) writes:
Hello,

I have been looking around the web for a complete kit for an audio
amplifier, for a circuit that I am building that needs to have a wide,
flat as possible frequency response (0Hz - 100Khz). Need to be able to
bring 400mV up to line level. I have seen several kits based on a
LM386, but I can't find any specs that show that circuit is reliable
beyond 20hz - 20Khz. I am a beginner, so keep that in mind when
responding.

-Scott, WU2X

But you may be looking for the wrong thing. That's not an audio amplifier,
that's a wideband amplifier. A good op-amp is likely going to be what
you want, because line level is no more than a volt (if even that), so
a gain of about 3 is going to be enough. Of course, if you are driving
something out of the ordinary, that may require something more.

Micahel VE2BVW

This will feed a computer soundcard running at a 192Khz sampling rate
(unbalanced line level in). -Scott

On Feb 13, 12:36 pm, (Michael Black) wrote:

But you may be looking for the wrong thing. That's not an audio amplifier,
that's a wideband amplifier. A good op-amp is likely going to be what
you want, because line level is no more than a volt (if even that), so
a gain of about 3 is going to be enough. Of course, if you are driving
something out of the ordinary, that may require something more.

Micahel VE2BVW

On 13 Feb 2007 10:29:23 -0800, wrote:

This will feed a computer soundcard running at a 192Khz sampling rate
(unbalanced line level in). -Scott

I think you'll get your best help if you ask this on
sci.electronics.design, it has a lot more traffic.

I'd definitely use a good op-amp, and definitely NOT an LM386
(single-chip audio power amp, meant to drive a small loudspeaker). The
manufacturer's page he
http://www.national.com/pf/LM/LM386.html
gives distortion as 0.2 percent, which is pretty bad by modern
standards. The soundcard and a good op-amp will surely give much
better performance.
You said in your original post you want response to DC (O Hz). All
the soundcards I've heard of are capacitively coupled, and have a
rolloff of around 5 to 10 Hz at the best, and even when this is
removed, the DC performance of such cards isn't guaranteed. It might
be better to use an "industrial" interface card such as made by
National Instruments.

On Feb 13, 12:36 pm, (Michael Black) wrote:

But you may be looking for the wrong thing. That's not an audio amplifier,
that's a wideband amplifier. A good op-amp is likely going to be what
you want, because line level is no more than a volt (if even that), so
a gain of about 3 is going to be enough. Of course, if you are driving
something out of the ordinary, that may require something more.

Micahel VE2BVW