Changing the built in clock for a nominally much more precise one is one of the two, I think I can safely say traditional ways of upgrading any CD player, the other being changing the inevitable built in op amps.
I have never touched the clock myself, so I cannot comment. But I've changed op amps quite a few times, and not infrequently one immediately hears the difference. As John said, there are many compromises made in many CD players, and sticking in NJR op amps of mzndane sonic qualities is ne of the, I understand they are dirt cheap when bought in quantity, as manufacturers do. Locally, Marantz CD players are very highly regarded and are very common, as are Philips players of the 9xx series. Experience shows that replacing the NJR op amps with OPA 275 will bring about an easily heard improvement. I don't know whether it's the OPA's settling times, typically ten times shorter that those of the NJR family that I've seen, it Butler front end, or its better slew rate, or all of that, but in the last 20 years or so, I've never yet run into a situation in which the old NJRs were preferred to the OPAs. Not once!
I now wonder what would happen if in addition to the op amps one also insalled a very precise and stable clock. Hopefully, something better yet, but the problem with very precise clocks is their price, which can be quite high for some models, and their build-in capability, depending on the model of the CD one is upgrading. You have to have the right version of it, not just any will do.
I have never touched the clock myself, so I cannot comment. But I've changed op amps quite a few times, and not infrequently one immediately hears the difference. As John said, there are many compromises made in many CD players, and sticking in NJR op amps of mzndane sonic qualities is ne of the, I understand they are dirt cheap when bought in quantity, as manufacturers do. Locally, Marantz CD players are very highly regarded and are very common, as are Philips players of the 9xx series. Experience shows that replacing the NJR op amps with OPA 275 will bring about an easily heard improvement. I don't know whether it's the OPA's settling times, typically ten times shorter that those of the NJR family that I've seen, it Butler front end, or its better slew rate, or all of that, but in the last 20 years or so, I've never yet run into a situation in which the old NJRs were preferred to the OPAs. Not once!
I now wonder what would happen if in addition to the op amps one also insalled a very precise and stable clock. Hopefully, something better yet, but the problem with very precise clocks is their price, which can be quite high for some models, and their build-in capability, depending on the model of the CD one is upgrading. You have to have the right version of it, not just any will do.
Try reading this for a start.....
The 10 Best Ways to Maximize Emission from Your Product
Then start on this....
High Speed Digital Design: A Handbook of Black Magic: Howard Johnson, Martin Graham: 9780133957242: Amazon.com: Books
It is basic digital design, in fact this is a good simple explanation... including how the signals propagate:
http://www.x2y.com/filters/TechDay0...log_Designs_Demand_GoodPCBLayouts _JohnWu.pdf
Then you will have more understanding about what we are talking about...And yes it is high speed, high speed digital has nothing to do with the clocks fundamental frequency and everything to do with rise and fall times... Plus the claims are increased signal integrity so we have to look at it very closely and that means all aspects of the modifications...
The worse one I saw ran the clock signal down one wire with no close return, the return was provided by the 0V connection of the power at the other side of the add on board and inches away on the modded PCB because he didn't want a ground loop!!!!
Now you have harped on about aerospace design etc, why do you think I do aerospace and similar layout, it could be because I know what I am doing, yet that knowledge is NOT GOOD enough to use to try and help Audio DIYers.....
Unlike marce I am not an expert on clock distribution (although I have done some reading on oscillator noise). However it seems obvious to me that an averagely-competent clock on the board is going to deliver a cleaner clock signal to the points which matter, than a perfect clock off the board with somewhat random connection arrangements. And off-board clocks are not always perefect!
In many cases the best clock upgrade is to use a higher quality crystal for the existing circuit. Modern quartz crystals are often cheap, and to a certain extent you get what you pay for. Decent crystals are expensive, as their manufacture requires very clean conditions - surface contamination is a major source of low frequency jitter in crystals.
Curiously, many people spend money on things like atomic clocks or GPS-locked clocks which can have poorer jitter than an ordinary crystal clock. Other things being equal, any crystal clock which has some form of automatic frequency control (such as the PLL used in these locked clocks, and maybe even some temperature compensated clocks) will have worse jitter than the same clock with the control components removed.
In many cases the best clock upgrade is to use a higher quality crystal for the existing circuit. Modern quartz crystals are often cheap, and to a certain extent you get what you pay for. Decent crystals are expensive, as their manufacture requires very clean conditions - surface contamination is a major source of low frequency jitter in crystals.
Curiously, many people spend money on things like atomic clocks or GPS-locked clocks which can have poorer jitter than an ordinary crystal clock. Other things being equal, any crystal clock which has some form of automatic frequency control (such as the PLL used in these locked clocks, and maybe even some temperature compensated clocks) will have worse jitter than the same clock with the control components removed.
George
I think we are in agreement the noise is from transformer. Please note my earlier measurements of the voltage induced into chassis.
I do have a test chamber that is 2' x 4' for this current bit of my power supply research.
I started this as a quick article for Ax three years ago. Still learning new bits and pieces.
Demian
Nice to see you followed up on the jitter tuner technique. It is just meant to be a quick and simple tool not a design aide.
Marce
I wish you would quit trying to bring experience and education to the forum. It is such a downer. Obviously the best way to do a PC layout is with tape on Mylar as that is the way I and others first did it. Then for a substrate whatever is most expensive and damaging to the environment is obviously best. Because in order to get those you have to use a real production house and not the cheap guys who use the lowest quality products they can get away with. We haven't even touched on additive or subtractive processes. Of course etching is better but then we have to decide which etchant sounds best. Of course it is hydrochloric acid. As ferric chloride adds iron traces to the card. Then we need to look at the plating. We can even discuss the importance of the neutralizing bath and the long term stability. Obviously multiple baths of triple distilled water are required with vacuum desiccation. Tin plating is obviously too common so gold is the only way to go. Now for the solder mask only special secret formulations can work here. The solvents used in ordinary ones obviously change the chemistry of the copper. Of course this also applies to any silk screened markings. Then we get into how they are packaged for shipping. Obviously only a metalized vacuum bag is good enough. Of course each card must be packed in it's own bag to avoid cross contamination.
Now this is just the basics for any audio quality PC Card. Forget those mil and aerospace requirements those IPC specs just have nothing to do with these special needs.
(gotcha!).
ES
I think we are in agreement the noise is from transformer. Please note my earlier measurements of the voltage induced into chassis.
I do have a test chamber that is 2' x 4' for this current bit of my power supply research.
I started this as a quick article for Ax three years ago. Still learning new bits and pieces.
Demian
Nice to see you followed up on the jitter tuner technique. It is just meant to be a quick and simple tool not a design aide.
Marce
I wish you would quit trying to bring experience and education to the forum. It is such a downer. Obviously the best way to do a PC layout is with tape on Mylar as that is the way I and others first did it. Then for a substrate whatever is most expensive and damaging to the environment is obviously best. Because in order to get those you have to use a real production house and not the cheap guys who use the lowest quality products they can get away with. We haven't even touched on additive or subtractive processes. Of course etching is better but then we have to decide which etchant sounds best. Of course it is hydrochloric acid. As ferric chloride adds iron traces to the card. Then we need to look at the plating. We can even discuss the importance of the neutralizing bath and the long term stability. Obviously multiple baths of triple distilled water are required with vacuum desiccation. Tin plating is obviously too common so gold is the only way to go. Now for the solder mask only special secret formulations can work here. The solvents used in ordinary ones obviously change the chemistry of the copper. Of course this also applies to any silk screened markings. Then we get into how they are packaged for shipping. Obviously only a metalized vacuum bag is good enough. Of course each card must be packed in it's own bag to avoid cross contamination.
Now this is just the basics for any audio quality PC Card. Forget those mil and aerospace requirements those IPC specs just have nothing to do with these special needs.
(gotcha!).
ES
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I wish I still did tape ups, standing up was a lot healthier and it was (felt !!!) more artistic, doing tape ups is the best way to learn PCB design, as mistakes are a pain to correct.
Last tape up I did was a 4 layer ADC card......1987 I believe, we had CAD then but still did tape ups and modded them for several years.
I use to like drafting the schematic as well, at least they looked neat, now they are just thrown down on a schematic capture package with no regard to line widths and connection spacing's.
I know that, Marce, my pont was that even super clocks expressly made for this or that CD player can, not too often, have problems with installation because in the meanwhole, the CD manufacturer changed something, so what could fit before cannot fit in any more. I've seen two cases of that happening.
As for the outboards, personally I wouldn't do it. Having a 15 MHz oscillator which has free space around it and needs a very speacial connection is not my idea of having fun. I'd prefer to invest in a costly good quality crystal.
He Who laughs Last....
I have tried the experiment of an amp running on my bench with no top cover fitted.
Then drop on a timber top cover, or aluminium top cover, or steel top cover.
Four different sounds........and of course the resident naysayers said this is not possible, or needed DBLT to prove it.
Thanks George.
Dan.
I have tried the experiment of an amp running on my bench with no top cover fitted.
Then drop on a timber top cover, or aluminium top cover, or steel top cover.
Four different sounds........and of course the resident naysayers said this is not possible, or needed DBLT to prove it
.Thanks George.
Dan.
Why not 44.1/16 vs HD through the same signal chain? No one I know made the claim you state.
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Dan, in a power amp, any magnetic box or chassis near the high current wires induce distortions you can measure. But i doubt you could hear any differences between copper and aluminum, apart from huge EMI RFi outside, or currents in the chassis earth.
All this is well known. That's the reason why most prefer Aluminium (light and non magnetic).
If you cannot avoid steel, keep the wiring far enough from the panels of your chassis.
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WTF, Jan??? You said in the your that:
All I did was asked YOU TO PROVIDE EXAMPLES of bad engineering. That's all that it was.
Try reading this for a start.....
Then start on this....
Then you will have more understanding about what we are talking about...
...why do you think I do aerospace and similar layout, it could be because I know what I am doing, yet that knowledge is NOT GOOD enough to use to try and help Audio DIYers.....
Marce, you're not even funny.
Why do you think that, because this is DIY forum, everyone posting here is some noob with 60W soldering iron in hand and desperate for your unasked advice? How do you know who you are talking to here? ;-)
IMHO, you are entitled to criticize others only if you have experience in your field RELATED TO AUDIO, in which case it shouldn't be difficult to provide practical examples of YOUR WORK IN AUDIO field to support your critique.
Telling people here how smart you are, how many space shuttle PCBs you have done and what mega-million dollar company pays your hotel bills is pointless showing off.
As to the links and papers... you know what? I can send you links and provide papers on the subject that will keep you busy reading for weeks.
Thanks, yes I understand this.
Some others perhaps don't...or it seems they have some kind of Vendetta.
Dan.
Dan, if the issue is back reflection of magnetic fields generated inside the amplifier, either a steel or an aluminum thin top cover reflects back all the magnetic field (they differ past some decimal place of a dB) that impinges on them. With a timber cover or no cover at all, there is no back reflection.
Then it is the important issue of shielding effect from sources outside the box (see attachment for a rough picture).
And of course there is the vibration (microphonics) behavior of the top covers depending on their mechanical properties.
George
Attachments
About microphonic of solid state devices, all the tests i had done reflected NADA, NOTHING, NIB, RIEN, QUE DALLE, DES CLOUS.
Apart bad welds, but it is a strange way to build a microphone.
With tubes, it is fun to try various tube bases on guitar amps and listen to the way it changes the sound ;-)
Your opinions ?
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