Sourcing Sanyo LC7881 via I2S

terranigma

Member
2007-02-11 12:06 am
Hello All,

I want to build an easy DIP socket type DAC, and Sanyo LC7881 looks very interesting to me. Easy build, few external components, native voltage -high impedance- outputs, but no standard i2s wiring compatibility.

I found this schematic on a Bulgarian forum. I don't know its author and I'm posting here within his/her tolerance. Any comments on circuit, especially i2s conversion on digital input section and additional info will be appreciated.

Regards.
 

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The best part of the LC7881 is that it plays music. It has a relaxed non digital type of sound but is more detailed than a TDA1543 going from memory. It is not as detailed as some of the flagship DAC chips, but due to its pleasant presentation of sound it can be forgiven for its very minor lack of some detail. I also like this chip because every time I heard it, it produces decent bass, and balanced sound. Despite its minor limitations I believe a well designed board could sound very enjoyable. I even enjoy listening to it with op-amp outputs. I think a valve output would sound very nice..
The musical fidelity tubalog DAC was based on the LC7881 so to build a DAC will not be impossible.

Perhaps I have found an easy solution?

The NAD 5325 CD player uses LC7881 and YM3404B oversampling filter.
The complete d/a DAC converter list - DutchAudioClassics.nl


The YM3404B is designed to work with the YM3623B digital receiver


YM3404B chip for sale here


YM3623B chip for sale here

I found a pre made receiver board here

Is there any reason this wouldn't work? ( the picture is from the Ym3404B datasheet and shows a PCM56)
YM3404.PNG
 
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No I don't right now as I've not powered up the DAC that's using that filter yet. I'm still working on the PSU design for it. But its an excellent idea to do this so I'll get to it once I've done initial listening to the design.

I'm fairly sure when I get pictures they won't show any stair steps, due to the extreme bandlimiting effect of the filter. The 20kHz one will be the most interesting as it'll have some 24.1kHz images present around 20-30dB down.
 
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Glue logic for LC7881 here.

Looks painful, and he does not show the SPDIF receiver used.

Link below for the source of the scheme:

Upgrade of cdp vega-122

http://semigor2.narod.ru/KarDAC.rar

In this particular case no spdif was used as the dac was connected to I2s provided by pci soundcard with software upsampling.

Some more info on vegalab forum, the first search link:
https://www.google.ru/?gws_rd=ssl#newwindow=1&q=цап+LC7881

but unfortunately the forum will be available on Monday, the most probably (database maintanance).
 
Actually yes. I followed the tweak posted above (output stage of cdp) and it sounded good.
It was many years ago so impressions are not so bright and the whole system was not a high level (amp and speakers). In my opinion the chip has a significant potential (though not so popular and is not considered as high-end device). Would be very interesting to hear it again with respect to current preferences.