C-2 Speaker Problem??

[Kurt K.]

I recently installed a original style speaker in my 67 coupe. After reading the article in the "Restorer" about speaker resistance(summer 04 pg 39),I thought I should test mine. It was about .6 ohms. I called L.I. Corvette and they quickly told me the speaker was fine and the article was all wrong. I don't know who to trust here?? The article states 1.5 ohms is needed to keep from hurting the radio/speaker. When I tested the speaker without the attached coil, it was 4 ohms. The coil was .6 to .7 ohms and wired in parellel. I wonder what the original speaker had for resistance??? Anyone run into this?? Thanks, Kurt

[Wayne W.]

Re: C-2 Speaker Problem??

The original speaker was 10 Ohms, but you are worried about nothing. If it works good, dont worry.

[Gerard F.]

Re: C-2 Speaker Problem??

Kurt,

I think the article in the Restorer is right. You could burn out your main transistor on your 67 AM-FM. I think I'd check with a shop that specializes in these radios. Some years ago I replaced my original speaker in my 67 with a sound shop 4 ohm (without coil) speaker. It worked fine for a while, then after extended use it would heat up and cut out. It finally blew the main transistor.

I had to replace both the speaker, and transistor (which is hard to find). I finally got a substitute for the DS501 from RadioShack online.

Jerry Fuccillo
#42179

[Joe C.]

Re: C-2 Speaker Problem??

Kurt:

The output transistor should get warm during radio operation. If you can't keep your finger on it for a few seconds, then it is too hot. If your speaker doesn't have enough impedance, then it will overload the output transistor.
In your post, I think your decimal might be in the wrong place. If you measured the resistance across the speaker/buffer assembly at 6 ohms (not .6), then you are borderline. Original spec is, more like 9 ohms. Try the finger test.

Joe

[Kurt K.]

Re: C-2 Speaker Problem??

Joe, I tested the transformer by itself and it was about .7 ohms. The speaker was 4 ohms. In a parellel circuit, the total resistance will be lower than the lowest component or, in my case .6 ohms. I had to unsolder the transformer to do the tests. I think the original speaker was 10 ohms and the transformer was 1.5 ohms. The total resistance would be about 1.3 ohms. I went to Radio shack and bought a 1 ohm resistor and put in series, now I have 1.5 ohms. I hope this works... Kurt

[mac peppers]

Re: C-2 Speaker Problem??

let us know if it works, i've been wrestling with the same problem. i've read you need to measure 1.5 ohms minimum and 1.5 volt dc when operating. i've bought a new speaker with transformer and it measures .3 ohms so i'm afraid to try it. hear is a site where i got my info.

www.wtv-zone.com/tonymac/corvette.html

[Kurt K.]

Re: C-2 Speaker Problem??

Mac, Its in and working. With the 1 ohm added, I have now 1.6 ohms thru the speaker. I will test the DC volts while playing and post the results. Kurt

[mac peppers]

Re: C-2 Speaker Problem??

hey kurt,
is it still working? i'm still struggling with mine, haven't found a 1 ohm resistor yet.
mac

[Kurt K.]

Re: C-2 Speaker Problem??

Mac, Works fine with the 1 ohm resistor. I held my finger on the transistor mounted on the back of the radio and it just got warm, not hot.. I dont get that garbled sound after it plays a while.. Nice and clear...I got the resistor at Radio Shack. They are two in a pack, about $2. Kurt

[mac peppers]

Re: C-2 Speaker Problem??

sounds great, thanks for the info. i'm off to the rat shack.
mac