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Old 4th February 2012, 06:37 AM   #1061
rsdio is offline rsdio  United States
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Quote:
Originally Posted by linuxworks View Post
forgive the 'informal construction' (lol)
What a minute... isn't styrofoam slightly conductive, which would be why it is used to store chips until they're soldered? You must be getting strange results running that board with its pins and bottom conductors touching foam.
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Old 4th February 2012, 06:46 AM   #1062
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Styrofoam has a very high surface resistance and you can destroy a chip pushing it into styrofoam from static buildup. Look for the black or pink foam/plastic for it to be conductive. Don't store Li cells in the pink or black foam or they will be dead. Using it this way should be fine.
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Old 4th February 2012, 06:52 AM   #1063
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Very interesting consideration, but I would say SPDIF input and USB input are fundamentally different, and should not be combined in a minimalist project.
I guess I was not clear that the combo was not a suggestion for this project. If you read through what the fifo does it is similar to what async usb is doing, in that the clock is fixed and at the dac end. The fifo acts as a dynamic buffer that allows a small difference between input and output frequencies. The output clocks could be the same clocks that the USB interface uses.

But that is not for Borge's project.
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Old 4th February 2012, 07:52 AM   #1064
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Nice! I'm working on a "formal construction" these days. The AB-1.12 board already has the ES9023 swapped out and the PCM5102 swapped in. I'm working on including the regulator by Demain and Oneoclock. In addition it will have footprints (but no PSU/IVC) for ES9012/18. It will also have an SPDIF output and improved front/back plates.

This will be a naked board (at least to begin with). That means you'll have to recycle the module and box from an AB-1.1 kit.

I'd like your input on:
- The purpose of the diode in the regulator and wheter a generic 1N4148-ish SMD can replace it.
- Pinout for external I2S interface, its driver / flip-flop and the direction of MCLK on such a thing.

Have a nice weekend!

BÝrge
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Old 4th February 2012, 01:24 PM   #1065
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What a minute... isn't styrofoam slightly conductive, which would be why it is used to store chips until they're soldered? You must be getting strange results running that board with its pins and bottom conductors touching foam.
I am getting one quirk: sometimes I hear skipping or some kind of data artifact; almost like analog tape saturation. I'm using older factory shipped firmware and standard linux using 16/44.1 (nothing higher; still using pulse audio). but I don't think its anything to do with the circuit. I probably need to upgrade firmware on the usb audio widget.

my longer range plans are to have the small dac on a board and also 2 gangs of spdif switch - as part of a larger preamp system. I'm thinking of using the wm8804/5 as the i2s decoder and this ti chip for the dac. the main purpose is to have 2 spdif switchable outputs, independantly, and also be able to feed one into a 'courtesy dac' (this dac chip added just because its cheap and easy and some users may find it useful).

once my wm8804 is built up, I'll move the 'foam board' (lol) to another box. for now, though, this was a super easy way for me to test the TI chip by having a convenient i2s there for me to splice into.

next test is to remove the system clock and have the TI chip derive it locally. that sounds more exciting to me; I like being able to run 1 less high speed data line!
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Old 4th February 2012, 09:25 PM   #1066
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removed the foam and moved the DAC chip over to an spdif receiver, for more testing:

Click the image to open in full size.

yes, I'm cheating - I'm using a $30 fiio d3 dac, out of its case, and tapping its i2s lines. (not easy to do with fat ribbon cable. I know, its my own fault, lol).

I really like this dac chip.

and I love the fact that it can run on 3wire i2s.

dump that ESS stuff and go PCM! the TI is much more DIY friendly (I was told that to buy the ESS, its min order of 25 units and is only sold via 'authorized distributors' which does not sound reassuring, to me).
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Old 5th February 2012, 12:10 AM   #1067
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This will be a naked board (at least to begin with). That means you'll have to recycle the module and box from an AB-1.1 kit.
I like the idea that you've designed a USB module that plugs in to an analog board. For one thing, I would like to make a balanced output analog board without necessarily messing with the USB again.

However, I'd like to suggest that maybe you should find a way to connect the boards without having the USB module eat up a bunch of blank space on the analog board. In terms of PCB costs, this blank space represents an extra charge for most methods of fabrication. Some smaller shops charge by the square inch, and this means you pay extra. Other shops do not specifically charge by size, but they cannot fit as many boards on a panel when the boards are bigger, so it still ends up costing more.

Seems like if you swapped the back panel jacks so that the RIGHT and LEFT were on the left side and with the USB jack on the right, then your analog board could be a much smaller rectangle that only fills about half the inside of the case. The USB module would then fit on its own.

I realize that this introduces a huge problem of how to connect the two boards. Would it be better to have separate ribbon cables for LCD, UART, power, GPIO, and then special cables for I2C?

Sorry for suggesting such a drastic change, but I always find it awkward when one PCB installs over another, especially if there is nothing but blank space below.
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Old 5th February 2012, 12:13 AM   #1068
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If you read through what the fifo does it is similar to what async usb is doing, in that the clock is fixed and at the dac end. The fifo acts as a dynamic buffer that allows a small difference between input and output frequencies. The output clocks could be the same clocks that the USB interface uses.
Similar, but still fundamentally different. Although it is possible to fix the clock at the DAC end of a FIFO, it is not possible to send rate control message back through SPDIF to the media source. With USB, there is a UAC protocol that passes the rate control back through USB, the driver, and to the audio software.

But, I understand that you're talking about a related design and not BÝrge's.
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Old 5th February 2012, 02:17 AM   #1069
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I am getting one quirk: sometimes I hear skipping or some kind of data artifact; almost like analog tape saturation.
darn it. update: it was my cd rip! doh! either a bad recording or a bad rip to flac. false alarm. carry on
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Old 5th February 2012, 02:23 AM   #1070
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Nice! I'm working on a "formal construction" these days. The AB-1.12 board already has the ES9023 swapped out and the PCM5102 swapped in. I'm working on including the regulator by Demain and Oneoclock. In addition it will have footprints (but no PSU/IVC) for ES9012/18. It will also have an SPDIF output and improved front/back plates.

This will be a naked board (at least to begin with). That means you'll have to recycle the module and box from an AB-1.1 kit.
that sounds good. spdif-out was one thing I wanted to add and I'm in the process of hacking a spare wm8804 into this for simple i2s->spdif conversion.

if you have room, dual output (concurrent) of toslink and coax would be a nice flexible option.

Quote:
I'd like your input on:
- The purpose of the diode in the regulator and wheter a generic 1N4148-ish SMD can replace it.
- Pinout for external I2S interface, its driver / flip-flop and the direction of MCLK on such a thing.

diode? which diode? (sorry if I was not following the 100+ page thread all the way).

pinout for i2s might having .1 spacing, IDC friendly rows and alternating grounds and signal? just a guess. include power and ground on there so that the connector is 'complete'.

maybe put the 'optional' mclock toward the end. how about missing 2 pins (as sort of a key) and then putting that optional clock on one pin and a gnd on the other. that way you could run a lesser-pinned cable and ignore the last 2 pins if you don't need that clock. the gap would allow (maybe) the 'abbreviated' IDC connector for those that don't need the clock.
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