Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

ceramic capacitors

Status
Not open for further replies.
Dear forum members,

I would like to know what is known about ceramic capacitors in audio amplifiers, what they the advantages and disadvantages to use them.

Sincerely,

Pim Driessen
 

ronsimpson

Well-Known Member
Most Helpful Member
Ceramic capacitors: There are different types of ceramic so the question is complicated.
1) Some types of capacitors, the capacitance varies with the voltage across the capacitor. As you can see in the graph the COG type of ceramic capacitor does not change capacitance much while the X7R is at 50% with 45 volts across a 50 volt cap. In a preamp where the audio is 0.1 volts this effect will not matter but in a output of a power amplifier this effect will cause distortion.
upload_2014-11-15_6-57-45.png

2) Some types of ceramics capacitors are like little microphones. They pick up audio vibrations. They are also like speakers. They can cause movement in air and vibrations in the PCB. If you place a capacitor for the right and left channel close together then the capacitors will "talk" to each other. You will have bad channel separation problems. ALSO A capacitor on the output of the amplifier may talk to a capacitor in the input of the amplifier and cause strange feedback and distortion. (ceramic microphone) and (ceramic speaker)

There are other effects but this will get you started.
 

audioguru

Well-Known Member
Most Helpful Member
A ceramic capacitor has a low impedance at high frequencies so it is used as a high frequency supply bypass capacitor that prevents an opamp or amplifier from oscillating at a high frequency.
I always use a plastic film capacitor to couple audio signals.
 
Dear Sir, thank you for the response.
I am also not in favor of ceramic capacitors, but my electronics background is a practice-oriented.
So I'm looking for some theoretical background


Sincerely,

Pim
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
audioguru said:
I always use a plastic film capacitor to couple audio signals.

Except when they get really big, like 10 uf. I'm going to eventually re-cap a 4-channel OEM audio booster with NbO Tantalum Caps. See: https://www.electronicproducts.com/...o_coupling_with_niobium_oxide_capacitors.aspx

The thing uses about 10 of the 10 uf, 16 V Electrolytic caps. One amp has channel difficulties (severe distortion) and the other won't turn on below about 65 degrees.

It also uses a 24 pin connector and an 8 pin connector. It has differential inputs and differential outputs and fixed equalization (some notch filters). It also "tells" the head unit, that it's a booster and the head unit lowers it's output levels accordingly. Wierd.
 
Status
Not open for further replies.

Latest threads

Top