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Optocoupler or Optoisolator for Audio

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Member level 1
Mar 23, 2005
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audio opto isolator


We have two channel audio to be seperated from the final stage audio amplifier.
Now becase of different products the final power ampifier keeps on changing and we come across gounding loop/ humming noise.
I know that optocoupler could be used to eliminate this.
Does any one knows any good one for audio (analog).

I am looking for.
1. Analog Optocoupler
2. Least THD
3. no ageing effects or possibly eliminated.


audio optocoupler

See this link, it may helpful:

**broken link removed**

audio opto-isolator

Thanks I actually read that. But didnt find a good one yet with a good linearity.
Ageing still seems to be an issue.I was wondering if there is any other techniue to acheive audio isolation. Transformer isolation doesnt seem attractive because it takes too much space and may be cost. Is there anything like Analog's Isocoupler which does onchip transformer. The problem with Analog's one is that it is for digital seperation and cannot be applied for analog signals.

optoisolator audio

try below link:
**broken link removed**

analog opto isolator

Well Kender. It is for high voltage application. In audio what we most care about is linearity, SNR figure of the Optocoupler, THD and how to eliminate ageing.

analogue opto isolator

Here is something from Agilent

audio optoisolator

Are you looking at this **broken link removed**
It is 15 pages

opto isolator schematic

E-design said:
Are you looking at this h**p://
It is 15 pages
Yes, that's what I was looking at. The datasheet doesn't have neither "Principles of operation" section nor (as I have mentioned before) a block diagram. Internally the chip seems quite sophisticated. One can guess that it has an A/D on the right side, a D/A on the left side and the digital signal crosses the boundary. It's a very clever scheme. But in the datasheet I couldn't find such "minor details" as sample rates and number of bits on the A/D and D/A.

optocoupler audio

Thanks E-design. I have already looked into that(Optoisolator made up of ADC and DAC). The problem with using such a device is that there are THD and noise introduced by the DAC and ADC and this will adversly affect your audio(especially when they havent mentioned the resolution and sampling rate). Apart from this this part is very very costly which makes it completely out of question. We already have a system in which the data passes through an ADC and DAC and this will again introduce error.

Kender, the purpose was to eliminate the ground loop issue. But finally I concluded that none of the current analog optocoupler are good for this application( audio groud loop isolation) because of their lower SNR of -80dB and ageing effect in the optoisolator. Typically isolation transformers are used. But that seem to be too big and out of our budget. We do not want to go for any part higher than 1- dollar.


optocoupler aging

kgeorge123 said:
Kender, the purpose was to eliminate the ground loop issue.

If you are playing the digital sound, you can put your audio DAC on the isolated side and run the digital signals through the optocouplers. That's the cleanest solution.

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