power amplifier

[vaustin89]

hello, i really need help in building my guitar amplifier.. i am planning to build an amp for both bass and guitar the bass should be switchable from 50 to 100watts while the guitar can be switched between 30 to 60 watts..my amplifier design is a solid state one, since i could not find tubes and there to expensive for a mere mortal like me.. i have a bunch of TDA 2030, can i use this for my project.. and are there other chips for power amplifier.. since my amp can switch between two wattage output, is bridging necessary?

[Tekko]

No and no! tda2030 can at most give 18 watts, about enough for a small practice amp at home, but wouldent even be audible with multiple instruments playing.

These kinda amplifiers has to stand up to so much abuse that it'll be much cheaper and safer to just buy a commercial guitar/bass amp.

Its not uncommon that these amps actually burst into flames, its rare but it happens.


Also the TDA2030 is about the worst chipamp ever released on the market, i dont think i've ever seen any diy around this that havent had oscillation problems.

[vaustin89]

any ideas for a chip power amp?

[Tekko]

The LM3886 is tried and proven, and has enough internal protection circuitry to be nearly indestructible.

I really tortured the smaller version LM3875, only think that was able to kill it was a direct short on full output, and that after hours of abuse like hard clipping and driving loads no commercial amp would survive and such.

Though the LM3886 is only 60 watts at most, but thats about as high power your gonna find in a chipamp unless you build a discrete design, then you can have over 100 watts, and by just halving the supply voltage, you can reduce output power to half.

[vaustin89]

ok thanks for the help..

[ingenieus]

You could bridge two LM3886 chips for 120W, but only if you are driving an 8 ohm load. Each chip then sees 4 ohms.

For a 4 ohm load, each LM3886 has to drive 2 ohms. This is very likely to activate its protection mechanisms.



A 120 Watt Bridged

http://www.dckits.com/app1.htm

[digits]

Vaust, why the need for diffirent power switch levels?
If you are worried you will blow your speaker because you have a 60W amp and a 30W speaker, don't. The more likely way to blow a speaker is with a 60W speaker and a 30W amp.... Just putting it out there. I'd look around for some DIY projects along those lines on the net first. What makes a good amp for listeing to music, does not make a good amp for a guitar.

[ingenieus]

The difference between 60W and 100W amounts to 2.2dB - why complicate things by trying to make it switchable? That is what the volume control is for.

[jaycee]

If you want a decent bass amp, it will have to be discrete and with rugged output transistors. A chip will either go into protection or die.