film vs ceramic audio cap

[Oznog]

I was wondering, I'd asked before about why film caps are needed for audio. So the ceramic cap will distort the audio a bit, as best I can tell because the capacitance varies a bit versus voltage. It's not just the temp coefficient issue right?

Now I do have a case though where I need to save some space and was noticing an ceramic X7R capacitor array might help quite a bit with the space problem, and is much cheaper and quicker to assemble too. This wouldn't normally be acceptable except I was noticing this is simply a coupling cap, not a filter. The cap just feeds a codec ADC input and the requirement is "0.1uf or greater". So that seems as if it will simply carry a fixed DC voltage on the cap.

Is this a particular case where a ceramic could be used without appreciable effects on the audio quality?

 

[audioguru]

If the ceramic coupling cap is used as a highpass filter then low frequencies will have even harmonics distortion as the capacitance value changes with voltage (signal).
If the gain is very high then a ceramic cap is microphonic.

 

[Oznog]

But here's what I'm looking at. The codec's ADC input is internally biased and the mike signal must be capacitively coupled in. The ADC input is spec'ed at 1Mohm making a 1.6Hz cutoff.

So the coupling here should basically mean a fixed DC voltage on the cap, that's where I'm wondering if the ceramic will work.

 

[audioguru]

The ceramic coupling caps will be fine.

 

[Nigel Goodwin]

But here's what I'm looking at. The codec's ADC input is internally biased and the mike signal must be capacitively coupled in. The ADC input is spec'ed at 1Mohm making a 1.6Hz cutoff.

So the coupling here should basically mean a fixed DC voltage on the cap, that's where I'm wondering if the ceramic will work.

Your concerns are mainly based on the lunatic HiFi buffs, don't forget to use oxygen free copper wires and it's vitally important that they are connected the correct way round. Also, putting pointy metal feet on your computer will vastly improve the picture and sound quality, as will replacing the mains lead with a highly expensive screened one.

You don't really 'need' specific capacitor types, but some people believe they make a difference to the sound quality - and it makes companies rich selling them components at inflated prices!.

 

[audioguru]

Your concerns are mainly based on the lunatic HiFi buffs

Rod Elliot measured 3% distortion across a ceramic capacitor to ground in a lowpass filter. Its true distortion is worse because it is attenuating its own harmonics. **broken link removed**

I have never seen a ceramic audio coupling or filtering capacitor in an audio product. Film capacitors are always used.

 

[Hero999]

And while oxygen free cable doesn't make much difference, it is vital to connect the speakers the right way round to avoid one channel canceling out the other.

Af course you need different capacitor types at different frequencies, for example a film capacitor is useless at RF because it behaves as an inductor.

 

[Nigel Goodwin]

And while oxygen free cable doesn't make much difference, it is vital to connect the speakers the right way round to avoid one channel canceling out the other.

Not the speakers, THE CABLE - some of these stupidly priced cables come with arrows on, showing you which way to connect them.

 

[Hero999]

LOL, that is stupid.

 

[Nigel Goodwin]

LOL, that is stupid.

You know that, I know that, but the people who pay massive amounts per metre for the cable don't!

 

[zevon8]

How about the $1000 dollar power cables. 16 GA 3 wire cord with a hospital grade plug on each end, ROTFL, costs about $15 dollars to make. It's still no better than the 50 cent job that comes with just about every piece of computer gear from China.

One of my all time favorites was a car audio place that sold 4 GA wire for about $30 a meter, and bragged how since it is welding cable it is sooo much better. Costs like 3 dollars a meter from any electric supply place, I use it everyday at work connecting generators and inverters on emergency vehicles.

 

[RadioRon]

Don't get me started on cables. What a scam! I'm still laughing about "uni-directional speaker cables" and that came out years ago (it was quite funny). Nowadays when I go to the audio-video specialty store and they try to sell me cables along with my new gadget, I always so no. Why? Well because they are trying to sell me a digital cable (like for example, an HDMI cable for my TV) on the basis that it delivers a better picture or sound than a cheap one would. I can understand that it is possible for a cable to be so badly designed that it can introduce errors by allowing interference or distortion, but I really don't believe that the ones and zeros spitting out the end of a $260 "designer" HDMI cable are any different than the ones that spit out the end of my $20 Walmart HDMI cable. Choosing cables should be a matter of engineering principles and common sense, not voodoo psuedoscience.

 

[Hero999]

I've got some left-handed hammers for sale and they cost 10 times as much as the right-handed variety, anyone want to buy one?

 

[eblc1388]

This is how one shop owner sells a $400 13A power cable.

When a customer expressed wishes to "upgrade" his home equipment by venturing into the wonderful world of interconnects(cables), the owner quickly tells the guy to return later to bring along one of his own trusted friends.

The owner then hands over two pieces of paper with an empty table on each in preparation for a number of sonic tests with an ordinary supply cable and the magic cable. Both cables are clearly labelled. The customer's friend is asked to fill in the order of sonic test using which cable for the amp power supply. The other piece of paper is kept by the customer who sits with his back facing the shop owner and his friend.

Similiar music pieces are played and the customer asked to tick on his paper whether he likes the sonic result. Then later the customer and his friend compare notes. Ten out of ten times the shop owner can make a sale without saying a word.

 

[Hero999]

How doe that work?

Is that just the power of sugestion? Because they've been told the magic cable is better they believe it so the music must sound better when it's played through it.

 

[Nigel Goodwin]

How doe that work?

Is that just the power of sugestion? Because they've been told the magic cable is better they believe it so the music must sound better when it's played through it.

Remember the old story, The Emperors New Clothes!.

 

[Styx]

Don't get me started on cables. What a scam! I'm still laughing about "uni-directional speaker cables" and that came out years ago (it was quite funny). Nowadays when I go to the audio-video specialty store and they try to sell me cables along with my new gadget, I always so no. Why? Well because they are trying to sell me a digital cable (like for example, an HDMI cable for my TV) on the basis that it delivers a better picture or sound than a cheap one would. I can understand that it is possible for a cable to be so badly designed that it can introduce errors by allowing interference or distortion, but I really don't believe that the ones and zeros spitting out the end of a $260 "designer" HDMI cable are any different than the ones that spit out the end of my $20 Walmart HDMI cable. Choosing cables should be a matter of engineering principles and common sense, not voodoo psuedoscience.

HDMI cable is different tho. HDMI is a digital signal carrying cable at quite high bandwidth, screening is needed to stop cross-talk.

Apart from that HDMI is evil so you should be using it, anyone

 

[Nigel Goodwin]

HDMI cable is different tho. HDMI is a digital signal carrying cable at quite high bandwidth, screening is needed to stop cross-talk.

Apart from that HDMI is evil so you should be using it, anyone

Don't you want HD TV then?.

Being installing Sky HD boxes all week, all via HDMI, as specified in the UK HDTV specifications. The current, first generation, boxes also have component outputs, but this will be left off later generation boxes, and will probably have restrictions imposed on using it.

 

[eblc1388]

How doe that work?

Is that just the power of sugestion? Because they've been told the magic cable is better they believe it so the music must sound better when it's played through it.

The trick only works and sounds convincing when the person listen to the music don't know which cable is being used. Of course he would hear a difference.

The owner makes sure the customer will hear a difference. In fact, everyone presence should hear a difference in sound quality. The trick is how to bring that about without the friend of the customer noticed. A secret tone switch, a remote control etc.. perhaps.

 

[Oznog]

Listening to audio on cables with oxygen in them causes cancer.
Really. Look it up.