Philips CD650 mods

[philpoole]

Isn't that fun though, watching the cones move? It will always right itself (even though the coils are still fed DC)
Anyway, I'm a right one to talk, I still have Martin's tants on my outputs.
You wouldn't catch me with a DC offset

 

[martin clark]

I'm sure I can find you something nicer in the bits box, Phil Wanna meet up again soon..?

 

[SimontY]

Tants, you Naim-phile!

 

[philpoole]

LOL! Naim phile! I wish. If you saw my wiring schema - you might disagree.
I do intend two solutions to this problem. Firstly, I shall invest (one day) in some nice caps and a 2mA current bias into the IV stage input to reduce any DC offset.
I also want dual DAC and XLR out, which would put any problems about DC to rest - ish.

My dual DAC adventures are getting funny. Each individual DAC works fine (hurray! no board errors!) but plug both in and...nothing. Hohum. They're using TL431 regulators, and I think the current limiting resistors are, umm, current limiting. Hopefully a false start, and it'll be working soon. So close!!!

Martin, yes I'd love to meet up at some point. I'll send you a mail. It will happen (honest!).

 

[SimontY]

Dual DACs, this sounds like an adventurous DIY project, good luck getting those playing, I'm sure it will be worth the wait/hassle!

Simon

 

[philpoole]

They both work fine on their own, they just don't quite want to share the power. Bless.

 

[tubee]

Dual DACs, this sounds like an adventurous DIY project, good luck getting those playing, I'm sure it will be worth the wait/hassle!

Simon

I still want to try an 4X hardware OS dac, have six 1541A's waiting for that and a shift register logic on pcb allready finisched.

 

[tubee]

Triode-al: the power transistors to the tray motor are really small. Mostly they fail. I think they are BC538 or something

 

[SimontY]

I still want to try an 4X hardware OS dac, have six 1541A's waiting for that and a shift register logic on pcb allready finisched.

Intense!

Triode-al: the power transistors to the tray motor are really small. Mostly they fail. I think they are BC538 or something

I'd better just leave Diana Krall where she is then I suppose!!

I have 2 x Mundorf Myltic 15000uF / 25V caps to play with. I'll either use both of them for a +/- 12V PSU for the op-amps or, perhaps, for the clock and digital filter power supplies... I'm not sure yet.

Simon

 

[tubee]

Oh yes forgot Simon: have still those N type caps, just grabbed them: They are not 47 but 33uF, Nonpolar (N type), if you want make a shot of them.

Try the Mlytic's for Ps near opamp (you like big caps isn't it )


For the 4x hardware dac there is 1 huge problem: TIME

 

[philpoole]

Is the shift registery thing like ecdesigns interpolation DI-DAC?

I haven't looked at that thread in ages. Got me building my first DAC, but its a big thread now - too big to reread.

 

[SimontY]

Oh yes forgot Simon: have still those N type caps, just grabbed them: They are not 47 but 33uF, Nonpolar (N type), if you want make a shot of them.

As an initial offer I'd like to suggest £10 UKP posted. I understand if this isn't enough, due to the very weak pound and strong Euro.

Please e-mail me, your e-mail link is not present.

Simon

 

[tubee]

Is the shift registery thing like ecdesigns interpolation DI-DAC?

I haven't looked at that thread in ages. Got me building my first DAC, but its a big thread now - too big to reread.

No my own interpretation of shifting the signals. He uses balanced differential signals, too complicated afaik/imo

 

[philpoole]

Well, I reduce the current limitation and the dual DACs work well.
I have some issues with (I think) grounding, where I hear some hashy noise at low levels - that's my next challenge.
However, I couldn't really tell much difference with Elgar, but Smashing Pumpkins Siamese Dream sounded awesome (I often find that a difficult recording to sound good). Hard to put my finger on it, but the attack and dynamics seems so much better than with a single TDA1541A.
Early days. I have this noise I want to fix, I've only heard a bit, and I'm a bit biased and excited I guess, but I'm quite surprised how well it sounds.

 

[SimontY]

Nice one Phil, I'd love to hear it some day. Hopefully another meet will happen eventually!!

 

[jnewbold]

The LM is hooked on the raw 11V dc (from filter cap) before the old dig +5V 7805 supply

The LM needs to be cooled, the standard cooler from cdp is enough in my cd880, with a smaller sink like in a CD640/660 (650?) it will get some warmer i bet. A separate sink it should be at least 6cm wide, and 3cm high or so, but only my approximate feeling on that.

When you use the standard cdp sink, the 7805 delivers less heat, and the LM's some extra, so only some small extra heat is added compared to original PS. (shunt vs series)

The BD can run without a sink, but had to mount it in cdp anyway.

And remember: it is worthwhile!

Hi Tubee,

I am slowly getting parts together to make the shunt reg, but time is at a premium. Thanks for your advice.

The shunt reg schematic shows a list of values for resistor R and I have selected the 4.9R value to give 220mA for the SAA7220.

From your experience, what Wattage do you recommend for resistor R.

Thanks

Joe

 

[jnewbold]

Hi Martin,


In post 6591 on the Marantz CD63 thread you wrote the following about the gyrator on the "Super Rayregulator":

So build your own darlington - BC547 driving the BD139; or arrange a 547 driver with say BD140 (PNP) as a Sziklai pair for absolute minimal dropout - I've seen less than 0.8v dropout this way. The compound transistor approach also allows you to use greater RC time constants for better filtering - say 33K/ 1uF film cap.

I would like to use a gyrator with Tubee's Shunt reg for the SAA7220.

Would a higher power and very high gain darlington like BD681 (hFe 750) work for the gyrator, and would the 33k/1uF RC be OK?

Thanks.

Joe

 

[tubee]

Hi Joe

I used 3W metalfilm resistors for the resistor near LM317. It gets only slightly warm. Remember the LM is connected as a current limiter, some tweaking around the right value is neccesary to get 5 V. But my chips run only on a humble 4.6V

My shunt resistor are around 6 ohms or some less. Paralleled one resistor with a 100 ohm small res. to get the right value/ output voltage.

My 7220 consumed only 180mA. To check current measure V drop over a 1 ohm resistor to 7210 and 7220 from old 7805. Standard players have often a 1 ohm i thought.

 

[jnewbold]

I used 3W metalfilm resistors for the resistor near LM317. It gets only slightly warm.

My 7220 consumed only 180mA. To check current measure V drop over a 1 ohm resistor to 7210 and 7220 from old 7805. Standard players have often a 1 ohm i thought.

Hi Tubee,

Thnaks for your help. My CDP is a Rotel RCD965BX which has only 7220 with a bitstream DAC. I have already given the 7220 its own LM317 reg which is running at 5.16V, but want to try the shunt reg. I measured the current draw by the 7220 a while ago and I think it is about 200mA, but will re-measure to make sure.

 

[UV101]

cd94 cd960

Hi Guys,

Just put a clock, FC smoothing caps, hexfreds, ZA's on filter and DAC, seperate 5v std regs on filters and DAC and OScons on the CDM1 of my CD960 (marantz CD94) and I have to say that I'm taking the SRegs and PSU's out of my cd63 and putting them in this one tomorrow!

Its sounds awesome and I don't think I've touched the surface!

I'm also going to speak to Lee about migrating the DOS from my 63 into this player as I belive he's been playing with the op stage on his 94 recently. I also want to source a crown DAC.

Loads of really usefull info in this thead, so thanks

Simon - your comments on the 63 mods thread about me still listening to my 63 were just a few hrs too early! you were right I'm converted!