Phillips/Marants TDA 1541 CD 80 mods. - diyAudio
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Old 13th December 2003, 04:15 AM   #1
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Default Phillips/Marants TDA 1541 CD 80 mods.

Hi to all:

I am new to this forum. Been reading here and in the AA about non oversampling mods for the phillips TDA 1541 and have decided to go for it. Would appreciate the help of all who can contribute.

Plan to proceed with mods as a one piece CD player (not as a transport and DAC). This is more reasonable and supposedly gives "better results" avoiding extra cables and XS jitter. My Phillips CD80 is in excellent condition has seen little use myself being the only owner. This is important because supposedly the laser optical mechanism is no longer available NOS only second hand. But according to repair experts here what "usually fails in these units is the moving hinges not the laser itself". Therefore these venerable old units with the best of DAC chips deserve the updating effort. Supposedly once modded they will match or surpass most anything out there. As a matter of fact the recent Marants CD7 is basically a copy of these older models even using the old double crown TDA 1541 S2 chips. Many think it "outperforms" the top of the line Sony SCD1".

A brief history...The Phillips CD 80 followed the CD 960 in the late 1980s. It was considered one of the better units of its time. It had the heavy transport CDM1 (or CDM2?), cupper clad chassis, TDA 1541 S1 chips, digital out as both coax and toslink, two sets of analog out one being variable via remote control. Soon after Phillips started making CDPs more inexpensively with increased use of plastic and lighter construction but similar basic circuit albeit with cheaper components.

I actually have little knowledge of CPDs except for recent reading mostly here but have done some modding and amp construction primarily with tubes. Do have a digital camera and can post pictures as we go along.

From my readings mods should include:

1) PS upgrading of +/-5V digital supplies and 15V analog supplies
2) Additional regulated supplies ideally with their own transformers for the
a)output section (wether opamp , transistor , FET or tube) and
b) synchronous clock and FIFA or asynchronous clock-some question here wether async clocks cause "drop out artifacts"
Another consideration for the output stage is using a high turn ratio transformer with or w/o tube output. Some guys are apparently using ONLY the 1/15 or greater turn ratio transformer w/o tubes with the "best of results". Others claim it reduces dynamics etc.
3) Lose SPIDF, Lose digital filters and use I2S directly into DAC chip. May need to adjust for the dropping freq past 10K??
4) So called wildmonkeysect 8412 mod...is this really needed in one piece CDP since we are bypassing the similar chip in this CDP??
5) DAC better/larger bypass caps, parallel DAC chips.
6) Chassis and transport dampenig
7) RF contamination control.

Plus likely other mods as per members suggestions...these are the main ones that I considered important from my brief readings.

Each of the general mod topics above encompasses quite a bit of material but I would appreciate any and all discussions and suggestions of each of the mod topics above. Realize that although I read in general about these mods I really do not know how to actually carry them out in detail. For example how precisely do you get I2S and connect it to the DAC.

It seems to me that if we can document the modding process of this particular model then it will also apply to all the very similar and common TDA 1541 variants. Supposedly this is also the way to get the best sound....that is the modded single chassis CPD with the best nonoversampling chip the TDA1541. I also have the later more common Magnavox 650 with CDM4 chassis and 1541A chip which I will use to contrast inner designs.

Again advice comments in any form ie: directions to threads in this or other forum or web site are apreciated.
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Old 13th December 2003, 02:26 PM   #2
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Some of us old timers have lots of mod stuff on CD-80s here. You may find some of it via the search function, but I would not bet on it.

Nor would I bet that non-o/s will sound best.

Jocko
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Old 13th December 2003, 03:16 PM   #3
alean is offline alean  Latvia
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Hi, goldears,

I now do a player of transport Marantz CD95. Really untouched have remained only CDM1. All is altered. Five transformers cost(s, ten stabilized power supplies are altered and made anew. It is made new DAC on TDA1541A/S2. If it is interesting, its circuit can be looked here:
http://public.fotki.com/alean/audio/dac_tda1541a_.html
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Old 13th December 2003, 03:28 PM   #4
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I've got a couple of modified CD80s and haven't heard anything I like better.

Modifications: EVERYTHING has an effect.

Put a scope on the +v pin of the SAA7220...
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Old 13th December 2003, 03:33 PM   #5
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Check those two threads:

Less simple I/V for TDA1543
Less simple I/V for TDA1541

IMHO, they represent the cutting edge in modding older Philips (Marantz) players (all complements to Rudolf, of course)
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Old 13th December 2003, 04:09 PM   #6
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I have a stock Phillips CD-80 also and have been thinking of getting it modded,but what I am looking at is just using it as a transport.

Should I invest in Modding the DAC section or what improvements\Mods can for just using it as a Transport?

Just thinking.
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Old 13th December 2003, 05:21 PM   #7
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Quote:
. If it is interesting, its circuit can be looked here
Alean
How to make your schematics bigger/more visible?
I couldn't make it.
Please tell me what are this huge amplifiers on the floor.
Really impressive.

Bartek
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Old 13th December 2003, 06:09 PM   #8
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I had the same trouble reading the schematic. Can you post a high-res version ?
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Old 13th December 2003, 06:13 PM   #9
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Quote:
Originally posted by Richard C
I've got a couple of modified CD80s and haven't heard anything I like better.

Modifications: EVERYTHING has an effect.

Put a scope on the +v pin of the SAA7220...

How true. OSCONS do a good job there. Don't forget to change that silly pcb track to the decoupling cap. The only real error in CD80.
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Old 13th December 2003, 06:15 PM   #10
alean is offline alean  Latvia
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Hi, zyqibajt,
I shall try to attach plan to this post. Can it will turn out.
In photos some amplifiers are shown. These amplifiers of manual manufacturing.
Lamp are single-ended monoblocks on lamps GM70, 300 kg weigh.
Rectangular are semi-conductor amplifiers with controllable thermodynamic function.
Attached Images
File Type: jpg dac_tda1541a_.jpg (56.4 KB, 1884 views)
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