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After learning about the Schwarz’s circuit Dima declared that it will be very simple to build into the unit a good quietly multiplex decoder as the plug in modules as a substitute to the original modules. This will change nothing in the Schwarz but the unit will output a fully stereo signal.

Now I am thinking about the design requirements. The multiplex after the Schwarz’s 63K filter will go to PLL decoding around HA11223W decoder. It is absolute chip but I have bought some of them. The HA11223W is used in TU-1X and considering the sound I am getting from this Sansui I have no doubts that this decoder will do fine. After stereo extracted it shell be de-emphasised. In US the de-emphasis is 75mS, starting from ~450Hz and spreading to 15kH at + 16.5dB. The RIAA corrector anyone?  I think to use Sowter’s indictors for de-emphasis instead of the standard RC filters – it shell be interesting… Then I would need a buffer, probably IC buffer. I have no experience with sound of different op-apms but on recommendation of my friends I would most likely go for AD797, if anything else is more advisable then let me know.

It might be an interesting to see if that decoder will do better then the stock TU-1X. Anyhow, it will be fun to have the default Rohde & Schwarz EU-6201 operating in full stereo. If anyone have done it or consider your Schwarz conversed to stereo then let me know.

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