Marantz CD50 mods

[Almeg69]

I have got hold of a very good condition Marantz CD50 cd player to play with and would like some advice as to where to start first. This will be my first attempt so any good advise would be welcome.

[Almeg69]

Help !

Anybody out there

[UV101]

Hi, As its a TDA1541 based player, check out the CD650 thread as well as the NOS 1541 thread.

If it has the SAA7220 filter chip, this responds very well to a decent regulator.

As always, good smoothers on the supply's along with Schottly's or Hexfreds starts to sort things. A sprinkling Rubycon ZA's or Black Gates to decouple supplies to DAC, Filter, Decoder and output stage will give good gains. Also replace the 4 op amps on the output of the DAC (I/V & Buffer) I think they will be singles. This will give a good improvement for not a lot of money.

The expensive bits to start with are a decent clock & good regulators.

Have you managed to find a service manual?

Ian

[Almeg69]

Thanks for that Ian, I also found your link for components very useful too.

I have found a manual with component positions, so will be starting on it over the weekend.

[UV101]

What do you plan to attack 1st?

[Almeg69]

I would like to start with the power supply by changing capacitors and uprating the rectifiers and regulators, then try the clock mods followed by the de coupling caps if you think that would be the correct path to take

[UV101]

Smoothers (Panasonic FC's or Mundorf if cost is no issue) and rec's (schottky or Hexfred if cost is no issue) are a good place to start. Don't replace the std regs with decent ones..........

Use dedicated regs. In that player, I'd start with 1 5v SPower (or similar) on the decoder chip (SAA7220) this will give very good gains. Its quite a greedy chip so the reg will need attaching to a heat sink. I'd also replace all the decoupling caps to the supplys on the DAC (3), Filter (1) and op amps(4) with something like rubycon ZA 220uf (let me know if you want to know how to get some) I'd also replace the 4 op amps with LME49710NA (about £5 each) That would do you for a start!!

Next i'd put on a decent clock and poss a devide by 2 for the bitclock (i'd need to check how the oversampling works on that player for the /2) A good regulator for the clock is also a must.

Next I'd sort the regs out on the DAC +5,-5 & -15v. Fairly costly for 3 decent regs!! but again worth it.

Finally if you've got any budget left, you could source a TDA1524 S1 or S2. Definately the finishing touches for that mod though!

Best of luck

Ian

[Symon]

I recently picked up a CD50-SE, and it's an interesting player, I like the sound but i't not a detailed as my CD63-SE.

Anyway, a couple of points:
the opamps are duals, and i replaced then with LME49720's in metal TO99 format. this does sound better but i feel it has a lot more to give.
second point is that the case is fully braced which means you have to remove the PCB to access the OPAMPs, and interestingly it sounds better with the thin base plate removed and sitting on the carpet. This is in contrast to the CD63 where the sound degrades when the covers are removed.

I'm taking a slow incremental approach to modifying this player, and after reading other threads I think improving the decoupling of each of tha major chips is a priority. As they all produce noise, and consume relatively high currents.

This will probalby take the form of separate regulators for each chip, but initially i thought I'd try Ray's simple replacement of resistors with small inductors and see what happens.

[UV101]

Hi Symon,

I was going off the schematic and missed the fact that the op amps are dual and only 2! (same number of amps overall!)

I agree with your opinion of the dual HA's (tin hats) they are much much better than the std DIL package.

Depending on how far you want to go with this player, I'd seperate the I/V stage (1st opamp) and Buffer stage (2nd opamp). I've got a Burson discrete doing my I/V and Rays DOS off the 63/67 thread for my buffer and they are awesome together. As I say that may be a little too far????

I'm quite familiar with the filter chip and would definately recommend getting it onto its own reg at least (much better with a low noise version). I'm pretty sure it'll draw upwards of 300mA so def sink it!

Ian

[Symon]

Well I replaced a few of the resistors with small inductors so the power to SAA7220 and TDA1541 have better HF filtering.

This simple change seems to have improved the sound a lot, so confrms the view that the first thing to do is improve power supply. And provide clean supply for all the main chips.