Anybody knows about commercial products which use PCM2706 or PCM2707.
I would like to buy one of this and modify to use as usb -> i2s interface to feed my diy dacs.
I built myself shuch a device with a pcm2707 and it works, but sometimes it stop playing on mains noise caused by turn on or turn off of nearby devices such pre, ampli, dac and i have to reboot the pc.
I circumvented the problem improving the mains filtering and eliminating turn on - off click and pop in my pre and ampli, but i never completly understood/solved the problem in the diy pcm2707 circuit.
So this is two question thread:
1) which commercial products with pcm270x?
2) which kind of problem/solution in my diy pcm2707?
For 2) i will post the circuit schematics and layout.
ciao
andrea
I would like to buy one of this and modify to use as usb -> i2s interface to feed my diy dacs.
I built myself shuch a device with a pcm2707 and it works, but sometimes it stop playing on mains noise caused by turn on or turn off of nearby devices such pre, ampli, dac and i have to reboot the pc.
I circumvented the problem improving the mains filtering and eliminating turn on - off click and pop in my pre and ampli, but i never completly understood/solved the problem in the diy pcm2707 circuit.
So this is two question thread:
1) which commercial products with pcm270x?
2) which kind of problem/solution in my diy pcm2707?
For 2) i will post the circuit schematics and layout.
ciao
andrea
Schematics and layout.
For the pcm2707 i used an adapter from TQFP-32 to four 8-pin 0.1 spaced sockets as you can see from the image.
The layout has been only used as an aid to mount the components on a protoboard with blu wires soldered bottom an red ones top, and so is unusable to do a real pcb, for this purpose i am thinking to design a good layout and send it to olimex or others that make this kind of service. I appreciate any kind of suggestion for this.
ciao
andrea
For the pcm2707 i used an adapter from TQFP-32 to four 8-pin 0.1 spaced sockets as you can see from the image.
The layout has been only used as an aid to mount the components on a protoboard with blu wires soldered bottom an red ones top, and so is unusable to do a real pcb, for this purpose i am thinking to design a good layout and send it to olimex or others that make this kind of service. I appreciate any kind of suggestion for this.
ciao
andrea
Attachments
raikkonen said:
Because pcm2902-06 don't have i2s out, only spdif and i already have one sample of 2707 which i used in the circuit of posts 2 and 3 and it works but with the problem explained in post 1.
ciao
andrea
raikkonen said:so it could also be a replacement for cs8414 receiver?
Yes, if your source have an usb port (tipically a pc full of mp3, ogg, wav, ... your preferred OS and your preferred mediaplayer).
No, if your source is a CD player with s/pdif out, in this case you can get rid of cs8414 receiver getting i2s directly from the Cd player (you need a service manual with schematics to see where you can get i2s).
ciao
andrea
sure, but pcm2902 allow the conversion from spdif to usb, and that's what i want to do, but some people say they tried without results...
raikkonen said:sure, but pcm2902 allow the conversion from spdif to usb, and that's what i want to do, but some people say they tried without results...
I am not interested in the conversion from spdif to usb so i did not try with pcm2902, you can look at this:
http://hepso.dna.fi/misc/pcm2902/PCM2902_usb_dac.html
in the pdf on the "schematics" link you can see a connector "P4" with DIN and DOUT, these are spdif in and out at logic level, to convert to have real spdif you can use simple circuits explained here:
http://www.epanorama.net/documents/audio/spdif.html
ciao
andrea
I have a PCB that uses the 2707 to get I2S out. You could certainly leave off most of it and sinply take the I2S signal from where the 1543 usually goes.
http://www.ecp.cc/HPDAC.html
http://www.ecp.cc/HPDAC.html
to anbello
nice project, very very nice...but does the din and dout work?i mean, the pcm2902 can be programmed via i2s, and i think that when powers up it goes into a state where the spdif I/O is not active, and that's probably the issue...comunque grazie!!😀
nice project, very very nice...but does the din and dout work?i mean, the pcm2902 can be programmed via i2s, and i think that when powers up it goes into a state where the spdif I/O is not active, and that's probably the issue...comunque grazie!!😀
raikkonen said:
No, pcm2902 have nothing to do with i2s and anyway i2s is not meant to program a chip it is a serial bus for digital audio (inter-IC sound) http://www.semiconductors.philips.com/acrobat_download/various/I2SBUS.pdf, maybe you are confusing it with i2c (Inter-Integrated Circuit).
From this excerpt of the pcm2902 i think it can get spdif works without problem:
"Digital Audio Interface (PCM2902)
The PCM2902 employs both S/PDIF input and output. Isochronous-out data from the host is encoded to the
S/PDIF output and the DAC analog output. Input data is selected as either S/PDIF or ADC analog input. When
the device detects an S/PDIF input and successfully locks the received data, the isochronous-in transfer data
source is automatically selected from S/PDIF itself; otherwise, the data source is selected to ADC analog input."
Anyway one of the best way to learn is always to read carefully the datasheet.
ciao
andrea
I built a USB DAC using a PCM 2902
It was powered from the USB, built with cheapo components (a few capacitors) and didn't sound so good so I put it aside for a while.
Then I installed it into an altoids box, and connected the SP/DIF instead of the analog signals. I built a DDDAC with 8 TDA1543s in parallel. This sounds pretty good actually. To cut the cost further, you could use just one TDA1543. I have a short USB cable to the 2902, then a long SP/DIF cable (an ordinary RCA <--> RCA cable) to the DAC on the other side of the room.
The PCM2902 data sheet has the schematic you would need, and there's lots of info available about the DDDAC. All the parts for this are pretty cheap, but will take some skill to assemble, unless you can find someone who has made PCBs.
Maybe your best bet is to buy an el cheapo USB --> SP/DIF convertor, and make something like a DDDAC which reclocks the recovered digital data.
It was powered from the USB, built with cheapo components (a few capacitors) and didn't sound so good so I put it aside for a while.
Then I installed it into an altoids box, and connected the SP/DIF instead of the analog signals. I built a DDDAC with 8 TDA1543s in parallel. This sounds pretty good actually. To cut the cost further, you could use just one TDA1543. I have a short USB cable to the 2902, then a long SP/DIF cable (an ordinary RCA <--> RCA cable) to the DAC on the other side of the room.
The PCM2902 data sheet has the schematic you would need, and there's lots of info available about the DDDAC. All the parts for this are pretty cheap, but will take some skill to assemble, unless you can find someone who has made PCBs.
Maybe your best bet is to buy an el cheapo USB --> SP/DIF convertor, and make something like a DDDAC which reclocks the recovered digital data.
I'm also looking for a 'finished' PC interface with I2S 'out'
I was looking into the PCM270x after seeing the $90 Trends UD-10 device which use the PCM2704 version
http://www.TrendsAudio.com/EN/Product/USB_Audio_desc.htm
But the PCM270x chips seams to have several limitation when comparing with todays 24/96 and 24/192 standard
Looking at the data sheet again I find it's only 16bit/48kHz
'The PCM2706 and PCM2707 can support the I2S interface, which is enabled by FSEL (pin 9). In the I2S
interface enabled mode, pins 4, 18, 19, 5, and 17 are assigned as DIN, SYSCK, BCK, LRCK, and DOUT,
respectively. They provide digital output/input data in the 16-bit I2S format, which also is accepted
by the internal DAC.'
and
Sampling Rate: 32, 44.1, 48 kHz
I was looking into the PCM270x after seeing the $90 Trends UD-10 device which use the PCM2704 version
http://www.TrendsAudio.com/EN/Product/USB_Audio_desc.htm
But the PCM270x chips seams to have several limitation when comparing with todays 24/96 and 24/192 standard
Looking at the data sheet again I find it's only 16bit/48kHz
'The PCM2706 and PCM2707 can support the I2S interface, which is enabled by FSEL (pin 9). In the I2S
interface enabled mode, pins 4, 18, 19, 5, and 17 are assigned as DIN, SYSCK, BCK, LRCK, and DOUT,
respectively. They provide digital output/input data in the 16-bit I2S format, which also is accepted
by the internal DAC.'
and
Sampling Rate: 32, 44.1, 48 kHz
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