External speaker plugged into 12 inch analog tv

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.

Reply to
mm
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Run the television earphone output to an amp. It doesn't have to be anything special. You could build a small one fairly easily. I'm guessing, due to the increased strength in modern magnets, that newer television speakers need less power to produce the same volume as older speakers. So the audio amplifiers in the television are going to have problems pushing those old current eaters. If you are driving the external speakers directly, it would probably be a good idea to match the impedances. A small audio transformer would do the trick for cheap. You could integrate that into a small amp, with a gain and volume pot, and even a balance and fade if you wanted to get fancy for under 20 or 30 bucks. There are schematics all over the internet for those sorts of things.

Reply to
Sansui Samari

How are you connecting your pot ? As a variable resistor in series with the speaker ? Not as a variable resistor *across* the speaker, I hope ...

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. 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.

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, 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.

Arfa

Reply to
Arfa Daily

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.

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 stores. An old stereo receiver or audio amplifier would do a very good job of driving the speaker you have. It would be much better than any TV's built in audio amplifier would be.

William

Reply to
William R. Walsh

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:

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Reply to
Kalman Rubinson

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**.

Yes.

No.

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

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.

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

**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.

Reply to
mm

I'll keep my eyes open.

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.

Reply to
mm

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.

Reply to
mm

Well, what speaker is it?

Kal

Reply to
Kalman Rubinson

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

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.

Reply to
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 ...

Arfa

Reply to
Arfa Daily

Thanks. That must be it.

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

Reply to
mm

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