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Old 13th December 2003, 07:08 PM   #11
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I think it's not enough visible,yet.
At least to read values of the parts.

Alean ,your system is extremely interesting.
Do you have your own site with schematics and some philosophy?

Can anyone supply the picture of inside of CD 80,please?

I have never seen it opened.
I'm using Marantz CD 65MKII ,so all mods can apply,but i might go for CD 80.

Bartek
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Old 13th December 2003, 07:46 PM   #12
alean is offline alean  Latvia
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Hi, answered a post,
Face values of elements not so are essential, they are considered.
Unfortunately I do not have own site. A little bit about philosophy it is possible to esteem on this site:
http://www.intexlabs.com/eng/index.htm
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Old 14th December 2003, 09:18 PM   #13
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Default Non OS with active mute mod

Located good source for NOS mod with active mute. This one is done on CD 960 which is basically same as CD80 or other similar TDA 1541 circuits. Mostly in Italian with some English translation
quite useful.

http://members.xoom.virgilio.it/hi_fi/


Enjoy and share

Roland
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Old 30th December 2003, 05:30 AM   #14
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Default Post IV modular tube preamp and 600ohm attenuator

Decided instead of working initially on the CD80 to work first on a Magnavox 650 to get some practice with this circuit plus it has more space. It uses the plain vanilla TDA 1541 chip and CDM 4 chassis.

Have noticed several authors are using tube amplification after the IV and often also a transformer volume control (TVR). Since I already have many Altec 458A tube mic preamp modules I have considered using these instead. They have an input tranformer with 50-500 ohm input followed by two 6072 tubes then an output transformer typically with 600 ohms output. Was thinking of simply attenuating this line level signal via an Altec 600 ohm to 600 ohm attenuator which I already have. The output of this going then to a power amp

Any foreseable problems?? Seems transformers and tubes are usable in these digital circuits for a variety of reasons.

Also need advice regarding what clock update to use?? The question is wether to use a synchronous vs an asynchronous type. Presently more inclined to go with a synchronous type since not totally sure that an asynchronous clock won't allow loss of bits. What do you think?? Of course whatever clock choice is made should have its own decoupled PS. The same for the receiver and dac.

Any comments, criticisms, or advice again appreciated.

Roland
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Old 30th December 2003, 05:46 AM   #15
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Default Any conclusions regarding Non OS vs 4x or less OS

In a fully modded TDA 1541 machine what sounds better the non OS or the 4x or less OS machine? Assume that most mods including reclocking etc were done. I ask because on Non OS machines I notice a lot of problems with HF noise also modulating as far down as 4K in freq!!. Apparently most of this remains poorly audible but has anybody compared these two versions and made some final conclusions? Would it be better to just update/mod the player but leave as 4X OS??

Roland
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Old 30th December 2003, 06:45 AM   #16
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Quote:
Would it be better to just update/mod the player but leave as 4X OS??
That's the question I ask myself too with every Philips/Marantz I have. Till now I left them 4 x OS whereas my separate DAC is non OS. You can mod/update and later try non OS if you like. If you want an impression of how non OS sounds you can build a separate TDA1543 based DAC in a few days and compare the sound with the 4 x OS cdplayer.
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Old 5th January 2004, 10:17 AM   #17
guido is offline guido  Netherlands
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Default Re: Post IV modular tube preamp and 600ohm attenuator

Quote:
Originally posted by goldears
Decided instead of working initially on the CD80 to work first on a Magnavox 650 to get some practice with this circuit plus it has more space. It uses the plain vanilla TDA 1541 chip and CDM 4 chassis.

Roland
Hi,

It uses a CDM 2, however, there is a compatibel CDM 4 variant.
Rebuild the display powersupply on some veroboard and remove the filter pcb: even more space :->

Greetings,
GuidoB
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Old 5th January 2004, 05:44 PM   #18
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Default TDA1541 mods

Apparently no definitive answer regarding NON OS vs OS?? Will proceed with switch controlled OS vs Non OS for definitive A and B testing. Wiil also remove filter board and also replace op amps with sockets to start A and B testing the variety of opamps available vs tube preamps modules. Thanks to all for input so far!!
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Old 17th January 2004, 05:13 PM   #19
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Default Opamp outputs

Been reviewing the opamp replacement possibilities for the output section and IV conversion. Although the sound quality likely will not come up to tube or suoerpair outputs the simplicity in their replacement may make them the choice for some.
I will include basic info here:

CDP outputs can be single or dual opamps. Browndog adapters can be used to make two single DIP or SOIC opamps into a dual DIP opamp. Browndog adapters run $2-3 a piece and making your own modulles can save you significantly. ie: LC Audio sells identical modules for $49!!

Best opamps to use are single browndog adapted to dual use for example AD 825, AD 826, AD 8065, OPA 627, OPA 637. Second best sometimes close to above are their dual cousins ie:
AD 8610, 8620. BB 2604, 2134.

Also instead of DIY it may be easier to buy your own additional regulated non digital +/- 5V, 15V power supplies. I seen these run $15 in Ebay!!. For beginners one of these PS to the new additional clock, old DAC chip, and output section along with updating the opamps and converting to non oversampling may be enough to keep you very happy.
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Old 17th January 2004, 08:27 PM   #20
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Hi,

Nobody seemed to be interesting in my obserations when I posted this a week ago ,but you can find there some of my obserations on the topic.

That's the link:

My OPA 660 I-V stage for TDA 1541A

All Best

Bartek
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