Akira,
That's good news - glad it's working - my DAC came presoldered on board so unless ESD damage before soldering? I will replace it - just waiting for 2706 samples to arrive.
Another simple DAC possibility is the TDA1387 - an I2S version of TDA1545 (although easier to implement than 1545 chip) which has been loosely compared to TDA1541 as in the same sonic character - analogue like. Slightly lower THD than 1543 -88dB Vs -75dB
Only two issues with this chip -
It is probably only available in smd - although your resoldering of PCM chip leads me to believe that is not a problem for you.
Output is lower than 1543 and will require active stage for I/V (this is also recommended for 1543 for best results)
John
That's good news - glad it's working - my DAC came presoldered on board so unless ESD damage before soldering? I will replace it - just waiting for 2706 samples to arrive.
Another simple DAC possibility is the TDA1387 - an I2S version of TDA1545 (although easier to implement than 1545 chip) which has been loosely compared to TDA1541 as in the same sonic character - analogue like. Slightly lower THD than 1543 -88dB Vs -75dB
Only two issues with this chip -
It is probably only available in smd - although your resoldering of PCM chip leads me to believe that is not a problem for you.
Output is lower than 1543 and will require active stage for I/V (this is also recommended for 1543 for best results)
John
Hi John
Even if it's already soldered to board, still is possible to ESD damage occurs while soldering the other components, isn't it?
You are lucky, TI dont send samples to this part of the world
.
Interesting this TDA1387.
I think it will not be difficult to obtain this DAC in Brazil.
akira
Even if it's already soldered to board, still is possible to ESD damage occurs while soldering the other components, isn't it?
You are lucky, TI dont send samples to this part of the world
.Interesting this TDA1387.
I think it will not be difficult to obtain this DAC in Brazil.
akira
Hi Akira,
I am assuming that this is the oscillator (crystal) with 3ps jitter spec
I sent my AWD3 board back to AW for repair - which they kindly offered to do free of charge. It took quite a time & got it back a couple of days ago. Believe it or not while wiring it up for TDA1543 output I stupidly switched the D+ & D- USB input signals & blew the chip.
At least this time I know what blew the chip & will set about cutting it off the board & resoldering new chip in place
Brent - looked at your site - nice looking board & good reviews - what is the approx price of the stuffing parts for the board?
John
I am assuming that this is the oscillator (crystal) with 3ps jitter spec
I sent my AWD3 board back to AW for repair - which they kindly offered to do free of charge. It took quite a time & got it back a couple of days ago. Believe it or not while wiring it up for TDA1543 output I stupidly switched the D+ & D- USB input signals & blew the chip.
At least this time I know what blew the chip & will set about cutting it off the board & resoldering new chip in place
Brent - looked at your site - nice looking board & good reviews - what is the approx price of the stuffing parts for the board?
John
DAC cost
Hi jkeny,
The cost for parts for my DAC is around $350 US. Which sounds high but it is really two separate circuits on one board and there are some expensive parts like Black Gate caps and OPA627 opamps.
Parts for just the DAC half of the board (there is a score line between the boards to separate them if one wishes or order half a board) is around $200.
The reason I include a Preamp/buffer is that a passive I/V stage sounds very lifeless without it. Having a volume control onboard makes it easy to connect directly to a power amp.
~~~~~~~~~~~~~~
On the subject of "dead PCM2707" chips... I am starting to think that some computers are more prone to killing PCM2706/7 chips. For example my computer is incapable of killing a PCM2706/7 chip but I recently sent a DAC to a fellow and while it was playing the power cord to the DAC fell out and the PCM2706/7 is now dead. A $20 USB hub may be one way to solve this problem, if it is a real problem.
Hi jkeny,
The cost for parts for my DAC is around $350 US. Which sounds high but it is really two separate circuits on one board and there are some expensive parts like Black Gate caps and OPA627 opamps.
Parts for just the DAC half of the board (there is a score line between the boards to separate them if one wishes or order half a board) is around $200.
The reason I include a Preamp/buffer is that a passive I/V stage sounds very lifeless without it. Having a volume control onboard makes it easy to connect directly to a power amp.
~~~~~~~~~~~~~~
On the subject of "dead PCM2707" chips... I am starting to think that some computers are more prone to killing PCM2706/7 chips. For example my computer is incapable of killing a PCM2706/7 chip but I recently sent a DAC to a fellow and while it was playing the power cord to the DAC fell out and the PCM2706/7 is now dead. A $20 USB hub may be one way to solve this problem, if it is a real problem.
Re: DAC cost
Or a $0.25 AND gate.
Why on earth would a hub make a difference, and isn't it just as likely, even if your thesis is correct that certain USB supplies are more likely to cause damage, that the hub would be more dangerous than the computer itself? And how would you ever figure this out?
Brent Welke said:
Or a $0.25 AND gate.
Why on earth would a hub make a difference, and isn't it just as likely, even if your thesis is correct that certain USB supplies are more likely to cause damage, that the hub would be more dangerous than the computer itself? And how would you ever figure this out?
board swap
Akira386,
Ah. I guess that offer was a little premature. Email me anyway if you like to discuss things or are interested in a board to play with.
My day job keeps me pretty busy but one of these months I will modify one of these DACs with a 8xTDA1543 tower and hear it for myself
Cheers,
Brent
Akira386,
Ah. I guess that offer was a little premature. Email me anyway if you like to discuss things or are interested in a board to play with.
My day job keeps me pretty busy but one of these months I will modify one of these DACs with a 8xTDA1543 tower and hear it for myself
Cheers,
Brent
Brent,
Looking at your schematic you have done what I quoted above :
Is leaving out power to internal DAC of PCM chip noticeably better than all not in self powered mode i.e. is this worth the effort or is running an external 5V (not from USB power) through the Vbus & letting the chip regulate internally to 3.3V OK?
I intend to try some configurations to find the best but as I have a tendency to blow chips i want to limit the options to only the worthwhile ones.
BTW, has anybody tried other active I/V output stages - I'm thinking of trying OPA660 stage, discrete I/V stage & John Swenson's stage based on Gary Pimms CCS. Anybody got experience with these?
John
Looking at your schematic you have done what I quoted above :
Is leaving out power to internal DAC of PCM chip noticeably better than all not in self powered mode i.e. is this worth the effort or is running an external 5V (not from USB power) through the Vbus & letting the chip regulate internally to 3.3V OK?
I intend to try some configurations to find the best but as I have a tendency to blow chips i want to limit the options to only the worthwhile ones.
BTW, has anybody tried other active I/V output stages - I'm thinking of trying OPA660 stage, discrete I/V stage & John Swenson's stage based on Gary Pimms CCS. Anybody got experience with these?
John
USB hub
Hi dsavitsk,
If my thesis is correct and I find an inexpesive USB hub that is incapable of damaging the PCM2706/7 then I would include it in my DAC kits.
I don't want to mess with current board (next version it would be included) but now that your question has me thinking more about it, I should at least see how simple it would be to attach your fix to my board and test it out.
I am a lazy man, would you mind pointing me to your prior posts regarding what exactly you recommend? For example what (DigiKey) part and so on.
Thanks,
Brent
Hi dsavitsk,
If my thesis is correct and I find an inexpesive USB hub that is incapable of damaging the PCM2706/7 then I would include it in my DAC kits.
I don't want to mess with current board (next version it would be included) but now that your question has me thinking more about it, I should at least see how simple it would be to attach your fix to my board and test it out.
I am a lazy man, would you mind pointing me to your prior posts regarding what exactly you recommend? For example what (DigiKey) part and so on.
Thanks,
Brent
jkeny,
I have not tried what you suggest for 3.3 source or I/V.
When I tried the clock oscillator (recommended by John Swenson) it made such a big difference over a crystal that I had to keep it. The clock requires a 3.3 V supply so a 3.3 V supply is required in my opinion. Two if you want to have some isolation between the PCM2706/7 and the clock.
Cheers,
Brent
I have not tried what you suggest for 3.3 source or I/V.
When I tried the clock oscillator (recommended by John Swenson) it made such a big difference over a crystal that I had to keep it. The clock requires a 3.3 V supply so a 3.3 V supply is required in my opinion. Two if you want to have some isolation between the PCM2706/7 and the clock.
Cheers,
Brent
I think if you look at the schematic for the dddac it uses the AND gate solution -- looks like a 14 pin part. There are also 5 pin AND gates (with a single gate -- the other 2 pins being power and ground), but iirc they are all very small so would be tricky to air wire -- though doable. Probably a DIP part would be easier.
http://www.diyaudio.com/forums/showthread.php?postid=897886#post897886
http://www.diyaudio.com/forums/showthread.php?postid=897886#post897886
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