Well, oxides have good electrical impedance over wide bandwidth so it makes sense. 
Oxides also cover a huge huge huge swath of materials, so one needs to drill down a little more.
Many high-K mlcc caps are made from barium titanate derivatives, i.e. Barium titanate - Wikipedia
While you can get BaTiO3 out into the k >= 5000, many of our more linear oxide insulators, e.g. TiO2, HfO2, ZrO2, top out with k < 100. Al2O3 is around 10 if I remember correctly. SiO2 is a mere ~4. Hard to make a big capacitor with SiO2 cheaply.
Oxides also cover a huge huge huge swath of materials, so one needs to drill down a little more.Many high-K mlcc caps are made from barium titanate derivatives, i.e. Barium titanate - Wikipedia
While you can get BaTiO3 out into the k >= 5000, many of our more linear oxide insulators, e.g. TiO2, HfO2, ZrO2, top out with k < 100. Al2O3 is around 10 if I remember correctly. SiO2 is a mere ~4. Hard to make a big capacitor with SiO2 cheaply.
Thanks PMA and George for the cap references.
I might point out that PMA's data sheet does not DIRECTLY infer non-linear distortion or DA (dielectric absorption) or linear distortion. X7R ceramic caps have both, big time. This is where many engineers go wrong. They try to get away with a ceramic cap that is the right size and price, that blocks any DC, BUT has distortion, both linear and non-linear when used as a coupling cap. Just look at Sony products! This is WHY many serious audio designers (not mid-fi) have designed out the vast majority of the coupling caps. It is just a more linear approach, and it is not that hard to do.
For example, the JC-3 Jr, which has up to 80 dB low frequency gain, gets away with a single simple servo per channel. It's cheaper than adding a quality cap to do it this way. Wake up guys, I am trying to give you some free advice, not sell you something.
I might point out that PMA's data sheet does not DIRECTLY infer non-linear distortion or DA (dielectric absorption) or linear distortion. X7R ceramic caps have both, big time. This is where many engineers go wrong. They try to get away with a ceramic cap that is the right size and price, that blocks any DC, BUT has distortion, both linear and non-linear when used as a coupling cap. Just look at Sony products! This is WHY many serious audio designers (not mid-fi) have designed out the vast majority of the coupling caps. It is just a more linear approach, and it is not that hard to do.
For example, the JC-3 Jr, which has up to 80 dB low frequency gain, gets away with a single simple servo per channel. It's cheaper than adding a quality cap to do it this way. Wake up guys, I am trying to give you some free advice, not sell you something.
Last edited:
I have seen many shielded cables where one end was not connected to the ground (shell in the case of RS422/485/232/TIWAY). In some cases, it makes a difference which end is grounded.
This was done to prevent ground current in the shield.
I have also seen double Faraday shielding with two shields, one connected at each end. This can also make a difference depending on which way the cable is connected.
With audio, unless there is a ground fault with major potential differences in the ground points, I see no need for this and there should be no effect on switching the direction of the cable.
This was done to prevent ground current in the shield.
I have also seen double Faraday shielding with two shields, one connected at each end. This can also make a difference depending on which way the cable is connected.
With audio, unless there is a ground fault with major potential differences in the ground points, I see no need for this and there should be no effect on switching the direction of the cable.
John, the enormous nonlinearities in capacitance vs. (temp, voltage, frequency) etc do directly infer massive non-linear distortion.
Look at AVX's charts on C0G dielectrics
http://datasheets.avx.com/C0GNP0-Dielectric.pdf
Or this:
https://ec.kemet.com/mlcc-dielectric-differences
It's staring you right in the face. It's pretty patent that the use of a x5r/x7r as a bypass cap is an exercise in cost cutting or a failure to read.
Look at AVX's charts on C0G dielectrics
http://datasheets.avx.com/C0GNP0-Dielectric.pdf
Or this:
https://ec.kemet.com/mlcc-dielectric-differences
It's staring you right in the face. It's pretty patent that the use of a x5r/x7r as a bypass cap is an exercise in cost cutting or a failure to read.
NPO or COG caps are perhaps OK for SMALL VALUES, personally I prefer polystyrene or mica, but maybe that is because I am used to them. They just are NOT PRACTICAL in values above 0.1uf, AND they get expensive as well. That is why the parts distributors will steer you to X7R or equivalent caps. They are cheaper, smaller, and available in large values, BUT they distort BADLY! But you will not necessarily easily catch their problem with a simple sine wave measurement, and trust me, you can destroy the sound quality of a remarkable design with just using X7R caps in a serious audio stage.
I got fired once by the Grateful Dead, because I (along with my colleagues) made such an error, back in 1971. I didn't know why my design failed until 3 years afterward, when Tektronics showed me what X7R ceramic capacitors behave like. You don't want to make the same mistake as I did, it is just not worth wasting your time.
I got fired once by the Grateful Dead, because I (along with my colleagues) made such an error, back in 1971. I didn't know why my design failed until 3 years afterward, when Tektronics showed me what X7R ceramic capacitors behave like. You don't want to make the same mistake as I did, it is just not worth wasting your time.
Typically you want a shield to conduct capacitvely coupled noise currents to the lowest noise reference point. if the whole system is inside a continuous shield one connection at the transducer would be ideal. That does not happen in audio. Usually you would connect the shield at the preamp end so the noise currents are not shared with the return line from the transducer (Phono cartridge?). However every system may be different.
It does clearly show nonlinear distortion as capacitance change vs. AC voltage. It also shows capacitance change as a function of DC voltage, which again means nonlinearity. My point is that some engineers should learn to read the datasheets. Linear distortion is shown as capacitance change vs. frequency. So all your objections are wrong, IMO, except that of DA. DA was not shown in those examples.
Last edited:
Yup! But that's also what x5r/x7r capacitors are made from and they're pretty ubiquitous for local PSU bypass when you need decently high capacitance in a low inductance package. And for cost savings.
Just try it....one scenario is standard ST3.5mm-ST3.5mm cable connecting phone to battery powered portable speaker.I don't spend a lot of time thinking about this kind of things
IME reversing this cable direction subtly affects the reproduced sound with spoken word/speech showing the difference more clearly.
I am not certain of the reasons for this behaviour but it is evident nevertheless.
Just sayin'.
Dan.
Hi Dan,
Each individual wire is pulled individually, then spun together to make the stranded center conductor. The pull direction will either be random, alternating or a mystery as no one keeps track of this information.
Now for the biggie issue. In test equipment at the high end and for space applications, this might be important as long as you can square that with the fact that AC current is equally bipolar. However, cables are checked for every defect known at extremely low levels. They don't mark them for direction.
Did you know that a metrology grade cable with either SMA or "N" connectors is worth north of $1,000 US. This is for a calibration lab (high end with very low uncertainties), and they are discarded after "x" number of matings. They perform better than any audio cable of any description ever will. They are thrown out after so many times they are mated, or in case anything happens such as a too tight radius corner, or slight compression under equipment (or shoe). Audio cables do not perform to this level of performance, and they can read reflections from a slight compression.
Anyway, cables for audio use don't come close to this level of performance. Any thought that they might is merely a lost hopeful dream. A little reality slipping into the world of audio cables.
Dan, study Metrology just a little and learn about cables and connections. Oh yeah, the only cleaner for cable connectors is IPA, nothing else.
-Chris
Each individual wire is pulled individually, then spun together to make the stranded center conductor. The pull direction will either be random, alternating or a mystery as no one keeps track of this information.
Now for the biggie issue. In test equipment at the high end and for space applications, this might be important as long as you can square that with the fact that AC current is equally bipolar. However, cables are checked for every defect known at extremely low levels. They don't mark them for direction.
Did you know that a metrology grade cable with either SMA or "N" connectors is worth north of $1,000 US. This is for a calibration lab (high end with very low uncertainties), and they are discarded after "x" number of matings. They perform better than any audio cable of any description ever will. They are thrown out after so many times they are mated, or in case anything happens such as a too tight radius corner, or slight compression under equipment (or shoe). Audio cables do not perform to this level of performance, and they can read reflections from a slight compression.
Anyway, cables for audio use don't come close to this level of performance. Any thought that they might is merely a lost hopeful dream. A little reality slipping into the world of audio cables.
Dan, study Metrology just a little and learn about cables and connections. Oh yeah, the only cleaner for cable connectors is IPA, nothing else.
-Chris
I like the idea of the philosophy, but don't see a strong enough consistency for avoiding a good, well chosen, capacitor if it's easier and/or better for topology.
My current fav input cap is under $1 and 5mm leadspacing, and same for a feedback cap. Maybe I'll upgrade to a REL cap that Richard help usher in, maybe I won't care once I have it.
And I never have to worry about DC.
How many designers out of midfi are really trying ceramic caps? Even a ProJect phono thing ($150, has USB output) that I have used lytics in the stock form. I swapped them with some Blackgates and have little complain about now if I use it. I'm just not sure whom you are educating.
Last edited:
Hi Dan,
Please try reading up some some material about cables from a metrology standpoint. I'm not kidding, the information directly applies to what you are trying to do. It will confirm some of what you know, and show why other things aren't what you thought they were.
I can promise you one thing. Once you read that material, you will have the means to get or make superior cables and enjoy the music more fully. It will also be less expensive unless you adopt to use SMA connectors and metrology grade cables!
-Chris
Please try reading up some some material about cables from a metrology standpoint. I'm not kidding, the information directly applies to what you are trying to do. It will confirm some of what you know, and show why other things aren't what you thought they were.
I can promise you one thing. Once you read that material, you will have the means to get or make superior cables and enjoy the music more fully. It will also be less expensive unless you adopt to use SMA connectors and metrology grade cables!
-Chris
- Status
- Not open for further replies.