I have a couple here on my bench. For the life of me, I don't hear a thing from them 😉 .
Seriously, it is common knowledge that caps distort depending on the signal level across them. Let's take as example a coupling cap. A competent designer will dimension the cap so that at the lowest frequency of interest, the signal across the cap is low enough not to increase the distortion above what's already there. This is basic stuff. Anybody can built an amp with distorting caps, but it's totally unnecessary.
Frightening non-engineering types by blanked statements like "ceramic caps distort" is doing no one a favor.
jan didden
OK, Jan, but if Sony is on the right track, then their tuner will never be hi fi, but relegated to mid fi, no matter what they did in the RF chip. That is my personal experience with an actual unit, over many hours, with the best FM sources available in the SF Bay Area, which is still rather extensive.
Further reading which may be of interest covering some of the coupling mechanisms etc.
UK site
EMC Information Centre - The EMC Journal (Free in the UK)
US site
EMC Journal portal | EMCJUSA
The latest issue #91 of the EMC journal has an excellent article by Keith Armstrong; "Maxwell's Equations, Quantum Electrodynamics, and good installation practices for SI, PI and EMC".
As to Caps, we have found that we had to flick the cap with a fingernail to get any significant readings, though unless size dictates we do not use them for interstage (X7R), COG and NPO we would use, and use them on RF boards for inter stage coupling due to size limitations.
UK site
EMC Information Centre - The EMC Journal (Free in the UK)
US site
EMC Journal portal | EMCJUSA
The latest issue #91 of the EMC journal has an excellent article by Keith Armstrong; "Maxwell's Equations, Quantum Electrodynamics, and good installation practices for SI, PI and EMC".
As to Caps, we have found that we had to flick the cap with a fingernail to get any significant readings, though unless size dictates we do not use them for interstage (X7R), COG and NPO we would use, and use them on RF boards for inter stage coupling due to size limitations.
Jan,
Put a small DC voltage on them and then the desired AC signal. Listen carefully you may actually hear something. Some ceramic capacitors are first cousins to the piezo transducers used for signaling.
Attached are the vibration measurements for some capacitors. The output is almost microphone level. Of more interest to me lately is the frequency response and the resonances.
I did try using a ceramic capacitor as a vibration contact pick up microphone on my CNC engraver. It can work for several hours by itself and being annoyingly noisy I don't stick around. So knowing when it has finished was the goal. Of course common sense kicked in and I found an even cheaper way!
ES
Attachments
I want to share an experience with ceramic coupling caps (2.2uF) that I had 40 years ago with the modification of a Fisher KM-60 vacuum tube fm tuner. The output cap on this tuner was fairly small, and I wanted to increase its value. Well, I had these 2.2 uF non-polar ceramics that were relatively EXPENSIVE at the time, but they were small, non-polar, good looking, and I could increase the output coupling cap's value by a factor of 10 or so, so I did it. I lived with it for awhile and I noticed that something was wrong. A slightly hard, 'grunge' was added, and guess where it came from?
It took me years to PROVE that ceramic coupling caps were really nasty, but I did, and I published it. And so it goes!
It took me years to PROVE that ceramic coupling caps were really nasty, but I did, and I published it. And so it goes!
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Lazy?
http://www.diycore.com/patrick/files/electronics/capacitor/capsound1.pdf
http://www.diycore.com/patrick/files/electronics/capacitor/capsound2.pdf
http://www.diycore.com/patrick/files/electronics/capacitor/capsound3.pdf
http://www.diycore.com/patrick/files/electronics/capacitor/capsound4.pdf
http://www.diycore.com/patrick/files/electronics/capacitor/capsound5.pdf
http://www.diycore.com/patrick/files/electronics/capacitor/capsound6.pdf
Is this how you do your research? You changed at least two variables, both the capacitor type and the low frequency cutoff of the circuit and what you heard that you didn't "like" you ascribed to one of them because it fit with your notion of what you already believe.
There's one problem with this theory about ceramic coupling caps though. A lot of so called golden eared audiophiles seem to love those old tube amps and preamps that used them. And how many recording consoles, recording amplifiers and playback preamplifiers processed signals for vinyl phonographs though them? How many ceramic capacitors did the signal go through from the time it left the microphone to the point where it drove the loudspeakers?
So far I find the arguments weak, unconvincing, purely qualititative, and mere testimonial evidence. Got any measurements showing under what conditions this distortion is audible and what the level of distortion is?
Gosh darn, the rights issues keep getting in the way. But I can send you a personal copy 🙂
I wanted to issue a CD of the ANSI standard articulation test lists. ANSI wanted $20,000 for the rights!
In the standard it tells you to make a recording to get consistent results! At that time the songwriter's royalty was about 5 cents! But nobody wanted to get lawyers involved, so no test disc. But I can send you a personal copy 🙂
Oh yeah both disc's would be Mono! No extra charge!
Wow, that's great! I know of course Cyril's work, in fact I still have his original articles ripped out of WW way back when. Never knew this was on-line.
Anyway, Cyril did a great job to research this cap distortion issue. With his results and standard engineering practise it should be possible to design a circuit such that this is no longer an issue. Ceramics or otherwise; it's, in the last analysis, a straightforward engineering decision.
jan didden
You and Ed sometimes crack me up 😉 Reminds me of the smoking/no smoking discussions we had some years ago.
Smoker: I had a grandpa who smoked two packs per day for his adult life. He lived to see 93, killed in a car accident!
Non-smoker: My brother smoked a package a day. Died of lung cancer at 39!
Two good, honest, real stories. But they're useless to help you to decide to smoke or not.
jan didden
Jan, please use ceramics. Big ceramics, little ceramics, any large value ceramics, whatever! OF COURSE, I don't use ceramics for coupling caps, but Sony does and that should be good enough for you. Have you tried the resistors that I gave you yet? Please use those resistors with ceramics coupled to and from them, with my personal blessing! ;-)
Jan,
From earlier posts John was talking about the Y7R type ceramic capacitors used at uF values in the Sony Tuner. So those were the curves I showed. Sorry if that was not clear. Lots of folks use NPO's in compensation circuits. So I don't see what the issue is, unless you really are using Y7R's in the audio path and get good results.
ES
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Yeah you're right, I know. It's just that I abhor those blanket unqualified statements "ceramics distort" without any qualification. People pick up on this, open their equipment, see what looks like a ceramic, think "aha! got you" and replace it. Even if it is the mains filter cap.
We all spend hours and hours on-line just bitching and moaning. Why not take some time to give a more balanced, qualified and really helpful response?
For the record: I'm not bitching at you, you're one of the few that take that time and do a good job.
jan didden
Jan,
Why not, I count on you, Scott and a few others to point out where I am vague. The problem comes in when I assume others understand something I just presume is obvious and it is completely foreign to them.
There are some times when I have to omit or be vague about information, because it may be in the area of trade secrets or other confidential information I have been privy to getting. I think I make it clear when that is the case. Recent examples are critical bandwidth/pitch perception and how loudspeakers designed for say horns or direct radiators may differ.
So when is the next issue of Linear Audio due?
ES
Ed, the VALUES of the ceramics used for coupling 1uf and 2.5 uf, SHOULD HAVE BEEN A CLUE!
Jan, please use Y7R, or equivalent large value, small size ceramic caps in ALL your designs. They are cheap enough, small enough, and can protect against minor DC offsets. They will allow miniaturization of virtually all audio components, including removing servos, that can be fussy and space consuming.
Better yet, write an article on these ceramics, putting it in your latest publication, after, of course, careful double blind evaluation, and PROVING their transparency and audio worthiness. However, I would appreciate it, if you left me out of your audio evaluations and opinions.
Jan, please use Y7R, or equivalent large value, small size ceramic caps in ALL your designs. They are cheap enough, small enough, and can protect against minor DC offsets. They will allow miniaturization of virtually all audio components, including removing servos, that can be fussy and space consuming.
Better yet, write an article on these ceramics, putting it in your latest publication, after, of course, careful double blind evaluation, and PROVING their transparency and audio worthiness. However, I would appreciate it, if you left me out of your audio evaluations and opinions.
Yep, and that's a shame. I don't think Sony has any intention of moving that unit, or any more releases, up to hi-fi audio performance.
Has the thread really degenerated into talk about why we should not to use ceramic caps in audio?
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