Re: NOS and Intermodulation distortion
Hi IAN01,
I'm interested in the Grundig. I have seen references to it having a superior earthing arrangement but cannot find any evidence of what that is ?
The circuits visible here look the same as a regular CD104
http://www.dcaudio.kgb.pl/grundig7550.htm
One minor inconsistency with the 104 is that the 7030 is that the power supply to the Digital filter (7030) is delivered by a wire link on mine, yet is shown as a 4.7uH inductor on the schematic . Given that the filter probably creates all kinds of modulation it would seem a good idea to decouple, I just have never got round to changing it.
IAN01 said:
Hi IAN01,
I'm interested in the Grundig. I have seen references to it having a superior earthing arrangement but cannot find any evidence of what that is ?
The circuits visible here look the same as a regular CD104
http://www.dcaudio.kgb.pl/grundig7550.htm
One minor inconsistency with the 104 is that the 7030 is that the power supply to the Digital filter (7030) is delivered by a wire link on mine, yet is shown as a 4.7uH inductor on the schematic . Given that the filter probably creates all kinds of modulation it would seem a good idea to decouple, I just have never got round to changing it.
GRUNDIG CD7550
Hi jives11,
First of all sorry for the typo on my previous post, the Grundig model is in fact the CD7550 as shown on your polish link.
I can certainly confirm that the on board electronics are the same as found in the Philips CD104 / 304. So with regard to special earthing, if that is the case then its has to be external to the printed circuit boards as I saw no evidence of any changes on these, they look completely original Philips boards.
However, the case seems to have been carefully designed with regard to screening and includes an internal die cast aluminium container which shields the decoder boards. I did notice that this was coupled directly to the output phono earths via a short wire.
I do find the player to have much better transparency and detail producing a very open sound when compared to my Philips counterparts, which is hard to explain seeing that the core components are the same! Maybe other members might be able to shed more light on this.
Your comments on the missing inductor on the ps feed to the 7030 is interesting. I had never noticed that. My CD104 has a wire link too!
Hi jives11,
First of all sorry for the typo on my previous post, the Grundig model is in fact the CD7550 as shown on your polish link.
I can certainly confirm that the on board electronics are the same as found in the Philips CD104 / 304. So with regard to special earthing, if that is the case then its has to be external to the printed circuit boards as I saw no evidence of any changes on these, they look completely original Philips boards.
However, the case seems to have been carefully designed with regard to screening and includes an internal die cast aluminium container which shields the decoder boards. I did notice that this was coupled directly to the output phono earths via a short wire.
I do find the player to have much better transparency and detail producing a very open sound when compared to my Philips counterparts, which is hard to explain seeing that the core components are the same! Maybe other members might be able to shed more light on this.
Your comments on the missing inductor on the ps feed to the 7030 is interesting. I had never noticed that. My CD104 has a wire link too!
Re: GRUNDIG CD7550
I really should swap in an inductor next time I have the "hood off" but if you look here :
CD104 schematic
Top left is an inductor labelled 5502. This would seem sensible as it provides a degree of supply filtering and is consistent with the LC filtering supplied to other chips.
However my CD104 just has a link here, as does yours and as does the 7550 based on the Polish picture. I also have the service guide for the B&O CDX which is another player based on the same internals. It correctly shows a wire link at this place.
I'm guessing there was some reason for using a link at this point ? It's hard to see that it was cost saving. I have heard that sometimes things are changed to make manufacturing easier for the automated component assembly lines
IAN01 said:
I really should swap in an inductor next time I have the "hood off" but if you look here :
CD104 schematic
Top left is an inductor labelled 5502. This would seem sensible as it provides a degree of supply filtering and is consistent with the LC filtering supplied to other chips.
However my CD104 just has a link here, as does yours and as does the 7550 based on the Polish picture. I also have the service guide for the B&O CDX which is another player based on the same internals. It correctly shows a wire link at this place.
I'm guessing there was some reason for using a link at this point ? It's hard to see that it was cost saving. I have heard that sometimes things are changed to make manufacturing easier for the automated component assembly lines
well I had a spare hour or so yesterday so decided to make a few mods I had queued up :
1) I replaced wire link 5502 with a 47uH inductor
2) I changed the two 12v supply caps by the opamps again. I have gone from old cerafines, to new stargels but I think Cerafines are better here, so now have new cerafines here. I have read that they have a better response across a wider spectrum. In the application they decouple both the analogue supplies and some of the 12v digital too.
3) changes my Tandy cables for some better /longer VanDamm shielded mic cable with shark plugs. These enable me to sit the player to the right of my Quad 44, where as the previous cables (Tandys finest) meant it had to sit under the Quad. Actually not too bad an arrangement as they have exactly the same width..
Not had a chance to listen beyond testing that it fired up and read the TOC. Will post when I have some results.
1) I replaced wire link 5502 with a 47uH inductor
2) I changed the two 12v supply caps by the opamps again. I have gone from old cerafines, to new stargels but I think Cerafines are better here, so now have new cerafines here. I have read that they have a better response across a wider spectrum. In the application they decouple both the analogue supplies and some of the 12v digital too.
3) changes my Tandy cables for some better /longer VanDamm shielded mic cable with shark plugs. These enable me to sit the player to the right of my Quad 44, where as the previous cables (Tandys finest) meant it had to sit under the Quad. Actually not too bad an arrangement as they have exactly the same width..
Not had a chance to listen beyond testing that it fired up and read the TOC. Will post when I have some results.
I compared all models of Philips. Model is to five versions 104. Model plays 304 three versions. Model plays 100,200,202,204,300,303,304, 150,350,.Marantz cd63, 73,74,84. Grundig cd7500.7550, cd35. Revox 225,B&O CDX. All 14 bits. It plays best 7550 Grundig. It plays natural sound. Most beautiful paint of instrument from mentioned models,.
I salute
I salute
Re: GRUNDIG CD7550
well there does seem to be a consensus that the Grundig 7550 is the 14bit CD player of choice. I'm wondering if there is any way to retrofit it's features into non 7550 machines. The CD104 does have a kind of box in which both large boards sit, with approx a 10mm air gap between them, but it is open top and bottom. Are you saying that the 7550 separates the boards into 2 separate metal boxes. It would seem a good idea ? I'm wondering if there is space to fit a metal sheet between the CD104 boards. I don't know how the 104 earths the diecast chasis, I'll have a look with a meter between the case and the signal ground.
IAN01 said:
well there does seem to be a consensus that the Grundig 7550 is the 14bit CD player of choice. I'm wondering if there is any way to retrofit it's features into non 7550 machines. The CD104 does have a kind of box in which both large boards sit, with approx a 10mm air gap between them, but it is open top and bottom. Are you saying that the 7550 separates the boards into 2 separate metal boxes. It would seem a good idea ? I'm wondering if there is space to fit a metal sheet between the CD104 boards. I don't know how the 104 earths the diecast chasis, I'll have a look with a meter between the case and the signal ground.
well there does seem to be a consensus that the Grundig 7550 is the 14bit CD player of choiceHumm, I cannot confirm this as I have not heard one, but I remain very impressed by the Meridian MCD, also a 14 bit (CD100/Marantz CD63).
Why I mention it is that it was modified by meridian, and the mods appear to be centered around the analog output stages, with a pair of ne5534 instead of the ne5532 and a lot more and bigger caps in all the power supply rails, both analog and digital. there is also a metal shield over the saa7020, so maybe there is something in the Grundig earthing...
Philippe
well after sone listening the caps and the inductor have done no harm at all. Sounds great. A bit hard at the top, but that is maybe a feature, but the bass is strong and the image huge. Maybe as the Cerafines bed in a bit the sound may warm up, who knows.
a quick ground test indicates 0.5 Ohm between chassis and signal ground. Not sure if this is design or just poor meter accuracy
a quick ground test indicates 0.5 Ohm between chassis and signal ground. Not sure if this is design or just poor meter accuracy
Sounds great. I might follow your lead and try the same mods. Interesting to hear your comments too GregAudio, you have carried out a far more comprehensive comparison than I.
Getting back to the Grundig machine, when I get the chance I'll pull it apart again and look at it in a bit more detail and get some close up pictures posted on here for you all to see.
One thing I have found though in all my comparison tests is that there always seem to be subtle differences to the sound of all these 14 bit CD players, even between two of the same model, which is intriguing, each player seems to have their own particular character. I have two CD100s which both sound open and airy but subtlely different from each other, then a CD303 which sounds a lot less airy but has stunningly more detail and the CD104 with its rich warm sound and rock solid imagery. Then the 7550 which seems to combine the best of all the others. Considering before the DAC it's all digital and afterwards the analogue stage is essentially identical from the CD100 to the CD104 I find it perplexing that they can sound so different from one another.
Getting back to the Grundig machine, when I get the chance I'll pull it apart again and look at it in a bit more detail and get some close up pictures posted on here for you all to see.
One thing I have found though in all my comparison tests is that there always seem to be subtle differences to the sound of all these 14 bit CD players, even between two of the same model, which is intriguing, each player seems to have their own particular character. I have two CD100s which both sound open and airy but subtlely different from each other, then a CD303 which sounds a lot less airy but has stunningly more detail and the CD104 with its rich warm sound and rock solid imagery. Then the 7550 which seems to combine the best of all the others. Considering before the DAC it's all digital and afterwards the analogue stage is essentially identical from the CD100 to the CD104 I find it perplexing that they can sound so different from one another.
phimor said:well there does seem to be a consensus that the Grundig 7550 is the 14bit CD player of choiceHumm, I cannot confirm this as I have not heard one, but I remain very impressed by the Meridian MCD, also a 14 bit (CD100/Marantz CD63).
Why I mention it is that it was modified by meridian, and the mods appear to be centered around the analog output stages, with a pair of ne5534 instead of the ne5532 and a lot more and bigger caps in all the power supply rails, both analog and digital. there is also a metal shield over the saa7020, so maybe there is something in the Grundig earthing...
Philippe
Hello, I have two CD-104 with the same problem :
Right channel is ok, but on the left channel there is very very very little sound (good sound without distortion)
I've done the "griplets" trick on one, but no succes.
If someone can give me an idea and also the service manual, because I'm not sure that I seen all the "griplets". ..
Thanks !!!
kikookATclub-internetDOTfr
Right channel is ok, but on the left channel there is very very very little sound (good sound without distortion)
I've done the "griplets" trick on one, but no succes.
If someone can give me an idea and also the service manual, because I'm not sure that I seen all the "griplets". ..
Thanks !!!
kikookATclub-internetDOTfr
