PCM56P-K replacement

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Hello everyone.

There is an old Yamaha CX-1000 DAC/preamp. I'm currently restoring one. Analog part working like a charm, but i have a problem with digital part. It uses PCM56P-K as a DACs. Sounded ok, but i tried to replace them with PCM61P-K, as they are totally pin-to-pin compatible and replaceable (so said datasheets), and PCM61 have better noise and DR specs. But all i got was crippled noise with no sound. Am i done something wrong or i just got faulty or fake PCM61P-K chips?

Can anyone, please, give me an advice to do this correctly? I want to use this restored preamp as a main DAC in my Hi-Fi system. Source is PC (E-MU1212m), power amp is Yamaha MX-600, speakers are NS-1000M.

P.S. Also can DAC part somehow be modified to use PCM1704? (my favourite multibit DAC chip).
 
pcm56 is 16bit, pcm61 18bit.

I was using pcm56 in nos mode with logic. One of pcm56's damaged while unsoldering, I had to use pcm61's for both channels, but i modified logic for 18bit.

You cannot use 18bit chip in 16bit position without modifying things...

Can you please be more specific? What needs to be done? Maybe - clk adjustment somewhere? Digital IO is YM3623B, filter is YM3414.
 
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Hi I still have an unused pair of AD1860 which were technically better than PCM56 and they are fully compatible. AD1860 truly has 16 bit operation (they were specified for 18 bit but have true 16 bit monotonicity). If you want those please send me a PM.

The Yamaha chips are famous for jitter and any modern receiver will perform way better. I would advise to use WM8804 if you use only 1 input.
 
Hi I still have an unused pair of AD1860 which were technically better than PCM56 and they are fully compatible. AD1860 truly has 16 bit operation (they were specified for 18 bit but have true 16 bit monotonicity). If you want those please send me a PM.

The Yamaha chips are famous for jitter and any modern receiver will perform way better. I would advise to use WM8804 if you use only 1 input.

Really? That would be great experiment with 1860s. (Also in theory i can replace SPDIF receiver - can't remember where, but i've seen "upgrade kit" somewhere in the internet).
 
Hi I still have an unused pair of AD1860 which were technically better than PCM56 and they are fully compatible. AD1860 truly has 16 bit operation (they were specified for 18 bit but have true 16 bit monotonicity). If you want those please send me a PM.

The Yamaha chips are famous for jitter and any modern receiver will perform way better. I would advise to use WM8804 if you use only 1 input.

BTW, AFAIK, these AD1860s are 18 bit too, so'll need to do some modifications? But where and how? (I mean, i can adjust distortions according to service manual but not more).
 
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