interested) and the Conversdigital offering is FastEthernet only, doesn’t do DSD (I think) but it is Roon Ready and affordable. The WiFi option, if one wanted to go that way, is under U$25. Not sure of current pricing but main board was under U$100 awhile back and is used by the likes of Bel Canto and Ayre.

You’d have a winner on your hands, both in the DIY community and OEM if you went with the open cage SFP and Roon Ready tag, DSD256, 32/384 etc. like the DOCK but with SFP in. Fiber is cheap nowadays - Netgear make a 2-port SFP switch for around $140. And it has a 12V input power jack so making your own LPS (Salas L-adapter) ticks that box. I’m even trying to talk my ISP into provisioning an SFP-equipped ONT so I can eliminate copper all the way to the DAC.
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We are providing the transceiver/cable to assure proper operation. This is a send and receive board and it does not know anything about Roon or RoonReady so all streaming protocols are supported:) Those devices you listed are endpoints or renderers. This is only an optical link for digital signals. The plan is to eliminate copper all the way to the DAC!
 
TNT

TNT

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Joined 2003
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vortecjr said:
From the first post, "The conversion chips utilised onboard have a low additive jitter of 30fs which is 100 to 1000 times less than the standard LVDS parts." That is based on the part spec. I don't have a measurement for you yet ...
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I'd be impressed if you can measure 30 Fs with any accuracy ;)

What is your test gear?

Can you tell us which circuits it's based on so we can read the spec-sheets?

//
 
vortecjr

vortecjr

Member
Joined 2009
sonore.us
TNT said:
I'd be impressed if you can measure 30 Fs with any accuracy ;)

What is your test gear?

Can you tell us which circuits it's based on so we can read the spec-sheets?

//
Click to expand...
Indeed. I have two partners and they are doing their own testing each being very well equipped. I'm going to do some basic measurements here with my AP comparing an internal i2s loopback, sending i2s doesn't through the AP's Digital Serial I/O interface and looping back the end of the cable, sending i2s doesn't through the AP's Digital Serial I/O interface and the optical i2s boards. I'm holding the circuit spec secret for now:)
 
vortecjr

vortecjr

Member
Joined 2009
sonore.us
TNT said:
Could you cater for some signal replication? Meaning that if I feed input 1, I get the same not only on output 1 but also on 2,3, and/or 4?

Example is that I would like to feed 2 DACs with one clock i.e. using 3 boards.

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With a custom board it is possible to do this. We have discussed internally making this board, but it's not in development yet. Some examples: i2s source feeding multiple devices. Master clock feeding multiple devices.
 
diyiggy

diyiggy

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Joined 2019
I'm not understanding the first illustration : 1. Send i2s from source to DAC and concurrently send the master clock back to the source.


does the device make that in the same time : you can with the same single fiber cable send i2s from a source behind the emiter and while the receiver gets the i2s signal and slave with a masterclock after it the emiter that clock the I2S source (if the source accepts to be slaved, Idon't have a source example in mind yet) ? The total jitter will be the one of the Masterclock + the 30 fs of two of your devices or do you need 4 devices to acheive that : 2 for the I2S and two for the clock signal treated separatly ?


An use I see is for instance feeding an Hypex plate amp after the receiver through the Hypex AES xlr inputt ?



I did not understand if this AES on Fusion amp plates are symetric with multiplexed I2S/I2C or 3 pin plugs I2S for each signal/pin- if first, it will ask a further board between your receiver and the Plate amp digital AES input plug.
 
Last edited:
vortecjr

vortecjr

Member
Joined 2009
sonore.us
diyiggy said:
I'm not understanding the first illustration : 1. Send i2s from source to DAC and concurrently send the master clock back to the source.

does the device make that in the same time : you can with the same single fiber cable send i2s from a source behind the emiter and while the receiver gets the i2s signal and slave with a masterclock after it the emiter that clock the I2S source (if the source accepts to be slaved, Idon't have a source example in mind yet) ? The total jitter will be the one of the Masterclock + the 30 fs of two of your devices or do you need 4 devices to acheive that : 2 for the I2S and two for the clock signal treated separatly ?

An use I see is for instance feeding an Hypex plate amp after the receiver through the Hypex AES xlr inputt ?

I did not understand if this AES on Fusion amp plates are symetric with multiplexed I2S/I2C or 3 pin plugs I2S for each signal/pin- if first, it will ask a further board between your receiver and the Plate amp digital AES input plug.
Click to expand...
These are setup possibilities and you can set it up as needed in your situation. The point is that the boards can send and receive at the same time over the same fiber optic cable. We are primarily discussing the i2s send/receive board, but we are planning AES-EBU send/receive board.
 
diyiggy

diyiggy

Disabled Account
Joined 2019
the AES-EBU may be liked as well by diy people here using pro sound cards external or internal : they are cheap and often with a good quality but mostly with AES-EBU inputs/outputs.


So in relation to the final price and prove of concept about the jitter I may be interrested too.
 
TNT

TNT

Member
Joined 2003
Paid Member
The "i2s" board obviously has an i2s input and a i2s output or you would not call it "i2s" I suppose. So I ask about the external interfaces, are they i2s aware in the sense that if you try to feed the board something else it will not pass it to the other side? If not it is a generic pulse-train conveyor with for separate lines on which you could send an i2s interface on.

But instead, say that you would like to send a a 10base-t signal over on of the lines - would that work?

If it would, I think you might want to reconsider the name of the board as it could do much more than i2s.

//
 
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