Marantz CD95 -- 2 x TDA1541A-S1 + 2 x SAA7220P/B -- How Does It Work?

[poynton]

All the information I can find states that the Marantz CD95 has 2 x TDA1541A-S1 + 2 x SAA7220P/B.

The photos only show the DAC chips not the SAA chips.

The manual is no good, refering to the CD12 which has one DAC, and only really showing minor differences.

Does it really have 2 of both ?
If so, how does it work ?


Andy

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[SoNic_real_one]

Originally Posted by SoNic_real_one

The SAA7220 digital output is just for the CD-Player side, for digital outputs "Optical" and "Coaxial 1/2" that exit from the CD Player side. Basically the 4x OS filter side is not connected to anything.
YM2637B with some "glue" logic takes care of sending the SPDIF from Digital Inputs thru the TDA 1541 DAC.
So it is just one DAC.
Service manual for CD-95 is basically just an addendum, it makes refference to the CD-12 schematic.

The manual of CD-95 says that is identical with CD-12, except the part related to controls.
It might have two DAC's fed by the same YM2637...

[amc184]

Don't get confused between the CD95 and CD95DR (the second of which is a transport).

I couldn't find enough information to be conclusive, but I've seen two SAA7220s in a player before at least twice, and it is invariably for the same reason; one functions only as a S/P DIF transmitter only.

That said, I wouldn't trust what is said in those CD mech / DAC lists 100%, I've seen and corrected mistakes in them before.

[StefanAC]

The dac section is the same as in the CD94 MKII – one SAA7220P/B and two TDA1541A S1.

The SAA7220 sits together with the SAA7210 on a separate board on the side of the casing. The two TDA1541s are on a separate board as well, but on top of the power supply/output board.

On the optical out board sits a logic which inverts the S/PDIF signal and feeds it to the dacs – they work in fully balanced operation.

Per channel you have three opamps in series – one dual opamp for I/U conversion, one dual opamp for the filtering and one single opamp for summing the inverted and non-inverted signal and buffering.

I have got a Wadia WT3200 transport which is almost exactly like the CD95DR or CD12 – only differences are an on/off switch which uses a relays, a different transformer, a BNC instead of a RCA output and an additional AT&T glass output.

I am converting it to an integrated CDP at the moment using a CD94MKII for spares. I changed the transformer, adapted the on/off switch, and added the power supply/output board, the dac board and the demodulator/filter board.

Most of the capacitors have been replaced with Sanyo Os-con SEPC, Elna Cerafine, Nichicon Muse KZ and Panasonic FC. The output caps are Mundorf tin foil. Opamps are AD825 and LT1028. Decoupling caps around both TDA1541s have been replaced with Wima MKS2 of appropriate size. Muting and de-emphasis circuits have been eliminated and a non oversampling conversion has been done using a dem reclocking board. The digital output is buffered with a fet, in case I use the CDP as a drive with the SAA7220 in place.

The CDP works fine but I have a problem – the display is not working correctly. The brightness of the time and track readouts is not bright enough while the other readouts can be seen which should not be the case.

I already added DF50 (RL103E) and CF50 (100uF/35V) which were absent on the Wadia display board – these are for converting AC to DC which is done on the power supply board for all the drives while it is done on the display board with the integrated CDPs.

Has anyone of you an idea where the fault is? Or a service manual for the CD95 or CD99 or the Wadia? I already have the manuals for the CD960, the CD94, the CD94 MKII and the CD95DR which is combined with the one for the CD12.

Best regards,

StefanAC

[guido]

Originally Posted by StefanAC

On the optical out board sits a logic which inverts the S/PDIF signal and feeds it to the dacs – they work in fully balanced operation.

DACs with S/PDIF inputs, don't think so. Probably I2S is used (as usuall).

And i also don't think fully balanced as in one DAC for each channel, balanced. Probably just left/right from one DAC and left/right inverted from the other. Easier to accomplish (inverting data to one DAC, disregarding the 1 bit .....).

[StefanAC]

Hello Guido,

Your right, it is not the S/PDIF signal that gets inverted but the DATA signal going to pin 3 of one TDA1541. I had no access to the service manual when I wrote the post during lunchtime.

And it is as you said, on dac gets the original DATA signal and the other the inverted one. But in the end, the CD94 MKII works in fully balanced mode from the dacs onward (and has only single ended RCA outputs) in contrast to the CD12 or LHH1000 that uses a balancing transformer to get a balanced XLR output.

So, now that this is out of the way – do you have an answer to the question I asked or is that too difficult for you?

Best regards,

StefanAC