What are 18 Ohm speakers for?

[Insane NiTEmare]

I recently came into possession of a couple of small 18 ohm speakers from a Sony TV salvage. While the 8 Ohms ones I took will be put to use I also pulled a pair of 18 Ohm speakers (diameter of 7cm each). Would these be more suitable for a vehicle surround sound system than an indoor sound system (not being 8 Ohm)?

 

[Cristi72]

Hello,

I don't think it will be a good idea, and not because they are 18 Ohm (or 16 Ohm maybe?); these speakers were used as tweeters, so you will have a limited frequency band response (from 1KHz upwards, so medium-high frequencies). Also, they can handle too little power (max. 5W I think) while the lowest-end car head-units/amplifiers can output at least 15W.

You should also check if the 8 Ohms can handle the power from your amplifier (they could range from 10W to 30W; check the TV specs).

 

[Insane NiTEmare]

Both the speaker pairs are 20w, the 8 Ohms will replace a set of blown RCA small speakers. As for the tweeters I've never used one (or seen one out of a speaker unit), thus I don't know what to do with them (more specifically because I already have a 5.1 set plus the 2 repaired)

 

[Cristi72]

The PC systems are mostly relying on full-range speakers on satellites, therefore they have only one speaker for each box.

A standard speakerbox for HI-FI contains 2, 3 or even 4 speakers, each having a specific frequency response (low, mid, mid-high and high). The frequency separation is done by using electronic filters (or crossovers).

For your Sony TV, probably it was the simplest filter, a single capacitor mounted in series with the 16(18) Ohm speaker. The best results will be using on each channel one 8O speaker + one 18O speaker and using the original capacitor (or the same value).

You can make an experiment: one of the channels using only the 8Ohm speaker and the other using both (don't forget the capacitor!). You will have much better response for the second channel in mid-high frequencies (trumpets, piano, violin, etc.)

For wiring, please check this:

http://i.imgur.com/MJ4DWe4.png

 

[Insane NiTEmare]

So if I was to sell the tweeter it would best be sold with the original woofer (granted they were a set to begin with). I don't have to use them myself.

 

[Cristi72]

So if I was to sell the tweeter it would best be sold with the original woofer (granted they were a set to begin with). I don't have to use them myself.

If you like how the woofer sounds in your enclosure without the use of the tweeter, you can sell only the tweeters. On the other hand, a "set" usually is more expensive than the sum of the components and is known to "work" as originally intended.

Also, you could keep them all, who knows when you'll need some good speakers (I assume it was a Sony CRT, I have a 25-years old Sony TV speaker box and it sounds very good even for today's standards).

 

[iam2thecrowe]

measure the "18 ohm" speakers with a multimeter to check the actual ohms, i have never seen an 18 ohm speaker. Normally the only use for high ohmage speakers is if your using them in parallel.

 

[Insane NiTEmare]

It was from a massive Sony Rear projection TV, a KP-51WS500 to be exact. I've still got a Toshiba TV to find out how to get the speakers out of it without destroying the chassis, they are massive but it's just 2 8 Ohms. The chassis will probably turn into a coffee table.

 

[iam2thecrowe]

like i said. measure the speakers with ohmmeter, multimeter to determine actual ohmage. DC restistance with an ohm meter, is usually slightly less than the actual acoustic ac resistance of the speaker, but close.