Author Topic: Stop there is a new King  (Read 1502 times)

Offline Rotten Johnny

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Re: Stop there is a new King
« Reply #15 on: January 25, 2017, 08:36:19 AM »
Really doesn't look that complicated to assemble.
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Offline gavinbirss

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Re: Stop there is a new King
« Reply #16 on: January 25, 2017, 08:54:19 AM »
Really doesn't look that complicated to assemble.

Yip, board, power and usb chipset.

Adding optical can be done for about R 75.

Only 3 supply rails +12V / -12V (can be transformer or DC) / +3.3V DC

4 i2s signal wires (GND, BCK, LRCLK, DATA)
4 output wires for RCA.





« Last Edit: January 25, 2017, 09:04:15 AM by gavinbirss »

Offline Hi-Phibian

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Re: Stop there is a new King
« Reply #17 on: January 25, 2017, 09:04:47 AM »
I2S at 3.3 or 5V level?


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Offline itscraig

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Re: Stop there is a new King
« Reply #18 on: January 25, 2017, 09:21:32 AM »
probably the most simple DIY i have ever done, more complicated to get it running via USB

Offline gavinbirss

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Re: Stop there is a new King
« Reply #19 on: January 25, 2017, 09:51:18 AM »
I2S at 3.3 or 5V level?


"If it sounds good, it IS good."
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3.3V

Offline Hi-Phibian

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Re: Stop there is a new King
« Reply #20 on: January 25, 2017, 09:55:46 AM »
Is it 5V compatible?


"If it sounds good, it IS good."
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Offline gavinbirss

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Re: Stop there is a new King
« Reply #21 on: January 25, 2017, 10:01:30 AM »
Is it 5V compatible?


"If it sounds good, it IS good."
Duke Ellington

Seems not, all at 3.3V level, volume pot +3.3V, Optical needs +3.3V and Coax needs +1.2V.

Offline craig-s22

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Re: Stop there is a new King
« Reply #22 on: January 25, 2017, 01:37:44 PM »
What would something like this cost?

Offline pwatts

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Re: Stop there is a new King
« Reply #23 on: January 25, 2017, 05:56:51 PM »
Is it 5V compatible?


"If it sounds good, it IS good."
Duke Ellington
Depends on the input buffer class, many can translate 5v to 3.3v without problem.

Offline Wolvebain

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Re: Stop there is a new King
« Reply #24 on: January 25, 2017, 07:28:17 PM »
If you want to ensure isolated power from your Soekris boards, can always get a DC Regulator Board, with dual 5V/3.3V output... similar to the MIKROE-192 that itscraig has, and feed it either from a wall-wart or a dedicated power supply for both voltages...

Or, you can take the 3.3v from the Soekris board:

>>Source<<

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Offline pwatts

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Re: Stop there is a new King
« Reply #25 on: January 25, 2017, 10:53:53 PM »
If you want to ensure isolated power from your Soekris boards, can always get a DC Regulator Board, with dual 5V/3.3V output... similar to the MIKROE-192 that itscraig has, and feed it either from a wall-wart or a dedicated power supply for both voltages...

Or, you can take the 3.3v from the Soekris board:

>>Source<<

Took a while to figure out what on earth is going on with the coax input.. then it made sense. Soekris decided to use the FPGA's native LVDS receivers instead of an external one, which is an unusual step and a bit brave since the noise doesn't go through a filtered buffer first but only relies on the transformer's bandwidth filtering. However, the FPGA has blazingly fast LVDS receivers so it's a sensible step. The 1.2V biasing via the 1k resistor is since that's the centre voltage of LVDS, capacitor is just to clean it up a bit. The 330R termination resistor is because the LVDS receiver has integrated 100R resistors, and  the parallel combo gives the required 75ohms.
Personally, I would consider the following changes:
- Use a centre-tapped transformer and apply the bias to the centre-tap instead
- Buffer the bias voltage with a low-noise opamp since the 1.2V rail is not exactly clean
- Add a DC-block to the input since this purely relies on the transmitter to be 100% DC-free (which it admittedly is most of the time, but pulse transformers saturate easily from even small DC currents)
- Perhaps experiment with an external LVDS repeater chip
- Add more filtering to the optical input, either with just a small chip inductor or a dedicated small LDO
« Last Edit: January 25, 2017, 11:04:09 PM by pwatts »

Offline gavinbirss

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Re: Stop there is a new King
« Reply #26 on: February 02, 2017, 11:16:00 AM »
Took a while to figure out what on earth is going on with the coax input.. then it made sense. Soekris decided to use the FPGA's native LVDS receivers instead of an external one, which is an unusual step and a bit brave since the noise doesn't go through a filtered buffer first but only relies on the transformer's bandwidth filtering. However, the FPGA has blazingly fast LVDS receivers so it's a sensible step. The 1.2V biasing via the 1k resistor is since that's the centre voltage of LVDS, capacitor is just to clean it up a bit. The 330R termination resistor is because the LVDS receiver has integrated 100R resistors, and  the parallel combo gives the required 75ohms.
Personally, I would consider the following changes:
- Use a centre-tapped transformer and apply the bias to the centre-tap instead
- Buffer the bias voltage with a low-noise opamp since the 1.2V rail is not exactly clean
- Add a DC-block to the input since this purely relies on the transmitter to be 100% DC-free (which it admittedly is most of the time, but pulse transformers saturate easily from even small DC currents)
- Perhaps experiment with an external LVDS repeater chip
- Add more filtering to the optical input, either with just a small chip inductor or a dedicated small LDO

How would one implement balanced LVDS to a HDMI(i2s) cable like PS Audio?

Offline pwatts

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Re: Stop there is a new King
« Reply #27 on: February 02, 2017, 12:12:30 PM »
Heh? HDMI has nothing in common with I2S.

Offline Wolvebain

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Re: Stop there is a new King
« Reply #28 on: February 02, 2017, 02:21:17 PM »
I believe gavinbirss is referring to the typical cable and external port connection used for I2S, which is HDMI.. seriously doubt he is referring to HDMI standards on I2S
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Offline gavinbirss

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Re: Stop there is a new King
« Reply #29 on: February 02, 2017, 02:53:24 PM »
See picture, also like Pink Faun i2s bridge.




http://www.tnt-audio.com/sorgenti/pinkfaun_i2s_bridge_e.html