Author Topic: Best, low cost single supply Op-Amp for audio preamp  (Read 15854 times)

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Offline tan98010

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Best, low cost single supply Op-Amp for audio preamp
« on: August 09, 2015, 10:54:15 am »
Dear all,

Can any one suggest me a single supply low cost op-amp for audio application. i configure TL072 in single supply but i does't work properly, but it works well on dual supply.

i am looking on NE5532, but will this opamp perform on single supply?

can any give me some suggestion? thanks....
 

Offline Aodhan145

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Offline Zero999

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #2 on: August 09, 2015, 11:07:10 am »
Any op-amp can be configured to work as an audio amplifier running from a single supply.

The issue is the minimum supply voltage it needs to work from.

The TL072 and NE5532 are specified down to a total supply voltage of 6V but whether it'll actually work depends on how it's configured and the requirements for the design.
http://pdf.datasheetcatalog.com/datasheet/philips/NE_SE5532_A_SA5532_3.pdf
http://www.st.com/web/en/resource/technical/document/datasheet/CD00000490.pdf

Please post a schematic.
« Last Edit: August 09, 2015, 11:15:31 am by Hero999 »
 

Offline tan98010

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #3 on: August 09, 2015, 11:37:34 am »
Any op-amp can be configured to work as an audio amplifier running from a single supply.

The issue is the minimum supply voltage it needs to work from.

The TL072 is specified to work down to 4.5V and the NE5532 down to 6V but whether it'll actually work depends on how it's configured and the requirements for the design.

Please post a schematic.

Thanks for your suggestion, i just configure the opamp as a non inverting voltage follower on a bread board, but for the TL072 i does't operate correctly, it has DC off set on the output when operate on single supply(+8V). the offset is disappear on dual supply (+/-5V), but No problem for LM358 it works perfectly on single supply.

i am injecting 1V peak to peak sin wave with dc 0.5V offset (i dint put any input or output capacitor,i just wire-up the op amp it self only)

i am not understand why.
« Last Edit: August 09, 2015, 11:42:05 am by tan98010 »
 

Offline nctnico

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #4 on: August 09, 2015, 11:43:30 am »
Ofcourse it will have DC offset when working from a single supply. Single supply means your ground level is at half the supply voltage. You'll need to add DC blocking capacitors at the input and output of the amplifier.

In your test the TL072 didn't work because (like many opamps) it cannot swing it's outputs close to the supply rails. Raise the offset to half the supply voltage and you'll see it will work.
« Last Edit: August 09, 2015, 11:45:15 am by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Aodhan145

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #5 on: August 09, 2015, 11:57:42 am »
Does a DC bias even effect the audio? It doesn't matter anyway because you can use a cap.
 I immediately realized after asking that it could burn out the speakers compared to having it not dc biased.
« Last Edit: August 09, 2015, 12:00:17 pm by Aodhan145 »
 

Tac Eht Xilef

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #6 on: August 09, 2015, 12:18:55 pm »
Thanks for your suggestion, i just configure the opamp as a non inverting voltage follower on a bread board, but for the TL072 i does't operate correctly, it has DC off set on the output when operate on single supply(+8V). the offset is disappear on dual supply (+/-5V), but No problem for LM358 it works perfectly on single supply.

Isn't the minimum supply spec for most TL072's something like ±4.something volts? 8v with a virtual ground would be just a bit low.

OTOH, from memory the LM358 is spec'd down to ±1.5v / 3v.

 

Offline dom0

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #7 on: August 09, 2015, 01:26:20 pm »
358/324 is crap for audio and not suitable for that.

A 5532/5534 works well from a single 9 V battery.

Dedicated audio R2R ops exist, but aren't really necessary for >= 9 V operation.
,
 

Offline tan98010

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #8 on: August 09, 2015, 01:52:11 pm »
thanks everyone, its the bloody blocking capacitor i should put it in.
 

Offline Zero999

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #9 on: August 09, 2015, 02:32:25 pm »
Thanks for your suggestion, i just configure the opamp as a non inverting voltage follower on a bread board, but for the TL072 i does't operate correctly, it has DC off set on the output when operate on single supply(+8V). the offset is disappear on dual supply (+/-5V), but No problem for LM358 it works perfectly on single supply.

Isn't the minimum supply spec for most TL072's something like ±4.something volts? 8v with a virtual ground would be just a bit low.

OTOH, from memory the LM358 is spec'd down to ±1.5v / 3v.
Different datasheets suggest different minimum recommended supply voltages. The one I refereed to in my previous post said 6V but the TI website says 7V which is probably a more conservative figure.
http://www.ti.com/product/TL072?keyMatch=TL072&tisearch=Search-EN-Everything

I suspect the minimum supply voltage depends on the design, the requirements for the: common mode rage, output voltage swing and load.

thanks everyone, its the bloody blocking capacitor i should put it in.
The circuit should look something like this.

There are a few extra components added for stability.
 

Offline tan98010

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Re: Best, low cost single supply Op-Amp for audio preamp
« Reply #10 on: August 10, 2015, 03:59:32 am »
Thanks for your suggestion, i just configure the opamp as a non inverting voltage follower on a bread board, but for the TL072 i does't operate correctly, it has DC off set on the output when operate on single supply(+8V). the offset is disappear on dual supply (+/-5V), but No problem for LM358 it works perfectly on single supply.

Isn't the minimum supply spec for most TL072's something like ±4.something volts? 8v with a virtual ground would be just a bit low.

OTOH, from memory the LM358 is spec'd down to ±1.5v / 3v.
Different datasheets suggest different minimum recommended supply voltages. The one I refereed to in my previous post said 6V but the TI website says 7V which is probably a more conservative figure.
http://www.ti.com/product/TL072?keyMatch=TL072&tisearch=Search-EN-Everything

I suspect the minimum supply voltage depends on the design, the requirements for the: common mode rage, output voltage swing and load.

thanks everyone, its the bloody blocking capacitor i should put it in.
The circuit should look something like this.

There are a few extra components added for stability.


Thanks Hero999, you are very helpful, i am very appreciate it :D
 


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