Continue to Site

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.

Audio Capacitor vs General Purpose (Electrolytics)

Status
Not open for further replies.

TimLaw

New Member
Hi,

I am going to start a simple amp project. I am also in the market for a sound card for my computer. I was looking around and saw an Asus card that used Nichicon KZ Audio Capacitors.

So, seeing those made me wonder what made an "audio capacitor" different than a regular old electrolytic. Oh and the KZs are electrolytics.

**broken link removed**

So I was wondering what difference these capacitors have with a general purpose electrolytic and where in an amplifier would they be most suitable?

Here's the circuit I am working on:

**broken link removed**

So what does it all mean?

Thanks.
 
Only C4 and C5 have audio in them and they also have DC so ordinary polarized electrolytic capacitors can be used.
C1 and C2 bypass the pins to ground with no audio across them. They can be ordinary polarized electrolytic capacitors.
C6 and C7 couple the 4.7 ohm resistors to the amplifier outputs at very high frequencies so they should be ceramic capacitors.

The open box symbol on the polarized capacitors is the positive wire. The solid box symbol is the negative wire.

The datasheet for the TDA2822M stereo amplifier shows a recommended pcb design.
 
Thanks. Would using these caps make any difference if used for C4 and C5?

So if not useful in an amp like this one, where would these be useful because I find them quite intriguing.
 
Last edited:
Most people cannot hear distortion less than 0.1%. But audio opamps are made with distortion as low as 0.00008% (an OPA2134). Some people add a DC load so that the output operates in class-A for even less(!) distortion.
An ordinary electrolytic capacitor has a terrible tolerance so if you need 20uF and use a 22uF capacitor its actual value might be only 10uF and will reduce low frequencies and distort them a little.

I didn't read the advertising (lies?) about the Japanese capacitor you found. If an ordinary electrolytic capacitor has distortion of 0.05% then this one might be 0.02% which doesn't matter because nobody can hear it from an ordinary capacitor anyway.

Maybe the new capacitor is useful in a recording studio where a signal passes through many capacitors and their distortions add up.
 

Attachments

  • OPA2134 details.PNG
    OPA2134 details.PNG
    17.2 KB · Views: 437
I've heard OPA2134s being used in headphone amps but not really a regular old speak amp.

I reckon they can't put out too much juice. But then again its an op-amp...soo...?

Do you have any suggestions for a better amp chip?

And how to measure distortion?
 
Last edited:
I've heard OPA2134s being used in headphone amps but not really a regular old speak amp.

I reckon they can't put out too much juice. But then again its an op-amp...soo...?

Do you have any suggestions for a better amp chip?

And how to measure distortion?
An opamp is not a power amp.
There are hundreds of excellent power amplifier ICs. The LM3886 produces 68W into 4 ohms or 50W into 8 ohms.
Distortion plus noise is measured by feeding in a low distortion sine-wave, measuring its level at the output of the amplifier then notching away the sine-wave and measuring the distortion and noise that remains. Then the ratio is calculated for the percentage of distortion plus noise.

An IM distortion test is more complicated.
 
Thanks a lot Audioguru. RIght and I knew that about Op-amps...Being stupid I suppose.

There are so many amp ICs. I'd like to run it off a battery because I'm not to sure about me making a wall power supply. (Death?) So that would mean low input voltage. Less than 15V preferably.

Or maybe I can make a power supply but I'm not sure of the dangers. I like to make everything myself if possible.

Any reccomendations. I'm sorry to bug you.
 
Last edited:
The power supply voltages for an audio power amplifier are not accessable.
But if the amplifier has a high max output power and the volume is near max then the signal voltage at the speaker terminals will give you a big shock. Simply don't touch them.
 
Ah thanks. Not accessible as in?

I'm 100% positive I could build a 5V power supply for the amp.

Toroidal tranformer?
 
Ah thanks. Not accessible as in?
The power supply terminals are covered so nobody can touch them.

I'm 100% positive I could build a 5V power supply for the amp.
An LM386 power amplifier has a "whopping" output power of only 0.11W into 8 ohms at clipping with a supply that is only 5V. Not much louder than headphones laying on a chair. A cheap clock radio is much louder.
An LM3886 has a power output of 50W into 8 ohms when it has a supply that totals 70V. It can produce bass that you can feel.

Toroidal tranformer?
A toroidal transformer is smaller than an ordinary one but costs more.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top