OPAxxx chip series

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My friend just tried the OPA541 because he thought the JFet input might be good. Using the same circuit as 3875 (25Vdc,22K/680 R) on 8Ohm speaker, the sound not much different as expected. Particularly compared the cost (US$16.xx for OPA541 compared US$4.xx for LM2875). Probably, it might be good for 4 Ohm speaker I guess.
 
OPA541AP can deliever 5A continously and 10A peak.
[5A/(sqrt2)] * 8ohm = 100W RMS
[5A/(sqrt2)] * 4ohm = 50W RMS

This is just theoretically though. Max voltage for the AP version is +/-35V and it svings to approx. [rail - 4,5V].

The OPA549 can deliever 8A continously, but here the max voltage is lower (+/-30V).
 

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The only expensive part on this amp was the transformer, 17,95€ Reichelt.

Connectors and Aluminium was from junk / University. Everything inside is point to point with 0,8 mm silver plated solid CU. Some steel between transformer and cicuit. Rectifier is made from some TO247 discrete diodes. Gain is 10, standart 1% metalfilm resitors used.
 

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If you want more power, build yourself a real amplifier. Also you could use a power OPamp as driver for a discrete hi power outputstage for 500W or 2kW monsteramps, if you need. Look at the datasheets, they show you how to make this with a OPA*** and some large bipolar transistors.

There is no real difference in getting 60W or 80W out of an amp. There is a small difference everytime you double the power, yes.

What do you want with all this power? My speaker does easy more than 120dB and needs not more than 30W for this. This run for power is stupid. If you want more SPL, use different speakers.

Instead of posting 4 times the same question, better a) read datasheets b) go and build ANY amp and see if you like it or not.



and the 549 isn't that powerful
What do you mean? Is there any kind of power into the chips, you could drain out of them after bought?

Think about power, SPL, Watt, energie, Joule, what it does, what you want.
If you only want a large number, build an amp with one 741, and draw yourself a nice sign with windows paint " 3700 WATT". Will impress all you friends.

If you want really a lot of power for small money, buy some diesel at the gas station.
 
you should read more.

No distortion is not possible. If you want really low THD, a class a amp will be better at low watt levels.

check my measurements.

the 549 is happy to drive every low impedance load as long as you cool it and don´t draw more than the 8 amp. current.

2 Ohm speakers are no problem.

If you read those datasheets, like i proposed for n+1 times, you will find how to bridge and how to parallel them, in case you want to drive a 0,01 Ohm speaker or so.

If you read the sboa082.pdf, you will find Burr Brown says they are fine for audio purpose. But they don´t need to print this on the playstic package, do they?

You will not need more power, in case you use the right speakers. Of corse one can´t expect much sound coming out of the system in case one connect something to the amp which is more sort of a resistor than a speaker.
 
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