External speaker plugged into 12 inch analog tv

[mm]

What can I do to keep using an external speaker and volume control
with my 12" analog TVs? My knowledge of electronics is modest.

For 35 years, I've taken the tvs I have and plugged a larger speaker
into it, usually a 6x9 speaker cabinet from a 60's or 70's stereo or
maybe better**. If there was no jack, I'd put one in. I'd put a pot
in the circuit to adjust the volume. Mostly this was in the bedroom,
and also in the bathroom so I could watch tv from the bathtub, and
also in the basement. (**In 2 consecutive bathrooms, for 35 years,
I've been using a woofer, tweeter, and crossover from a 1930's record
player, mounted on a new piece of chipboard, covered in decorative
burlap and mounted in the corner between the ceiling and the wall of
the bathroom, with 45^ moldings I cut and stained.)

10 or 20 years ago, I ran out of tvs that used tubes and had to do
this with transistor tvs. It seemed not to work as well. I would have
to keep the volume closer to the top to avoid distortion. I only used
two wires, with the variable resistor in the circuit.

Are my suspicions correct,
a) that it didn't work as well because they were transistor tv's and
not tube tvs?
b) that if I used 3 wires, 2 wires from the tv to the pot and 2 wires
from the pot to the speaker, and used it as a voltage divider, I would
have a fixed load on the audio output so I would get less distortion,
but I would also have a lower maximum volume?

I've done this with 6 or 7 transistor tvs total, but the last two tvs
have failed with audio problems, distortion, although only after
several years use for each. The last one is a Sony 9" transistor tv,
about 20 or 30 years old. It had two earphone jacks, one that
disconnected the internal speaker and one that ran sound to the
earphone and the speaker both. I used the first jack, and because the
volume wasn't high enough, I bypassed the resistor in the jack circuit
which is meant to lower the volume for an earphone. Did doing this
ruin the audio output? -- The other tv that failed was 9" -- I
forget the brand -- and had two jacks, one for an earphone but come to
think of it, the second was for an external speaker, so maybe the
sound distortion failure there was coincidental? Or maybe even though
there was a jack, it wasn't fully capable of powering the speaker over
the course of years, an hour or two a day?


Now I have another Sony, this time 12 inches, also 20 or 30 years old,
with no jack afaict and I want to put one in, but I'd like to avoid
damaging the audio (even if it takes years to do it.)

Or I have a much newer tv with remote, but I would like to put a jack
in that and use the knob that is in the little box next to me in bed
to adjust the volume. It works much faster, easier, and with more
precision than remotes do. Now that I'm using a mechanical volume
control, I hate to go back to the remote.

So the problem/question is the same.


The other thing complicating this is that I've had a little tinnitus
in one ear since I was 10 or 20, I think, but since I'm 63 six months
ago, it has gotten louder. I can't tell if it is my ear causing the
problem or the tv, until the tv problem gets pretty bad. (I have an
appointment with the ear doctor, but not for 3 weeks.)

Sorry for the long post.
Thanks for any health you can give.

 

[Kalman Rubinson]

What can I do to keep using an external speaker and volume control
with my 12" analog TVs? My knowledge of electronics is modest.

For 35 years, I've taken the tvs I have and plugged a larger speaker
into it, usually a 6x9 speaker cabinet from a 60's or 70's stereo or
maybe better**. If there was no jack, I'd put one in. I'd put a pot
in the circuit to adjust the volume. Mostly this was in the bedroom,
and also in the bathroom so I could watch tv from the bathtub, and
also in the basement. (**In 2 consecutive bathrooms, for 35 years,
I've been using a woofer, tweeter, and crossover from a 1930's record
player, mounted on a new piece of chipboard, covered in decorative
burlap and mounted in the corner between the ceiling and the wall of
the bathroom, with 45^ moldings I cut and stained.)

10 or 20 years ago, I ran out of tvs that used tubes and had to do
this with transistor tvs. It seemed not to work as well. I would have
to keep the volume closer to the top to avoid distortion. I only used
two wires, with the variable resistor in the circuit.

Are my suspicions correct,
a) that it didn't work as well because they were transistor tv's and
not tube tvs?
b) that if I used 3 wires, 2 wires from the tv to the pot and 2 wires
from the pot to the speaker, and used it as a voltage divider, I would
have a fixed load on the audio output so I would get less distortion,
but I would also have a lower maximum volume?

I've done this with 6 or 7 transistor tvs total, but the last two tvs
have failed with audio problems, distortion, although only after
several years use for each. The last one is a Sony 9" transistor tv,
about 20 or 30 years old. It had two earphone jacks, one that
disconnected the internal speaker and one that ran sound to the
earphone and the speaker both. I used the first jack, and because the
volume wasn't high enough, I bypassed the resistor in the jack circuit
which is meant to lower the volume for an earphone. Did doing this
ruin the audio output? -- The other tv that failed was 9" -- I
forget the brand -- and had two jacks, one for an earphone but come to
think of it, the second was for an external speaker, so maybe the
sound distortion failure there was coincidental? Or maybe even though
there was a jack, it wasn't fully capable of powering the speaker over
the course of years, an hour or two a day?


Now I have another Sony, this time 12 inches, also 20 or 30 years old,
with no jack afaict and I want to put one in, but I'd like to avoid
damaging the audio (even if it takes years to do it.)

Or I have a much newer tv with remote, but I would like to put a jack
in that and use the knob that is in the little box next to me in bed
to adjust the volume. It works much faster, easier, and with more
precision than remotes do. Now that I'm using a mechanical volume
control, I hate to go back to the remote.

So the problem/question is the same.


The other thing complicating this is that I've had a little tinnitus
in one ear since I was 10 or 20, I think, but since I'm 63 six months
ago, it has gotten louder. I can't tell if it is my ear causing the
problem or the tv, until the tv problem gets pretty bad. (I have an
appointment with the ear doctor, but not for 3 weeks.)

Sorry for the long post.
Thanks for any health you can give.

Others have already explained that driving a passive speaker directly
from a headphone jack, with or without pot/resistor, is not the right
way to do this. Today, there are many, many powered speakers (that
is, speakers with built-in amps and volume control, that will run just
fine from a headphone jack and they are cheap. I have seen them for
as little as $5 but you can spend up to $50 for something more
powerful and elaborate.

Here are some examples:
http://cgi.ebay.com/Altec-Lansing-F...er_MP3_Player_Accessories?hash=item5ad69edbc8
http://cgi.ebay.com/EDIFIER-PREMIUM...mQQptZSpeakers_Subwoofers?hash=item1c0e6b1f45
http://cgi.ebay.com/1200-Watt-PC-2-...mQQptZSpeakers_Subwoofers?hash=item2ea199bc98
http://www.staples.com/office/suppl...ds-_-Computer Accessories-_-computer speakers

 

[mm]

Thank you, Sansui. At this stage of my life, it would be a problem to
try to build this myself. I'm so far behind on everything else I have
to do, and falling further behind. But I appreciate your suggestion
that an amp is the way to go.

My only real question is at the very end**.

How are you connecting your pot ? As a variable resistor in series with the
speaker ?
Yes.

Not as a variable resistor *across* the speaker, I hope ...
No.

In general, simple transistor stages (and IC stages come to that) don't mind
too much, what impedance they have presented to them, as long as it's above
some minimum amount.

Well, it never goes below the resistance of the speaker (two speakers
in the same box maybe).

In contrast, simple tube output stages also don't care
too much, as long as some maximum amount is not exceeded - ie semiconductor
stages don't like shorts, tube output stages don't like opens. So, as long
as you are connecting your pot as a variable resistor in series with the
speaker, and the speaker is not too chunky, and of the correct nominal
impedance, I see no reason why it would cause any damage to any
semiconductor output stage that you would find in a portable TV.

However, by just connecting a variable resistor in series with the speaker,
you are never going to get the volume down to zero, and the more you try, by
fitting higher value pots, the more one-ended the control range will become.

Yes, that's a problem, but I think I reached a good compromise. The
only time I want the volume that low is when I'm on the phone, and the
phone in the bathroom no longer works. (Some wiring problem between
the basement and the second floor.) But I get fewer calls than I used
to anyhow, and I let the machine answer. Before I had a tv with
remote in the bathroom, there was no way to turn off the tv while I
was in the tub, but in the bedroom I can turn it off if I want to have
a phone conversation.

Putting a pot across the audio output pair (of wires), but connected as a
pot, not a variable resistor, (so with the 'top' of the pot track connected
to the output stage, and the wiper of the pot connected to the speaker, and
the 'bottom' of the pot common to both), will allow you to get down to zero,
without the load ever dropping to a 'short', but as you go higher in volume,
the impedance presented to the amplifier will still drop,

Oh, yeah. I didn't think of that.

as the speaker
becomes an increasing load in parallel with the pot track resistance.
Therefore, the value of the pot needs to be chosen so that the total load on
the output stage, when the volume is up high, is not below what the
manufacturers designed it to handle. Low value pots are not all that common,
so you may have to compromise a little. Be aware also, that the speaker
impedance in a modern small portable TV might not be the low 4 or 8 ohms
that you are used to finding in a tube TV. They can be as high as 32 ohms,
as are many modern headphones.

**So maybe the Sony tv, even though 20 years old or more, has a higher
impedance speaker, and plugging in an 8 or maybe even 4 ohm speaker to
the earphone jack, after bypassing the resistor that led to the jack,
COULD have damaged the output stage of the audio??

Actually, encouraged by the replies I got here, I changed to the other
Sony tv, about the same age, and plugged in same speaker without
bypassing the internal resistor, and the sound was still bad, but
afterwards still not bad when listening through the built-in speaker.
So maybe there is a problem with the speaker I've been using for 26
years. More in my reply to William.

Thanks to Sansui and you and William and Kalman for the help.

 

[mm]

Hi!


Probably not. One has to consider how powerful the amplifiers in these
TVs were, as well as the speaker they were driving.

In late model CRT type TVs, I've noticed that the speakers usually have
oddball impedance ratings, such as 3.2 ohms. If you were to drive an
external speaker, its impedance rating probably wouldn't match that of
the speaker the TV came with, and that could result in poor audio
performance.

I think what you really want to do is to buy a TV with either a line
level output or earphone connection that could be plugged into an
outboard amplifier (such as an old stereo receiver?) If a used set were
acceptable, you could probably get one for as little as $5-30 depending
upon condition and screen size. And maybe if you offered to haul it
away, you could get one for free.

I'll keep my eyes open.

The same is true of an old stereo receiver. Lots of perfectly good
choices are around, and most would be very cheap. Look in secondhand

That sounds good. Hey, come to think of it, I had a portable record
player from the 70's, the kind where the turntable folded up into the
cabinet, and the speakers were on the sides but could be pulled apart,
and it was very broken so I cut off the top, with the transistor
stereo amp, about 14 inches wide by 4 high by 6 deep. It's in the
basement, I just have to find it.

 

[mm]

Others have already explained that driving a passive speaker directly
from a headphone jack, with or without pot/resistor, is not the right
way to do this. Today, there are many, many powered speakers (that
is, speakers with built-in amps and volume control, that will run just
fine from a headphone jack and they are cheap. I have seen them for
as little as $5 but you can spend up to $50 for something more
powerful and elaborate.

Here are some examples:
http://cgi.ebay.com/Altec-Lansing-F...er_MP3_Player_Accessories?hash=item5ad69edbc8
http://cgi.ebay.com/EDIFIER-PREMIUM...mQQptZSpeakers_Subwoofers?hash=item1c0e6b1f45
http://cgi.ebay.com/1200-Watt-PC-2-...mQQptZSpeakers_Subwoofers?hash=item2ea199bc98
http://www.staples.com/office/suppl...ds-_-Computer Accessories-_-computer speakers

Well even after I read William's post about an amp, it didn't occur to
me to use computer speakers, until I looked at your list above. I
guess because they are small usually and I figured the bigger cabinets
are better. But not better than what I have now. So I actually have
spare computer speakers that I buy at the end of hamfests and a pair
or two that people gave me when they got a whole new computer. And I
looked last night and found one that even has an real AC cord on the
end, not an adpapter, and has RCA inputs. I plugged it in the same
place the tv is plugged in, so when I turn the tv off with the remote
switch, it turns off the speaker too.

I was going to put the speaker on the bed to use its volume control
but the audio cord with the RCA plug is too short, so for now it's
near the bed and I have 3 !! volume controls for it, one in the tv,
one in the wire to it (my old control in the bed with the pot and an
on/off switch) and the control in the amp. The first and third are
set pretty low and the range with the other is pretty good.

Maybe something was wrong with the speaker I've been using for 26
years. I'll check it out later.

It seem much better, except once in a while. Maybe the noise in my
ear (sort of like water running through a pipe) makes a beat frequency
with certain sound frequencies. If it is really tinnitus, afaik
there is no remedy usually. I only notice this when I'm in bed,
watching tv or listening to the radio. It's really not bad, then and
the rest of the day I have to pay attention to notice it. I'll see
what the doctor says.

The current amplified speaker has 3 RCA jacks, In L & R,
and Out SP. Do you know what SP stands for?


(I have no use for Out now. It's a monaural tv and I don't have the
other speaker anyhow, but i'm curious what SP might stand for.)

Thanks to you and to Sansui, Afra, and William.

 

[Kalman Rubinson]

The current amplified speaker has 3 RCA jacks, In L & R,
and Out SP. Do you know what SP stands for?


(I have no use for Out now. It's a monaural tv and I don't have the
other speaker anyhow, but i'm curious what SP might stand for.)

Well, what speaker is it?

Kal

 

[mm]

Maybe SP stands for speaker, even though both S and P are capitalized.

Well, what speaker is it?

Oh, it has no brand name at all! No model number, or embossing, other
than the labeling of the inputs and output. Just a little gold strip
that says "Made in somwhere", I didn't look where.

And it seems like a nice one. It's heavy for its size, has two
speakers, 4 or 5 inches and a smaller one, showing through the metal
grill, has some sort of air port in the front (that might be real, not
just a decoration) volume, bass, and treble controls, an LED that
lights when it's on, and has a real cord with a plug, not an AC
adapter.

I think I've only once before seen something decent with no brand or
model number.

 

[mm]

I would imagine that it is an abreviation for SP-eaker, and is the standard
arrangement for this type of setup, where the little stereo amplifier is
contained within one cabinet, along with the power supply electronics and
one speaker connected to one channel output of the amp, and the other
channel output is connected to that "SP" socket, to where you would connect
the other cabinet, which contains just a speaker ...

Thanks. That must be it.

I never got the other part, so this works out well since the tv is
monaural.