On Mon, 15 Jul 2019 18:38:35 -0400, Paul
wrote:

wrote:
I want to learn some Chinese, but find these old ears cannot hear the
audio very well at

https://chinesecharacteraday.com/one-word-a-day/

at least.

All I have is an old set of earphones plugged to audio on a W10 PC.
Even at max audio. The phones have no volume control of course.

I want to buy something cheap to make the volume higher. Thinking of
buying a new set of earphones with an amplifier, or just the latter to
add to what I've got. Or maybe USB instead?

What do you think?

Wei


There is a *lot* of crap on the market.

Take those NE5532 products for $15.
Without additional transistors and a crafted output
stage, and good VCC supply, you can't get ear-blistering
sound levels.

Another product I saw for $36, one commenter said "it's
not loud enough". Which means the circuit is probably only
driving about 1VRMS into 32 ohms.

Stereophile amps of that sort, start at nice round numbers
like $199.00 for the "beginner amp", and going up in
increments of hundreds. This is obviously not the way to
get an amplifier. I'm sure there is plenty of level on those.

The audio industry is just as crooked as it was
fifty years ago.

You can find kits to assemble, for conventional amplifiers,
but they expect a speaker load of 4 ohms or 8 ohms, and
that's not a good match for 32 ohm headphones. I use
a 40W bridged Canakit for my Test Machine audio output,
which works OK. But it just isn't the right beast
for headphones. The signal would probably still be
a bit on the weak side. While the amp is 40W (2x20W),
in actual usage into 8 ohm speakers, the output is
just 2W per channel. And fortunately, with a tuned port
speaker, this is good enough.

You need a good supply of voltage, like maybe +12V and -12V,
to get a good swing on the output. An opamp with class A
output or class AB output, would work, but you need plenty of
source voltage because the impedance of the phones (32 ohms)
is so high.

You *can* get excellent results with piezoelectric earphones.
I drove those directly with a 741 and I could get a 9V signal
across those, which would pop an eardrum. Unfortunately,
you can't find those any more (the kind I had). Those even
manage to produce base, which I thought at the time was
pretty amazing for something little bigger than an earbud.

It would take hours of miserable catalog searches, to
begin to find something which is reasonably priced
and happens to also work properly.

Paul

Thanks for ur insight Paul. As always.
So much for learning Chinese. Thought it was a good idea - I have a
'bucket' item to sail up the Yangtze. Oh well.
zaigien
Wei