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-   -   What type of capacitor is appropriate? (http://www.diyaudio.com/forums/chip-amps/173805-what-type-capacitor-appropriate.html)

TheLaw117 18th September 2010 12:57 AM

What type of capacitor is appropriate?
 
Hello everyone,

I have a basic amplifier circuit that I am looking to make. This is my first time building an amplifier so I am not too literate in the amp world. It would be great if you could help me out.

I was wondering if the capacitor type in this circuit made a difference with how it will sound? Right now I was going to use some high temp 135C Nichicons I had laying around for all sections. All of them are rated >50V so I suppose that would be decent.

But I have heard that some people prefer ceramic or tantalum or something other than electrolytics due to the general voltage/capacitance nature of electrolytic caps.

I was wondering if that would apply in this circuit?

Thanks.

http://i288.photobucket.com/albums/l...AmpCircuit.png

neutron7 18th September 2010 01:38 AM

For the output capacitors, since they are quite a high value you probably do not have much choice besides electrolytic, but you can bypass them (put in parallel) with some lower value but better quality ones. you could jsut use film caps you have lying about, 0.5 to 2 UF, or something like these
Dayton DFFC-0.47 0.47uF 400V By-Pass Capacitor | Parts-Express.com
or something fancier if you like,

for the input and servo ones, also use film capacitors (almost any would be better) to replace the electrolytics (not so sure how much it matters to replace the servo one)

as long as the voltage rating is more than the supply voltage you should be fine.

star882 18th September 2010 01:41 AM

Use good electrolytics for the big ones and high quality ceramic or film for the small ones.

TheLaw117 18th September 2010 03:20 AM

Ah why thank you.

I have one other question regarding op-amps because I think I might change it around a bit.

I was looking at a LM1875 as well as the LM1876.

For the 1876 it says something about "single supply". What does "Single Supply" mean and what effect does it have?

Does anyone know if the single supply thing applies to the LM1875?

Thank you.

Minion 18th September 2010 06:14 PM

A single supply circuit uses a power supply that has a Ground and a Posistive Voltage .....

A dual supply circuit uses a power supply with a Ground , a Positive voltage and a negitive voltage .....

The differance is basicly that a single supply circuit will need to have output capacitors because half of the Single supply DC Voltage will be on the output of the Chip , so the capacitors Block that DC Voltage from getting to your speakers .....

A dual supply curcuit is preferred because there is some Sound degridation when useing output capacitors ......


Cheers

TheLaw117 18th September 2010 07:43 PM

Something like a 9V battery would be considered a single source, then?

This could present some difficulties...

star882 19th September 2010 01:38 AM

An even better solution for high power is to use BTL. You could synchronize the carriers and modulate the two outputs 180 degrees out of phase so the carrier partially cancels out, simplifying filter design.

qusp 26th September 2010 11:44 AM

actually arcotronics make a 470uf stacked film cap that would work well here depending on space. as its stacked film, its reasonably small as large value films go, but still not actually small, about 40mm x 30mm box I think from memory.

you can make a split supply with batteries, but it will still have DC on the output unless you use a charge pump/inverter or something like that to produce a real bipolar supply from them.


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