In , on 11/19/03
at 02:42 PM, elfa said:

...

The amp has an 'input' of 450 mV and a max output of 2W. The speaker
is 8 ohm and max of 6W. Without impedence matching, my little low
power amp over drives the speaker. I just want to reduce the
distortion. I'm not an audiophile so I really don't care about the
'perfect' sound system. I have a hearing disability and the whole
point of this project is to listen to my small radios (shortwave) with
their tiny speakers without the frustration of not understanding what
I'm hearing.

[ ... ]


Consider rethinking the project. Most amplifiers won't care about your
mismatch. Many "8 Ohm" speakers are closer to 6 Ohms anyway.
Technically, if your amplifier is optimized for 4 Ohms, you are not
driving the speaker as hard as you could. However, why bother? If the
speaker is being overdriven now, you don't need to deliver any more
power to it.

Further thought:

Depending on its design, you may be overloading the input stage of your
amplifier.

You may also be overloading the small radios as you connect them to the
amplifier.

Because of your hearing disability, you need more acoustic power than
that little speaker can provide. Consider finding a larger speaker in a
proper enclosure. You may need more power.

Also, consider using a tone control or equalizer to taylor the
frequency response of your speaker system to compliment your hearing
deficiency.

---

"WHAT? DON'T SHOUT, I CAN HEAR YOU," has been part of my life for
decades. Since I'm a stranger, I'll take the liberty of sharing one of
my pet issues.

Living with a hard of hearing person can be very frustrating for the
rest of us. Often, the hard of hearing person will deny they have a
problem. We do catch on after a while and we want learn how to deal
with the situation, but the hard of hearing person can sometimes be
more helpful. I don't want to drag all my dirty laundry out on this
forum, but please be mindful that, what seems like a comfortable
listening level to you, could be painfully loud and distracting to
nearby normal listeners. (and I do mean physical pain)

Having you listen through headphones to your TVs and radios would be
much more comfortable for the rest of us, but I know there is a concern
that you won't be able to hear or understand what is going on in the
room.

A better project for you would be to build a TV/radio headphone
amplifier that mixes in sound from the room. You could fiddle with the
frquency response of the amplifier to heighten your comprehension. I
can imagine that features such as separate muting and volume controls
for each input would be useful. A plus would be a provision for hearing
the phone and doorbell.

Some types of hearing loss result in a limited dynamic range. You can't
hear quiet sounds, but even moderately loud sounds cause discomfort.
There is a very narrow loudness range where your hearing can operate.
If this is your situation, consider adding a compressor to your
headphone amplifier.

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