[ITZBITZ]

Quote:

Originally Posted by guzzler I've finally worked out how to make it bus powered with a decent quality of supply, and (as always) it's so simple: jumper from a pad on R7 (which is otherwise unused) to the +ve side of the BATT connector. That way the 5V USB power gets stepped up by the switcher then regulated at 5 and 3.3V levels to provide a reasonably clean power source, though probably still not as good as batteries!

I'll make a jumper that plugs into the battery connector tonight to see how it works out and report back. Right now, the background is dead silent on my PC that generates audible hum when using the Sonica. The Sonica picks up noise from the power supply on this really crap Dell at work. At home the Sonica is quiet so my high-end supply at home seems to be filtered better. So this will be a good test for me to try out as I have a very dirty PC to check it out on.

 

[00940]

TI reported the arrival of new PCM2702 from July 7th to Aug 2nd.

I won't get mine soon

 

[momerath]

Quote:

Originally Posted by ITZBITZ If you want an S/PDIF output, but a Hi-Fi Link ($49US). It's cheaper and it has both coaxial and optical outputs. This board will easily cost $70-$100 to build, so it's not feasible if all you want is a digital output.

I've read several different places that the xitel Hi-Fi Link is only capable of outputting at 48K. Do you know differently or have a suggested product that doesnt resample. (and has linux drivers/supports standard usb audio)

 

[PinkFloyd]

Sorry.......... talking ***** hence edit.

 

[guzzler]

Here's a revised power plan for the DAC, remember the USB supply is as yet untested!

R1, D1 and LM317 form a CCS to charge the battery. S1 is a DPDT switch that cuts power to the DAC on the right, and connects the battery to the DC supply on the left. The LED just confirms that DC is present. D1 prevents any back current if DC isn't connected, don't know if it's true but better safe than sorry. D1 is a 1N400x or equivalent. I recommend a charge rate of ~100mA to prevent overcharging. You could, of course, implement a charger with a controller chip on it, like the PPA board for example.

S2 selects between battery power or USB. It should be an SPDT switch. D2 prevents a situation where DC is connected and the device is powered from USB, so no current flows TO the USB connector from DC.

g

 

[ITZBITZ]

As mentioned by guzzler, I'm going to be handling the US distribution of the boards and parts.

The boards will be sold as a kit with everything except for the IC's included. A detail of all the parts is shown below. Estimated cost of the boards and parts is pending a final total from guzzler, but I'm guessing that it is going to be close to $30 (plus shipping).

If you are interested, send me an e-mail (chris (at) campcreations (dot) com) so I can get your information on the list. First serve comes to those on the thread that expressed initial interest. To verify your identity, send me e-mail via head-fi so I can add your username to the list.

All kits will be shipped USPS priority mail ($3.85) unless other arrangements are necessary.

The US kit I'll be delivering includes all the following items:

1USB DAC Board
1Vishay/Dale 100K
1Vishay/Dale 330K
1SMD 0805 1M
1Vishay/Dale 1.5K
1Vishay/Dale 22.1
2SMD 0805 MF 330K
2Tant 10uF 10V
21000uF Panasonic FC
2NP0 ceramics 32pF
8WIMA MKS-02 100nF
2Sanyo OS-CON
2Black Gate 47uF
1Crystal Pad
1C&D Radial 10uH
1Crystal 12.0 MHz 32pF
1Berg 61729
1Molex KK 2-pin header
2Molex KK pins
1Molex KK 2-pin plug

YOU WILL NEED to obtain your own PCM2702E, regulators and DC convertor.

These are all the parts I used to build the prototype board and everything fit nicely and worked perfectly.

Regards,

Chris

 

[Kenny12]

hm.. intresting are there any australian distrobuters?

also does this bypass the sound card? so you would just connect to pc and make it work?

 

[guzzler]

Quote:

Originally Posted by Kenny12 hm.. intresting are there any australian distrobuters? also does this bypass the sound card? so you would just connect to pc and make it work?

no one in Australia, but I'd be happy to ship a board to you, minus the kit parts unless ITZBITZ can do them for you.

It's plug and play in Win2K and WinXP, and comes up as a seperate sound device so you can A/B between your sound card and the USB device just in software. I'm interested to see if it works in Linux, as I saw it mentioned that were drivers for the PCM2702 in the kernel, but you need to move them from USB to Audio or something

g

 

[nleahcim]

Quote:

Originally Posted by ITZBITZ As mentioned by guzzler, I'm going to be handling the US distribution of the boards and parts. The boards will be sold as a kit with everything except for the IC's included. A detail of all the parts is shown below. Estimated cost of the boards and parts is pending a final total from guzzler, but I'm guessing that it is going to be close to $30 (plus shipping). If you are interested, send me an e-mail (chris (at) campcreations (dot) com) so I can get your information on the list. First serve comes to those on the thread that expressed initial interest. To verify your identity, send me e-mail via head-fi so I can add your username to the list. All kits will be shipped USPS priority mail ($3.85) unless other arrangements are necessary. The US kit I'll be delivering includes all the following items: 1USB DAC Board 1Vishay/Dale 100K 1Vishay/Dale 330K 1SMD 0805 1M 1Vishay/Dale 1.5K 1Vishay/Dale 22.1 2SMD 0805 MF 330K 2Tant 10uF 10V 21000uF Panasonic FC 2NP0 ceramics 32pF 8WIMA MKS-02 100nF 2Sanyo OS-CON 2Black Gate 47uF 1Crystal Pad 1C&D Radial 10uH 1Crystal 12.0 MHz 32pF 1Berg 61729 1Molex KK 2-pin header 2Molex KK pins 1Molex KK 2-pin plug YOU WILL NEED to obtain your own PCM2702E, regulators and DC convertor. These are all the parts I used to build the prototype board and everything fit nicely and worked perfectly. Regards, Chris

I would pick one up *if* it runs entirely off of USB power.

 

[guzzler]

ITZ tried it off the USB supply, and whilst it does work it raises the noise floor to unacceptable levels, as I suggested earlier in the thread. Please, again, read the updates to the thread. You could run a trickle charger off the USB supply to a couple of AA/AAA batteries very easily if that would make you happier...

g

 

[nleahcim]

Quote:

Originally Posted by guzzler ITZ tried it off the USB supply, and whilst it does work it raises the noise floor to unacceptable levels, as I suggested earlier in the thread. Please, again, read the updates to the thread. You could run a trickle charger off the USB supply to a couple of AA/AAA batteries very easily if that would make you happier... g

Oh I looked at your picture that said something about the USB supply being untested - and so I assumed someone had figured something out. My problem is not so much the use of batteries - it's the size of them. I need something that is ridiculously small. The board alone is pushing my limits.

BTW - would this circuit be able to act as a line out as well as a headphone amp?

 

[guzzler]

there isn't a headphone amp on board, the output is only line level. This is, AFAIK, the smallest USB DAC you'll find easily, and as such you'll have to either compromise on quality, or compromise on your design to fit batteries into place, after all 2xAAA batteries is not taking up much space

g

 

[nleahcim]

Quote:

Originally Posted by guzzler there isn't a headphone amp on board, the output is only line level. This is, AFAIK, the smallest USB DAC you'll find easily, and as such you'll have to either compromise on quality, or compromise on your design to fit batteries into place, after all 2xAAA batteries is not taking up much space g

Wow - I seriously suck at reading.

So this could drive the line in of a stereo system, or of amplified speakers?

 

[guzzler]

Quote:

Originally Posted by nleahcim Wow - I seriously suck at reading. So this could drive the line in of a stereo system, or of amplified speakers?

yes

 

[Wodgy]

Can anyone post RMAA measurements of this project?