Radio Speakers Impedence

[Dave6T4]

I am at the point of choosing speakers to match my Custom Autosound radio. I see that speakers come in either 4 ohm or 8 ohm impedence. Does one type have any advantage over the other? Why are there two types available?

 

[Xp29h]

Depends on the amp within your stere, it’s outputs and how many speakers you plan to have.


here’s a couple good reads that may help..

How to Wire Speakers in Parallel & Series, and how does it affect Impedance?

SERIES & PARALLEL SPEAKER WIRING


if you want to post up info on your stereo and intended set up that could help

 

[Rockland71GTX]

The 8 ohm speakers were original equipment on our older cars. I'm not sure when they changed to 4 ohm. Using a 4 ohm speaker with an OEM radio will cause double the current to flow from the amps and could damage the radio. The custom autosound radio may be designed for 4 ohm speakers do use what they recommend.

 

[bandit67]

In the old days most all aftermarket speakers for autos were 4 ohm. And then more radios/receivers for cars/truck/boats were being made with 8 ohm outputs. I think most OEM radios in the 60s and 70s were 10 ohms, in general. You need the speaker ohms to match your radio output ohm requirements.

 

[MWbirdLOVER70]

From my a Mopar friend that works on classic radios from another site

 

[Dave6T4]

I looked at the aftermarket radio spec's, and it said 4 or 8 ohms. I just wondered if there was any advantage of one over the other. Thanks all for your replies. If I use 4 ohms speakers all around, I should be good?

 

[Rockland71GTX]

4 ohm speakers will work fine then. They will be louder than 8 ohm speakers too.

 

[Geoff 2]

The 'impedance' is NOT the resistance of the voice coil inside the speaker that many think it is.
Using a speaker that is matched [ has the same impedance ] as that of the device will ensure maximum volume is delivered; mismatched impedance will lower the volume & might cause sound distortion.

 

[Xp29h]

I looked at the aftermarket radio spec's, and it said 4 or 8 ohms. I just wondered if there was any advantage of one over the other. Thanks all for your replies. If I use 4 ohms speakers all around, I should be good?

No real sound advantage Within a small confined space like a vehicle and lower volumes of a car stereo. Putting in a huge system with onboard amp sets, yes it could make a difference.

Guitar cabinets, imo definitely a difference. I love the 16 ohm cabs but that isn’t your application here. The Stereo and actual speakers make up the difference. The level of ohms matters when adding more speakers and creating the load on the amp within the unit. Early car stereos were just basically one, maybe 2 speakers and evolved from there.

 

[twecomm]

Have a look at this video which explains nicely..

 

[1963JAM]

I recently asked myself that same question. As mentioned above, match ohm ratings on car radio, most likely 4 ohms. 8 ohms is common for home speakers.

 

[RJRENTON]

The 8 ohm speakers were original equipment on our older cars. I'm not sure when they changed to 4 ohm. Using a 4 ohm speaker with an OEM radio will cause double the current to flow from the amps and could damage the radio. The custom autosound radio may be designed for 4 ohm speakers do use what they recommend.

Basically true, except some GM/Delco radios using the Delco DS-501 output transistor (aka the "door knob") used a network of the speaker, a parallel inductor and capacitor to ground....usually with a 10 ohm speaker
Google Image Result for https://www.physicsforums.com/attachments/mine-jpg.231508/
The image is s little blurry, but you can see the DS-501 PNP germanium transistor. Unusual circuit that divided the transistor collector current between the inductor, capacitor and speaker. High resistance output circuit connections USUALLY resulted in the DS-501 failing. Just talking out loud....
BOB RENTON

 

[AR67GTX]

I don’t know where I came up with this but I think I researched this back around 2003 for my 67 and I came up with the answer the radios, at least around this time, used 4 ohm speakers. That is what I used in my 66 and 67 and they seem to work fine. They do have a pretty good amount of volume.

 

[RJRENTON]

I don’t know where I came up with this but I think I researched this back around 2003 for my 67 and I came up with the answer the radios, at least around this time, used 4 ohm speakers. That is what I used in my 66 and 67 and they seem to work fine. They do have a pretty good amount of volume.

The impedance of the speaker has nothing to do with the decibel level or sound output. The impedance (AC equilivant of DC resistance, because the audio information is an AC signal) matches the output of the sound source, beit a car radio or a home Stereo of HiFi sound system. The Stereo amplifiers usually had output connection terminals of: 4, 8, 16 ohm, to match the speaker systems. The best speakers, like Acoustic Research AR-3A's were 8 ohm LOW EFFICIENCY design that, at high power levels, produced the cleanest most faithful representation of true concert hall sounds over a frequency range of 20 Hz to 20,000 Hz +/- 3.0 dB. Automotive sound systems don't have that same degree of sophistication, but must produce a relatively clean audio quality that reasonably allows high listening levels under adverse conditions.....windows down, high MPH, loud exhaust system. Its really up to the final amplifier's design and frequency response without distortion. Mis-match of the speaker to device's amplifier results in high distortion and eventually a failure. Just my opinion of course.
BOB RENTON

 

[AR67GTX]

They still seem to work just fine and have pretty good volume.

 

[RJRENTON]

They still seem to work just fine and have pretty good volume.

Its not the audio level (are you measuring the dB level) but the frequency range of the information AND the faithfulness of the audio presented without distortion....or viewed with an oscilloscope....just saying.....
BOB RENTON

 

[MWbirdLOVER70]

So if you wanna run factory sounds just use 8 ohm speakers for the purists and for aftermarket systems go 4 ohm

 

[RJRENTON]

So if you wanna run factory sounds just use 8 ohm speakers for the purists and for aftermarket systems go 4 ohm

Based on what? Please advise the power levels in Decibels (dBa) and distortion levels at what frequency range being measured. Its NOT a sole function of speaker impedance to device or wire size, or air density, or degrees of spark advance, or ported or manifold vacuum source....and not what is a perceived listening level, but using actual measured figures. Unless of course the methodology used to make the determination is based on the next door neighbor's cousin's sister's husband's best buddy's friend's determination down at the local watering hole on Tuesday...or, how high is up principle.....or not.....just talking out loud....
BOB RENTON

 

[Dave6T4]

This is starting to go sideways! Anyway, I bought some 4 ohm speakers through Amazon. Anyone familiar with '63-'64 B-bodies know they have an odd sized front 7" round speaker that is impossible to find. I found a 6 1/2" speaker with an adapter plate that I was able to modify and make it fit. I got a pair of 3" round speakers that I will mount on the " B"-pillars, and a 6" X 9" oval for the package tray. Thanks to everyone for their input.

 

[70rcode]

It's just car radio, guys....where any good 8--10 ohm speaker load will work safely & sound loud enough & clear on any solid state car radio ...... New radios that allow 4 ohms will play good on 4 & up ohms ....Just not that critical for most apps.....