Hi,
I have a USB kit with PCM2706/TDA1543 dac on hand. The schematics is as follows:
http://www.audioworkshop.com.hk/download/AW_D3.pdf
I have already replace the usb power for the pcm2706 and pull the power from the lt317 using a tl431 for 5v. There is some improvement after this mod but I can improve this further by using the self-power mode.
I tried to convert the circuit for pcm2706 for self-power mode but failed, got a "malfunction usb device error". Here is what I did:
1. cut the trace and put the P-sel pin to ground
2. connect the Host pin to USB power with 1M resistor to ground
3. connect all voltage pins to a 3.3V power.
Is there anything else I missed? Thanks in advance.
BTW, this dac sound very good, (direct out to a NI gainclone without buffer)
I will stack another 1543 on top for my next tweak.
I have a USB kit with PCM2706/TDA1543 dac on hand. The schematics is as follows:
http://www.audioworkshop.com.hk/download/AW_D3.pdf
I have already replace the usb power for the pcm2706 and pull the power from the lt317 using a tl431 for 5v. There is some improvement after this mod but I can improve this further by using the self-power mode.
I tried to convert the circuit for pcm2706 for self-power mode but failed, got a "malfunction usb device error". Here is what I did:
1. cut the trace and put the P-sel pin to ground
2. connect the Host pin to USB power with 1M resistor to ground
3. connect all voltage pins to a 3.3V power.
Is there anything else I missed? Thanks in advance.
BTW, this dac sound very good, (direct out to a NI gainclone without buffer)
I will stack another 1543 on top for my next tweak.
I finished my first PCM2706 DAC some days ago, to play with different modes.
But, I did not realize, that FSEL must set high to use the internal DAC, same setting as for SPDIF-out.
In the link from audioworkshop you pointed to, Chuck, I found the little comment about FSEL (J2 in this circuit) and got my DAC playing now.
BTW: I found, the chip is sounding better with 4V (actually trying 4.3V
) than with 3.3V.
Franz
But, I did not realize, that FSEL must set high to use the internal DAC, same setting as for SPDIF-out.
In the link from audioworkshop you pointed to, Chuck, I found the little comment about FSEL (J2 in this circuit) and got my DAC playing now.
BTW: I found, the chip is sounding better with 4V (actually trying 4.3V
) than with 3.3V.Franz
Attachments
Thanks for the circuit, Cyteen.
It seems the Vcom, Vccl, Vccr do not need to be connected to 3.3v, that
strange.
I recheck the datasheet, Vcom don't need to be connected but Vccl, Vccr should be connect, this pin is for the dac/analog output.
Hi Franz, good work, yeah the Fsel needs to be selected between SPIF out or internal dac. Are u using the self-power mode?
It seems the Vcom, Vccl, Vccr do not need to be connected to 3.3v, that
strange.
I recheck the datasheet, Vcom don't need to be connected but Vccl, Vccr should be connect, this pin is for the dac/analog output.
Hi Franz, good work, yeah the Fsel needs to be selected between SPIF out or internal dac. Are u using the self-power mode?
I could drastically improve the sound of the first version, by
- decoupling the Vccl/Vccr from the digital voltages by CLC-filter 1000uF/330uH/1000uF
- replacing the 0.022uF MKT caps in the I/V conversion by sowjet MKP's. This caps are a key part, when using internal DAC.
- adjusting the voltage to 3.99VDC (by listening, with regulated supply).
It's sounding definitively better than anything else I heard out of a PC!
Franz
- decoupling the Vccl/Vccr from the digital voltages by CLC-filter 1000uF/330uH/1000uF
- replacing the 0.022uF MKT caps in the I/V conversion by sowjet MKP's. This caps are a key part, when using internal DAC.
- adjusting the voltage to 3.99VDC (by listening, with regulated supply).
It's sounding definitively better than anything else I heard out of a PC!
Franz
Attachments
Franz, did you set the Psel pin high or low (to ground).
Yes, they very good by itself.
I also add your decoupling, but just couldn't bypass the internal regulator.... hey, what am I saying, you are using it in self-power mode, otherwise, you couldn't set it to 3.99v!
Could you tell me which of the V pins are connected to your 3.99v (that is a pretty precise voltage)
Yes, they very good by itself.
I also add your decoupling, but just couldn't bypass the internal regulator.... hey, what am I saying, you are using it in self-power mode, otherwise, you couldn't set it to 3.99v!
Could you tell me which of the V pins are connected to your 3.99v (that is a pretty precise voltage)
That makes sense now I think about it, the above were for i2s only operation. I was forgetting the D3 has the option of either i2s to the tda1543 or the internal DAC.
I have one of these kits on its way, should be with me in a week or so.
One of the other suggested tweaks is to replace the 12Mhz crystal with a Crystek C3390 XO clock.
Any other comments you have about the build would be appreciated.
I have one of these kits on its way, should be with me in a week or so.
One of the other suggested tweaks is to replace the 12Mhz crystal with a Crystek C3390 XO clock.
Any other comments you have about the build would be appreciated.
I do apologies, I didn't intend to take any credit, I just have a pile of spontaniously saved info regarding this which I yet to collate.
I'll take the time in future to save enough back ground to allow full credit to be given or direct links used instead.
http://www.diyhifi.org/forums/files/pcm2707b_112.jpg
which should be:
http://www.diyaudio.com/forums/showthread.php?postid=476950#post476950
http://www.diyaudio.com/forums/attachment.php?s=&postid=476950&stamp=1095592456
and the other:
http://www.diyhifi.org/forums/viewtopic.php?p=6571#6571
http://www.diyhifi.org/forums/files/pcm2707_schematic_413.jpg
well thats where I can across them.
I first came across mention of the XO clock over at the Computer Audio Asylum where John Swenson has been suggesting it. Just search for PCM2706.
I'll take the time in future to save enough back ground to allow full credit to be given or direct links used instead.
http://www.diyhifi.org/forums/files/pcm2707b_112.jpg
which should be:
http://www.diyaudio.com/forums/showthread.php?postid=476950#post476950
http://www.diyaudio.com/forums/attachment.php?s=&postid=476950&stamp=1095592456
and the other:
http://www.diyhifi.org/forums/viewtopic.php?p=6571#6571
http://www.diyhifi.org/forums/files/pcm2707_schematic_413.jpg
well thats where I can across them.
I first came across mention of the XO clock over at the Computer Audio Asylum where John Swenson has been suggesting it. Just search for PCM2706.
Thanks Franz.
Guess I'll have to check my wiring, but converting the existing board to self-power is not so easy as I'll have to pull up the Host pin from the board and connect it to usb power, I must have made a mistake somewhere.
Anyways, some impression of the sound is the pcm2706 dac sound is very good, more hi-fi compare to the TDA1543 which is much more musical.
One interesting note: the data line from the I2S goes though a 74acht before the 1543 and it works without the 5v power (I forgot solder a power jumper), the sound is smooth and somewhat blur, adding 5v to the 74acht and the detail and bass comes back.
Guess I'll have to check my wiring, but converting the existing board to self-power is not so easy as I'll have to pull up the Host pin from the board and connect it to usb power, I must have made a mistake somewhere.
Anyways, some impression of the sound is the pcm2706 dac sound is very good, more hi-fi compare to the TDA1543 which is much more musical.
One interesting note: the data line from the I2S goes though a 74acht before the 1543 and it works without the 5v power (I forgot solder a power jumper), the sound is smooth and somewhat blur, adding 5v to the 74acht and the detail and bass comes back.
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