Re: low pass filter
After many tryings, this low pass filter is the best I tried. This low pass filter frequency is the one choosen by Cirrus in their CS4398 evaluation board. I think that this is also their recommendation.
crazyfrog said:
After many tryings, this low pass filter is the best I tried. This low pass filter frequency is the one choosen by Cirrus in their CS4398 evaluation board. I think that this is also their recommendation.
Has anyone gotten one of the usb/upsampling boards to work with a 192k input source via coax? My board is marked LM-DAC3 V6. It works well with 48k and 96k inputs, but not with 192k.
Re: low pass filter
Let me try to explain my meaning. Using larger value resistors takes some load off of the dac output, increasing the bass response slightly.
What cap value you use can be totally arbitrary, what ever you think sounds best to your ears, be it 1000pf or .010uf or somewhere in between. It just changes the filter corner frequency. A 50khz corner might cause some phase shift in the upper reaches of the audio band but it isn't anything to really worry about.
Use whatever sounds good to you, that's all that really matters.
Legarem's observations are every bit as valid as anyone elses, but ultimately you have to decide what sounds best.
Best regards, Bill
crazyfrog said:
Let me try to explain my meaning. Using larger value resistors takes some load off of the dac output, increasing the bass response slightly.
What cap value you use can be totally arbitrary, what ever you think sounds best to your ears, be it 1000pf or .010uf or somewhere in between. It just changes the filter corner frequency. A 50khz corner might cause some phase shift in the upper reaches of the audio band but it isn't anything to really worry about.
Use whatever sounds good to you, that's all that really matters.
Legarem's observations are every bit as valid as anyone elses, but ultimately you have to decide what sounds best.
Best regards, Bill
Re: Sumlink ST-DV709 Digtal Audio isolation transformer
Can anybody answer this please.
shuggi67 said:
Can anybody answer this please.
Re: Re: Sumlink ST-DV709 Digtal Audio isolation transformer
One of the guys with more digital knowledge really needs to answer this.
The transformer only provides isolation to prevent ground loops and eliminate some trash from entering the digital stream. If your transport has a transformer coupled digital output, and most good ones do, then you really don't need another transformer at the input.
I am going to wire up two inputs with separate transformers so I can switch inputs by utilizing a simple front panel switch. I don't yet know exactly what they are using on the board for input circuitry so I don't know exactly what I need to change or add yet. It sure would have been nice to get a schematic with the board.
Most of the trafo manufacturers,Sowter and Lundahl for sure, make the digital pulse trafos also.
I'm sure someone in this thread has added a digital trafo by now, we need to hear from them.
Best, Bill
shuggi67 said:
One of the guys with more digital knowledge really needs to answer this.
The transformer only provides isolation to prevent ground loops and eliminate some trash from entering the digital stream. If your transport has a transformer coupled digital output, and most good ones do, then you really don't need another transformer at the input.
I am going to wire up two inputs with separate transformers so I can switch inputs by utilizing a simple front panel switch. I don't yet know exactly what they are using on the board for input circuitry so I don't know exactly what I need to change or add yet. It sure would have been nice to get a schematic with the board.
Most of the trafo manufacturers,Sowter and Lundahl for sure, make the digital pulse trafos also.
I'm sure someone in this thread has added a digital trafo by now, we need to hear from them.
Best, Bill
shuggi67 said:
Another source for info is the CS8416 data sheet. It shows the trafo implementation for an aes/ebu input, just change the resistor from 110 ohms to 75 ohms for a standard SPDIF input. Notice the DC blocking cap to protect the trafo.
Bill
I have misspoken about the 75 ohm resistor, I'm reasonably sure that resistor is already on the board.
Bill Fuss said:
Yes, it is on the board
The cap you see on the pictures goes from the BNC ground plug to the ground of the dac.
The BNC plug goes directly in the transformers without cap between the transformer and the BNC
piero7 said:
Digital gear does RF transmission so an isolation transformer will help to get rid of RF from the transport to the dac.
With the transformer, the sound is mellower, less edgy, seems more natural.