Audio opamp power supply

Sep 27, 2010 4 Replies
M

Most of the opamp based audio filters, I-V converters, differential to single ended converters, preamps, buffers use +/-12V or +/-15V supply though the opamp can be operated from as low as +/-5V. Is there any benifit of using higher volatge power supply for opamps used particularly in audio related circuits? I have AD797 for DAC output stage for I-V converter and then for differential to single ended conversion. What are the disadvantages w.r.t audio quality parameters like THD+N, Dynamic Range if we operate the opamp at lower volatge like +/- 6V?



Thanks Mahenk



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B

Read the data sheet. The critical difference is that the AD797 guarantees a +/-11V swing into a 600R load with +/-15V supplies, and only +/-2.5V with +/-5V rails, so the higher voltage rails offer significantly more dynamic range. Power and common mode rejection are also a bit better with +/-15V rails, but the difference is less dramatic, and few designers of audio electronics are carefull enough about layout and power supply decoupling to be in a position to take advantage of the extra rejection.

-- Bill Sloman, Nijmegen

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M

s

Thanks Bill, but with output being 2V RMS max do I still need to bother about the limited +/-2.5V and subsequently the limited dynamic range.

Mahenk

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R

Mahen K schrieb:

[...]
2 V RMS are about 5.6 V pp: that's hardly possible with only 5 V supply voltage ...

Just my 2 cents

Reinhard

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B

In this context +/-2.8V ptp. The O/P can't do this with +/-5V rails. With +/-6V rails - as he seems to be proposing to try - he'd have enough headroom.

RMS isn't a good way to specify music amplitude; peak-to-peak amplitude in normal music is a couple of orders of magnitude bigger than mean amplitude. Some cheap-skate amplifier designers try to exploit this ...

-- Bill Sloman, Nijmegen

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