Radio Speakers

[Les G.]

I am in the process of putting the original monural radio back in my 1970 convertable. In the dash are 10 ohm speakers is this correct? If not would that damage the radio?

[Edward J.]

Re: Radio Speakers

Les ,
I Just Went Through This With My 72 Coupe, 10 Ohm Is Correct For Your Car . Stay With What The Factory Installed .anything Else May Damage The Radio Amp.

[Jerry R.]

Re: Radio Speakers

If they will fit, you can use an after market speaker that is marked for 8 ohms. Never use 4 or 16 ohm speakers. The commonly available 8 ohm or the Delco factory specified 10 ohm speakers are the same electrically. These values do not correlate to pure resistance but reactive resistance as measured at a specific frequency. Delco just happened to pick a non standard frequency when establishing their impedance specification.

Almost all of the 68 to 71 Corvette radios have an audio output bias adjustment inside the radio which is accessible from outside the case. The later models sometimes had an alternate audio board in them that did away with this adjustment. If the quality of your audio is highly distorted this adjustment may be incorrect. You can place a voltmeter across the green and black speaker leads (both speakers connected) and you should measure very close to 1.25 volts DC. That is the optimum setting and close enough for most installations.

Jerry

[Paul C.]

Re: Radio Speakers

Am having my 71 radio restored now. The radio man (Tony Crutchfield--Crockett Sound Lab) said only use 10 ohm--the others like 4 ohm will burn out your radio. I installed new delco 10 ohm speakers and am now waiting to get the radio back. There was a 6 month wait to get it worked on.
Paul

[Jack H.]

Re: Radio Speakers

This is an EXCELLENT tutorial! Impedance is NOT resistance as stated. AND, when specifying impedance you have to also state the frequency you're measuring at...

If memory serves, today's 'norm' is 1004 Hz. But, that doesn't preclude individual mfgr's from specing their speaker products at other/different frequency points.

Bottom line, matching the speaker's impedance to the radio's output drive impedance is the way in which you 'optimize' power transfer from the electronics to the speaker. Being off design center by a little bit, doesn't hurt. But, being off center by a country mile CAN do damage to the drive electronics!

The difference between 8-ohms and 10-ohms is about 20% and that's well within typical design safety margin tolerences...

[Paul C.]

Re: Radio Speakers

Someone asked if I meant 6 weeks--no 6 months. I put my name on a waiting list and after 6 months was notified to mail it in.
Paul

[Kurt G.]

Re: Radio Speakers

Les, I just put new speakers in my 72. Zip Products is the only one that had the correct 10 ohm speakers that would fit in the car. There is a slight modification that needs to be made even to these, but the mod is easy, just drill out some plastic that covers the holes for the speaker mounting studs. They are the GM speaker, are about $35 each, but well worth it. I ordered 4 sets of speakers, and returned 3 because they wouldn't fit. Also, brush up on your soldering skills, cuz you'll have to solder the leads on The replacement speaker has a quick connect plug on it. You'll have to take the leads off the old speaker and re-solder them to the new speakers. Black and green wire is the P, green wire goes to the C post.

[Steven N.]

Re: Radio Speakers

Since we are on radio's, I have been dying to ask this question. I see radio's that are re-built, but i noticed that I have never seen one from someone that restores the case. Am I the only one that restores the case ? Thanks.............

[Joe L.]

Re: Radio Speakers

I am in the process of putting the original monural radio back in my 1970 convertable. In the dash are 10 ohm speakers is this correct? If not would that damage the radio?

Les-----


As others have stated, 10 ohms are what you need. Also, as Jerry mentioned, 8 ohms will work ok----I've used them for years without problem. If you wish to upgrade speakers, your only choice is 8 ohm since I know of no high quality speakers available which are rated at 10 ohms.

Want to replace the originals with equivalent speakers? GM #15173232 will do the trick. These are the current GM replacements for your originals. Are they configured exactly the same? No. Will they sound better than the originals? I doubt it, but they may sound better than 40 year old originals.About 50 bucks, each, GM list.

[Jerry R.]

Re: Radio Speakers

Steven - yes, others do cases.

http://electrodesign.us/PreviouslyCompletedProjects/Project11-1967FordMustangAMFM/index2.htm

That's not paint.

Joe - so true! Call me cynical (and I'm agreeing with you) but the quality of the amplifiers in the 60's to mid 70's cars teamed with the simple FM quadrature detectors just doesn't justify adding a high quality speaker. Perhaps you'll agree that the correlation is something like putting a Holley double pumper on a Sears garden tractor? No burnouts in any gear.

A recently completed 55 Wonderbar received a very nice new model speaker with a floating cone. It required extra shimming to stop the enhanced cone from slapping the metal grill but the radio sure could deliver bass compared to the original speaker. So much so that I had to boost the treble to keep up. The old radios are worth the extra speaker cost IMHO.

For those still reading and interested in the minutiae of old car radios, units with tube amps from the 20's to about 57 (53 to 57 for the Vettes) had excellent sound potential but then everything seemed to go to heck (blame transistors) until Bose came to the rescue.

And what's with the tone controls from the 60/70's? If turned to bass, they actually just short out the treble.

Rant finished, too much coffee, back to the cave.... (big block bass from stereo side pipes was Delco's best audio system!)

[Dennis C.]

Re: Radio Speakers

[quote=Jerry Rudbeck (31874);408880]Steven - yes, others do cases.

http://electrodesign.us/PreviouslyCompletedProjects/Project11-1967FordMustangAMFM/index2.htm

That's not paint.


What is the finish on Wonderbar cases?

Regards,

Dennis