don't remember the number part, it was long time ago... bought them at Mouser & Farnell. Farnell has the Cornell Dublier CDA caps (20%) and Mouser the PPS from Panasonic (2%, 10%, 20%). Size are often 1210 and 0805 for the smallest values. Try Cornell Dubier if precision is not mandated.
Don't know about the Rubycons, ask GreginMississipi perhaps !
Don't know about the Rubycons, ask GreginMississipi perhaps !
Cornell Dubilier - CDE caps
FWIW, I used FCA1206C684M-H3 .68uF caps that I had on hand when diyiggy suggested replacing the 3 ceramic caps supplied on iancanada's clock adapter which I was using with NDK SDA caps on Ian's FIFOpi.
I was getting very good sound with NDK SDA FIFOpi. But I perceived a slightly irritating digital edge to the sound. I installed a single .68 cap to replace 3 .1uF caps and to my ear the irritating sound was replaced by a smooth clean sound. To be clear, we are talking about a minor change, but one I considered worth the effort.
On the other hand, with the WTMC constructed as specified by Andrea, I have zero motivation to mess with it. After a few days I consider it perfect. It will no doubt get better as it settles, and I have yet to finish my best effort power supplies or vibration dampening. Perhaps if diyiggy and/or others find some way of improving this clock, I'll later be inclined to follow a new best practice. But for now the darn thing is so good its hard to get motivated to just finish it let alone start modifying.
FWIW, I used FCA1206C684M-H3 .68uF caps that I had on hand when diyiggy suggested replacing the 3 ceramic caps supplied on iancanada's clock adapter which I was using with NDK SDA caps on Ian's FIFOpi.
I was getting very good sound with NDK SDA FIFOpi. But I perceived a slightly irritating digital edge to the sound. I installed a single .68 cap to replace 3 .1uF caps and to my ear the irritating sound was replaced by a smooth clean sound. To be clear, we are talking about a minor change, but one I considered worth the effort.
On the other hand, with the WTMC constructed as specified by Andrea, I have zero motivation to mess with it. After a few days I consider it perfect. It will no doubt get better as it settles, and I have yet to finish my best effort power supplies or vibration dampening. Perhaps if diyiggy and/or others find some way of improving this clock, I'll later be inclined to follow a new best practice. But for now the darn thing is so good its hard to get motivated to just finish it let alone start modifying.
@wlowes,
Hi, thanks to correct me : indeed the name of Cornell Dublier acrylic caps are FCA (not CDA as I wrote).
Did you finally try it without the // BG NX ?
I have enough former Discroll boards to benchmark ceramic vs acrylic but unluckilly have just at-cut in 5/20/22 MHz to play with it !
For the 5 M Hz sc-cut in 47 size, I have to wait the new Discroll : I will take two for the same test and will report (I have only one sc-cut but I will find a way no to solder it for the listening tests to swap it from a board to the other one... Perhaps blue tack will be enough for that to choose the caps I prefer in relation to my whole setup... just subjective feeling as no tools to measure that.
It will be with a Clock II board (which has no acrylic cap on board as the new FifoPi, perhaps the reason I have more than a subtle change). For the moment the CCHD-957 is the only one on air on the Clock II.
I totally agree with you the equilibrium has to be found at ears with the usefull caps as you did with the BG NX // CDA: the result only matters and each owner has a too specific hifi to claim an universal rule. Developpers have to follow the electronic rules and best practises we are not talking about with our specific tweaks for subjective result. If it means worst local measurement but a better subjective result at listening position : I have no problem with that. It's cool to share and have the choice in our hobby and caps is often an easy way to EQ.
I had a gifted 0.47 BG NX but the mate needed it 2 years later so I returned it seing he was not finding his hapyness on the second hand markett...
Hi, thanks to correct me : indeed the name of Cornell Dublier acrylic caps are FCA (not CDA as I wrote).
Did you finally try it without the // BG NX ?
I have enough former Discroll boards to benchmark ceramic vs acrylic but unluckilly have just at-cut in 5/20/22 MHz to play with it !
For the 5 M Hz sc-cut in 47 size, I have to wait the new Discroll : I will take two for the same test and will report (I have only one sc-cut but I will find a way no to solder it for the listening tests to swap it from a board to the other one... Perhaps blue tack will be enough for that to choose the caps I prefer in relation to my whole setup... just subjective feeling as no tools to measure that.
It will be with a Clock II board (which has no acrylic cap on board as the new FifoPi, perhaps the reason I have more than a subtle change). For the moment the CCHD-957 is the only one on air on the Clock II.
I totally agree with you the equilibrium has to be found at ears with the usefull caps as you did with the BG NX // CDA: the result only matters and each owner has a too specific hifi to claim an universal rule. Developpers have to follow the electronic rules and best practises we are not talking about with our specific tweaks for subjective result. If it means worst local measurement but a better subjective result at listening position : I have no problem with that. It's cool to share and have the choice in our hobby and caps is often an easy way to EQ.
I had a gifted 0.47 BG NX but the mate needed it 2 years later so I returned it seing he was not finding his hapyness on the second hand markett...
diyiggy - I did not remove the BG to hear it with the acrylic alone.
WTS - I am not a very good scientist. I seldom try all the permutations to understand the best. I tend to take in a lot of input from others and then build what I think will work and fit my build ability. If it sounds good, I am content to leave it even if there may be some slightly more optimal combination.
With Andrea's WTMC, I was grateful that it worked and sounds so good. There were a few resistors specified that were out of stock, so substitutions were required. I am just relieved I did not screw it up and am happy to leave it alone. It is unlikely I'll go back to make changes as I plan to build it into a tight little chassis to insulate it from the rest of the system. The plan is to leave it powered up and enjoy it.
WTS - I am not a very good scientist. I seldom try all the permutations to understand the best. I tend to take in a lot of input from others and then build what I think will work and fit my build ability. If it sounds good, I am content to leave it even if there may be some slightly more optimal combination.
With Andrea's WTMC, I was grateful that it worked and sounds so good. There were a few resistors specified that were out of stock, so substitutions were required. I am just relieved I did not screw it up and am happy to leave it alone. It is unlikely I'll go back to make changes as I plan to build it into a tight little chassis to insulate it from the rest of the system. The plan is to leave it powered up and enjoy it.
Hi Andrea,
I have finally build the oven for my sc-cut crystal!
The problem is that I cannot get it adjusted.
I use the same laser thermometer as recommended in the manual, the temperatures vary when moving from middle to the edge of the crystal. Getting to 82degreesC is difficult.
Also the transistor is getting really hot (around 80degreesC) is this normal?
There is a lot noise after a minute or so warming up; measuring around 65degreesC in the middle of the crystal. This seems to be frequency drift.
The noise disappears when I switch of the oven, but also when I touch the crystal or oven copper heater tube with a metal screw driver (grounding?).
What am I doing wrong?
I have finally build the oven for my sc-cut crystal!
The problem is that I cannot get it adjusted.
I use the same laser thermometer as recommended in the manual, the temperatures vary when moving from middle to the edge of the crystal. Getting to 82degreesC is difficult.
Also the transistor is getting really hot (around 80degreesC) is this normal?
There is a lot noise after a minute or so warming up; measuring around 65degreesC in the middle of the crystal. This seems to be frequency drift.
The noise disappears when I switch of the oven, but also when I touch the crystal or oven copper heater tube with a metal screw driver (grounding?).
What am I doing wrong?
Attachments
Hi,
The transistor of the oven runs very hot, it's not a problem. Also a little frequency drift is not an issue in digital to analog conversion.
It seems you have a ground loop problem, or maybe the oscillator is catching something from the environment. It could be a power supply ground loop, how did you connect the oven ground?
Andrea
Hi,
The oven is powered by a separate power supply (the one on top of the batteries) that gets dc power from a connected smps that is feeding the battery supply (charging the battery pack while the dac is off, and feeding the raspberry pi, battery control logic and the oven ps when it is on)
The clock unit and dac is battery powered and not grounded. The oven is also not grounded.
The noise was apparent while testing the streamer with a headphone and wifi connection so only the smps was grounded to the power socket, no ground loops.
The strange thing is that the noise comes up after about one minute when the oven is switched on, when I cut the power to the oven the noise disappears in about 30sec.
I can try grounding the oven ps, but to what component? I want to prevent ps noise getting to the clock or streamer via the connected ground.
Recommended grounding
Andrea, I'd also appreciate your recommendation as to grounding. Everything in my DAC is ultimately grounded to safety earth (the 3rd prong in NA power cords). I assumed I should also ground the WTMC-D and the Oven to safety earth. They will be in their own chassis with separate windings on their transformer. As I understand it, the SMA cable shield connects the ground plane of the WTMC-D to the ground of the FIFOpi.
FYI Supersurfer.. In my current temporary setup, the WTMC-D has a linear PS that is tied to the ground of the Rpi. My Oven has its own linear PS with it's own transformer. It is floating with no earth ground. Works fine without noise.
Andrea, I'd also appreciate your recommendation as to grounding. Everything in my DAC is ultimately grounded to safety earth (the 3rd prong in NA power cords). I assumed I should also ground the WTMC-D and the Oven to safety earth. They will be in their own chassis with separate windings on their transformer. As I understand it, the SMA cable shield connects the ground plane of the WTMC-D to the ground of the FIFOpi.
FYI Supersurfer.. In my current temporary setup, the WTMC-D has a linear PS that is tied to the ground of the Rpi. My Oven has its own linear PS with it's own transformer. It is floating with no earth ground. Works fine without noise.
I have checked the battery circuit and noticed the - pin from the oven ps is connected to the - pin of the raspberry pi, so they are grounded.
I also did a test with a separate linear ps with toroid for the oven power and this also introduces the same noise, both in floating and grounded to raspberry pi power.
Grounding the dac (via rca output connector) or putting oven and connected raspberry pi - pin to ground of the wall connector does make some difference; the noise level is a bit lower but not gone.
I do not know how to proceed with this
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@Supersurfer:
Hi ... A couple of comments - the first of which is that you don't happen to have a bad soldering/bad connection somewhere on the oven / oscillator PCBs? The timing 60s / 30s might suggest heating and cooling phenomena associated with a bad solder joint ...
And then, if not a bad solder joint, my guess would be that you have some kind of HF or RF oscillation that causes the noise. Looking at your pictures I notice that the oven copper heating plate seems to be very close to the crystal. I reckon that if it actually shorts to the crystal the crystal's noise pick-up area would increase significantly (maybe Andrea can comment here?).
Also, even if you use twisted pair wiring it looks as if you lead them quite close to the crystal/oven assembly. Might I suggest that you try to separate the cables and make them cross at 90 degrees ...
Thirdly, depending on how your detailed schematic and practical build is I wouldn't place an overall grounding near a digital part. As you may know digital signals often are very high frequencies which causes inductive impedances in the traces leading these signals - thus potentially leading to significant voltage potentials between ground points. Personally, I likely would ground the oven onto the oscillator PCB's ground so as to keep the ground loops associated with the oven/oscillator as short as possible - and then connect the oscillator output + ground to the DAC's ground.
Additionally, I might try to increase the input/output capacitance on the 7812 regulator that feeds the oven circuitry (e.g. 1000uF). Not that it may make this circuitry work better - I don't think it will - but it may change the relative "influencing" frequencies that this circuitry has.
Well, a couple of ideas ;-)
Cheers,
Jesper
Hi ... A couple of comments - the first of which is that you don't happen to have a bad soldering/bad connection somewhere on the oven / oscillator PCBs? The timing 60s / 30s might suggest heating and cooling phenomena associated with a bad solder joint ...
And then, if not a bad solder joint, my guess would be that you have some kind of HF or RF oscillation that causes the noise. Looking at your pictures I notice that the oven copper heating plate seems to be very close to the crystal. I reckon that if it actually shorts to the crystal the crystal's noise pick-up area would increase significantly (maybe Andrea can comment here?).
Also, even if you use twisted pair wiring it looks as if you lead them quite close to the crystal/oven assembly. Might I suggest that you try to separate the cables and make them cross at 90 degrees ...
Thirdly, depending on how your detailed schematic and practical build is I wouldn't place an overall grounding near a digital part. As you may know digital signals often are very high frequencies which causes inductive impedances in the traces leading these signals - thus potentially leading to significant voltage potentials between ground points. Personally, I likely would ground the oven onto the oscillator PCB's ground so as to keep the ground loops associated with the oven/oscillator as short as possible - and then connect the oscillator output + ground to the DAC's ground.
Additionally, I might try to increase the input/output capacitance on the 7812 regulator that feeds the oven circuitry (e.g. 1000uF). Not that it may make this circuitry work better - I don't think it will - but it may change the relative "influencing" frequencies that this circuitry has.
Well, a couple of ideas ;-)
Cheers,
Jesper
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