Audio Speaker Devolution

[C00P]

G'Day Audio Experts,

Before handing the Series III over to me my children installed an all-singing, all-dancing U-beaut Stereo AM/FM radio with various gew-gaws, and lots of flashing lights. It also has a removable front panel. Apart from looking out of place, a couple of trips up north over roads resembling Custom Orb soon shook it to bits so that now it only works intermittently. (I suspect the front panel contacts couldn't stand the hammering).
I'd like to replace it with a much more robust old push-button radio salvaged from an old Honda. The labels on this state it needs a 4-ohm speaker. Dunno the impedance of the two x two-way speakers presently installed, but the old radio is mono only, so I'm not sure how to wire things up.
If the existing speakers are 8-ohm, can I wire them in parallel and thereby get 4-ohm impedance?
If the existing speakers are 4-ohm, can I use them at all? Or only one of them?
Dunno the impedance of the existing speaker systems yet, am hoping to find out when I take them down and open them up. There appears to be no information on the outside.
I've included a picture of the speakers.
Regards

Coop
49077

[C00P]

Well, I've made some progress, but still puzzled.
I've jury-rigged the old radio and demonstrated that it works well with a 4-ohm speaker. I've found some information that suggests that the static resistance (measured with a multimeter) of an 8 ohm speaker should be around 5.2-6 ohms, and for a 4 ohm speaker it should read about 2.6-3 ohms. Measured mine this evening and got 4.2 ohms (smack in the middle). So I still dunno how to wire these up. Can anyone offer me some suggestions?

Coop

[EchiDna]

4ohm is the typical standard for car speaker systems and 8ohm is normal for home hifi... 2ohm exist, but pretty darn rare!

worst case scenario, wire in parallel and the volume will be higher per speaker (due to less than design resistance), in series and it will be quieter (due to more resistance)... if the speakers are precious to you, don't do the above at all ;-)

[C00P]

4ohm is the typical standard for car speaker systems and 8ohm is normal for home hifi... 2ohm exist, but pretty darn rare!

worst case scenario, wire in parallel and the volume will be higher per speaker (due to less than design resistance), in series and it will be quieter (due to more resistance)... if the speakers are precious to you, don't do the above at all ;-)

Thanks EchiDna, Think I'll put them into storage and replace them with a couple of cheap 8 ohms wired in parallel. The existing ones aren't precious to me, but the kids liked them.....

Thanks for the help,

Coop

[Bradtot]

Use them in series but make sure u go pos/neg when joining the 2 or they will be out of phase and will cut your bass down. As one speaker cone moves out the the other moves in therefore cancelling out each other with a result of a tinny sound if you have them out of phase..
You can always go up in impedance but never below what the radio requires.
ie if you go paralell with 2 4ohms it will give you 2 ohms at the radio. the radio says 4 ohms min so you run the risk of blowing up the output stage in the radio.
if your speakers are 8 ohms and you wire in pararlel that will give you 4 ohms at the radio which is ok
Brad:)

[C00P]

Use them in series but make sure u go pos/neg when joining the 2 or they will be out of phase and will cut your bass down. As one speaker cone moves out the the other moves in therefore cancelling out each other with a result of a tinny sound if you have them out of phase..
You can always go up in impedance but never below what the radio requires.
ie if you go paralell with 2 4ohms it will give you 2 ohms at the radio. the radio says 4 ohms min so you run the risk of blowing up the output stage in the radio.
if your speakers are 8 ohms and you wire in pararlel that will give you 4 ohms at the radio which is ok
Brad:)

Thanks Brad, I decided to go with a single 4-ohm speaker which may have been the original for the old radio. It's not a stereo radio, so two speakers not necessary, and the places we will be listening will be largely out of range of FM stereo anyway. And we mostly listen to Radio National (ABC) so all in all, the one speaker will do the job. It only has to work when we are stationary, as the old Series III is too noisy for radio when travelling on the highway.
(In fact, so noisy, we are fitting it with an intercom for in-cockpi... er... in cabin conversation when on the highway). :)
Thanks for the info and advice.

Regards

Coop