# The Perfect input driver for an SQ amplifier?



## fertigaudio (Jul 18, 2010)

This essentially could be the perfect line driver and/or op amp for use in the input section of a high end SQ amp. NO?

Setting a benchmark for performance, the LM4562 audio op amp specifies a *THD+N figure of 0.00003%*. The device combines a 6-MHz, unity-gain bandwidth operational amplifier with a proprietary stereo-audio power amplifier. Specs include an input noise density of 2.7 nV/√Hz at 217 Hz, 1/f noise corner of 60 Hz, and a 600Ω output drive. Compensating for noise under high loads, the device has a slew rate of 20 V/µs and a 56-MHz gain bandwidth. Unity-gain stable over a supply range of* ±2.5V to ±17V*, it delivers output currents up to 45 mA. Over this supply range, input circuitry maintains common-mode and power-supply rejection rates in excess of 108 dB and a typical input bias current of 10 nA. In 8-lead SOICs and DIPs, prices are $2.35 and $2.65 each/1,000, respectively. The LM4562 is also available in metal-can packages, priced at $9.95 each/100. NATIONAL SEMICONDUCTOR CORP., Santa Clara, CA. (800) 272-9959.
Referenced here. http://electronicdesign.com/article/analog-and-mixed-signal/audio-op-amp-slices-thd33793.aspx


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## progettosuono (Aug 14, 2010)

AD797
20v/us slew rate
110 Mhz bandwidth
50 mA current drive
power supply e common mode rejection 130 dB


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## fertigaudio (Jul 18, 2010)

progettosuono said:


> AD797
> 20v/us slew rate
> 110 Mhz bandwidth
> 50 mA current drive
> power supply e common mode rejection 130 dB


ahhh well crap... lol, that thing is sexy and so are some of the preamps that are built around it!

Could not find a THD+N % and I really dont care to convert the -120dB given on the spec sheet. But from what I have read;


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## SoundChaser (Apr 3, 2009)

I was actually planning on trying out these:
Digi-Key - LME49720NA-ND (Manufacturer - LME49720NA/NOPB)

Mounting them on these:
Digi-Key - AE9986-ND (Manufacturer - A08-LC-TT-R)

So maybe later on I could easily try those:
http://electronicdesign.com/article/...-thd33793.aspx

Let the experimentation commence.


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## dodgerblue (Jul 14, 2005)

The discontinued LM4562 is identical to the newer lme49720.
The lme line of opamps are specified for audio. Due to thier wider bandwidth they may not be drop in performers as they may oscillate and additional bypassing etc. may be needed to keep them stable .Here is a good read on some of the lme line.
http://www.diyaudio.com/forums/solid-state/132471-national-opamp-inflation.html



Also you may benefit using a higher quality socket.These make much better contact at the pins and have a wider surface area underneath them for the solder pads. Digi-Key - ED56083-ND (Manufacturer - 110-13-308-41-001000)


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