Bought one of these as it looked easy to modify and was cheap enough. Not recieved yet but has anyone got one?
Assembly TDA1543+CS8412 DAC Audio Decoder Board Stereo HiFi Audio DAC | eBay
First job will be checking the output stage against the data sheet and looking to add separate psu rails.
Is worth powering the CS8412 with it's own rail?
Cheers
Assembly TDA1543+CS8412 DAC Audio Decoder Board Stereo HiFi Audio DAC | eBay
First job will be checking the output stage against the data sheet and looking to add separate psu rails.
Is worth powering the CS8412 with it's own rail?
Cheers
Finally took delivery of this board.....took ages to come but was well packaged.
It has 2 lm317. Haven't measured but assume the reg for the tda1543 is at 5v, but will confirm.
I shall improve the psu side. I have a couple of XRK simple cap mx boards and also a couple L adapters signed up for. I am good with the PSU side.
However, I'd like to improve the output stage. It appears to employ a single resistor and cap per channel. Simple enough. Caps are 220uf Panasonic FC...the resistors I haven't yet removed to check value. Although I shall test it as shipped first to check it works.
I have had a good read around about this DAC chip and associated I/V and output stage. I find so many different values of R and for the filter...can a recommendation be made here for this board?
Am I right in thinking the value of the I/V R alters with DAC chip Vdd? I will initially stay at 5v but maybe would like to try upping the voltage. Is there a formula for working this R ?
And does this R value need to change if I stack multiple tda1543 on top.?
Thanks
...edit.
Got the IV wrong.....there are 1k R and some Epcos Film....unsure of values....so the FC and other R must be the DC blocking.
It has 2 lm317. Haven't measured but assume the reg for the tda1543 is at 5v, but will confirm.
I shall improve the psu side. I have a couple of XRK simple cap mx boards and also a couple L adapters signed up for. I am good with the PSU side.
However, I'd like to improve the output stage. It appears to employ a single resistor and cap per channel. Simple enough. Caps are 220uf Panasonic FC...the resistors I haven't yet removed to check value. Although I shall test it as shipped first to check it works.
I have had a good read around about this DAC chip and associated I/V and output stage. I find so many different values of R and for the filter...can a recommendation be made here for this board?
Am I right in thinking the value of the I/V R alters with DAC chip Vdd? I will initially stay at 5v but maybe would like to try upping the voltage. Is there a formula for working this R ?
And does this R value need to change if I stack multiple tda1543 on top.?
Thanks
...edit.
Got the IV wrong.....there are 1k R and some Epcos Film....unsure of values....so the FC and other R must be the DC blocking.
Last edited:
@DF96 has the definitive guide to choosing resistors for TDA1543 : Dave Kimber's audio pages - TDA1543 passive I/V resistors
I must confess I can't yet see why a 5V supply cannot work with an 820R resistor to GND.
My math goes like this - perhaps you can spot my error:
The output compliance range is 1.8V to 3.8V with a 5V supply - that's a 2V swing.
Since the full-scale output current is 2.3mA the resistor needs to be 2/2.3mA which is 870ohm so choose the nearest lower value - 820ohm. This gives us 1.89V swing in practice.
To set the quiescent point mid-way between the compliance extremes means 2.8V. At the quiescent point the current through 820ohm is 2.8/0.82 = 3.4mA. The current through the controlled current source (to GND) will be 1.15mA so the fixed current source needs to produce the sum of these two currents which is 4.55mA. Half this is 2.28mA. The reference voltage is 2.2V hence we need a 2.2/2.28mA = 965ohm hanging from pin7.
Where did I slip up?
My math goes like this - perhaps you can spot my error:
The output compliance range is 1.8V to 3.8V with a 5V supply - that's a 2V swing.
Since the full-scale output current is 2.3mA the resistor needs to be 2/2.3mA which is 870ohm so choose the nearest lower value - 820ohm. This gives us 1.89V swing in practice.
To set the quiescent point mid-way between the compliance extremes means 2.8V. At the quiescent point the current through 820ohm is 2.8/0.82 = 3.4mA. The current through the controlled current source (to GND) will be 1.15mA so the fixed current source needs to produce the sum of these two currents which is 4.55mA. Half this is 2.28mA. The reference voltage is 2.2V hence we need a 2.2/2.28mA = 965ohm hanging from pin7.
Where did I slip up?
Well if my math isn't in doubt then @DF96's must be. Probably not his math though, perhaps an assumption too far - like assuming the controlled current source pulls 2.3mA at the quiescent point, that would do it as then the fixed current source can't deliver enough to maintain 2.8V on the output. Pure speculation though.
Checked the supply voltage and it is indeed regulated to 5v.
However I haven't managed to get any music out of it yet! And I removed the DC Jack and RCA connectors so I can't really send it back....hey ho.
Any easy tests I can do with a DMM? Powers up but that's about it. Have tried coax and opti....played with the switch....zip.
However I haven't managed to get any music out of it yet! And I removed the DC Jack and RCA connectors so I can't really send it back....hey ho.
Any easy tests I can do with a DMM? Powers up but that's about it. Have tried coax and opti....played with the switch....zip.
Power supplies are always the first thing I check - presumably you have 5V between pin4 and pin5 of the DAC chip. So do you have power on the CS8412?
With a DMM I don't think you can check for the presence of an S/PDIF signal, that would call for a 'scope. You can perhaps check for there being a WS - if your DMM responds to the average you can see if TDA1543 pin 2 has a 50% duty cycle squarewave on it. It should read half the CS8412's supply voltage (use DCV range, not ACV) when a valid signal is decoded by the CS receiver.
With a DMM I don't think you can check for the presence of an S/PDIF signal, that would call for a 'scope. You can perhaps check for there being a WS - if your DMM responds to the average you can see if TDA1543 pin 2 has a 50% duty cycle squarewave on it. It should read half the CS8412's supply voltage (use DCV range, not ACV) when a valid signal is decoded by the CS receiver.
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