Simple Audio Splitter with NE5534

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JR.
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Re: Simple Audio Splitter with NE5534

Post by JR. » Sun Sep 27, 2015 6:12 pm

b1gtuna wrote:Hello everyone, I am back with another question. I appreciate all your guidance!
The short-circuit maximum current of NE5534 is 38mA (as per the datasheet). Can I assume that I can power 2 X NE5534 with an 80mA boost circuit?
Not sure I understand the question. If you are asking can 2x5534 be powered from an 80mA power supply yes. Not sure what you mean by boost circuit?
I have tried calculating the power requirement. So far I got only this far:

A pair of Sennheiser HD449 has 38ohm impedance. The gain of my design is 3.2 ((2.2k + 1k)/1k). So I don't think the output will ever reach the 12V r.m.s as long as I feed a sane input audio signal.
You will never reach 12V rms from +/-12V dc rails. the op amps will run out of PS voltage and clip.
I read somewhere that iPod's have output voltage of 1.1v r.m.s. With the gain of 3.2, the output from the amp is 3.52v (1.1v * 3.2 gain).

Hence the power output from the amp is about 0.1 watt (3.2v * 38mA).
Power is (E^2)/R so (3.5V ^2)/38 ohm= 326mW
Can I assume that an output voltage based on 0.1watt and the impedance of my headphones (38ohm)?
for 100mW into 38 Ohms the voltage needs to be 1.94V

JR
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b1gtuna
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Re: Simple Audio Splitter with NE5534

Post by b1gtuna » Sun Sep 27, 2015 11:06 pm

Thanks JR for answering my question.

I guess I wanted to find out if a power supply that can provide 80mA maximum current is enough for my amplifier design. I am looking at a 5v to +/-12v boost converter: http://www.ti.com/tool/lownoisesplitrai ... -boost-ref. It looks like this might do the job!
The RMS voltage of 12v is 8.5v (12v/sqrt(2)), which is much more than the expected output of 3.52v with the gain of 3.2.

And this brings me to another question: is 3.52v at the output too much for a pair of over the year headphones like the Sennheiser HD449? I just don't want to blow stuff up =).

Thank you very much for your help as always!
JR. wrote:
b1gtuna wrote:Hello everyone, I am back with another question. I appreciate all your guidance!
The short-circuit maximum current of NE5534 is 38mA (as per the datasheet). Can I assume that I can power 2 X NE5534 with an 80mA boost circuit?
Not sure I understand the question. If you are asking can 2x5534 be powered from an 80mA power supply yes. Not sure what you mean by boost circuit?
I have tried calculating the power requirement. So far I got only this far:

A pair of Sennheiser HD449 has 38ohm impedance. The gain of my design is 3.2 ((2.2k + 1k)/1k). So I don't think the output will ever reach the 12V r.m.s as long as I feed a sane input audio signal.
You will never reach 12V rms from +/-12V dc rails. the op amps will run out of PS voltage and clip.
I read somewhere that iPod's have output voltage of 1.1v r.m.s. With the gain of 3.2, the output from the amp is 3.52v (1.1v * 3.2 gain).

Hence the power output from the amp is about 0.1 watt (3.2v * 38mA).
Power is (E^2)/R so (3.5V ^2)/38 ohm= 326mW
Can I assume that an output voltage based on 0.1watt and the impedance of my headphones (38ohm)?
for 100mW into 38 Ohms the voltage needs to be 1.94V

JR

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JR.
Posts: 3657
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Re: Simple Audio Splitter with NE5534

Post by JR. » Mon Sep 28, 2015 9:46 am

b1gtuna wrote: And this brings me to another question: is 3.52v at the output too much for a pair of over the year headphones like the Sennheiser HD449? I just don't want to blow stuff up =).

Thank you very much for your help as always!
I could not find a power handling spec even from the mfr.

Good Luck...

JR
Cancel the "cancel culture", do not support mob hatred.

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