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LM386 Balanced Amp

post #1 of 8
Thread Starter 
Hey Guys,
am finally at home now, which is far away from any electronics shops, but i am feeling hungry for some diy.at my disposal, i have a CMoy based on OPA2132PA, and 4 lm386 chips.now, can i make myself a balanced amplifier for my RE ZEROS?i am literally dying to see sumthng happen, coz my hometown is super quiet al time through the year.i can manage 9V batteries and tools requird, jus need a schematic or a scheme on how to use "2 stereo amps" both individualy based on 2 LM386 ICs in a balanced configuration.my source is an unbalanced Sansa Fuze.
post #2 of 8
Thread Starter 
Nobody?
post #3 of 8

What exactly do you mean by "balanced amplifier"? LM386 is not an opamp , it's a power amp and it is pretty much limited to what you can find in the data sheet ( a notable variation being the headbanger amp ).

post #4 of 8
Thread Starter 
@raindog1975,
i have 2 headbanger amps with me.now, i am posting using my cellphone, without internet access, so all i found was
http://www.microwaves101.com/encyclopedia/balancedamp.cfm
Edited by psgarcha92 - 3/31/11 at 5:30am
post #5 of 8

After some "googling" I came to the conclusion that balanced amps are used only in high frequency applications ( microwave band ) , the only thing similar, as far as audio signals are concerned, is the impedance balanced line used for connecting  microphones to preamps or mixers or connecting preamps/mixers to power amps over larger distances ( line level signal ) . 

post #6 of 8

I would say build a nicer single ended amp. With power amp chips you need to consider that the random noise of a balanced amp is worse than a SE version, which is VERY important when chips designed for speakers are used as they dont always have very good noise specs by headphone standards. You may also run into stability issues at the relatively low gain required by headphones as compared to the much higher gain these chips are designed for.

 

Try a PPA or M^3 depending on what you think you will personally prefer. Many reviews of both can be found on these forums. 
 

Quote:
Originally Posted by raindog1975 View Post

After some "googling" I came to the conclusion that balanced amps are used only in high frequency applications ( microwave band ) , the only thing similar, as far as audio signals are concerned, is the impedance balanced line used for connecting  microphones to preamps or mixers or connecting preamps/mixers to power amps over larger distances ( line level signal ) . 


If you avoid global feedback balanced operation offers a GREAT way to reduce THD while avoiding the creation of higher order distortions, and other far less natural distortions. The more feedback is more better brigade lost a lot of credibility with the garbage they were pawning off on the world in the 1960-80s despite measuring well in some limited ways. Newer amps win it back, but a reputation for 20-30 years (~1980 is when SOME MFR's started to get it and fix the real problems in high-global-feedback amps) of selling trash to the world dosnt wear off quick.

post #7 of 8
Thread Starter 
@nikongod,
i have a CMoy based on an OPA2132PA already, and am slowly moving towards a Mini^3.
But there is time before that happens, and i really want to make a Balanced Amp for fun.
I am low on resources, but have plenty of LM386 chips from previous projects (2 headbanger headphone amps) and the OPA2132PA in the CMoy.is there any way to get a balanced amp using the above?
post #8 of 8

I bridged a couple of LM386 chips once. There were three version of that chip at the time I had them. I can't remember how much power I ended up getting out, it was enough to run an 8-ohm speaker pretty powerfully though. My circuit involved and op amp to invert the phase going to one chip, the two LM386s, some caps, a zener for biasing my op amp, and a 9V...might have been a little more...can't remember though. It didn't sound too bad at all in the end. Definitely not an audiophile system, but decent enough to make most people happy.

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