c-2 Radio/Speaker Problem

kobi67 · 10-10-04, 08:30 PM

I replaced the speaker in my 67 with a unit from LI corvette. The sound is not good, kind of distorted... When I tested the resistance, I had none. The transformer is wired to the speaker in parellel not series, strange??? I cut out the transformer now I have 4.4 ohms. the transformer is .25 ohms. If I put the transformer in series, I have 4.6 ohms..I don't understand why the transformer is not in series? Is it not to raise the total resistance to 8-10 ohms??? I suspect this is my problem? Any help would be appreciated. Kurt

Ken Anderson · 10-11-04, 03:30 PM

Cal them & explain your problem. You need at least 8.5-9 ohms resistance to keep from harming a stock radio.

KEG64 · 10-12-04, 08:57 PM

The speaker for my 64 has the transformer in parallel with the speaker. If you hook up a standard 4 or 8 ohm speaker to the radio it will damage the speaker. I believe all original midyear radios require the speaker with the transformer (wired in parallel).

Ken Anderson · 10-12-04, 09:08 PM

You are incorrect, it was wired in series from the factory.

KEG64 · 10-12-04, 09:26 PM

This is how the speaker I purchased from LI Corvette is wired(transformer is wired in parallel). This is correct according to the schematic I have for the radio. My radio and speaker work. This is for a 64, maybe the 67 is different.

kobi67 · 10-13-04, 08:55 AM

I guess I don't understand... The .25 ohm coil is wired across the circuit so that when you measure resistance you get less than 4 ohms (the speaker itself is 4 ohms). If the unit must have 8 to 10 ohms, this is a problem. I would think the coil should be a 4-5 ohm unit wires in series( one side of the circuit) to add to the total resistance..What am I missing here???

KEG64 · 10-13-04, 10:20 AM

Speakers do not present a purely resistive load to the audio output circuit. It is measured in impedance, which is determined by the capacitance, inductance and resistance of the speaker. The actual impendence of the speaker will vary depending upon the audio frequency. Measuring the resistance of the speaker only gives you the resistance of the speaker, it is not a true indication of the actual load the speaker has on the audio output circuit.

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kobi67 · 10-13-04, 02:28 PM

I found an interesting article in a NCRS publication that warned about replacement speakers that had the wrong total resistance. Mine had .6 ohms. I just bought it from L.I. Corvette. Today, I called them and they were quick to tell me that the article was all wrong and these speakers are fine. The article says the resistance should be about 1.5 ohms with the coil. I may be fooling myself here but, I ran to Radio Shack, and got a 1 ohm resistor and put it is series with the speaker. Now I have 1.6 ohms!!!! I hope this keeps from hurting the radio. Wonderbarman.com, provided the article. Corvette Restorer, vol 31, #1, summer 2004, page 39. Kurt