Using a 4 ohm speaker

[Guest]

I need the brain power of an electronic expert.

I've found a speaker that'll work for my car but its impedance is 4 ohms and my old Delco uses an 8. What would I need to use to match the circuit?
Thanks!

[gordr]

Get another matching 4-ohm speaker, install it in the rear speaker location, and wire the pair in series. You won't be able to do a front-rear fade, but both will play.

IIRC, some Delco radios used a 10-ohm speaker.

You ought to be able to find the right speaker, though.

Gord Richmond, within Weasel range of the Alberta Badlands

[BobGlasscock]

4 ohm resistor inline should do the same thing.

'50 Champion, 1 family owner

[StudeRich]

All of the '56 to '66 Delco Studebaker Radios I have seen and owned (dozens) have all had 10 Ohm speakers. Less then that, I am told will damage the power supply eventually.

[starlightchamp]

Impedance is a function of Inductance,capacitance,resistance and frequency.
I would suggest looking on Ebay. There are many sizes and shapes of 8 ohm speakers
and you won't risk damaging your radios output speaker transformer.
...Dick

[Mike]

On mid '60's Delco radios, the transistor that drives the speaker is the big one in the heat sink on the rear. If you use a speaker with lower impedance than intended, it will theoretically distort the sound, and overheat. The distortion and overheating may or may not be immediately noticed; but they are happening.
Technically, this transistor is a "power amp". Folks often confuse it with power supply. The only power supply in these radios is made up of a couple of resistors.
This looks like a source of 10 ohm speakers:
http://www.turnswitch.com/speakers.htm .
Mike M.

[StudeRich]

They have the GOOD STUFF, these speakers WILL work!

Cool Mike! [^]

[Guest]

Thems the ones! Thanks Mike and all!

[tim87114]

Tom and all,

As luck would have it, I once worked as a Manufacturing Engineer for a company that manufactured Heavy equipment Backup alarms. We designed and manufactured our own speakers for our products. We had both basket/magnet motor designs and others. Prior to that I spent 5 years as a professional car audio installer.

A speakers Impedance is measured by the manufacture during operation through frequency ranges and factored during design phase of the motor assembly. 8ohms is generally the minimum a speaker would produce if that is the given spec. When you look at an 8 ohm speaker versus a 10ohm speaker they are so close to each other the stereo will not know the difference because most stereos and speakers are manufactured upto +/-20%. A single 8 ohm speaker will not cause harm to your stereos internal amplifier because you will also need to factor in the Connectors and the wire within the vehicle, which will add some resistance. If you wire two 8 ohm speakers in series you will now put 16ohms onto the amplifier output. This is also OK. What you do not want to do is to install two 8 ohm speakers in parallel. If you do this will drop the load to 4 ohms and may cause the amplifier to react as a current source which will shorten its life quickly.

Also, for those whom have a stereo with only one speaker out but wish to have Front to rear fade. There are very inexpensive Faders now on the market that you can place inline of your speaker wire feed. I have used them in the past and they work very well.

[StudeRich]

Yeah but, are not most of the speakers readily available out there now-days mostly all 4 OHM or 4-8 Ohm? That does not sound like 8 OHMS to me!