Hi Guys,
Would it be better to power the output stage opamp via 14.5v unregulated power or add low noise regs say 12 to 12.5v.
Issue is that I have already 12v transformers.
Opamp typicall operate anywhere from 5v - 20v. Is it always better to run them at higher voltages?
Would it be better to power the output stage opamp via 14.5v unregulated power or add low noise regs say 12 to 12.5v.
Issue is that I have already 12v transformers.
Opamp typicall operate anywhere from 5v - 20v. Is it always better to run them at higher voltages?
Good to see some activity over here 🙂
Opamps in CD players are generally powered by a +/-12V supply. Some types can handle a higher voltage, but the reason for using +/-15V is under discussion. An opamp uses a lot of internal current sources, so the operation point is mostly independant of the supply voltage. The output signal is 2V rms so that means you could get away with +/-5V in theory. Actually, I never tried it! 😀
12V transformers will give you about 17V unregulated voltage. It's not high enough to get 15VDC out of. You have to take into account a low mains voltage situation for example, so you need some headroom. Maybe if you use large rectifier caps, of course schottky diodes and a low-drop voltage regulator. It will be a bit higher if the transformer is larger than the required power, close to 20VDC unreglated. But +/-12V should be o.k.
Regards,
Ray
Opamps in CD players are generally powered by a +/-12V supply. Some types can handle a higher voltage, but the reason for using +/-15V is under discussion. An opamp uses a lot of internal current sources, so the operation point is mostly independant of the supply voltage. The output signal is 2V rms so that means you could get away with +/-5V in theory. Actually, I never tried it! 😀
12V transformers will give you about 17V unregulated voltage. It's not high enough to get 15VDC out of. You have to take into account a low mains voltage situation for example, so you need some headroom. Maybe if you use large rectifier caps, of course schottky diodes and a low-drop voltage regulator. It will be a bit higher if the transformer is larger than the required power, close to 20VDC unreglated. But +/-12V should be o.k.
Regards,
Ray
Absolutely do not run unregulated supplies on the opamps. If you do not have the headroom for 15v regs using your transformers, go for 14v or even 12v. The better quality regs you use, the better the audio will be.
Decent PSU's are most of the battle with audio design!
Decent PSU's are most of the battle with audio design!
Thanks for the advice.
UV101, you posted some time back a higher voltage driving the output stage at 15v which pricked my interest to do this, but I didnt come across any mention of better low noise supply and which would be more effective. I would do a higher voltage, but fitting another transformer to be too big of a challenge.
Ray, would a higher voltage or better current supply be more beneficial for the opamps internal sources. In saying, if sufficient current supply which is not a bottleneck feeding the opamps, having a higher 15v supply will not have advantages over a beefier 12v supply, or in rhat case, having sufficient capacitance feeding the opamp.
There might be a relation to the higher voltage and optimal operating temps of the opamp.
Reason is that I came across another mod which advocates using low noise regs for the opamps at the output stage as part of the mod.
Thanks Guys
UV101, you posted some time back a higher voltage driving the output stage at 15v which pricked my interest to do this, but I didnt come across any mention of better low noise supply and which would be more effective. I would do a higher voltage, but fitting another transformer to be too big of a challenge.
Ray, would a higher voltage or better current supply be more beneficial for the opamps internal sources. In saying, if sufficient current supply which is not a bottleneck feeding the opamps, having a higher 15v supply will not have advantages over a beefier 12v supply, or in rhat case, having sufficient capacitance feeding the opamp.
There might be a relation to the higher voltage and optimal operating temps of the opamp.
Reason is that I came across another mod which advocates using low noise regs for the opamps at the output stage as part of the mod.
Thanks Guys
I think a good supply is more important, quality over quantity. It's better to have a good low-noise 12V supply than a crappy 15V.
Like UV101 says, the regulators are important.
Like UV101 says, the regulators are important.
What he said!!! ^^^^^^^^^^^😉
Some of my posts may be out of context if read individually.
I may not have mentioned in that specific post I have discrete opamp feedback regulators everywhere (in everything!!)! I think the highest number I achieved in the 63 was somewhere in the 20's 😱 I was also running multiple transformers and from memory, I think the analogue output stage was using an 18+18v transformer which when rectified gave plenty of headroom for running 15v regulators.
There are some excellent commecial series regualtors on the market which are drop in replacements for the std 3 pin 780x 790x types.
I ended up making my own which were very successful.
The basics of an opamp feedback series regulator can be found here
DC voltage regulators
You will find information throughout this thread relating to "rayregs" (6h5c) as he designed lm317 regs on veroboard that are simple to build and can replace the std regs as well as individually supply specific area's of the player if you want to go that far 😎
Look at the decoupling, this is also mimportant...
http://mksa.dii.univpm.it/biblioteca/sala_tecnica/scaffale_dispositivi/instr_amp/AN-202.pdf
http://mksa.dii.univpm.it/biblioteca/sala_tecnica/scaffale_dispositivi/instr_amp/AN-202.pdf
Update: I have been allocated a slightly larger room, Syndicate Room 3 on the 1st Floor.
UV101,
Apologies for the late response owing to being away for some time.
I have a mix of regulators. In the early days I used Fidelity Audio's SPower regs, but then, to cut down on cost, I changed to Dexa Technologies NewClassD regs available from HiFiCollective.
Apologies for the late response owing to being away for some time.
I have a mix of regulators. In the early days I used Fidelity Audio's SPower regs, but then, to cut down on cost, I changed to Dexa Technologies NewClassD regs available from HiFiCollective.
Hi
Did anybody tried using HDAM only in this player? Cut off NFB, put both phases from DAC on input LTP, get some filtering there and go from it straight to out (maybe muting relays)?
Mike
Did anybody tried using HDAM only in this player? Cut off NFB, put both phases from DAC on input LTP, get some filtering there and go from it straight to out (maybe muting relays)?
Mike
Hi,
I am back from a long hiatus (over a year - I moved house). I am just getting back to my CD63 and have some regs questions:
1) For the Decoder I am using Higlander's post 19107(pg1911). My question is why do you have to cut the ground at pin 12 and hardwire pin 12 to the ground at pin 22 (this is shown in the picture). Surely the grounds are all connected underneath the chip??
2) For the DAC I have one reg feeding the analogue and two for the digital power (UD200, RD01 and RD04). I found a note attributed to Brent (Fidelity Audio) that says "you need to make a minor circuit change to the copper straps at the back of the PCB as one of the digital supplies is connected to the analogue supply." I cannot find any connection between these traces, could someone enlighten me?
3) For the Servo is it just R122 and R123 that are replaced?
Thanks!!! Henry
I am back from a long hiatus (over a year - I moved house). I am just getting back to my CD63 and have some regs questions:
1) For the Decoder I am using Higlander's post 19107(pg1911). My question is why do you have to cut the ground at pin 12 and hardwire pin 12 to the ground at pin 22 (this is shown in the picture). Surely the grounds are all connected underneath the chip??
2) For the DAC I have one reg feeding the analogue and two for the digital power (UD200, RD01 and RD04). I found a note attributed to Brent (Fidelity Audio) that says "you need to make a minor circuit change to the copper straps at the back of the PCB as one of the digital supplies is connected to the analogue supply." I cannot find any connection between these traces, could someone enlighten me?
3) For the Servo is it just R122 and R123 that are replaced?
Thanks!!! Henry
For the DAC supplies the link between the analogue and digital 5V is U200 - if you've put the analogue reg in there then you've already separated analogue from digital.
Only further refinement is to separate the L+R analogue channels ie pins 17 and 21 on one reg, 22 and 26 from another. I haven't (yet...) done this but it's meant to give better channel separation, as will separate L+R regs on the opamps for both the + and - supplies.
Like you I've yet to do the decoder, so I'll see what replies you get on that one before finalizing my plans!
Only further refinement is to separate the L+R analogue channels ie pins 17 and 21 on one reg, 22 and 26 from another. I haven't (yet...) done this but it's meant to give better channel separation, as will separate L+R regs on the opamps for both the + and - supplies.
Like you I've yet to do the decoder, so I'll see what replies you get on that one before finalizing my plans!
I have a slight issue with my 67OSE in that I have a very slight mains hum from speakers when connected to amp, I swapped it out with a 6000OSE KI and no mains hum.
I removed main board and re-soldered RCA connectors but no change.
It has a Kwak CLock 7 with it's own dedicated PSU fitted.
Any advice please
Tom
I removed main board and re-soldered RCA connectors but no change.
It has a Kwak CLock 7 with it's own dedicated PSU fitted.
Any advice please
Tom
Is the ground on the clock connected to the player gnd?
usually I would ground at the PSU end only not the clock end to stop any ground loops but its worth checking. Def the sot of issue caused by ground problems. You could ground the Clock end only and the not the PSU end and see if that makes any difference. I normally use coax from the clock to the DAC but only connect the braid to the clock not the DAC.
Whatever you do, make sure its connected to the gnd end somewhere preferably only once!
Clock grnd is connected to the grnd position of the original Xtal caps on the main board (caps removed).
Originally when I first fitted the clock I only connected clock signal to board it worked fine but was advised to also connect grnd (didn't make any audible difference).
So have + and - volts with GND from PSU (supplied by mains input) and 2 wires for crystal signal to main board (aprox 25mm long)
The clock has been installed for a couple of years now but not sure how long the hum has been present.
Tom
Originally when I first fitted the clock I only connected clock signal to board it worked fine but was advised to also connect grnd (didn't make any audible difference).
So have + and - volts with GND from PSU (supplied by mains input) and 2 wires for crystal signal to main board (aprox 25mm long)
The clock has been installed for a couple of years now but not sure how long the hum has been present.
Tom
After modding a Marantz CD63 and a CD67OSE I decided to make a list of all the various mod's I found here and elsewhere on the internet.
I'd like to donate my files to this forum, for all to enjoy! 😀
Of course I do not pretend this list to be complete.
This is all I've done to the players so far and more good tips are welcome!
Greetings,
Ray.
Hi Ray
My Marantz 63 has err 02 focus error
I have replaced the old laser with the VAM-1201 but having the same problem
I did see a youtube video Marantz 67 by placing a resistor on R112 on the pcb and this did solve the problem
https://youtu.be/G7iV-LvQMec
Only on the Marantz 63 mother board I could not find R112
What would be the equivalent number on the 63?
Any advice would be appriciated