Hi all,
Just picked up this player (CD473) for silly money. It sounds pretty good in stock form (first impressions are that it betters my internally similar Mission PCM4000), but I'm already thinking about some basic mods.
I've opened it up and it's a CDM2 (was expecting CDM4) and TDA1541. It has a separate board which contains much of the audio circuitry but not the DAC. This is probably where the remote volume stuff etc happens.
I'm definately going to put one of Guido's clocks in it but my question is this - Should I just clock it and use it as a transport (been offered a meridian 203 at a good price) or go for NOS or other modifications to the analogue/audio side of the player?
I do like the sound of the old 16bit dacs in general but in terms of system matching where my amp and speaker choices are based around my turntable setup maybe a "smoother" bitstream DAC would suit the system better... Ultimately my main requirements are transparency and naturalness of sound. Maybe NOS would be a bit too "in your face" with a revealing system?
If I do decide to use it as a transport will there be a significant difference between using Guido's basic 30euro clock kit (X01) and the standard onboard digital out or the more expensive one (X03) with custom digital out provided?
Sorry, there's more. Having opened it up there's a wire hooked up directly soldered to one pin (4th from top left) of the TDA1541 to a seemingly random point on the board just above the DAC chip (joining onto a small cap/resistor - can't remember which). Any idea if this a mod and if so what for? I could get a photo if this helps.
One last thing. TDA1541 uses a 5v supply, right? So I could use this for the basic Tent Clock? So where should I take it from, and would it require any further regulating/smoothing?
Thanks in advance and sorry to put so many questions in one post! If any one has better ideas than the ones I've already mentioned don't be shy - I'm new to all this.
Tom.
Just picked up this player (CD473) for silly money. It sounds pretty good in stock form (first impressions are that it betters my internally similar Mission PCM4000), but I'm already thinking about some basic mods.
I've opened it up and it's a CDM2 (was expecting CDM4) and TDA1541. It has a separate board which contains much of the audio circuitry but not the DAC. This is probably where the remote volume stuff etc happens.
I'm definately going to put one of Guido's clocks in it but my question is this - Should I just clock it and use it as a transport (been offered a meridian 203 at a good price) or go for NOS or other modifications to the analogue/audio side of the player?
I do like the sound of the old 16bit dacs in general but in terms of system matching where my amp and speaker choices are based around my turntable setup maybe a "smoother" bitstream DAC would suit the system better... Ultimately my main requirements are transparency and naturalness of sound. Maybe NOS would be a bit too "in your face" with a revealing system?
If I do decide to use it as a transport will there be a significant difference between using Guido's basic 30euro clock kit (X01) and the standard onboard digital out or the more expensive one (X03) with custom digital out provided?
Sorry, there's more. Having opened it up there's a wire hooked up directly soldered to one pin (4th from top left) of the TDA1541 to a seemingly random point on the board just above the DAC chip (joining onto a small cap/resistor - can't remember which). Any idea if this a mod and if so what for? I could get a photo if this helps.
One last thing. TDA1541 uses a 5v supply, right? So I could use this for the basic Tent Clock? So where should I take it from, and would it require any further regulating/smoothing?
Thanks in advance and sorry to put so many questions in one post! If any one has better ideas than the ones I've already mentioned don't be shy - I'm new to all this.
Tom.
Funny, I just got the same player today. Mine has a cdm4 and SAA7220P/A, TDA1541 (non-A sadly, a piece of 1987).
I only tried it from the headphones output. Sounds ok, a bit too much midbass and piercing highs. But that could come from the headphones amplification stage.
I have the same wire going from the pin25 of the tda1541 to another point of the board. If my memory is any good, it's the right channel output. It probably simply goes to the I/V stage.
I plan to replace the I/V stage with Jocko's, with his own PS. And of course, complete change of the electrolytic caps.
I only tried it from the headphones output. Sounds ok, a bit too much midbass and piercing highs. But that could come from the headphones amplification stage.
I have the same wire going from the pin25 of the tda1541 to another point of the board. If my memory is any good, it's the right channel output. It probably simply goes to the I/V stage.
I plan to replace the I/V stage with Jocko's, with his own PS. And of course, complete change of the electrolytic caps.
Ok, I've got the service manual and I remove the pcb (the cd473 has one big pcb, everything on it).
It looks like Philips changed its mind a few times when designing it. The service manual doesn't match the player on several details :
The service manual shows a fixed output, there is none on the cdp, only a variable one.
The volume control circuit is different.
They brought one of the output of the TDA1541 to the I/V stage by a wire and manually destroyed the corresponding pcb track (factory made, the wire used is clearly the same).
It looks like Philips changed its mind a few times when designing it. The service manual doesn't match the player on several details :
The service manual shows a fixed output, there is none on the cdp, only a variable one.
The volume control circuit is different.
They brought one of the output of the TDA1541 to the I/V stage by a wire and manually destroyed the corresponding pcb track (factory made, the wire used is clearly the same).
I just got one of these recently too. Mine has the CDM2, SAA7220A and TDA1541 (not A), but I don't recognize the wire from the 1541 to elsewhere on the board.
I did much the same mods to it as I did to an even older Philips CD450 back in 1990. I added another 7805 to feed the SAA7220, removed the opamps (LM833) and replaced with sockets and OPA2604s, added bypass caps (some years ago I bought a job lot of nice polystyrene caps, so that is what I've used) close to power pins of the op-amps, the 1541 and the 7220.
I also disconnected the volume control board in the CD473 (turned around it fits back inside the player without poking out the back, so I know where to look if I should want it one day) and took the output from near to the connector which feeds the volume control board (this is after the op-amps) directly to new sockets on the back panel through caps to block the considerable DC. If you want to reinstate the headphone output, it's possible to plug the cable from the headphone output which used to go to the volume control board straight onto the connector on the main board instead of going through the remote volume control first. I've not bothered as I don't want to use the headphone socket.
I think it sounds good. I just might make or buy a clock circuit for it one day, but I wonder how worthwhile this is given that I've got the less linear non A version of the TDA1541 in there even if it is somewhat more linear than the ever popular TDA1543. Anyway, I'd put a separate supply in for the clock. The 5V going to the 1541 is supplied by a single 7805 chip which also supplies everything else using 5V. That's why I added another 7805 for the 7220, which is responsible for generating the clock and the digital output, and which has a reputation for injecting noise. 7805s only cost about 50p (about $1), so it's no problem to add loads of those.
I also have a seperate DAC. A QED digit much modified, with extra power supplies etc. Same DAC as the Meridian 203. I've used it extensively over the years with the older Philips CD player driving it and after that died, with a DVD player. Sadly, it has never sounded very good to me with the DVD player.
I think the CD473 sounds much better as it is now than the DVD player does through the digit DAC. I've yet to bother with connecting the digit to the CD473.
Anyway, that draws my first post to diyaudio to a close.
David.
I did much the same mods to it as I did to an even older Philips CD450 back in 1990. I added another 7805 to feed the SAA7220, removed the opamps (LM833) and replaced with sockets and OPA2604s, added bypass caps (some years ago I bought a job lot of nice polystyrene caps, so that is what I've used) close to power pins of the op-amps, the 1541 and the 7220.
I also disconnected the volume control board in the CD473 (turned around it fits back inside the player without poking out the back, so I know where to look if I should want it one day) and took the output from near to the connector which feeds the volume control board (this is after the op-amps) directly to new sockets on the back panel through caps to block the considerable DC. If you want to reinstate the headphone output, it's possible to plug the cable from the headphone output which used to go to the volume control board straight onto the connector on the main board instead of going through the remote volume control first. I've not bothered as I don't want to use the headphone socket.
I think it sounds good. I just might make or buy a clock circuit for it one day, but I wonder how worthwhile this is given that I've got the less linear non A version of the TDA1541 in there even if it is somewhat more linear than the ever popular TDA1543. Anyway, I'd put a separate supply in for the clock. The 5V going to the 1541 is supplied by a single 7805 chip which also supplies everything else using 5V. That's why I added another 7805 for the 7220, which is responsible for generating the clock and the digital output, and which has a reputation for injecting noise. 7805s only cost about 50p (about $1), so it's no problem to add loads of those.
I also have a seperate DAC. A QED digit much modified, with extra power supplies etc. Same DAC as the Meridian 203. I've used it extensively over the years with the older Philips CD player driving it and after that died, with a DVD player. Sadly, it has never sounded very good to me with the DVD player.
I think the CD473 sounds much better as it is now than the DVD player does through the digit DAC. I've yet to bother with connecting the digit to the CD473.
Anyway, that draws my first post to diyaudio to a close.
David.
I've not taken the board out of the player to look, but 4051s and a 5532 definitely sound right. The board was mounted on two plastic pillars upside down above the main PCB, and as a result, the back panel left and right outputs were upside down too (right at the top instead of more conventionally at the bottom).
The 4051s are used with a load of resistors to provide 8 levels of attenuation.
I didn't much like the idea of the sound going through the 4051s. The TI CD4051 datasheet says they add 0.12% - 0.3% distortion all on their own. The onsemi MC14051 datasheet just says 0.07% of 2nd harmonic (not mentioning what other harmonics might be doing). Either way, this seems not really quite like hifi to me. We really don't need the extra NE5532 opamp, either. It's only there to put some oomph behind the output of the 4051s.
Something I forgot to mention about removing the volume control board is that you also automatically lose the muting transistors as that's where they are in this player. The presence of the board makes tweaking this player much easier than most, as it's so easy to remove all this dodgy stuff. You just pull a connector off.
I took my output from the pads on the main board near the connector for the volume control board. This means you can choose your own output impedance. Rather than 0ohm (I was concerned that my opamps might not like that if the output was shorted), I put 20ohm resistors in series with my DC blocking caps. Quite a bit lower that on the output of the volume control board so it should make the signal more immune to what follows.
David.
The 4051s are used with a load of resistors to provide 8 levels of attenuation.
I didn't much like the idea of the sound going through the 4051s. The TI CD4051 datasheet says they add 0.12% - 0.3% distortion all on their own. The onsemi MC14051 datasheet just says 0.07% of 2nd harmonic (not mentioning what other harmonics might be doing). Either way, this seems not really quite like hifi to me. We really don't need the extra NE5532 opamp, either. It's only there to put some oomph behind the output of the 4051s.
Something I forgot to mention about removing the volume control board is that you also automatically lose the muting transistors as that's where they are in this player. The presence of the board makes tweaking this player much easier than most, as it's so easy to remove all this dodgy stuff. You just pull a connector off.
I took my output from the pads on the main board near the connector for the volume control board. This means you can choose your own output impedance. Rather than 0ohm (I was concerned that my opamps might not like that if the output was shorted), I put 20ohm resistors in series with my DC blocking caps. Quite a bit lower that on the output of the volume control board so it should make the signal more immune to what follows.
David.
Yes, I noticed the muting transistors were there; I suppose I can now remove also the whole muting circuitry which isn't on the volume board. It is shown on the pic below. In the green rectangle what is on the main board, crossed in red, what should have been there for the fixed output and never was installed. Pads and holes are there on the pcb though. I will remove this circuitry to get access to +/-19VAC, to power a discrete I/V and buffer stage instead of the opamps. The opamp +/-15VDC supply will be used for the TDA1541, to reduce interaction with the digital supply.
Attachments
hi there,
I just mod my CD473 few months back. come with CDM4, TDA1541A. Removed SAA7220 and removed the vol control board.
Find that there are DC when ever track change. I am wondering if you faced this problem when you by passed the vol control board ?
I am doing the mod without a correct manual. Just have a manual of CD630 using CDM4 TDA1541A, SAA7220.
If possible can send me the manual on the DAC part ? Many Thanks in advance.
I just mod my CD473 few months back. come with CDM4, TDA1541A. Removed SAA7220 and removed the vol control board.
Find that there are DC when ever track change. I am wondering if you faced this problem when you by passed the vol control board ?
I am doing the mod without a correct manual. Just have a manual of CD630 using CDM4 TDA1541A, SAA7220.
If possible can send me the manual on the DAC part ? Many Thanks in advance.
Hello,
I've got a Philips CD 473 and I plan to bypass the volume board but I'm a newbie...
Does anyone know where I could find a copy of the service manual please? I would like to directly connect the out connectors on the pcb connector of the volume board but I don't know what cables use and If i have to put some capa? etc? between.
Thank's for you help
and sorry for my english
Christophe
France
I've got a Philips CD 473 and I plan to bypass the volume board but I'm a newbie...
Does anyone know where I could find a copy of the service manual please? I would like to directly connect the out connectors on the pcb connector of the volume board but I don't know what cables use and If i have to put some capa? etc? between.
Thank's for you help
and sorry for my english
Christophe
France
) surprise this one
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.