Will I ruin something doing this? Stereo Q

Factual Questions
1

I have an older Emerson stereo, maybe 8 years old. Its a pretty good little piece of equipment, but lately its started to give me problems and I have no knowledge of these kind of things.

I have my computer hooked to it so I can play music from my hard drive on it. I have also recently added two extra speakers. To do this I had to use a 2 to 1 reducer kind of thing (splitter?). I plug two speakers into this bit of wire and then plug said bit into the back of the stereo, and repeat for the other two.

My problem now is that one of the places in back that you plug the speaker into (port?socket?) has crapped out. So what I’ve done is taked a THIRD splitter thingy and hooked ALL FOUR speakers to the one port. How bad an idea is this? I plan to only use it this way until Saturday when I can get my other stereo out of storage. Will I ruin either the speakers or the stereo doing this?
I do know that this stereo has an impedence of 8. Two of the speakers in question came with it, and the two additional ones also have an impedence of 8. Unfortunately, I don’t really have any idea what ‘impedence’ is all about. I just thought it might be useful information.
I know this is long, but I wanted to make sure you all got all the info you might need :slight_smile: .

Am I doing any damage like this?
Thanks

2

Short answer- as long as you don’t turn the volume up too loud (relative to the max volume of that stereo), you’ll probably be ok short term.

Longer answer- the impedance of speaker is it’s electrical resistance to current flow. If the stereo is rated at 8 ohms, it likes to see that impedance across each of the speaker terminals. The wrong impedance will generally cause it to get hotter than normal- and the higher you crank the volume, the hotter it gets.

To keep the stereo happy, you can connect the four 8-ohm speakers together in such a way as to maintain an overall impedance of 8 ohms. If you connect two speakers in parallel (i.e. tie one wire from each speaker together and put it in one terminal of the stereo, and tie the other two speaker wires together, and put that in the other speaker terminal), the impedance is half, or 4 ohms (technically it’s 1/(1/R1+1/R2), which = half if the two impedances are equal). On the other hand, if you put two speakers in series (i.e. tie one wire from each together and tape it up, then take the other wire from each speaker and put them separately into the stereo terminals), the impedances add, you you’d get 16 ohms.

Now, given those rules, take two speakers, and connect them in parallel, to form a 4-ohm speaker, we’ll call it “big speaker A”. Take the other two speakers and do the same thing to make “big speaker B”. Now combine “big speaker A” and “big speaker B” in series- this makes “super big speaker C”, which will present an 8-ohm impedance to your stereo.

Let me know if that was a little confusing …

Also, I’ve glossed over the issue of speaker polarity …

Arjuna34

3

BTW, by using the splitter to combine speakers, you’re putting them in parallel, lowering the impedance. Your stereo probably doesn’t like that (and responds by getting hotter than normal for a given volume level), but again as long as you don’t crank the volume up (and depending on how over-designed it is), you should be ok. There’s no way to combine two 8-ohm speakers to give an 8 ohm result (you either get 4 or 16 ohms).

Arjuna34

4

Arjuna - thanks for the reply.

Let me see if I’ve got this right.

The way I originally had this set up, with speaker A and speaker b both hooked together into one port, and speaker c and speaker d both hooked to the other, I had lowered the impedence by half to 4. But with A,B,C and D all crammed into one port, I’ve doubled the impedence to 16.

And by lowering or raising the impedence, the stereo will get hotter faster? I would never have known that. I thought that lowering the impedence would make the stereo work less hard. That’s good information to have.

I’ll take it easy and make sure the stereo is getting enough air.

Thanks again.
3Bunnymama

5

With all four speakers connected together with splitters the way you were going to do it, you were connecting them in parallel, which put two sets of 4 ohms in parallel, making a net of 2 ohms- even worse for the stereo.

You can connect four 8-ohm speakers together and still get a total of 8 ohms as decribed earlier (if that made any sense without drawings …).

For the same power into the speakers, a lower speaker impedance will make the stereo work harder, and get hotter. A higher speaker impedance isn’t as bad, but will probably limit the max volume you can get out of the system.

Arjuna34

6

Ok, I gotcha now.

Thank you heaps.
3BunnyMama

7

The speaker impedance has to match the amplifiers own output impedance to get maximum power transfer.

Lower impedance means that proportionally more power is dissipated as heat in the output stages of the amplifier rather than as useful work, in this case sound, which is why the amp gets hot.

Higher impedance means, curiously, the same thing if you try to get the same volume out of it.

Arjuna knows this I’m sure of it, including max power transfer theorum, but to explain it requires more math than would be appropriate.

If you were to draw a graph with the bottom axis being load impedance and the vertical being power output in the load, you would get an upturned parabola and the peak would be just at the point where the load impedance = amplifier impedance.

One problem though is that speakers do not have a linear frequency response and impedance is taken at a frequency specified by the manufacturer.

Hooking up a combination of speakers to give your 8ohm impendance may have unforseen effects, if you favour rock music with its high upper frequencies then it might be enough to cause some problems or maybe if you go for club music with its strong bass content that might give problems, but it isn’t easy to predict, in the end you do what everyone else does, try it out and see if it gets hot.

Another option might be to go for higher efficiency speakers, they usually are rated at ‘so many dB’s per Watt’
at some specified distance from the speaker.In the hi-fi game there are lots of differant measuring benchmarks and it can be incovenient to try and cross interpret them.

The small Bose speaker produce lots of noise per Watt input so do the Bang and Olufsons which are really Kef designed items.

If you have enough confidence and a soldering iron I would be inclined to take the amplifier cover off and run a couple of wires from inside it,through a hole in the casing(make one if you need it) and connect these ends up to a bit of connector block.It might be possible to buy speaker outlet connections from somewhere like Tandy and replace the faulty ones.

8

IMHO, when one channel craps out, it’s trash anyway. And when you add this to the scenario:

Why worry? Crank it!

9

LOL, Delta - that’s I’m starting to feel that way…

casdave - Thank you for posting. It never occured to me to try to replace the outlets. I will definitely look into that. I really like this stereo and it has a phonograph so I’d like to keep it as long as possible.

Thanks everybody.
3Bunnymama