Experience with this DIY DAC ? - Page 224

Netdewt · 13th March 2010, 02:55 PM

Is there a PS I can get from digikey (Hammond?) that would be very similar to the kit PS in how it is implemented? It would be cheaper (and maybe better?) than getting the kit PS by quite a bit (for me at least, $20).

I have been emailing with Bill, but I just don't understand much. I was going to try using a Hammond 229 series split bobbin, but is looks like it will take some additional circuits to make it work right. I don't know how to make stuff up like that. I need it spelled out. I need to just get started with something. Not interested in mods yet.

Would a Hammond 166 be a more direct swap?

Bill Fuss · 13th March 2010, 10:12 PM

I am truly sorry that you aren't able to follow my advice. There has to be a basic knowledge level of electricity to begin changing things. I recommended that you purchase the power transformer with the dac board because of your knowledge level. It was not meant in a denigrating way, just realistic. Small steps. Use GOOGLE, Wikipedia, learn.

Best, Bill

Netdewt · 14th March 2010, 04:57 AM

Quote:

Originally Posted by Bill Fuss

It was not meant in a denigrating way, just realistic.

And I'm not trying to be annoying, just frustrated. Trying to be frugal and learn at the same time.

Bill Fuss · 14th March 2010, 12:31 PM

Well, here is the main problem with using a single 15-0-15 trafo. 15vac rectified to dc is about 21vdc, the digital regulator circuits are 5v so they have to get rid of 16vdc at whatever amount of current is passed through the regulators. If it is 500ma then the excess power is 8watts, and I don't know if the heat sinks are big enough to comfortably handle that. You will have to try it, and if they get too hot you will have to either use a smaller voltage trafo, use another preregulator circuit to cut the voltage down to 10v or so before the board connection, or use a fan, or put bigger heatsinks on the regs. It's not a good idea to start with, digital and analog circuits should not be powered by the same windings. Digital circuits are loaded with noise. It is a compromise that is not necessary, when you can get another trafo for the digital section at Radio Shack for 10 bucks.

Best, Bill

RichLund · 14th March 2010, 06:27 PM

Hi all

I am experiencing a problem with my DAC's left channel output. It is considerably lower than the right channel. There is faint music coming through together with a faint hum. It was working fine a while ago but I have been away and not used it for a while.

I am using UTC A-20 output transformers which seem to be ok. The problem occurs if I use the transformer RCA's or direct from the PCB RCA's via the op-amps so it seems the fault is with the DAC chip (CS4398) ? Does this sound likely?

Sound is provided via the on board S/PDIF connection on my PC motherboard.

Has anyone else had problems like this? Any advice would be greatly appreciated.

Thanks

Rich

Bill Fuss · 14th March 2010, 07:32 PM

Hi Rich,
It really isn't likely, but anything is possible. Are you sure you have eliminated the other possibilities, such as a bad interconnect. Have you swapped the cables at the preamp. Check all your solder jobs and use your meter to make sure you have continuity from the chip output pins to the resistors on the board that feed the signal to the opamps. The board traces are not very robust and can be easily damaged. If you are not using resistors in line with the trafos primaries you possibly could have damaged the 4398.

RichLund · 14th March 2010, 09:34 PM

Thanks Bill, will check for continuity tonight.

I have Riken 510 ohm resistors in line with primaries with 1nf polyester caps across and 1.2k resistor with 1nf across secondaries. I was going to play with changing to Kiwame but will need to sort this out now!

I swapped amplifiers and amp connects and the problem is certainly with the source. unfortunately I do not have another 75ohm S/PDIF lead and have no other S/PDIF source (soundcard) other than the PC motherboard so cannot rule these out yet.

I'm thinking that at some point the primary leads from left and right channel that are attached to the board must have touched while powered up causing a short?

Shame as I have just recieved my Modushop cases and was ready to finish the job.

Bill Fuss · 14th March 2010, 10:55 PM

Another source like a cd or dvd player would be handy right now. Could you try the USB input with your puter.

RichLund · 14th March 2010, 11:39 PM

Just tried it with a CD player and the problem is still there. So I think I have fried the DAC chip.

I have contacted Ian Ma and will get another CS4398 chip board and might get a DIR9001 while I'm there! $30 for a new DAC isn't too bad.

Does anybody know how much he charges for the DIR9001 board?

Need to be more careful...

RichLund · 14th March 2010, 11:56 PM

Quote:

Originally Posted by Bill Fuss

Could you try the USB input with your puter.

Actually I tried the USB awhile ago and couldn't get it to work. So I gave up and left it as I was more than happy with the S/pdif.

I remember reading that the selection jumpers on the PCB are not correct according to the manual.

Could someone give me a run down on configuring the USB input correctly?

Many thanks

Rich

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13th March 2010, 02:55 PM	#2231
Netdewt diyAudio Member Join Date: Jan 2010	Is there a PS I can get from digikey (Hammond?) that would be very similar to the kit PS in how it is implemented? It would be cheaper (and maybe better?) than getting the kit PS by quite a bit (for me at least, $20). I have been emailing with Bill, but I just don't understand much. I was going to try using a Hammond 229 series split bobbin, but is looks like it will take some additional circuits to make it work right. I don't know how to make stuff up like that. I need it spelled out. I need to just get started with something. Not interested in mods yet. Would a Hammond 166 be a more direct swap?

13th March 2010, 10:12 PM	#2232
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	I am truly sorry that you aren't able to follow my advice. There has to be a basic knowledge level of electricity to begin changing things. I recommended that you purchase the power transformer with the dac board because of your knowledge level. It was not meant in a denigrating way, just realistic. Small steps. Use GOOGLE, Wikipedia, learn. Best, Bill

14th March 2010, 12:31 PM	#2234
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	Well, here is the main problem with using a single 15-0-15 trafo. 15vac rectified to dc is about 21vdc, the digital regulator circuits are 5v so they have to get rid of 16vdc at whatever amount of current is passed through the regulators. If it is 500ma then the excess power is 8watts, and I don't know if the heat sinks are big enough to comfortably handle that. You will have to try it, and if they get too hot you will have to either use a smaller voltage trafo, use another preregulator circuit to cut the voltage down to 10v or so before the board connection, or use a fan, or put bigger heatsinks on the regs. It's not a good idea to start with, digital and analog circuits should not be powered by the same windings. Digital circuits are loaded with noise. It is a compromise that is not necessary, when you can get another trafo for the digital section at Radio Shack for 10 bucks. Best, Bill

14th March 2010, 06:27 PM	#2235
RichLund diyAudio Member Join Date: Jan 2009 Location: Shropshire, UK	Hi all I am experiencing a problem with my DAC's left channel output. It is considerably lower than the right channel. There is faint music coming through together with a faint hum. It was working fine a while ago but I have been away and not used it for a while. I am using UTC A-20 output transformers which seem to be ok. The problem occurs if I use the transformer RCA's or direct from the PCB RCA's via the op-amps so it seems the fault is with the DAC chip (CS4398) ? Does this sound likely? Sound is provided via the on board S/PDIF connection on my PC motherboard. Has anyone else had problems like this? Any advice would be greatly appreciated. Thanks Rich

14th March 2010, 07:32 PM	#2236
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	Hi Rich, It really isn't likely, but anything is possible. Are you sure you have eliminated the other possibilities, such as a bad interconnect. Have you swapped the cables at the preamp. Check all your solder jobs and use your meter to make sure you have continuity from the chip output pins to the resistors on the board that feed the signal to the opamps. The board traces are not very robust and can be easily damaged. If you are not using resistors in line with the trafos primaries you possibly could have damaged the 4398.

14th March 2010, 09:34 PM	#2237
RichLund diyAudio Member Join Date: Jan 2009 Location: Shropshire, UK	Thanks Bill, will check for continuity tonight. I have Riken 510 ohm resistors in line with primaries with 1nf polyester caps across and 1.2k resistor with 1nf across secondaries. I was going to play with changing to Kiwame but will need to sort this out now! I swapped amplifiers and amp connects and the problem is certainly with the source. unfortunately I do not have another 75ohm S/PDIF lead and have no other S/PDIF source (soundcard) other than the PC motherboard so cannot rule these out yet. I'm thinking that at some point the primary leads from left and right channel that are attached to the board must have touched while powered up causing a short? Shame as I have just recieved my Modushop cases and was ready to finish the job.

14th March 2010, 10:55 PM	#2238
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	Another source like a cd or dvd player would be handy right now. Could you try the USB input with your puter.

14th March 2010, 11:39 PM	#2239
RichLund diyAudio Member Join Date: Jan 2009 Location: Shropshire, UK	Just tried it with a CD player and the problem is still there. So I think I have fried the DAC chip. I have contacted Ian Ma and will get another CS4398 chip board and might get a DIR9001 while I'm there! $30 for a new DAC isn't too bad. Does anybody know how much he charges for the DIR9001 board? Need to be more careful...

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