Cadillac 1955 Speaker : 4 or 8 Ohm?

[Cadillac1955]

Im going to buy new speakers for my Cadillac 1955. I wonder if those old speakers where 4 or 8 Ohm???

Where to buy??

Many thanks,
Andrè

[randy appleberry]

any 8 ohm 6x9 speaker should work. i used  cutlass speakers on mine, just changed connectors.

[David King (kz78hy)]

I think the original was 10 ohm, 8 is close.

David

[J. Gomez]

Im going to buy new speakers for my Cadillac 1955. I wonder if those old speakers where 4 or 8 Ohm???

Where to buy??

Many thanks,
Andrè

Andrè

The original impedance for the speaker’s front or rear was 3-4 ohms. If a higher impedance i.e. 8 ohm speaker is use the sound would be a bit distorted as the output transformer is also 3-4 ohms and both are balance.

Good luck..!

[markl]

Jose,
I think you are painting too dire a picture here.  In 1955, the radio would have been tube (assuming it is original), so if you can determine what the output was intended to be (I'll leave that to others), it can safely drive speakers of the rated output, or lower impedance.  There will be a loss of efficiency if they are not properly matched, but no noticeable distortion unless you over-drive them.

Andre,
If you have one of the original speakers, and the voice coil is not burned out, you can check it w/ an Ohm meter to determine the impedance.  Set the meter to 20 ohm max, and a 4 ohm speaker will read 3-3.5 ohms.  If it was originally an 8 ohm speaker, I believe it will read 6-7.5.  I have never encountered other than 4 or 8 ohm outputs in car radios, and modern solid-state radios are almost universally 4 ohms.

Mark Lowery, CLC#25216

[bcroe]

I would expect 4 ohms until the first transistor output stages used 10 ohms.  Not very critical though.  A matching transformer can make it perfect if you are really fussy.  DC resistance isn't a great way to measure audio impedance.  Bruce Roe

[TJ Hopland]

Its the other way around if the amp is rated at 8 ohm you can safely run a 12 (or 100) ohm load but you will loose efficiency.   If its rated for 8 and you try to drive a 4 (or 2) ohm load it could get interesting if you tried to push it at all.  This would be the most likely way to get distortion but it would depend on the amp design, condition, and what sort of signal you were using.   It happens all the time because when someone decides they need 2 speakers on one output they most often connect them in parallel + + and - -.  IF these were both 8 ohm that would make a 4 ohm load.   Most amplifiers will tolerate that even if they are not rated for it because typical program material is dynamic enough that there does not tend to be extended periods with sustained notes.   Now you put one on the bench with a tone generator you can get smoke pretty quick.  It gets worse if you hook 3 or 4 speakers up that way, 2.6 or 2 ohms.   Apparently some modern 'car amps' are rated down to 0.5 ohms.   I would like to get one of those on the bench.   I bet its like your 6.0 HP shop vac that runs on a 15 amp 120v cord,  magic!   It probably sounds like a shop vac also. 

[J. Gomez]

Jose,
I think you are painting too dire a picture here.  In 1955, the radio would have been tube (assuming it is original), so if you can determine what the output was intended to be (I'll leave that to others), it can safely drive speakers of the rated output, or lower impedance.  There will be a loss of efficiency if they are not properly matched, but no noticeable distortion unless you over-drive them.

Mark,

The reference I made was related to the vacuum tube OEM radio with the audio output transformer secondary listed as 3-4 ohms same as the speakers per the specs. Using speakers with difference impedance as the output transform would cause an impedance mismatch as the fix load (speaker) would change the impedance matching between both source and load.

Could you drive the higher impedance speaker yes you can, but again once you extend the output power beyond mid-range you start placing a stress that could potentially burn the output transformer secondary winding. Similar concept as TJ comments above.

[Doug Houston]

Like somebody has aready said:  a vacum tube set won't care  with a mismatch. The eet, if not a convertible, willo  have a rear speaker, with a balancing control, and that alone  is a mismatch to the output transformer in the set. Any impdance from 4 to 8 ohms will work like new.

In the cse of a transistor output with a 10 Ohm speaker, it is pretty critical. You caan use an 8 ohm speaker in plac e of a 10 ohm, but not a good idea Delco was the big user of 10 ohm speakers.

[Cadillac1955]

Orginal speakers from the 50s are grounded in the speaker body, which in turn is grounded in the body ... Speakers today has two terminals. "+" and "- ". I wonder if I need to ground the "-" in the body and then in the car body??

[bcroe]

If there is only one wire, you will need a ground.  It won't matter which is grounded if you don't have stereo.  Bruce Roe

[Cadillac1955]

I use the orginal radio..... Can I buy a new speaker 4 ohm and ground the negative to the chassie as orginal speakers??

[J. Gomez]

I use the orginal radio..... Can I buy a new speaker 4 ohm and ground the negative to the chassie as orginal speakers??

Andrè,

You have to ground the “-“side of the speaker to a chassis ground. Also, if the speaker is for the radio/amp unit the original has a rectangle magnet housing, new ones will be round so you may have clearance issues placing the new speaker inside the unit.

Good luck..!

[Cadillac1955]

I mean to replace a brand new speaker and trash the old one...... My questions is : At a new speaker, shall I ground the negative "-" to the chassie??

[J. Gomez]

I mean to replace a brand new speaker and trash the old one...... My questions is : At a new speaker, shall I ground the negative "-" to the chassie??

Yes you have to...!