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Chip Amps Amplifiers based on integrated circuits

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Old 8th July 2005, 04:53 PM   #1
sr2002 is offline sr2002  India
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Default simple but powerful

helo i am new to diy.

i have just built an amp with opa541 the circuit is below.
thing is i am using it to power a 12ohm sub. with a power supply of 26-0-26 5amp. i have added a 22k resistance in series with input. and connected a 50ohm resistance from pin1 to ground.

should i make any modifications?

and also is there something more powerful than opa541. yet as simple as opa541.
and which can run on maybe +/- 30 or 40 volts and 2-3amps.

if know it then please post schematics and if possible pcb layout (i am an amateur)
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Old 8th July 2005, 11:13 PM   #2
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well, the lm3886 does boast a litle more power than the opa541, but it's really not a lot to speak of. 10W to the max rating i belive. not a lot when speaking of db..

since this is a subamp, i belive the the place to gain the most from improvements are power suply capasitans. more is better offcource. no less than 20.000uf. (according to me)

-Marius
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Old 9th July 2005, 06:45 AM   #3
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If you're interested, my local suplus dealer (jkelectronics) has 3300uF 150V EL caps made by mallory for $.99
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Old 9th July 2005, 03:52 PM   #4
sr2002 is offline sr2002  India
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then which amp do u guys think i should build?
i need a powerful yet simple to build amp.

my problem is that the transformers available over here are become really costly once u go above 5amps, so like 10amp trafos are outa of question. so the think is i need an amp which can run on like 3-5amps and can handle +/- 30-50 volts so that the power supply has a greater 'va' rating.

this time i need it for regular purpose that is 20khz to 20hz or something.

that is to power regular speakers.

and could u also send a schematic for opa549? wut do u think of this chip?

along with a schematic of making it a stereo amp.

i hope i am not askin much. i am an amteur so please bear with me
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Old 10th July 2005, 07:00 AM   #5
asc is offline asc  United States
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My personal fav, www.chipamp.com has some really rockin' stuff. Brian, you rock!
Another great one is www.qkits.com has lm1875 (25W) kits for $10. It's a good starter kit.

-ASC
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Old 10th July 2005, 07:50 AM   #6
sr2002 is offline sr2002  India
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hey thanks 4 ur suggestion but the thing is i live in india so its kinda impossible 4 me to get the stuff off the net stting here.

so may be it will be hlp full if u could provide me a bridge schematic of a lm 3886 chip
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Old 10th July 2005, 06:32 PM   #7
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sr2002, just download the overture guide at national.com

it has what your looking for.
http://www.national.com/an/AN/AN-1192.pdf

-Marius
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Old 12th July 2005, 05:19 PM   #8
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hey thanks a lot ,

that AN-1192 file is excellent.

thing is i can directly build the circuits given over there, without adding any thing right? i mean the circuits are correct right?

which one do u think is better ba100 or pa100?

and wut kind of current should i supply through the trafo?

will 5amps give me good enough power (atleast 80watts)?

hey and that guy on that site "shine7.com" he has also built the pa100

with lots of mods and he is using a 500va trafo. but still he says he is just getting 50watts into 8ohms, why is that ?

cuz the amp in the an1192 is rated 100watts?
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Old 12th July 2005, 08:25 PM   #9
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well, given the high impedans nature of the subs in question, i'd go with the bridged amp.

I think sonically, they behave the same, it's still lm3886's either way.
Now, i havn't had a look at that file for a long time, but i think circuts just need a psu and they will do the job.

concider adding a zobel network instead of the output coil. (search: "zobel", "zoble" or "t-network" on the forum)

Why that guy gets just 50w is probably a mix of low suply voltage, and the fact that the paralell amp is meat for low impedance loads, as 4 ohms, not 8 ohm.

ohms law you know. no matter if he had a 50Mw nukelar power plant for power suply, it's the voltage over R-load that matters.
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Old 13th July 2005, 10:33 AM   #10
sr2002 is offline sr2002  India
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hey i have assembled the board,

thing is i am plannin to use +/-30v 5amp trafo.

so do u think it will do it? and i am not using this one to power a sub ok? i just want the amp to play on regular home cinema speakers.

so the thing is i will be building a stereo amp that is total 4 lm3886.

so will 5amp +/-30v be enough? i mean cuz u know the trafos. get real costly once u cross 5amps.

and could u send me a simple regulated power supply schm?

and about the zobel network, i chose the one that carlos has sent.
I'm sorry, but the amp needs a zobel

so i will need one zobel per chip right so 2 on one bridge ?

i'll send u a pic of wut i mean.

and thats it right no more mods ?
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