CD723/753 tweaking!

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For all you guys tweaking the CD713 & CD723:

Built yourself s DIY Kwak-Clock.
Connect it at the crystals original location, BUT, also use it directly as BitClock on the TDA1545A :att'n:
Since this player is 4* oversampling, BCK just happens to be 8.X MHz like the system clock. :idea: This will give you much more improvement than connecting at the servo/decoder chip only.

Get rid of the opamp I/V and replace it with a discrete common base stage or the "looped cascode" as can be found in earlier posts on the DIGITAL forum.

I promise you'll get a very decent player (except for the oversampling of course :devily: ).
 
PS
it's even possible to use a very simple "passive" I/V for the TDA1545A. Output voltage swing will be quite low (see datasheet for voltage compliance of this dac) and you need a current source connected to the output of the dac & Riv to set the "no signal" voltage level.

A few hints:
Vsupply=5.5V
Riv=2.2k
Iccs=1.3mA
Vout=0.78Vrms
 
TDA1541 to Sony Transport

kasra said:
Elso Kwak, intresting reading.

I have a sony x5000 with cxd-2515, and im on final stages of my NOS (tda1541a) dac. I have seen your digital interface that you recomended in the digital transformer thread.
Would you recomend me using it as an alternative to regular transformer? I have the schematics for the 2515.

Also, what setting would you recomend on the CS8412 (M0,M1,M2,M3) for use with that dac/transport?

regards - kasra:)
Hi Kasra ,
I found my transformerless interface better than the standard transformer alone in my Sony CDPX33ES and my Philips CD-650.
Still better is the one box solution, but this is only feasable with the Philips without glue logic.
http://www.diyaudio.com/forums/showthread.php?postid=136132#post136132

The TDA1541 is also I2S format so you need mode #2
M3=0
M2=0
M1=1
M0=0


:cool:
 
TDA1543A

chodzio said:
What with tda1543a as nos in cd723. It has Japanese input format too??? Only ifthe same ??
Hi chodzio,
The TDA1543A is not two's complement as the other DAC chips mentioned above .
It is offset binary format that can not be made working with the Crystal CS8412 or 8414.
I learned this the hard way as I only was able to get a loud noise with the CS8412.
It is really a shame Philips does not mention this version in the datasheet. Also Philips nomenclature is very confusing as the TDA1545A is for Sony/BB format and the A in TDA1541A indicates a selection grade, but is for I2S format.
I found the TDA1543A in a Aristona TK610. It is directly connected to a Mitshubishi M50423FP. I see no way to make it NON-OS...

:bawling:
 
Disabled Account
Joined 2002
Totally off-subject, sorry: Do you know something about that Mitshubishi M50423FP chip, Elso ? It seems to have the oscillator inside. In my collection of old Philips players I have this weird CD110.
All plastic low-budget BUT with a CDM4ish kind of mechanical block that comes totally out of the player when eject is pressed !!! :crazy:

Not just a drawer, no the whole mechanics slide outside. It is equipped with this Mitsubishi chip. It also powers off automatically when not used for some minutes. Very strange and contradictive cdplayer : low cost and mechanics better than some of their more expensive cdplayers of that time. And despite the age it plays CDR's with pleasure.

Just curious if that TK610 is the same thing...
 
Mitsbushi chip

Hi Jean-Paul.
I took apart the Aristona TK610 that was abolished by my daughter. I was hoping for a functioning player with SAA7220 and TDA1543.
As it turned out it was with the TDA1543A and the Mitshubishi chip. So I couldn't change to NON-OS either.
The CDP has a CDM4 plastic mechanism. If your drawer comes totally out on eject I suspect the notch is broken off. This notch on the drawer comes to halt at the frontplate. The notch has a rubber ring around it .
Or do you mean the whole mechanism is on a drawer?. I remember very early first generation players had that.
Anyway I am not fond of Mitsubishi chips, had to replace to many in Akai players.:bawling: I know nothing about this M. chip... helas...
 
rbroer said:
Get rid of the opamp I/V and replace it with a discrete common base stage or the "looped cascode" as can be found in earlier posts on the DIGITAL forum.


rbroer said:
PS
it's even possible to use a very simple "passive" I/V for the TDA1545A. Output voltage swing will be quite low (see datasheet for voltage compliance of this dac) and you need a current source connected to the output of the dac & Riv to set the "no signal" voltage level.

A few hints:
Vsupply=5.5V
Riv=2.2k
Iccs=1.3mA
Vout=0.78Vrms

A little schematics?
Not everybody here can make use of your precious suggestions.
And I'm among those....
 
Disabled Account
Joined 2002
Or do you mean the whole mechanism is on a drawer?

Yes ! For that it has a very long flexprint you'll understand. Did you repair Akai stuff as a profession ?

So there is no solution to circumvent the M50423FP unfortunately. Soundquality is not OK now with TDA1543A and the Mitsubishi as a digital filter. Even an ordinary crystal was too expensive for this cd-player.

Too bad because I really like this so-ugly-that-it-becomes-beautyful-again machine with it's red-light-district-display :yikes: It is a real attack on good taste if I may say so. You should see the faces of people when I press the Eject button...

Sorry for disturbing the thread : back to the subject !
 
Joining the foray

Well I've become interested in this thread as I need to get a CDP & wanted something I could tweak. I settled on the Marantz CD5000 & after a search came up with this link:

http://www.heartaudio.nl/enter.html?target=Tubed_CD_playersHeart_CD5000.html

Is it what you guys had in mind? or did you only want SS mods?

This tweak would definitely be at the end of my projects list but it does interest me. The tube guys would probably have a few suggestions as well.

Cheers

Paul
 
Hi,

tschrama said:


Let's hear it from you, what should we do with that horrible tda1545? Any idea how to make it a low jitter, NOS parallel TDA1543 or TDA1541 DAC?


First, the TDA1545 is sonically much closer to the TDA1541 than the TDA1543. I personally like it quite a bit more.

Secondly, the CD72X series uses the 4 X oversampling digital filter hardcoded into the CD-Processor/decoder chip. This is controled (enabled) by the software hardcoded into the CD-Players control uP and thus cannot be disabled by hardware mods.

I did previously look extensively at how to defeat this, but I could not find a reliable "hardware" mode for the Chip, so it would mean extracting the uP Program and then writing a new one with the single register set to not switch the digital filter on.

Sayonara
 
Re: Apologies

Nuuk said:
If anybody does come across additional mods for the CD723, I would be pleased to add them on my site. Of if you have a radically modified CD723 and have pictures, I would be pleased to link to them (or even host them on DD).

I used to do a lot of work on the 721, which shares a lot of things with the 723.

The key changes I made apart from reinforcing the chassis:

1) New Clock (Tricord I think)

2) Analogue Stage with LM6182 and a DC offset circuit to allow direct coupled outputs. For this the feedback loop capacitor and the LC circuit was removed. The Lowpass was realised AFTER the LM6182 100 ohm Output Resistor with 22nF to ground.

3) 120VA torroidal Transformer plus Schottky Diodes, low Z Electrolytics supply regulated via LM317/337 supplying +/-15V for the Analogue Stage, good local decoupling for the Analogue Stage. A seperate 5V supply tapped off the +15V for the TDA1545 DAC.

The result sounded more than jolly decent and outclassed my later aquired Marantz CD-67 SE that it lead to even more extreme mods to that player, which ended up being a lot better onde fully modified.

I also have a cute little valve based analogue stage for the TDA1545 (it needs to be modified for 2mA full scale current though - 2 resistors changed - see datasheet), as attached.

An externally hosted image should be here but it was not working when we last tested it.


Sayonara
 
Thanks Audiofanatic!

Time to go to a diy-store and get a bit marble.
On Hawk Audio they say:
"The result of all the cutting, glueing and soldering job on the inside of this black box
is that we now have a CD-player which performs remarkably"

Does anybody know more or even has some pics what they "glued" in there?
 
This is my intention.

AF.
 

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Hi,

Wombat said:
Kuei Yang Wang, may i ask how you reinforced the chassis exactly?

WEEEELL.

I put a 15mm MDF plate below the player (I'd use natural, unadultaretd but violin lacquered wood now) under the bottom of the player, put on MDF "side cheeks" and fitted a new top m,ade from modestly thin plywood. So in effect, I rebuild the case....

:)

Sayoanra
 
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