Hi Guys,
I am currently experiencing problems after performing the NOS mod to my CD-104s.
Absolutely no doubt that this mod has a fantastic effect on the sound, there's no going back to OS for me! However I have noticed a lot of background noises in NOS which are not there in OS! If I turn the volume up I can hear a constant whine and the ticks of the laser hovering over the disk when the player is paused, pressing next to go to the next track whilst paused causes a lot of whine and clicking noises. These noises are not there in OS mode and are obviously muted in some way.
When I modified my TDA1541A to NOS, I also did the mute mod (Pin 23 from SAA7220 to pin 11 to SAA7210) but there doesn't seem to be a mute mod for the TDA1540. Looking at the SAA7030 filter chip, it doesn't have a mute pin, so it would appear that there is nothing that can be done about these noises - This seems to indicate that either the muting was done internally by the SAA7030 or that the chip filtered out all these noises. I'm suprised no one else has noticed these noises who has done this mod (or maybe they have but decided that this problem was minor compared to the tremendous gain in SQ the NOS mod brings).
Does anyone know of a way to eliminate this noise other than reinstall the SAA7030? I can live with these noises because the quality of sound is so much better in NOS.
If the SAA is in fact filtering out these noises rather than muting them, where do they originate? Noise on the supply? If so which supply? All the noises seem to be generated from the laser seeking process and can't be heard whilst music is playing.
I just bought a faulty Marantz CD-74 which I have now repaired, I might just try the NOS mod on that to see if I get the same noises once the SAA7030 chip is removed. Incidently, the sound of the CD-74 seems better than the standard (OS) CD-104 which is bourne out by better scope traces of the L and R data and the clock (more square edges), the board layout and use of Poly caps at the DAC helps, but the PSU seems to be better as well. Having said that, the CD-74 sounds definately inferior to a CD-104 in NOS mode - The CD-104 sounds alive, more dynamic and a lot better all round.
I will probably sell the CD-74 on, as I really like everything about the CD-104 from its solid construction to its serviceability. I also had a B&O CDX which I liked, but it was a major pain in the rear end to work on and also I didn't like the fact that the perspex lid attracts dust through static and the laser is exposed under that lid.
I want to reach audio Nirvana with the CD-104! Don't laugh! I have owned a lot of players in my time and the modified CD-104 sounds better than any of them!
I am just testing a synchronous reclock mod I contrived out on my NOS 104 and that has made a big difference!
I believe that the humble TDA1540 is the best DAC ever made, I was previously a TDA1541A fan, but not anymore!
I am currently experiencing problems after performing the NOS mod to my CD-104s.
Absolutely no doubt that this mod has a fantastic effect on the sound, there's no going back to OS for me! However I have noticed a lot of background noises in NOS which are not there in OS! If I turn the volume up I can hear a constant whine and the ticks of the laser hovering over the disk when the player is paused, pressing next to go to the next track whilst paused causes a lot of whine and clicking noises. These noises are not there in OS mode and are obviously muted in some way.
When I modified my TDA1541A to NOS, I also did the mute mod (Pin 23 from SAA7220 to pin 11 to SAA7210) but there doesn't seem to be a mute mod for the TDA1540. Looking at the SAA7030 filter chip, it doesn't have a mute pin, so it would appear that there is nothing that can be done about these noises - This seems to indicate that either the muting was done internally by the SAA7030 or that the chip filtered out all these noises. I'm suprised no one else has noticed these noises who has done this mod (or maybe they have but decided that this problem was minor compared to the tremendous gain in SQ the NOS mod brings).
Does anyone know of a way to eliminate this noise other than reinstall the SAA7030? I can live with these noises because the quality of sound is so much better in NOS.
If the SAA is in fact filtering out these noises rather than muting them, where do they originate? Noise on the supply? If so which supply? All the noises seem to be generated from the laser seeking process and can't be heard whilst music is playing.
I just bought a faulty Marantz CD-74 which I have now repaired, I might just try the NOS mod on that to see if I get the same noises once the SAA7030 chip is removed. Incidently, the sound of the CD-74 seems better than the standard (OS) CD-104 which is bourne out by better scope traces of the L and R data and the clock (more square edges), the board layout and use of Poly caps at the DAC helps, but the PSU seems to be better as well. Having said that, the CD-74 sounds definately inferior to a CD-104 in NOS mode - The CD-104 sounds alive, more dynamic and a lot better all round.
I will probably sell the CD-74 on, as I really like everything about the CD-104 from its solid construction to its serviceability. I also had a B&O CDX which I liked, but it was a major pain in the rear end to work on and also I didn't like the fact that the perspex lid attracts dust through static and the laser is exposed under that lid.
I want to reach audio Nirvana with the CD-104! Don't laugh! I have owned a lot of players in my time and the modified CD-104 sounds better than any of them!
I am just testing a synchronous reclock mod I contrived out on my NOS 104 and that has made a big difference!
I believe that the humble TDA1540 is the best DAC ever made, I was previously a TDA1541A fan, but not anymore!
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Thanks for your response, there are already muting relays at the output which don't seem to be being activated at the right time (i.e.when the playback is paused). I'm not sure where the mute signal originates (possibly the microprocessor on the servo board) but removing the filter/oversampling chip seems to have removed this muting fascility. I will study the diagram again in regards to the mute circuit and see what has happened to this function.
On looking deeper, it appears the mute enters the Decoder board and goes to the SAA7020.....
On looking deeper, it appears the mute enters the Decoder board and goes to the SAA7020.....
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Thank you for your input, I haven't had time to replace the SAA7020 yet because I bought two more faulty CD-104s. I currently now own three CD-104Bs and one early CD-104 (non B) with TDA1540D and that sounds really good! The CDM1 is a very early one with different boards and a different motor which does not appear to be the adjustable turntable height type. The CD-104Bs are all modified to NOS and are reclocked; which makes a clear difference over the standard, but the plain 104 is in standard form and sounds almost as good - why is that? Do the ceramic 1540Ds make that much of a difference? Also, without a bearing to wear down on the early motor, are these CDMs better?
TDA1540D vs TDA1540P
As mentioned (in the comment above with no title!), I have two versions of Philips CD-104, the early one has a different revision of CDM1 (A compared to G), but also the early one has TDA1540D DACs (compated to P=Plastic). The early 104 sounds better than the later ones (I have several 104Bs), is that because the ceramic DAC package makes a difference? Even after the NOS mod and synchronous reclocking to the 104Bs the early Philips is not far behind!
Does anybody know the reason why the CD104/00 version sounds cleaner with a better sound stage?
As mentioned (in the comment above with no title!), I have two versions of Philips CD-104, the early one has a different revision of CDM1 (A compared to G), but also the early one has TDA1540D DACs (compated to P=Plastic). The early 104 sounds better than the later ones (I have several 104Bs), is that because the ceramic DAC package makes a difference? Even after the NOS mod and synchronous reclocking to the 104Bs the early Philips is not far behind!
Does anybody know the reason why the CD104/00 version sounds cleaner with a better sound stage?
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