Opamp Audio Amplifiers (rehash)

[RST Engineering \(jw\)]

There was a thread going on in here that died out before we got to the heart
of the matter. It concerned an audio amplifier built around an LM386 that
was a little too noisy for their use.

I'd like to take it a step further. I've got a pet circuit that I use for
opamp input driving what we used to call complementary symmetry output
devices, but I'm always willing to learn new tricks.

Here's my limitations: Drive (using smaller or larger devices) between 4
and 600 ohms, separate amplifiers for the hi-z and lo-z loads. Automotive
battery supply, so PSRR with gawdawful spikes necessary. Prefer to drive as
close to the rails as possible. Voice only, no music, up to 10% distortion
acceptable. Cheap parts -- LM324, TIP output devices for high power,
2222/2907 for the low power. Automobile environment ... hot in the summer,
cold in the winter.

Anybody got any pets that they are very happy with?

Jim

 

[Eeyore]

There was a thread going on in here that died out before we got to the heart
of the matter. It concerned an audio amplifier built around an LM386 that
was a little too noisy for their use.

I'd like to take it a step further. I've got a pet circuit that I use for
opamp input driving what we used to call complementary symmetry output
devices, but I'm always willing to learn new tricks.

Here's my limitations: Drive (using smaller or larger devices) between 4
and 600 ohms, separate amplifiers for the hi-z and lo-z loads. Automotive
battery supply, so PSRR with gawdawful spikes necessary. Prefer to drive as
close to the rails as possible. Voice only, no music, up to 10% distortion
acceptable.

You truly *want* it to be bad ?

Cheap parts -- LM324, TIP output devices for high power,
2222/2907 for the low power. Automobile environment ... hot in the summer,
cold in the winter.

Why do you want to use such miserable and oudated semis ?

TIPs were in short supply years ago btw.

Graham

 

[Genome]

There was a thread going on in here that died out before we got to the
heart of the matter. It concerned an audio amplifier built around an
LM386 that was a little too noisy for their use.

I'd like to take it a step further. I've got a pet circuit that I use for
opamp input driving what we used to call complementary symmetry output
devices, but I'm always willing to learn new tricks.

Here's my limitations: Drive (using smaller or larger devices) between 4
and 600 ohms, separate amplifiers for the hi-z and lo-z loads. Automotive
battery supply, so PSRR with gawdawful spikes necessary. Prefer to drive
as close to the rails as possible. Voice only, no music, up to 10%
distortion acceptable. Cheap parts -- LM324, TIP output devices for high
power, 2222/2907 for the low power. Automobile environment ... hot in the
summer, cold in the winter.

Anybody got any pets that they are very happy with?

Jim

How about I read between the lines and call you a useless ****.

DNA

 

[Jim Thompson]

How about I read between the lines and call you a useless ****.

DNA

Sno-o-o-o-ort ;-)

...Jim Thompson

 

[mpm]

Anybody got any pets that they are very happy with?

We once had a product that used the LM386 and it just didn't have
enough "oomph" to it.
So (eventually) we redesigned it.

Now it uses the LM4950TA from National Semiconductor.
Major, major, major improvement!!!

 

[RST Engineering \(jw\)]

You truly *want* it to be bad ?

No, but I don't *need* to be good at the expense of cost. I am, after all,
in a competitive consumer market.

Why do you want to use such miserable and oudated semis ?

For the same reason that I used miserable and outdated devices like the 6V6
and 50C5 when I first got into design. They were dumb simple, popcorn
available, and did the job. And, here fifty years later I can still get
them if I really need them.

TIPs were in short supply years ago btw.

Fairchild Semi is making them by the boxcar load. How many billion would
you like?

Jim

 

[RST Engineering \(jw\)]

How about I read between the lines and say that you don't have a frikkin'
clue how to answer so you resort to what you are an expert in ... ad
hominem.

I've got students that try and bullshit an answer also ... it doesn't work.

Jim

 

[RST Engineering \(jw\)]

I've got a lot of respect for the work you've done, Jim. What is this
supposed to mean?

Jim

 

[RST Engineering \(jw\)]

I got my bath of fire using a Plessey single source synthesizer chip that
was taken off the market just as my product went ON the market.

Never NEVER again a single source for anything, including National.

Jim

 

[Genome]

How about I read between the lines and say that you don't have a frikkin'
clue how to answer so you resort to what you are an expert in ... ad
hominem.

I've got students that try and bullshit an answer also ... it doesn't
work.

Jim

I apologise.

Monster

40 billion bonus points for an 'ad hominem'...........

Don't work like that. You asked something you should be able to Google and
use a bit of intelligence to work out. You also asked it in such a greasy
obtuse way. Ooooooooh Yickkkyyyyyy!

Your students would not bullshit an answer if you did not bullshit the
question in the first place.

DNA