Re: Best results
If you bypass the output stage, you also bypass the output LPF.
CS4397 features a SCF LPF, which removes aliasing residuals veryeffective, but it generates noise @ its working frequensy. This means that the chip generates noise @ around 400KHz just 14-16 dB below full scale. That is not very good working conditions for the next amplifier. At best your preamplifier is to slow to get bothered by the noise, or the input is filtered, at worst you create massive amounts of distortion.
The Crystal DAC´s calls for post filtering by 2. order @ 50 KHz acording to application notes, in our project we ended up with 2. order @ 100KHz without problems, but without post filtering the noise can be lethal for preceeding amps.
edinm said:Hello to all,
I played with this board for some time. Change components, replace OPAMP with 2111, but THE best results is if you solder left and right chanels directly on DAC schip (there are 4 caps after chip and before output stage. On first connectr one chanel, and on last one connect another chanell. There should be 2 caps between these two connections.
So whole output stage together with OPAMP i trashed
Chears
If you bypass the output stage, you also bypass the output LPF.
CS4397 features a SCF LPF, which removes aliasing residuals veryeffective, but it generates noise @ its working frequensy. This means that the chip generates noise @ around 400KHz just 14-16 dB below full scale. That is not very good working conditions for the next amplifier. At best your preamplifier is to slow to get bothered by the noise, or the input is filtered, at worst you create massive amounts of distortion.
The Crystal DAC´s calls for post filtering by 2. order @ 50 KHz acording to application notes, in our project we ended up with 2. order @ 100KHz without problems, but without post filtering the noise can be lethal for preceeding amps.
Ipanema said:
Our analog stage is discrete, so I don´t think you can use the design, but anyways here is the design of the analog stage. http://img25.imageshack.us/img25/7729/analogstagetl8.jpg
It only shows 1 pole of the filter, the second is driven directly by the chip 0,22nF paralleled by a resistor of which I don´t remember the value, but that can easily be calculated.
You can se pictures of the project here http://www.diyaudio.com/forums/showthread.php?s=&threadid=138230&perpage=25&pagenumber=1
lampucera 96khz
I have recently purchased three lampucera dacs cs4397/cs8416 from lawrence in Hong Kong. I have lifted pin 2 on the dac and bridged it to pin 16 on the receiver and am still unable to playback audio from a dvd on any of the boards. I am using the spdif out from my yamaha dvd/cd/sacd player, can anyone help me out, cd's play excellent but when I bridge the two pins I get no output.
I have recently purchased three lampucera dacs cs4397/cs8416 from lawrence in Hong Kong. I have lifted pin 2 on the dac and bridged it to pin 16 on the receiver and am still unable to playback audio from a dvd on any of the boards. I am using the spdif out from my yamaha dvd/cd/sacd player, can anyone help me out, cd's play excellent but when I bridge the two pins I get no output.
But of course!
Any good line level transformer will do just fine. I tend to use the 1:1 or 600:600 ohm models. No filter is needed because so little noise gets thru the transfo. Much of the noise is common mode, anyway, so the transfo cancels that out.
I've used many different brands. Edcor, Jensen, Sowther, Onetics, various no name and Chinese. They all work, they all sound different.
The CS chips are specified for a 1K load. They will work well from about 600 ohms on up. With a 1:1 transformer, the DAC chip will see the same impedance that you put on the secondary. So if your following amp or preamp has in input impedance of 50K, that's basically what the DAC "sees" on the transfo primary.
Depending on the circuit and the transfo, there can be ringing. A simple resistor across the output winding or even Zobel can tame this. If you have access to an oscilloscope, you can check and fine tune this. Or just put 3.3K across it and be happy.
Any good line level transformer will do just fine. I tend to use the 1:1 or 600:600 ohm models. No filter is needed because so little noise gets thru the transfo. Much of the noise is common mode, anyway, so the transfo cancels that out.
I've used many different brands. Edcor, Jensen, Sowther, Onetics, various no name and Chinese. They all work, they all sound different.
The CS chips are specified for a 1K load. They will work well from about 600 ohms on up. With a 1:1 transformer, the DAC chip will see the same impedance that you put on the secondary. So if your following amp or preamp has in input impedance of 50K, that's basically what the DAC "sees" on the transfo primary.
Depending on the circuit and the transfo, there can be ringing. A simple resistor across the output winding or even Zobel can tame this. If you have access to an oscilloscope, you can check and fine tune this. Or just put 3.3K across it and be happy.
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