94 mk II before / after

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aparatusonitus said:
Hi,

A quick one: those TDA1541A, are they in // or push-pull for each chanel?

Don't have the circuit diagram... the audio signal appears to be fully balanced, derived from halves of each DAC chip.

Luis P. said:
Hi Estreme_Boky, do you have a cd-94 MKII schematic ? I don´t find it. Where do you connect the clock?? thanks

No circuit diagram... pin 11 on SAA7220, but confirm on AudioCom and LCAudio (and similar...) sites. Datasheets are good.
 
Hey Boky,

You have been busy.... Rather than ask you what you did, maybe the better question would be what didn't you do (if anything, I'm sure this list is short)?

I see a lot of putty, why do you use that? The flat connector wire, is that silver? No insulation? What circuit upgrade went on the breadboard?

I asked you this on a Rotel you did also, How does it sound now? Was this kind of upgrade big money? Did you take it as far as you felt was a good value (I know that is subjective)?

Of all the CD Players that you have done, how does this one rate?

This is encouraging for us beginners to see, it takes away some of the mystery and fear! Thanks!

Regards//Keith
 
KP11520 said:
Hey Boky,

You have been busy.... Rather than ask you what you did, maybe the better question would be what didn't you do (if anything, I'm sure this list is short)?

I see a lot of putty, why do you use that? The flat connector wire, is that silver? No insulation? What circuit upgrade went on the breadboard?

I asked you this on a Rotel you did also, How does it sound now? Was this kind of upgrade big money? Did you take it as far as you felt was a good value (I know that is subjective)?

Of all the CD Players that you have done, how does this one rate?

This is encouraging for us beginners to see, it takes away some of the mystery and fear! Thanks!

Regards//Keith


Hi Keith,

This is the 3rd CD94mkII I modified. From the experience I gained with the first 2 players, I suggest you modify the digital power supply section and leave analog one as is – it’s already pretty good. This player suffers from closed-in sound with limited high frequency extension. However, it is one of the most natural sounding CD players I ever heard. So, start with the best clock oscillator and its power supply & transformer you can get your hands on. Save some money by making your own power supply. I used fast switching soft recovery diodes, Black Gates FK and N types, JRC 12V regulator, silver ribbons. You could feed properly distributed / buffered clock signals to each DAC chip for best results. Replace sound coupling caps (my favourite best performance / cost cap is AURICap) and try to use solid core conductors – silver ribbons if possible; avoid litz cables. Check the photos above which will explain what caps I used. There are some 0.1uF high quality caps I used for DAC board power supply rails decoupling with great results. I also used them to replace disk ceramic caps on the main board – same function. The IC’s are AD826 X 4 + OPA672 X 2 (all socketed – I to V can be AD8066 if properly decoupled and if the rest of the system can cope with this amazing IC). Mains wiring was replaced as well with silver ribbons – this application requires double run of much wider ribbons. If you want to play with silver conductors – make sure they are annealed. The “figure 8” mains connector was replaced with IEC connector that allows use of different power cables. This requires a fair bit of cutting and drilling… Depending on the rest of the system and personal preferences, solid core copper, silver plated copper, silver-and-then-gold plated copper, or pure silver mains IEC cables can be used with different results. Servo board has also received 0.1uF decoupling caps in place of ceramics.

There’s no point in randomly replacing all the caps hoping for good results. This will usually provide worse than the original sound results and it can be very costly experience. The above mods provide very good value for money and will open the sound providing upper range sparkle, very good definition, very wide and high sound stage while preserving the natural sound presentation that’s so easy to listen to for extended periods of time.

Start with clock oscillator and power supply, install IEC connector and replace the IC’s as suggested. This mod will give you risk-free results you’ll be amazed. Follow with Black Gates and 0.1uF caps, section by section, and check the sound after each.

And don’t forget two sets of belts – one for clamping and the other set for sliding mechanism sections. All 3 CD94’s I modified arrived to my place with clamping / sliding problems.

Good luck
Boky
 
Hi Boky,

You are a gentleman and a good sport! That is a great and very informative summary and will be a one stop thread for future DIYers with a 94 mkII!

It seems like the AD8066, in the right situations can be one of the best!

Thanks again for the info! Keep them coming, they are going to be a selling feature for this site as they fill up the reference library! It's too bad we don't have a way, like on "Star Trek" to file the before and after results and differences that can be downloaded and experienced right from our own PC. I think they call it a "Holodeck" on the newer Star Trek movies and series spin offs. That would be nice to have in the DIYaudio "Reference Library"!

Regards//Keith
 
Hi Boky,

Thanks for this impressive upgrade.

On my CD 94 (first version), I ground IC's radiations by putting coper plate or piece of board on each of them. (TDA1541 of course and all over). Don't forget to link coper plate short to ground.

I link ground plane to the box (blue square on the picture). Original PCB has only one connexion between ground and box.

You probably already do it, grounding box to earth greatly enhance sounding too.

Regards

Eric
 

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Hi Eric,

The photos I've taken are of the unit I modified for the customer. I agree with you about copper shielding and improvements this mod brings to the sound. I use very wide pure silver ribbons if the customer is willing to pay (and is a believer).

I am not sure if the original CD 94 uses "green-caps" 0.1uF around TDA1541 chip. Try replacing them with 0.1uF Nx Black Gates. Great improvement.

Cheers,
Boky
 
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