PCM56P-K replacement

[Javik50k]

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).

 

[weissi]

Ad1856 would be a second source replacement for pcm56.

 

[rfbrw]

YM3414 = 16bit
PCM56 = 16 bit.
PCM61 = 18 bit.
PCM1704 = 24bit
You need the YM3434 for PCM61.

 

[euro21]

Replacing PCM56 is a mistake.
This is one of the best (after PCM63) tonality R2R DAC chip.

 

[Javik50k]

Replacing PCM56 is a mistake.
This is one of the best (after PCM63) tonality R2R DAC chip.

As for me, PCM61 a bit better than 56 (of course, both must be K grade). But if replacement will fail, i'll simply use original japanese 56-K, they are fine too.

 

[starbender]

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...

 

[Javik50k]

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.

 

[starbender]

Afaik 3414 is not compatible with 18bit dacs.

 

[Javik50k]

Maybe 61P will just operate as 16bit with lower noise?
Anyway i need to order new set of 61P-Ks (from Japan preferrably), as mine are really suspicious ones. 56P-Ks are real japanese ones. Using them now.

 

[merlin el mago]

Replacing PCM56 is a mistake.
This is one of the best (after PCM63) tonality R2R DAC chip.

+1

 

[Javik50k]

BTW, i'm using 24/48 and PCM56 working very well in that mode. At least, in CX-1000. Sound is very pleasant.

 

[merlin el mago]

I used both PCM56 & PCM63 and for me the SQ of PCM63 is better.

 

[Javik50k]

Of course PCM63 is better. But it seems impossible to replace 56 with 63, even with hardware modification.

 

[canvas]

Not worth the effort. The Yamaha digital receiver and filter sucks. It will introduce lots of jitter into data/clock stream. I would just leave as is or find a 9018k2m board instead.

 

[Javik50k]

I don't like how ESS sounds. Maybe will search for new AK4499...but later.

 

[jean-paul]

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.

 

[Javik50k]

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).

 

[Javik50k]

But please clean your inbox. I cannot PM you.

 

[Javik50k]

So, i totally argee with idea to test AD1860. PM me when you can.

 

[Javik50k]

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).