ADC converter to Audio interface makes noise crackle

Brad_Pit

New member
In short, the sound card I have is behringer fca610. Then I have an Analog to digital converter. when I connect the ADC to the sound card, even if I do not turn on the audio, there is still noise, crackling. I connect via ODT Toslink.

Audio goes through the chain, but still a lot of noise.

Maybe you need to configure the asio buffer or sample rate. Or where there is so much noise, or you can’t insert the converter into the sound card. And you need to insert into the amplifier or av reviser?

By the way, the sample rate of the ADC is 48,000 hertz. And the output audio is LPCM

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Just out of curiosity....why do you have the separate ADC/DAC units when the Beringer FCA610 is already an ADC/DAC...?
 
Just out of curiosity....why do you have the separate ADC/DAC units when the Beringer FCA610 is already an ADC/DAC...?

I want to pass audio through the chain --> SPDIF output of FCA610 -> DAC -> ADC -> SPDIF input of FCA610. How do you do the same if you only have an audio interface?

I understand the noise occurs because of the electronics which is right next to the ADC or is there a digital clock or sample rate does not match. I don't know how to sync clock between devices.
 
But what's the point...why do you want to pass audio out from the FCA610 to the DAC and then ADC back into the FCA610...?
What the reason for doing that...?

The FCA610 is an audio interface...it already has converters.
Normally you take your analog audio mic/inst and plug into the FCA610...it's converted to digital...that's it. Why the additional DAC to ADC...?
 
I have that card. It doesnt have ADAT . Why don't you just plug your audio into the two inputs at the front ? Unless of course you want to input more than two channels.Anyway crackles can clear up by increasing buffer size.
 
Could be the buffer size, but it also could very well be clocks. Can you set the outboard converter to chase the FCA610 somehow? Not sure if you can have your ADC chase the spdif out of the FCA as it looks like you are using that for something else. Honestly it looks like that set of converters has RCA for the analog audio? If so I don't think I;d bother. The FCA is not bad
 
You may need to set the interface to slave to the incoming SPDIF signal. It would likely be in the ASIO control panel for the interface.
 
You may need to set the interface to slave to the incoming SPDIF signal. It would likely be in the ASIO control panel for the interface.

Yes and counter-intuitively the received wisdom is that you should use the 'worst' device as the master clock. More sophisticated converters can correct 'jitter'.

Dave.
 
Yes and counter-intuitively the received wisdom is that you should use the 'worst' device as the master clock. More sophisticated converters can correct 'jitter'.

Dave.

Actually, the master clock must be the device furthest upstream. The interface must slave to the ADC and the DAC must slave to the interface. There is no other option.

If the external converter were a single device with a shared internal clock then either the interface or the converter could be the master.

Also, once analog signal is digitized, any jitter is baked into the sigal. But clocks are pretty good these days so that's probably not worth worrying about. Clocks are so good that external clocking of an ADC will almost always result in a microscopically increased level of jitter, so if you want to be OCD about it, always use the internal clocking of an ADC.
 
Actually, the master clock must be the device furthest upstream. The interface must slave to the ADC and the DAC must slave to the interface. There is no other option.

If the external converter were a single device with a shared internal clock then either the interface or the converter could be the master.

Also, once analog signal is digitized, any jitter is baked into the sigal. But clocks are pretty good these days so that's probably not worth worrying about. Clocks are so good that external clocking of an ADC will almost always result in a microscopically increased level of jitter, so if you want to be OCD about it, always use the internal clocking of an ADC.

I am not qualified to argue but that rather goes against things I have read several time in Sound on Sound.

Dave.
 
I am not qualified to argue but that rather goes against things I have read several time in Sound on Sound.

Dave.

If a receiving device isn't clocked to the incoming stream, or if they aren't both clocked to a common source, the receiving device will drift relative to the sending device. It's a basic fact of digital interconnection.
 
I am not qualified to argue but that rather goes against things I have read several time in Sound on Sound.

Dave.

Or maybe you were referring to the jitter issue. According to Sound on Sound tests, using the internal clock is virtually always better (unless the internal clock is very badly designed and the provision for external clocking isn't, which would be a very unusual condition), but using an external clock results in a very minor increase in jitter.

Does Your Studio Need A Digital Master Clock?

Jitter in an ADC will result in sampling the voltage at inconsistent times, which distorts the waveform. That becomes part of the signal that is indistinguishable to downstream devices from the correct waveform. Combined with the information in the above article, it means using the internal clock of an ADC will result in slightly better conversion.

Jitter in a digital interconnection can be corrected (by well designed PLL on the clock inputs, I think).
 
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