| Nuuk |
| quote: | | Nuuk - Yes, thanks, I had already seen your mods. I would prefer to keep it as a front loader - fits in my rack better. |
I know what you mean Dave. Having just added a DAC, I have virtually nowhere to put it.
I would suggest that with mechanical mods to a CD player or DAC that empirical methods are probably as good as any (providing you have the time to experiment). :smash:
Did you ever read about the 'string suspension' that was popular in Germany for a while? |
|
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Dave S
I'm really looking for some scientific explanation of why it should or should not be mass loaded / damped / rigid / sprung etc. |
To keep it short and sweet. The lase system will "misread" more easily if the drive is exposed to vibrations. Many components are microphonic in varying frequency ranges and to varying degrees.
One can deal with vibrations and resonances in many ways. I personally have my favourite approaches which center around lossy, rigid natural materials (eg. Wood) combined with suspension methodes around string/spring etc.
Clear enough?
Sayonara |
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| Bricolo |
| when you mention wood, do you mean as a support, or to modify the case with wood? |
|
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Bricolo
when you mention wood, do you mean as a support, or to modify the case with wood? |
Both actually. I don't want to (or have time to) trot out all my philosophy and experience on the subject, however as a rule, conventional damping or excessive massloading does not to me seem to result in all that good sound.
Keeping things fairly light, lossy and rigid seems to help. Suspending vibration sensitive items helps too. If resonances cannot be avoided those from wood "sound" less offensive (and hence better) than those from metal or plastic.
Sayonara |
|
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| Bernhard |
| Upgrade to a transport that has been assembled by elfs. |
|
|
| Fin |
Hi Thorsten
Please see Post #96 of this thread, if you have time.
I have tried to digest your power supply recommendations and adapt them to my application, and the parts I already have.:dodgy:
It would be great if you could have a quick look at my understanding of how to implement them. :whazzat:
I am unsure about the arrangement of the components and what to use as a final regulator. :confused:
1: Analogue output stage:- one dual opamp.
Use one 2*22Vac 25VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +/- 31Vdc. Pass this through 3R3 - 470uF - LM317/337 pre-reg - 10R - 4700uF - ????? final reg???
Use capacitors like Rubycon ZA/ZL throughout this supply.
Would Panasonic FC or Rubycon YXF be OK here for the higher values?
Use Audio Grade capacitors (Elna Silmic or Starget) at the output of the reg ie. the 4700uF cap??
Is Nichicon Muse KS also good for this?
2: Analogue side of the DAC chip:- four +5V supplies.
Use one winding of the 2*15Vac 25VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +21Vdc. Pass this through 3R3 - 470uF - LM317 pre-reg -10R - 4700uF - ????? final regs (maybe 4 regs)???
Same type of caps as above??
3: Digital side of the DAC(including filter) and Decoder:- three +5V supplies.
Use second winding of the 2*15Vac 25VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +21Vdc. Pass this through 3R3 - 470uF - LM317 pre-reg - 10R - 4700uF - ????? final regs (maybe 3 regs)???
Same type of caps as above?
4: Supply for the Servos: +/-10V
Use 2*12Vac 30VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +/- 17Vdc. Pass this through 3R3 - 6800uF - LM317/337 Reg 10R - 6800uF - to provide one +10V supply and one -10V supply. This is connected to the main pcb traces feeding the servo section.
Would Rubycon YXF be OK here as they have this value?
Does each servo need a separate regulator/supply?
5: Supply for Master Clock:- Tent XO2 clock module.
Using dedicated Tent XO Supply.
6: Supply to the rest of CDP:- Display, uP, remote control...
Use original internal TF. Change existing capacitors in the original +/-5V/10V supplies from 6800uF and 1000uF to 470uf caps. Increase the size of the caps after the regs???
Have I understood any of what you have said or have I got it totally wrong?:o :xeye:
In your article on modifying the CD63/67 you built the following:-
Say two 330 Watt Toroidal Transformers (one 2 X 18 Volt AC and one 2 X 12 Volt AC) with 12,000uF (12 X 1,000uF Nichicon PL or panasonic FA Series) Filtering per Voltage and some Chokes and polypropylene Cap's thrown in for good measure with LM317/337 Pre-Regulators.
This would give us two separate "raw" 12Volt Voltages for the two 5Volt Supplies and the "raw" +/- 18 Volt Voltages for the +/- 12 Volt Supply. In this case the +/- 12 Volt regulators should be really replaced with Linear Technologies LT1033/1085.
Is the move away from the 12,000uF filtering mainly due to space inside the CDP? :bigeyes:
Thanks again for all your help. :) |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
1: Analogue output stage:- one dual opamp.
Use one 2*22Vac 25VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +/- 31Vdc. Pass this through 3R3 - 470uF - LM317/337 pre-reg - 10R - 4700uF - ????? final reg??? |
Nope, I'd go rectifier - 3R3 470uF 10R 4,700uF - Reg
| quote: | Originally posted by Fin
Would Panasonic FC or Rubycon YXF be OK here for the higher values? |
Sure.
| quote: | Originally posted by Fin
Use Audio Grade capacitors (Elna Silmic or Starget) at the output of the reg ie. the 4700uF cap?? |
Large values on the output of LM317/1085 do not bring that much improvement, try 100uF each on adj to negative and on the output.
| quote: | Originally posted by Fin
Is Nichicon Muse KS also good for this?
|
Maybe, never really worked with it. I like Elna Silmic best among "Audio" electrolytics and they are neither expensive nore hard to get.
| quote: | Originally posted by Fin
2: Analogue side of the DAC chip:- four +5V supplies.
Use one winding of the 2*15Vac 25VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +21Vdc. Pass this through 3R3 - 470uF - LM317 pre-reg -10R - 4700uF - ????? final regs (maybe 4 regs)??? |
Same as above. Stick to RCRC filtering and one Reg. Also, not so much voltage. Keep around 3 - 5V headroom, no more. So no more than 10V DC for the 5V supplies. All else equally applies.
| quote: | Originally posted by Fin
3: Digital side of the DAC(including filter) and Decoder:- three +5V supplies.
Use second winding of the 2*15Vac 25VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +21Vdc. Pass this through 3R3 - 470uF - LM317 pre-reg - 10R - 4700uF - ????? final regs (maybe 3 regs)??? |
See two previous posts, use Sanyo Os-Con in the Local decoupling and around the regulators.
| quote: | Originally posted by Fin
4: Supply for the Servos: +/-10V
Use 2*12Vac 30VA PCB torroidal TF. Use Schottky diodes to build recifiier bridge. This produces +/- 17Vdc. Pass this through 3R3 - 6800uF - LM317/337 Reg 10R - 6800uF - to provide one +10V supply and one -10V supply. This is connected to the main pcb traces feeding the servo section. |
I would omit any resistors, just rectifier and maybe 0.33R, then a big Cap (10,000uF ballpark), 1A (or better 3A) fixed voltage regulators and a large value cap on the output of the regulator.
| quote: | Originally posted by Fin
Would Rubycon YXF be OK here as they have this value? |
Sure.
| quote: | Originally posted by Fin
Does each servo need a separate regulator/supply? |
Never tried it, I think it's mostly important to have a high current supply separated from the rest of the circuitry.
| quote: | Originally posted by Fin
6: Supply to the rest of CDP:- Display, uP, remote control...
Use original internal TF. Change existing capacitors in the original +/-5V/10V supplies from 6800uF and 1000uF to 470uf caps. Increase the size of the caps after the regs??? |
Leave the original supply as is, large cap's only increase peak currents and reduce conduatcion angle and to only drive "administrative" functions of a CDP there is no benefit.
| quote: | Originally posted by Fin
Is the move away from the 12,000uF filtering mainly due to space inside the CDP? :bigeyes: |
No, change in Philosophy.... ;-)
Sayonara |
|
|
| Fin |
Thanks again Thorsten :angel:
| quote: | Originally posted by Kuei Yang Wang Konnichiwa,
Nope, I'd go rectifier - 3R3 470uF 10R 4,700uF - Reg
Large values on the output of LM317/1085 do not bring that much improvement, try 100uF each on adj to negative and on the output.
I like Elna Silmic best among "Audio" electrolytics and they are neither expensive nore hard to get. |
OK - For the analogue stage (opamp) I'll use:
3R3(Carbon Film) - 470uF (Pana FC) - 10R(Carbon Film) - 4,700uF(Pana FC) - LM317/337 - 100uF(Silmic*2). Should I forget about the Pre-Reg/Final Reg arrangement? :confused:
LM6172/OPA2604/OPA2134 - Decoupled with 100uF(Silmic) - 100uF DC Blocking/Coupling(Nichicon Muse ES Bi-Polar). Are Silmics good for DC blocking as well?
Any other comments?
| quote: | Originally posted by Kuei Yang Wang
Same as above. Stick to RCRC filtering and one Reg. Also, not so much voltage. Keep around 3 - 5V headroom, no more. So no more than 10V DC for the 5V supplies. All else equally applies. |
OK - For the analogue side of the dac I'll use:
Same RCRC as above and one Reg. Does "one Reg" mean:- one reg for all four analogue supplies to the dac; or:- forget about Pre-Regs and still consider one reg per suppliy pin on the dac?
The reason I went for the higher voltage tf is to allow for Pre Regs - but I gather you don't like that idea??? :bawling:
Should I use something like Elna Silmics for decoupling on the analogue side of the dac?
| quote: | Originally posted by Kuei Yang Wang
See two previous posts, use Sanyo Os-Con in the Local decoupling and around the regulators. |
OK - For the digital side of the DAC and Decoder I'll use:
Same as above with a separate Reg for the DAC and a another for the Decoder.
Is it definitely OK to group these together on the same winding? :eek:
What value Os-Cons would you suggest? There are 33uF electrolytics with 100nf smd ceramics in place originally. Should the 100nF's be removed? Would Rubycon ZA with the ceramics left in place be nearly as good as the Os-Cons? :bigeyes:
| quote: | Originally posted by Kuei Yang Wang
I would omit any resistors, just rectifier and maybe 0.33R, then a big Cap (10,000uF ballpark), 1A (or better 3A) fixed voltage regulators and a large value cap on the output of the regulator. |
OK - For the supply to the Servos I'll use:
3A Schottky Diodes - 0.33R - 8,200uF/16V(Pana FC - the biggest they have) - 3A Reg - 8,200uF.
Would it be better to use 2*4,700uF or 5*2,200uF instead of 1*8,200uF?
Should the Regs set the voltage at +/-12V or +/-10V? :dodgy:
Will any of the servos or laser current need any adjustment after this? :smash:
| quote: | Originally posted by Kuei Yang Wang
Leave the original supply as is, large cap's only increase peak currents and reduce conduatcion angle and to only drive "administrative" functions of a CDP there is no benefit. |
So - they only need something like 470uF??
| quote: | Originally posted by Kuei Yang Wang
No, change in Philosophy.... ;-) |
Change in Philosophy away from banks of capacitors or large capacitance in analogue supplies or both? |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
Should I forget about the Pre-Reg/Final Reg arrangement? :confused: |
To me a pre/post reg arrangement only makes if the post reg is optimised for low and constant with bandwidth output impedance with the pre reg providing the bulk of ripple rejection. Just cascading multple 317's does not seem to give much advantages.
| quote: | Originally posted by Fin
LM6172/OPA2604/OPA2134 |
I do not recommend the LM6172 in this application. USe LM6182 or AD812.
| quote: | Originally posted by Fin
Decoupled with 100uF(Silmic) |
Keep the original decoupling arrangement and add local at the Chip one Cap between +V & -V, be it a 1uF Epcos stacked film or a Kemet 0.1uF "Gold" Ceramic.
| quote: | Originally posted by Fin
100uF DC Blocking/Coupling(Nichicon Muse ES Bi-Polar). Are Silmics good for DC blocking as well? |
DC blocking? What for? You can cancel the offset and direct couple.
| quote: | Originally posted by Fin
Is it definitely OK to group these together on the same winding? :eek: |
In what sense? Will it be no worde than using seperate windings? I feel seperate windings are ALWAYS better.
| quote: | Originally posted by Fin
What value Os-Cons would you suggest? |
Whatever fits PCB and Budget, I usually keep bags of 22uF/6.3V SH Series around for Digital Mods.
| quote: | Originally posted by Fin
Should the 100nF's be removed? |
Yes, but replace by local SMD Capacitors 10nF/0805 X7R and 100nF/0805 Z5U/Y5U.
| quote: | Originally posted by Fin
Would Rubycon ZA with the ceramics left in place be nearly as good as the Os-Cons? :bigeyes: |
Nope.
| quote: | Originally posted by Fin
Would it be better to use 2*4,700uF or 5*2,200uF instead of 1*8,200uF? |
Usually No.
| quote: | Originally posted by Fin
Should the Regs set the voltage at +/-12V or +/-10V? :dodgy:
|
Measure whatever is in place originally and replicate, or check in the datasheets what the nominal supply is for the Chips used in the player.
| quote: | Originally posted by Fin
Will any of the servos or laser current need any adjustment after this? :smash: |
In modern players - no.
| quote: | Originally posted by Fin
So - they only need something like 470uF?? |
Probably. Why not check the Datasheets, total up worst case supply current and use Duncanamps Powersupply Designer to see how low you can go?
| quote: | Originally posted by Fin
Change in Philosophy away from banks of capacitors or large capacitance in analogue supplies or both? |
I never used banks of capacitors nor do I feel they have merit, other than to lower costs in commercial production.
Sayonara |
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| Bricolo |
"in modern players - no"
and in my CD-62? (CDM4)
One thing: some people like to parallel caps (the 100uF+smd ceramic is seen quite often, the triplet is also a well spread technique), but Guido Tent's article abous PS decoupling nearly convinced me that it's not a good idea.
Thorsen, all your help here is based on a good technical explanation (either here or in your articles). Could you tell us why the use of the paralleled caps? Aren't the oscons effective enough at high frequencies? |
|
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Bricolo
"in modern players - no"
and in my CD-62? (CDM4)
|
Maybe, I would think not if you match the original voltages.
| quote: | Originally posted by Bricolo
One thing: some people like to parallel caps (the 100uF+smd ceramic is seen quite often, the triplet is also a well spread technique), |
For very good reasons too.
| quote: | Originally posted by Bricolo
but Guido Tent's article abous PS decoupling nearly convinced me that it's not a good idea. |
How so? I would not think that Guido is arguing against using local bypass capacitors of suitable nature, which invariably means multiple value capacitors in parallel FOR EACH SUPPLY NODE.
| quote: | Originally posted by Bricolo
Could you tell us why the use of the paralleled caps? |
In order to retain a low impedance PSU nore for each and every given PSU into the high 2 digit MHz range.
| quote: | Originally posted by Bricolo
Aren't the oscons effective enough at high frequencies? |
Well, normal 'lytics **** out usually around 100KHz, Os-Cons have a lower ESR and remain capaictive to 300...500KHz, neither one is sufficient for the kind of switching frequencies for the logic in modern gear. So further local bypassing is essential, plus Os-Con's are physically quite large, meaning they will remain placed at a considerable distance from the actual PSU node, adding a lot of leadlength and PCB inductance. Thus the combination of multiple capacitors with different ESL and C to spread and dampen any LC tank circuit resonances and to keep the PSU node impedance low.
A reasonable overview of the topic is found here:
http://fibbla.ce.chalmers.se/underg...lektorpaper.pdf
Sayonara |
|
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| Peter Daniel |
| quote: | Originally posted by Bricolo
One thing: some people like to parallel caps (the 100uF+smd ceramic is seen quite often, the triplet is also a well spread technique), but Guido Tent's article abous PS decoupling nearly convinced me that it's not a good idea.
Thorsen, all your help here is based on a good technical explanation (either here or in your articles). Could you tell us why the use of the paralleled caps? Aren't the oscons effective enough at high frequencies? |
I was almost convinced about that too, but nevertherless, I tried adding ceramic bypasses and the sound improved, while using BG N type caps (10u and 100u). Some other people also observed improvement with adding ceramics SMD caps (not all of them are the same, a proper choice is important) |
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| Bricolo |
| Something like this? |
|
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| Fin |
Hi Thorsten
I'm sure your are getting tired of our non-stop questions! :smash:
Unfortunately, I'm not an electronics student and I'm struggling to keep up with the rest of you. :bawling:
| quote: | Originally posted by Kuei Yang Wang
To me a pre/post reg arrangement only makes if the post reg is optimised for low and constant with bandwidth output impedance with the pre reg providing the bulk of ripple rejection. Just cascading multple 317's does not seem to give much advantages.
|
Would it be worthwhile using the pre/post reg arrangement that you used in the CD63/67 TNT article - quoted below? :confused:
| quote: | Taken fron the TNT CD63/67 article.
Say two 330 Watt Toroidal Transformers (one 2 X 18 Volt AC and one 2 X 12 Volt AC) with 12,000uF (12 X 1,000uF Nichicon PL or panasonic FA Series) Filtering per Voltage and some Chokes and polypropylene Cap's thrown in for good measure with LM317/337 Pre-Regulators. This would give us two separate "raw" 12Volt Voltages for the two 5Volt Supplies and the "raw" +/- 18 Volt Voltages for the +/- 12 Volt Supply. In this case the +/- 12 Volt regulators should be really replaced with Linear Technologies LT1033/1085. |
| quote: | Originally posted by Kuei Yang Wang
I never used banks of capacitors nor do I feel they have merit, other than to lower costs in commercial production. |
Maybe my use of the term; "banks of capacitors", was incorrect. :o
| quote: | Originally posted by Kuei Yang Wang
Keep the original decoupling arrangement and add local at the Chip one Cap between +V & -V, be it a 1uF Epcos stacked film or a Kemet 0.1uF "Gold" Ceramic. |
For us "Dummies", this is between pins 4 and 8 on a dual opamp - and not from supply to ground? :xeye:
| quote: | Originally posted by Kuei Yang Wang
DC blocking? What for? You can cancel the offset and direct couple. |
Maybe I have used the wrong term here again! The original arrangement in the CD624 has a 100uF/16V Nichicon Muse Bi-Polar electrolytic directly in each output path from pins 1 and 7 from the NJM5532 opamp. :eek:
I need to find out more about cancelling offset.
| quote: | Originally posted by Kuei Yang Wang
In what sense? Will it be no worde than using seperate windings? I feel seperate windings are ALWAYS better. |
I suppose what I am trying to ask here is: Which of the following two arrangements would be better, if I want to power the SAA7310 Decoder IC and the SAA7321 Bitstream DAC/Filter IC from one dual secondary transformer?
Option 1. The four +5V supplies of the analogue side of the dac powered from one winding, and;
The two +5V supplies for the digital side of the dac and the +5V supply for the decoder powered from the second winding.
OR :bigeyes:
Option 2. The four +5V supplies of the analogue side of the dac and the two +5V supplies for the digital side of the dac powered fron one winding, and;
The +5V supply for the decoder powered fron the second winding.
| quote: | Originally posted by Kuei Yang Wang
Whatever fits PCB and Budget, I usually keep bags of 22uF/6.3V SH Series around for Digital Mods. |
You obviously feel that the SG (audio) Series is not necessary here?
| quote: | Originally posted by Kuei Yang Wang
Yes, but replace by local SMD Capacitors 10nF/0805 X7R and 100nF/0805 Z5U/Y5U. |
So - for decoupling around the DAC - I should remove the existing 33uF/16V electrolytics and the 100 nF SMD's. These should be replaced with Os-Cons (around 22uF - whatever fits neatly) and 10nF/0805 X7R and 100nF/0805 Z5U/Y5U?? :whazzat:
| quote: | Originally posted by Kuei Yang Wang
Measure whatever is in place originally and replicate, or check in the datasheets what the nominal supply is for the Chips used in the player. |
Is there any point in changing any of the opamps (NJM4560) in the servos? :dodgy:
| quote: | Originally posted by Kuei Yang Wang
In modern players - no. |
If the CD624 falls into this category - then I'm happy as I don't fancy messing with this. :)
| quote: | Originally posted by Kuei Yang Wang
Probably. Why not check the Datasheets, total up worst case supply current and use Duncanamps Powersupply Designer to see how low you can go? |
I will definitely be looking at this! :cool: |
|
|
| Fin |
| quote: | Originally posted by Bricolo
One thing: some people like to parallel caps (the 100uF+smd ceramic is seen quite often, the triplet is also a well spread technique), but Guido Tent's article abous PS decoupling nearly convinced me that it's not a good idea.
Thorsen, all your help here is based on a good technical explanation (either here or in your articles). Could you tell us why the use of the paralleled caps? Aren't the oscons effective enough at high frequencies? |
I tried to address this in another thread. :smash:
Optimum Decoupling in Digital IC's |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Bricolo
Something like this? |
Not really.
First, I would always use pre-regulators (317/1085) with LM/TL431 Shunt Regs.
Secondly, the shuntreg and bypass capacitors for each IC should combine at a local star, the ground pin of the IC.
One final "refinement", R1/R2 and R3/R4 can be split and distributed across the two supply lines, preferablyt using inductive wirewound resistors with added ferrite beads.
Sayonara |
|
|
| Bricolo |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
Not really.
First, I would always use pre-regulators (317/1085) with LM/TL431 Shunt Regs.
Secondly, the shuntreg and bypass capacitors for each IC should combine at a local star, the ground pin of the IC.
One final "refinement", R1/R2 and R3/R4 can be split and distributed across the two supply lines, preferablyt using inductive wirewound resistors with added ferrite beads.
Sayonara |
one pre reg per shunt, or one per secondary?
do you mean, the shunt+cap's ground should be placed at the chip's ground? so no direct connection to the bridge?
I don't understand the last one :( |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Bricolo
one pre reg per shunt, or one per secondary? |
One per secondary.
| quote: | Originally posted by Bricolo
do you mean, the shunt+cap's ground should be placed at the chip's ground? so no direct connection to the bridge?
I don't understand the last one :( |
Remember my mantra - look where current will flow....
You have your IC's, their grounds are joined via a Bus/Groundplane System. You have several pre-regulated, "clean" supplies you wish to feed to various Supply Nodes, in most cases individual per IC, meaning the negative supply to ground pin and the positive to the supply pin via a resistor/ccs, assuming the shunt regulator is locat to the Chip, where it belongs (otherwise it's > 100KHz bandwidth is wasted).
If you have several IC's to supply look at the one that pump's the most junk into the supply/ground loop and/or which requires the cleanest "ground" and attach the negative wire to the relevant chip's (hard to say which is more relevant) ground pin, then fan out individual resistors/ccs per chip to the positive supply pin's.
Allways thinbk of the circuit (chip) as posessing one positive and one negative power pin and as having one signal ground and several I/O Pin's. Sadly for us the signal ground and negative pin have usually been combined, be it in logic circuits or in Op-Amp's and single ended audio circuits.
However, you still CAN separate the supply current and signal current loops by having seperate supplies (galvanically seperate) per chip.
Clearer?
Sayonara |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
Would it be worthwhile using the pre/post reg arrangement that you used in the CD63/67 TNT article - quoted below? :confused:
|
Maybe, probably not. In those days I failed to understand what really went on in supplies and hence followed the (arguably pretty reliably applicable) "bigger transformers, capacitors and more regs are good" credo. I have since learned that once you understand the goings on you can get "more with less".
| quote: | Originally posted by Fin
Maybe my use of the term; "banks of capacitors", was incorrect. :o |
I understand it as using several smaller value capacitors in parallel instead of using one suitable value part of sufficient quality.
| quote: | Originally posted by Fin
For us "Dummies", this is between pins 4 and 8 on a dual opamp - and not from supply to ground? :xeye: |
You. Just try to think where the Op-Amp's ground pin is. Can't see it? It usually is the negative supply pin, but sometimes the positive supply pin. Only this current loop is essential for stability at high frequencies.
| quote: | Originally posted by Fin
Maybe I have used the wrong term here again! The original arrangement in the CD624 has a 100uF/16V Nichicon Muse Bi-Polar electrolytic directly in each output path from pins 1 and 7 from the NJM5532 opamp. :eek:
I need to find out more about cancelling offset. |
It implies to introduce a direct current/voltage into the circuit in such a mannner that at the Audio Stages output the Output is held reliably at or close (enough) to 0V.
| quote: | Originally posted by Fin
I suppose what I am trying to ask here is: Which of the following two arrangements would be better, if I want to power the SAA7310 Decoder IC and the SAA7321 Bitstream DAC/Filter IC from one dual secondary transformer? |
One supply for DAC digital, one for Decoder. Tap of the 5V supplies for the Analogue side of the DAC from the +/-15V supply of the Output Stage, using seperate regs directly of the raw rectified supply.
To be absolutely certain what should be consideredn analog and what digital and what pin's are noise sensitive one would have to go in detail through datasheet and apps notes, which I cannot find on the quick.
| quote: | Originally posted by Fin
You obviously feel that the SG (audio) Series is not necessary here? |
Or apropriate.
| quote: | Originally posted by Fin
So - for decoupling around the DAC - I should remove the existing 33uF/16V electrolytics and the 100 nF SMD's. These should be replaced with Os-Cons (around 22uF - whatever fits neatly) and 10nF/0805 X7R and 100nF/0805 Z5U/Y5U?? :whazzat: |
If SMD's are in place, you may find they are okay to leave and to add a 10nF SMD directly at the chip Pin's (as close as you can get). Replace the existing 'lytics by Os-Con's.
| quote: | Originally posted by Fin
Is there any point in changing any of the opamps (NJM4560) in the servos? :dodgy: |
Maybe, but doubtful. One would have to see the full schematic and details on the other integrated circuits to be certain.
| quote: | Originally posted by Fin
If the CD624 falls into this category - then I'm happy as I don't fancy messing with this. :) |
I think yous has the old swingarm mechanism, a very nice drive but rather aged and yes, these do tend to require adjustment eventually, as not yet all adjustments where on-chip dynamically.
BTW, a final warning. What you are trying to do should IMHO really only be done by people with both substantial theoretical grounding in electronics and substantial practical experience. If you are in doubt about something - don't do it. Any of my comments and suggesting are basically aimed at qualified and experienced EE's, as I cannot see how people without this can truely understand what they are doing. If this limits the extend of your modifications, tough luck.
Sayonara |
|
|
| Fin |
Thanks again, Thorsten, for the good advice.
| quote: | Originally posted by Kuei Yang Wang
You. Just try to think where the Op-Amp's ground pin is. Can't see it? It usually is the negative supply pin, but sometimes the positive supply pin. Only this current loop is essential for stability at high frequencies. |
The "Us Dummies" comment was only referring to myself and anyone else reading this thread who might find themselves on the same learning curve. :Ouch:
Also - I never said the op-amp had a ground pin - but thanks for the clarification. :cheeky: :sorry:
| quote: | Originally posted by Kuei Yang Wang
One supply for DAC digital, one for Decoder. Tap of the 5V supplies for the Analogue side of the DAC from the +/-15V supply of the Output Stage, using seperate regs directly of the raw rectified supply.
To be absolutely certain what should be consideredn analog and what digital and what pin's are noise sensitive one would have to go in detail through datasheet and apps notes, which I cannot find on the quick. |
I can send them to you if you like............................:joker:
| quote: | Originally posted by Kuei Yang Wang
Or apropriate. |
So - where would one use Os-Con SG series? :confused:
| quote: | Originally posted by Kuei Yang Wang
If SMD's are in place, you may find they are okay to leave and to add a 10nF SMD directly at the chip Pin's (as close as you can get). Replace the existing 'lytics by Os-Con's. |
I was hoping you would say that the existing SMD might be OK! :D
If the Vdd and Vss pins are not next to each other - but are on adjacent sides of the IC - what do you think of using an axial 10nF ceramic directly across the pins? :idea:
| quote: | Originally posted by Kuei Yang Wang
Maybe, but doubtful. One would have to see the full schematic and details on the other integrated circuits to be certain. |
Again, I can send them to you if you like............................:joker:
| quote: | Originally posted by Kuei Yang Wang
I think yous has the old swingarm mechanism, a very nice drive but rather aged and yes, these do tend to require adjustment eventually, as not yet all adjustments where on-chip dynamically. |
Yes - it is a CDM4/19 - in mint condition - hardly used. :devilr:
| quote: | Originally posted by Kuei Yang Wang
BTW, a final warning. What you are trying to do should IMHO really only be done by people with both substantial theoretical grounding in electronics and substantial practical experience. If you are in doubt about something - don't do it. Any of my comments and suggesting are basically aimed at qualified and experienced EE's, as I cannot see how people without this can truely understand what they are doing. If this limits the extend of your modifications, tough luck. |
Thanks for the warning :cop: :judge: - I have taken note of it. :skull: Yes - it is my tough luck that I studied Chemisry instead of Electronics! :crying: :bawling: |
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| Fin |
.................but that is nothing new (from me)! :cubehead:
I hope I am asking this in the correct thread as it is also applicable to Optimum decoupling in digital IC's. :dunno:
Here we have been discussing the addition of extra transformers to separate sections of the CDP and break up ground loops.
If a new tf is added and the ground of the new supply is connected to the appropriate star ground for that circuit - how does that influence decoupling? :boggled:
For example, a decoupling capacitor is connected as close to the supply pin as possible - but where is it connected to ground? :scratch:
Is it best to connect it directly to the main groundplane, or via a trace to the star ground (which is connected to the new tf)? :scratch2: |
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| Bernhard |
| quote: | Originally posted by Fin
Yes - it is a CDM4/19 - in mint condition - hardly used. :devilr:
|
The most mediocre swing arm transport I'm aware of, with brush motor and missing ceramic cap across motor psu pins :dead: |
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| Fin |
| quote: | Originally posted by Bernhard
The most mediocre swing arm transport I'm aware of, with brush motor and missing ceramic cap across motor psu pins :dead: |
Where is Jean-Paul when I need him???????
It doesn't have to be the best, have CDM1 stamped on it, have S1 or S2 printed on it (genuine or fake), or have the lowest noise and distortion as measured on your scope, for it to be worthwhile and fun to improve and listen to.
The CD624 was probably one of the cheapest implementations of the CDM4/19. It is unlikely that the CDM4/19 is the limiting factor in this project!!
Surely the crappy Bitstream DAC, poor ground plane, sub-standard power supplies, inferior decoupling, non existant shielding, flimsy plastic case and jitter ridden clock are all far worse than the mechanism/laser!! :rolleyes:
What constructive suggestions do you have for me, Bernhard? |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
Also - I never said the op-amp had a ground pin - but thanks for the clarification. :cheeky: :sorry:
|
No, but I did. And the Op-Amp indeed has an "AC Ground" Pin (or perhaps better called signal current loop return) which in MOSt (but not all) Op-Amp's is the negative supply.
| quote: | Originally posted by Fin
I can send them to you if you like............................:joker:
|
If you have them, try working out the pin assignements etc. by yourself, good excercise in analytic thinking and electronics.
| quote: | Originally posted by Fin
So - where would one use Os-Con SG series? :confused:
|
I don't. They are supposed to be "audio grade" with OFHC Copper leads, but I don't like any 'lytics in audio coupling applications, so I don't use them at all.
| quote: | Originally posted by Fin
If the Vdd and Vss pins are not next to each other - but are on adjacent sides of the IC - what do you think of using an axial 10nF ceramic directly across the pins? :idea:
|
If it can be done, great. I always tend to solder my SMD Cap's directly next to the IC body on the IC pin's, for non SMD Chips.
| quote: | Originally posted by Fin
Again, I can send them to you if you like............................:joker: |
Again, try to make as much sense as possible yourself.
If that means getting Horrorwitz & Hell "Art of Electronics" and reading it (actually, the Authors are Horrowitz & Hill IIRC), so be it...
Sayonara |
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| Bricolo |
Here's another drawing.
Is this the correct layout? (of course, the prereg is missing)
The shunts will be placed close to the ICs; but still on a small separate board (since the main PCB isn't designed to house them)
When the prereg will be added, where will his ground go? To the most critics IC's ground, or to the gridge's ground? |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Bricolo
Here's another drawing.
Is this the correct layout? (of course, the prereg is missing)
The shunts will be placed close to the ICs; but still on a small separate board (since the main PCB isn't designed to house them) |
Pretty much so, with your added qualifications.
| quote: | Originally posted by Bricolo
When the prereg will be added, where will his ground go? To the most critics IC's ground, or to the gridge's ground?
|
The answer of course is neither.
Remember, ask yourself where the current flows, the complete loop, the whole loop and nothing but....
For the whole powersupply in effect a "BUS" wire system applies up to the point where it feeds the actual circuit. I would retain a local star ground around the pre-regulator for the adj pin resistor and capacitor plus the output load and input bypass capacitor (if used), as this defines the local AC loops for the regulators.
Sayonara |
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| Fin |
Hi Thorsten
| quote: | Originally posted by Kuei Yang Wang
To be absolutely certain what should be consideredn analog and what digital and what pin's are noise sensitive one would have to go in detail through datasheet and apps notes, which I cannot find on the quick.
If you have them, try working out the pin assignements etc. by yourself, good excercise in analytic thinking and electronics. |
I have the datasheet for the DAC and the schematics for the CDP. The implementation of the DAC is slightly different in both documents - mainly just the values of the decoupling capacitors. In the datasheet they are 47uF lytics with 47nF ceramics. In the CDP schematics, they are 33uF lytics with 100nF ceramics.
If anyone is interested:-
SAA7322-3.PDF
Pin 22 (Vdd1; +5V for digital section) and Pin 23 (Vdd2; +5V for crystal oscillator) share one supply network which is different in structure to the other (analogue) supplies to the dac. This supply contains a network of resistors and an inductor.
The supplies to the analogue pin 39 (Vdda; analogue logic), pin 11 (Vddal; analogue left) and pin 42 (Vddar; analogue right), are simpler and only comprise of a resistor and decoupling.
The supply to pin 15 (Vddref) is the same as the analogue supplies.
I assume that the two digital supplies are most sensitive as they been given more attention. The fact that they have a different supply network would suggest that they could benefit from being separated from the analogue supplies,
However, Rotelian has just highlighted the following two statements in the datasheet:
| quote: | General
The device only require one +5V supply; the required reference voltage is generated internally.
and
Notes to the limiting values.
1. All Vdd and Vss pins must be connected to the same external power supply unit.
|
Does this place a limit on the extent to which the supplies can be separated?
Is this the type of "analytic thinking" that you suggest?
| quote: | Originally posted by Kuei Yang Wang
If it can be done, great. I always tend to solder my SMD Cap's directly next to the IC body on the IC pin's, for non SMD Chips. |
The dac is a SMD IC - but I think it may be possible to get close to it.
| quote: | Originally posted by Kuei Yang Wang
Again, try to make as much sense as possible yourself.
If that means getting Horrorwitz & Hell "Art of Electronics" and reading it (actually, the Authors are Horrowitz & Hill IIRC), so be it... |
I will look for this book. |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
I have the datasheet for the DAC and the schematics for the CDP. |
I had a look at the datasheet. Not to discourage you, but rather than spending a lot of time modding this player I would think it is better to dispose of it apropriatly and to get a sensible modification basis, maybe a pre CD720/21/22 (the 723 seems less desirable due to the prescaling prior to the digital filter).
An old and inherently compromised swing arm mechanism, a DAC chip with unbypassable Op-Amp's of the "not so hot" variety on chip and with in general poor sound (I remember this generation) is best safely deposited in a nearby recycling plant where the plastic and metal can be reclaimed....
Sayonara |
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| Fin |
Hi Thorsten
| quote: | Originally posted by Fin
The CD624 was probably one of the cheapest implementations of the CDM4/19. It is unlikely that the CDM4/19 is the limiting factor in this project!!
Surely the crappy Bitstream DAC, poor ground plane, sub-standard power supplies, inferior decoupling, non existant shielding, flimsy plastic case and jitter ridden clock are all far worse than the mechanism/laser!! :rolleyes:
|
You didn't have to agree with me!!!!!!! :nod:
| quote: | Originally posted by Kuei Yang Wang
I had a look at the datasheet. Not to discourage you, but.......
|
You just did! :Ohno: :faint:
Along with everyone who owns:- Philips AK601, AK630, AK640, AK729, CCD310, CCD320, CD110, CD115, CD130, CD140, CD162, CD164, CD210, CD230, CD340, CD380, CD480, CD482, CD500, CD502, CD582, CD583, CD584, CD600, CD604, CD608, CD610, CD614, CD615, CD618, CD624, CD634, CD780, CD781, CD820, CD824, CD830, CD834, CD840, CD850, CDC586, Marantz CD40, CD41, CD42, CD50, CD52, CD60, CD62, CD65II, CD72, CD583, CD593, CD883, Technics SLP177A, SLP202, SLP212, SLP222, SLP277A, SLP377A, SLP477A, SLPG100A, SLPG200A, SLPG400A SLPG420A, SLPG440, SLPG500A, SLPG520A, SLPG540A, SLPJ24A, SLPJ24A, SLPJ26A, SLPJ27A, SLPJ28A SLPJ325A, SLPJ37A, SLPJ46A, SLPS620A, SLPS740A, Rotel RCD855, RCD955, RCD965, Micromega Trio Mk1/MK2, Micromega Leader, Meridian 203, Meridian 206, Arcam Alpha........................ :down:
| quote: | Originally posted by Kuei Yang Wang
rather than spending a lot of time modding this player I would think it is better to dispose of it apropriatly..........
|
Put it in the bin rather than see what is possible???? :gasp:
| quote: | Originally posted by Kuei Yang Wang
get a sensible modification basis, maybe a pre CD720/21/22.
|
Go for an easier option??????? :irked:
Isn't a "pre CD72X", a CD6XX? :rain:
| quote: | Originally posted by Kuei Yang Wang
An old and inherently compromised swing arm mechanism........
|
The newer ones are better??????? :sad:
| quote: | Originally posted by Kuei Yang Wang
a DAC chip with unbypassable Op-Amp's of the "not so hot" variety on chip........ |
Look again at pins 10 and 44 (maybe even pins 1 and 9). :sigh:
| quote: | Originally posted by Kuei Yang Wang
and with in general poor sound (I remember this generation) is best safely deposited in a nearby recycling plant where the plastic and metal can be reclaimed.... |
Starting with something that already sounds good is not really a challenge and doesn't have as much room for improvement. :sing: |
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| jean-paul |
Ahem, I don't want to interrupt you people but I happen to own a CD634 and I modded some CD624 models. There is not much wrong with these players except for the plastic case that does not deserve that name. CDM 4/19 still beats a lot of newer transports, I would not call it an inherently compromised swing arm mechanism. It is old, that's true but I've seen many new transports that fail at very young age so age itself does not need to be a problem. If it would be **** it wouldn't have functioned for nearly 15 years. I saw and heard some quite good DVD transports recently that sounded good apart from video quality, especially when combined with Wolfson DACs. Nevertheless their longevity is not comparable with older swingarms, lots of RMAs anyhow. I haven't found a quality alternative for CDM 1/4/9 yet to be honest, it plays nearly everything I throw at it so I'll continue using them for a while.
The 1 bit DAC has its weaknesses in the highs ( smearing at peak signals ) but really sounds OK overall. The machine needs work as any Philips cdplayer and is a good base for starters. It is not high end but what can you expect for that price. The SAA7321/22/23 are one of the better sounding 1 bit DAC types Philips produced. IMO better than the newer DAC 7 ( TDA1547 ) types. Believe it or not not but these cdplayers sound better than Teac VRDS 10, both in unmodded state ;)
So throwing the cdplayer away seems a waste of capital to me, certainly when it is in good working order. An excellent cdplayer for learning how to mod and to gain experience in the field. |
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| Audiofanatic |
| quote: | | The SAA7321/22/23 are one of the better sounding 1 bit DAC types Philips produced. IMO better than the newer DAC 7 ( TDA1547 ) types. Believe it or not not but these cdplayers sound better than Teac VRDS 10, both in unmodded state |
I agree with Jean-Paul for 100%.
Audiofanatic ;) |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
Put it in the bin rather than see what is possible???? :gasp:
|
Well, maybe drastic....
| quote: | Originally posted by Fin
Go for an easier option??????? :irked:
Isn't a "pre CD72X", a CD6XX? :rain:
|
No. The CD-720 is what I am talking about. I meant pre 723 CD 71X/72X.
| quote: | Originally posted by Fin
The newer ones are better??????? :sad:
|
Well, their lasers are pretty new, their chipsets are adjustment free and they have a much better (sounding) Multibit DAC (TDA1545).
| quote: | Originally posted by Fin
Look again at pins 10 and 44 (maybe even pins 1 and 9). :sigh: |
Yes, there is a really cheap and nasty Op-Amp (not even NE5532 grade) hardwired inplace as I/V converter and no, it cannot removed from the circuit either, so this Op-Amp is the absolute limit of the Analog stage quality, no matter what you do behind it. Of course, as the DAC is a very early Bistream device (and as Philips never yet managed to make a decent sounding Bitstream DAC chip - they seem to get worse with every subsequent generation) the limitation in the Ananlog stage is likely not to matter much anyway.
| quote: | Originally posted by Fin
Starting with something that already sounds good is not really a challenge and doesn't have as much room for improvement. :sing: |
Starting with something where the foundation is not at least competent and competently implemented is a complete waste of time, in my view.
In many attemps I have yet to get good CD sound out of ANY of the various Bitstream DAC's (Philips, BB, AD,Cirrus,AKM) that have their own on-board analog filters and Op-Amp's. When I say "good sound" this is meant in direct comparison to well implemented Bitstream (NPC) or Multibit (Philips TDA1541, BB PCM 63/1702/1704 especially). Hence my take at "safely dispose".
Sayonara |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by jean-paul
CDM 4/19 still beats a lot of newer transports, I would not call it an inherently compromised swing arm mechanism. |
Well, compared to those in the better Philips/Marantz gear they are rather awful. Just compare this CD-624 (I know know the kind of machine this is) to a Marantz CD-94 which is nowadays going 2nd hand for a song. Why bother with this plastic rubbis with a bad transport and DAC if a better basic design is readily and cheaply available?
| quote: | Originally posted by jean-paul
The SAA7321/22/23 are one of the better sounding 1 bit DAC types Philips produced. IMO better than the newer DAC 7 ( TDA1547 ) types. |
Which is not saying much, in my view. The 1547 is awful.
| quote: | Originally posted by jean-paul
Believe it or not not but these cdplayers sound better than Teac VRDS 10, both in unmodded state ;) |
Not much of an achievement, thanks to the CD7 DAC's in the 10.... ;-)
| quote: | Originally posted by jean-paul
So throwing the cdplayer away seems a waste of capital to me, certainly when it is in good working order. |
Okay, pass it on to a friend or relative.
| quote: | Originally posted by jean-paul
An excellent cdplayer for learning how to mod and to gain experience in the field. |
Only in the mechanical sense. In the sonic sense the basic platform is sufficiently crippled (IMNSHO) to merit summary dismissal, a fate that arguably applies to practically all Bitstream/Delta-Sigma DAC equipped players out there. Very few have even the slightest potential, those with NPC DAC's being one of the very few exceptions to the rule (especially marantz CD63/67 and certain Arcam types, not sure about the recent Wolfson DAC's, no played with them, but Cirrus, BB and AD Delta/Sigma are mostly best avoided, especially the lower end stuff).
Sayonara |
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| Dave S |
Here are my plans for mechanical mods:
Make a base out of 2 pieces of 9mm MDF with neoprene sandwiched in between, these layers will be glued. The upper sheet of MDF will be cut into two sections so that the transport has its own section mechanicaly decoupled from the rest of the player. The 4 bent metal tabs that currently support the mech will be removed and I will use 15mm dia wooden dowel in their places (glued to the transport's decoupled MDF section).
I hope this all makes sense, anyway the idea is to provide some decoupling of the transport from the rest of the player and from the whole player to the equipment rack, without adding excessive mass (energy storage) or making the thing look truly hideous. I guess I'm going for the Sondek approach rather than the Trio LO7D (the hideous comment relates to an MDF monster not the LO7D).
I have searched the wonderful WWW and cannot find a really good objective explanation of mechanics for CD players (there's plenty of marketing drivel and speculation) so it looks like I'm going to have to take a punt on the above approach.
Any opinions or ideas before I get the tools out?
BTW, I looked at the data sheets for the LM1085 - the transient response looks poor compared to LM317 i.e. 30uS versus 5 uS to recover from full load to 100mA (50mA for the LM317). Ripple rejection at HF is also inferior. From the data sheets it looks like LM317 is a better choice. Maybe I should use some NOS samples of LT1038CK (date code 8512) I found in the loft - these are almost vintage (might be corked by now??). |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Dave S
Make a base out of 2 pieces of 9mm MDF with neoprene sandwiched in between, these layers will be glued. |
I recommend instead solid needlewood or needlewood ply.
Remember, damping resonances usually makes them more audible with music, so consider leaving the neoprene out at this juncture.
| quote: | Originally posted by Dave S
The upper sheet of MDF will be cut into two sections so that the transport has its own section mechanicaly decoupled from the rest of the player. |
Good idea. Make a "large" overall solid wood section for the whole chassis and a seperate section for the Transport, preferably using string suspension (the large plate can supply the frame) and enlarge the holes in the chassis so the transport is (string) suspended on it's own platform.
| quote: | Originally posted by Dave S
BTW, I looked at the data sheets for the LM1085 - the transient response looks poor compared to LM317 i.e. 30uS versus 5 uS to recover from full load to 100mA (50mA for the LM317). Ripple rejection at HF is also inferior. From the data sheets it looks like LM317 is a better choice. |
The ripple rejection at HF is indeed orse, but the load transient plots are not directly comparable, you MUST use a fairly large Cadj with the LT/LM1085 and LM317 to compare. Peruse the Linear Tech LT1085 datasheet for that plot, which shows a much smaller deflection of the Output with a full current (3A there) step.
As usual, one must be able to correctly interporet datasheets to be able to draw conclusions from them. Often different companies show different ways of generating what appears to be the same (and hence comparable) plot.
| quote: | Originally posted by Dave S
Maybe I should use some NOS samples of LT1038CK (date code 8512) I found in the loft - these are almost vintage (might be corked by now??). |
The LM1085 will substantively behave identically, other than that, go for it.
Sayonara |
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| Fin |
What an interesting thread this is turning out to be.
| quote: | Originally posted by jean-paul
There is not much wrong with these players except for the plastic case that does not deserve that name.
|
Actually, with a little bit of ingemuity and thinking "outside the box" (pardon the pun), the plastic case can be viewed as a bonus. The internal bracing provides quite good structural integrity and can be useful for attaching additional parts/components. Also, these braces can be used to nicely sheild off sections of the pcb. They just happen to line up perfectly with positions that you would want to place shielding to separate the various sections of the circuit board. By simply attaching copper foils (and some damping material) to each of the vertical faces of the plastic braces and deviders, it is easy to produce a structure that should rival most others on sheilding and resonance.
:wiz:
Also - this plastic case has a very nice separate section to the left of the pcb. This can again be sheilded with copper foil and used to accommodate all the additional transformers and power supplies that Thorsten mentions - sort of like an internal/external PSU.
:house:
Alternatively - this space could be used to place a new audio board for a different (filter), dac and output stage. Maybe even Thorsten's Thermionic Valve stage could fit in there - just have to be careful with the heat - it could melt the plastic!
:hot: :warped:
For those who don't want to go to all this trouble, just placing a brick in this empty space should work wonders by increasing weight and stability.
:tons:
| quote: | Originally posted by jean-paul
I haven't found a quality alternative for CDM 1/4/9 yet to be honest, it plays nearly everything I throw at it so I'll continue using them for a while.
|
Yes Jean-Paul, my understanding is the with most things mechanical/electromechanical, quality is inversely related to date of manufacture.
:geezer:
| quote: | Originally posted by jean-paul
The 1 bit DAC has its weaknesses in the highs ( smearing at peak signals ) but really sounds OK overall. The machine needs work as any Philips cdplayer and is a good base for starters. It is not high end but what can you expect for that price. The SAA7321/22/23 are one of the better sounding 1 bit DAC types Philips produced.
|
Specially designed for those of us who dare to be different. :tilt:
| quote: | Originally posted by jean-paul
So throwing the cdplayer away seems a waste of capital to me, certainly when it is in good working order. An excellent cdplayer for learning how to mod and to gain experience in the field. |
:trash:
Even if it is as bad as some suggest - then it is virtually impossible to not have a positive result for first time modders.
:scared: |
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| Fin |
Hi Thorsten
I appreciate your honesty and understand that you think I might be setting myself up for failure. However, in this situation, I think this one is worth a go. Jean-Paul has had good results and I hope I can too. Besides, I don't have a lot of choice. You guys in the UK and Europe are spoilt for choice when it comes to finding good machines a reasonable prices. A quick look on eBay Australia will highlight my point. If ever there is anything half decent, the bidding goes so high that it gets ridiculous.
:$:
| quote: | Originally posted by Kuei Yang Wang
Well, maybe drastic.... |
I think so! :yikes:
| quote: | Originally posted by Kuei Yang Wang
Well, their lasers are pretty new |
This CDM4 has hardly been used. :spin:
| quote: | Originally posted by Kuei Yang Wang
chipsets are adjustment free |
How often would adjustment be required? :wrench:
| quote: | Originally posted by Kuei Yang Wang
they have a much better (sounding) Multibit DAC (TDA1545). |
The SAA7310 decoder has 1*fs I2S out and the SAA7321 DAC has 4*fs I2S out - allowing the use of many multibit DACs, and O/S or Non O/S. Maybe extreme - but it could even be possible to have three different approaches to D/A conversion in one CDP.
:drool:
| quote: | Originally posted by Kuei Yang Wang
Yes, there is a really cheap and nasty Op-Amp (not even NE5532 grade) hardwired inplace as I/V converter and no, it cannot removed from the circuit either, so this Op-Amp is the absolute limit of the Analog stage quality, no matter what you do behind it. Of course, as the DAC is a very early Bistream device (and as Philips never yet managed to make a decent sounding Bitstream DAC chip - they seem to get worse with every subsequent generation) the limitation in the Ananlog stage is likely not to matter much anyway. :wchair: |
The advantage I see to this CDP is that you can progressively move backwards through the signal path and improve or bypass one stage at a time. This could start with the existing opamp output satge, then the final on-board opamps could be bypassed, then the D/A part of SAA7321 could be bypassed, then the filter part of the SAA7321 could be bypassed..............until you find a sound you like. :Present:
All this in one CDP with only one outlay for a good clock, transformers, power supplies, mechanics improvements, etc.
| quote: | Originally posted by Kuei Yang Wang
Starting with something where the foundation is not at least competent and competently implemented is a complete waste of time, in my view. |
I think I read something similar near the start of this thread! :usd:
| quote: | Originally posted by Kuei Yang Wang
In many attemps I have yet to get good CD sound out of ANY of the various Bitstream DAC's (Philips, BB, AD,Cirrus,AKM) that have their own on-board analog filters and Op-Amp's. When I say "good sound" this is meant in direct comparison to well implemented Bitstream (NPC) or Multibit (Philips TDA1541, BB PCM 63/1702/1704 especially). Hence my take at "safely dispose". :yuck: |
So - if I skip all of the experimentation and connect a TDA1541 to the SAA7321 or SAA7310, or a SM5842/PCM63 combination to the SAA7310, then it could be a worthwhile project?
:headbash: :note: |
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| Fin |
| quote: | Originally posted by Kuei Yang Wang
Well, compared to those in the better Philips/Marantz gear they are rather awful. Just compare this CD-624 (I know know the kind of machine this is) to a Marantz CD-94 which is nowadays going 2nd hand for a song. Why bother with this plastic rubbis with a bad transport and DAC if a better basic design is readily and cheaply available? |
Believe me - If I could find one - I would buy it! These types of machines might be readily available and cheap where you are.
But now we are no longer comparing like with like. What mechanism is in the CD72X?
| quote: | Originally posted by Kuei Yang Wang
Only in the mechanical sense. In the sonic sense the basic platform is sufficiently crippled (IMNSHO) to merit summary dismissal, a fate that arguably applies to practically all Bitstream/Delta-Sigma DAC equipped players out there. Very few have even the slightest potential, those with NPC DAC's being one of the very few exceptions to the rule (especially marantz CD63/67 and certain Arcam types, not sure about the recent Wolfson DAC's, no played with them, but Cirrus, BB and AD Delta/Sigma are mostly best avoided, especially the lower end stuff). |
So - is the mechanism good or bad?
What did you think it was when you said?| quote: | | I think yous has the old swingarm mechanism, a very nice drive but rather aged |
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| Fin |
| quote: | Originally posted by Audiofanatic
I agree with Jean-Paul for 100%.
Audiofanatic ;) |
Please tell us more. |
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| Fin |
| quote: | Originally posted by Dave S
Here are my plans for mechanical mods:................
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Hi Dave
I'm sorry for causing your thread to be diverted somewhat - it was not my intention and it just developed that way. Actually it is really Bernhard's fault - things were fairly relevant, or at least gerenic, until he opened the can of worms about the CDM4. I hope you find some of our discussion interesting anyway. Maybe it should be moved to a new thread, but I don't know how to do that. |
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| Audiofanatic |
| quote: | Originally posted by Fin
Please tell us more. |
Hi Fin,
I can try to tell you what I think of the 1Bit DAC's, but Jean-Paul is better at this than I am. I can only say that I bought a DAC7 to replace the DAC in my partners CD-Player and after a few months she wanted it the way it was befor cause it did'n sound better.
And I had to agree, it was not good!
Best regards,
Audiofanatic ;) |
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| rbroer |
Hmmm,
I do like the 1 bit system in a Sony DVD 9000ES SACD player with Allan Wright Vacuumstate level 4 output module and clock upgrade.
For SACD's I deifinitely prefer it above my best modded cd players :cool: |
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| Bernhard |
| quote: | Originally posted by Fin
Actually it is really Bernhard's fault - things were fairly relevant, or at least gerenic, until he opened the can of worms about the CDM4
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What ?
A medriocre transport in a medriocre player, this perfectly fits the thread title.
IMHO on most boards of CDM4 players it is possible to upgrade to CDM2 with brushless spindle.
Just a few parts on the board have to be changed. |
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| jean-paul |
If CDM 4 is mediocre I truely wonder how mediocre a CDM 12 or even CD Pro is. Maybe some mechanics are more mediocre that others ???
Only VRDS mechanics are real good IMO ( I have no real experience with the CEC cdplayers ). However the used DAC's in those cdplayers are less than mediocre and the lasers fail earlier than those in CDM 4. The newer generation mechanics in CD723 live a bit longer than their predecessors but still leave a lot wish for. Mechanical/pcb/whatever quality of those flimsy boxes is Mediocre with a capital.
So please tips on which newer mechanics are an alternative, I haven't found a good quality one yet.... |
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| jean-paul |
| If moving the last posts to a new thread is what you want Fin just give me a new threadname. |
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| Bernhard |
| quote: | Originally posted by jean-paul
If CDM 4 is mediocre I truely wonder how mediocre a CDM 12 is. Maybe some mechanics are more mediocre that others ??? |
Never seen a CDM9 or 12, swingarm ?
One thing is for sure: The Mabuchi makes RF noise and there is no ceramic cap to suppress it :(
Some threadjacking:
Ever seen ceramic TDA1540 ? |
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| jean-paul |
I stock new CDM 9 and those are better but definitely live shorter than any of the CDM 4 variants.
CDM 12 is *not* a swingarm mechanics, it is a poorly designed, short living result of engineering off-days. Just as the new lasers in Philips DVDplayers. One year, maybe two and they're gone ( in general, exceptions confirm the rule as they say ). |
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| Dave S |
Fin, no worries mate (excuse my pitiful stereotyping) on your CD624 threadjacking.
Jean-Paul, same comment. Discuss mechs to your heart's content, it's all of interest in the general discussion of whether a cheap (or maybe expensive) player is worth the effort to mod and how far you can go.
I'm still amazed that nobody except KYW and Nuuk is prepared to offer any info on improving the mechanical aspects of CD players - maybe that is worth starting a new thread for?
Where does VAM1201 fit into the CDMxx lineup? |
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| TDA1540 |
quote:
Ever seen ceramic TDA1540 ?
Bernhard, TDA1540D is ceramic IIRC.
and yes,I have seen it.
I am listening to two right now. |
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| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Fin
You guys in the UK and Europe are spoilt for choice when it comes to finding good machines a reasonable prices. A quick look on eBay Australia will highlight my point. |
Hmmm. Considered an E-Bay Shanling CD T-100 or SCD T-200? ;-)
| quote: | Originally posted by Fin
This CDM4 has hardly been used. :spin:
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Are you sure? If so first step in the reclamation project, replace all the ancient 'lytics.
| quote: | Originally posted by Fin
How often would adjustment be required? :wrench:
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Whenever supply voltages change drastically or the laser ages. Hard to say, every 4/5 years maybe if used often.
| quote: | Originally posted by Fin
The SAA7310 decoder has 1*fs I2S out and the SAA7321 DAC has 4*fs I2S out - allowing the use of many multibit DACs, and O/S or Non O/S. Maybe extreme - but it could even be possible to have three different approaches to D/A conversion in one CDP.
:drool: |
Now you are talking. But earlier you where asking how to bes power a rather junky DAC, not if it was a good idea to chuck it out and put something decent on a seperate PCB in....
| quote: | Originally posted by Fin
The advantage I see to this CDP is that you can progressively move backwards through the signal path and improve or bypass one stage at a time. |
Start with the DAC, it's a good place... :-P
| quote: | Originally posted by Fin
This could start with the existing opamp output satge,
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What for? The limit is the on-chip junk.
| quote: | Originally posted by Fin
then the final on-board opamps could be bypassed,
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Ahhm, you actually cannot do that, trust me.
| quote: | Originally posted by Fin
then the D/A part of SAA7321 could be bypassed,
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Well, key parts of the analog stage are on teh DAC chip, so it's "bypassing" the lot.
| quote: | Originally posted by Fin
So - if I skip all of the experimentation |
You don't HAVE to skip it. But do you want play around or get good sound?
| quote: | Originally posted by Fin
and connect a TDA1541 to the SAA7321 or SAA7310, or a SM5842/PCM63 combination to the SAA7310, then it could be a worthwhile project? :headbash: :note: |
Maybe. How good are you designing High End Gear? Small Mod's are one thing, effectively from scratch design another....
| quote: | Originally posted by Fin
What mechanism is in the CD72X?
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Generic CDM-12. Mine still works after almost 10 years. The good quality swingarm mechanisms are better, the lower grade ones IMHO not., too many cost saving compromising.
Sayonara |
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| Bernhard |
| quote: | Originally posted by TDA1540
quote:
TDA1540D is ceramic IIRC.
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IIRC ???
Found a pair in a Grundig CD7500.
Measures as bad as TDA1543, but I was satisfied with plain CD304 for a decade.
I think they were plastic. |
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| TDA1540 |
| quote: | | I was satisfied with plain CD304 for a decade.I think they were plastic. |
I think you are right.I have never seen a 304 with d-chips. |
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| Fin |
Hi Bernhard
| quote: | Originally posted by Bernhard
What ?
A medriocre transport in a medriocre player, this perfectly fits the thread title.
IMHO on most boards of CDM4 players it is possible to upgrade to CDM2 with brushless spindle.
Just a few parts on the board have to be changed. |
Of course! I had to shift the blame - and you seemed like a good candidate! :devilr:
| quote: | Originally posted by Bernhard
One thing is for sure: The Mabuchi makes RF noise and there is no ceramic cap to suppress it :(
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Please tell us more about upgrading the CDM4. Can this cap be added easily?
Hi Jean-Paul
| quote: | Originally posted by jean-paul
If CDM 4 is mediocre I truely wonder how mediocre a CDM 12 or even CD Pro is. Maybe some mechanics are more mediocre that others ??? |
This was my understanding after reading a lot of related threads on this forum. It is also one of the main reasons I thought the CD624 would be worth keeping.
| quote: | Originally posted by jean-paul
If moving the last posts to a new thread is what you want Fin just give me a new threadname. |
I'm quite happy to leave things as they are - if everyone else is - and if it's not breaking too many of the forum rules.
Hi Dave
| quote: | Originally posted by Dave S
Fin, no worries mate (excuse my pitiful stereotyping) on your CD624 threadjacking.
Jean-Paul, same comment. Discuss mechs to your heart's content, it's all of interest in the general discussion of whether a cheap (or maybe expensive) player is worth the effort to mod and how far you can go.
I'm still amazed that nobody except KYW and Nuuk is prepared to offer any info on improving the mechanical aspects of CD players - maybe that is worth starting a new thread for?
Where does VAM1201 fit into the CDMxx lineup? |
Stereo-typing - the first part of the word is applicable - (but my typing is bad). Actually, I'm not a genuine Ozzie, but I do love some of the fair dinkum expressions.
For mechanical upgrades, I have mainly thought about strengthening the base and providing some shielding at the same time. The plan is to add a 3 - 5mm aluminium plate to the base and back plate. Shielding could then be applied to the inside of the case in the form of copper or aluminium sheeting/foil. All of the shielding, the base, and backplate could be joined together with strips of copper to provide a complete metal enclosure.
Another thought was to add small rubber/polyeurothane washers on top of the supports for the pcb. I have no idea if this would be good or bad - but it seems to make sense.
Not sure if I'm game, at this stage, to start pulling the mechanism out or apart to do specific mechanical mods there - but if I end up doing Bernhards suggested conversion - it might be worth looking at.
Hi Thorsten
| quote: | Originally posted by Kuei Yang Wang
Hmmm. Considered an E-Bay Shanling CD T-100 or SCD T-200? ;-)
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Yes - there are six Shanling CDPs on E-Bay at present. Three are in the UK and range in price from | | | |
