Picture of Marantz CD7 with Double Crown

[rfbrw]

What's the big secret about the CD7? How are the dacs feeded, differential? And I/V, Marantz like with Hdam's? If so it can be done diy too

Digital
VAM1252 -> SAA7372 -> 74HC257 -> DSP56004 -> 2x TDA1541A/S2
TDA1315 -> SM5844 -> 74HC257
Analogue
3x HDAM per channel. Two for the balanced output and for single ended.

 

[cartman]

Hi rfbrw!

If I use the CD7 in normal CD mode (44.1kHz 16bit), is the signal skips the DSP56004???

Which is the IC what divides the digital signal to L & R channel??

Thx!

 

[rfbrw]

Hi rfbrw!

If I use the CD7 in normal CD mode (44.1kHz 16bit), is the signal skips the DSP56004???

No. The 74HC257 is used to switch between the CD and the incoming SPDIF stream.

Which is the IC what divides the digital signal to L & R channel??

Thx!

The second DSP56004.

 

[cartman]

Thanks rfbrw!

What is the recommemded upgarde for CD7?
The clock?
Which freq.?
What is the exact CDM type in CD7?
VAU1254/21 or /31? (like in the CD-Pro2M)

Have you the serivice manual?

My cd7 is "only" less than 3 yrs, but I'd like to stock one CDM for spare for the future

Thx in advance!

 

[rfbrw]

What is the recommemded upgarde for CD7?

No idea.

The clock?
Which freq.?

33.8688 MHz
and
36.8640 MHz

What is the exact CDM type in CD7?
VAU1254/21 or /31? (like in the CD-Pro2M)

VAM1252

Have you the serivice manual?

Somewhere.

 

[cartman]

33.8688 MHz
and
36.8640 MHz

2 different clocks... the upgarde isn't simple

VAM1252

We're producing the VAM1254 & VAU1254 now in Hungary...
What is the difference between VAM1252 and VAM1254

I think not too much...

Somewhere.

If you found it, can you share with me?

Thx in advance!

 

[cartman]

atrocity!!!

I checked the serivce manual, and found two EL.CAPS on output signal !!!

I guess this is an atrocity!!!

Why did the designer like this???

see the attachment...

 

[tbla]

remove/short those......

new clock for the 44,1 line......

schotky rectifiers.......
and if you can afford - black gate bg-N allover the dacboard.........

 

[cartman]

Thanks tbla!

remove/short those......

are you sure?

what is the function of these caps?
just the DC decoupling (for safety)?

rfbrw! What do you think?

 

[tbla]

just safety caps - remove/short them and sound opens like you never heard before......

 

[rfbrw]

I would check for the presence of DC before removing any caps.

 

[tubee]

Depends what you have in preamp, if there are (good) dc caps you can remove the lytics in CD7, also with a slight dc offset. But try first.

 

[cartman]

Thanks Guys!

I will check the DC presence, casue my "pre-amp" is a passive ladder network without any decoupling caps, and my power amp is a JE Labs 300B without any caps at input also...

I hope, the designer of CD7's buffer was a genius, and these caps are just for SAFETY...

 

[tubee]

I think you'll get an offset. Try a film cap of around 10uF or the smaller BG "C" type caps.

 

[tbla]

we didn't get any offset when we tried this......

 

[cartman]

as I know the maximum acceptable offset is about 10mV (if I'd like to short it)

right?

 

[D.A.R.R.Y.L.]

Hi,
I own a CD-7 and modded some. There is DC for sure!!!! On XLR there is .5v DC. I replaced with Mundorf Silver/Oil 1µF (high impedance on integrated amp, so low value cap did it for me).
I changed the clock (only the 33.xxxx one) with a TentX02 feeded by XO supply. Nothing with Black gates or schottkey's yet.

There is a huge difference between VAM1252/00 and VAM1254/01.
Different chip (CD-7 laser uses TDA1302T) and pin config of flatcable is different.

I am corresponding with a German Dude. Possibly found a laser replacement (laser assembly is self-adjusting, so would be snap-in replacement).

 

[cartman]

Thanks D.A.R.R.Y.L.

 

[D.A.R.R.Y.L.]

No thanks ;-)
I have the service manual in pdf. E-mail?
This file is courtesy of Elso Kwak.

 

[cartman]

Many thanks, but meantime I got it