I recently purchased a 68 327/350. (Congrats to me for joining the ranks of you other wonderful c3 owners!)

My original speakers are toast, so I ordered a replacement set online from ZipCorvette. My question is this. My original speakers are marked 10 ohm on the back, and the replacements I received are reading at about 3.5 ohms. Is this going to pose a potential disaster for my OEM radio???

Anyone else have these installed with any positive/negative feedback??

Thanks

~Rich
68 Vette 327/350HP
#'s match
72K original miles

 

Don't understand that your old ones are stamped 10, but new ones "read" at 3.5. Clarify?

 

I don't think it will do much. I ran some 4 ohm speakers on my 69 back when it had the stock stereo in it (it also came with 10 ohm speakers). Nothing ever happened to the stereo. The amp draw will go up, but not enough to hurt the stereo I guess.

 

They will roast your radio, don't use them. Delco offers some very nice 10 ohm speakers, part number 13033662

 

What I meant by "read" was I hooked them up to a multimeter and the ohms were at 3.5. I'm assuming that these are supposed to be 4 ohm speakers.


Big Fish---Where can I get the Delco replacements? Do they fit in the kick panels without any clearance issues???


Thanks all for the quick replies.

~Rich

 

Rich, sorry, but I didn't realize you needed kick panel speakers. The part number I gave is for oval shaped speakers that fit in the dash.

Try GM Parts Direct, I know they have the oval speakers, but I'm assuming your speakers are round?



Edit: The dash speakers are 4 X 6, kick panel speakers are maybe 4 X 10? You still need 10 ohm speakers unless you change to a modern radio

 

Not round. These are 4X10. Really odd shape, and I guess difficult to replace. I'll check with GM Parts Direct.

Thanks,

~Rich

 

Rich, you will probably need to go through customer service on those. The part numbers come up for the 4 X 6, but they are not listed in restoration parts. Good chance the 4 X 10's won't be either. Delco calls (the number I gave) "upgrade" speakers. They have heavier magnets and are 2-way.

 

I will be calling them in the morning.

Just want to say that I have been reading the forum every day for a few hours each day and I love the community here! You guys are always willing to help out, and us new guys really appreciate it!!

I'll let you know what I find out in the morning.


~Rich

 

I'm an avid speaker builder and fairly knowledgeable about it. The 3.5 ohms you read with a meter is DC resistance. This is not equivalent to the 10 ohms which is basically derived from an AC impedance plot. The listed ohms is also just an average over a frequency range.

Verify with the vendor what they really are. You can't do it with a multimeter like you did.... I use a computer test setup to measure impedance.

Just a heads up.
-Matt

 

Do you think an average stereo shop will have the proper equipment to verify if these speakers will work or not? Or should I just return these and look for a different set from another source?

As far as asking the vendor, Zip didn't have a clue as to what the impedence rating was. They did offer to return the speakers for me if I feel they wont work, but I dont want to end up on a wild goose chase trying to find correct speakers.

~Rich

 

Typical carspeakers are 4 ohm and will draw quite a bit more power than the original 10 ohm speakers. Modern aftermarket stereos and amps are usually stable down to 2 ohms so they aren't effected much by varying speaker impeadance or multiple speaker hookups as long as they're not ridiculous. But if you're using an original low powered radio there's a chance that you may draw more current than the amplifier can supply. When an amplifier is asked to deliver more than it's designed for it goes into clipping. To visualize this think of a smooth sine wave.When an amp starts to clip the top of the wave becomes flat instead of rounded. More clipping lowers the flat portion of the wave. Severe clipping ends up eventually becoming almost straight DC current which will fry a speaker and damage the amplifier. Since the original radio was only rated at a few watts output into 10 ohms I think it would be relatively easy to get it into clipping and hurt both the radio and speakers. You can ask this same question in the Audio section of the forum but I don't think I'm that far off.

 

You're right on vettefixr. A car stereo shop probably does not have a clue about taking an impedance curve of a speaker. Low impedance will overcurrent an amplifier. Older amplifiers will heat up too much and can toast in no time if you play it loud.

You can
A. Play it at low levels only
B. Try to find the supplier of the speaker and verify the impedance
C. Opt for some known good replacements. 8 ohms probably won't hurt anything especially if you don't normally blast it.
D. If you are in northeast OH I could try and plot a curve for ya. Chances are vettefixr is right and they are 4 ohm speakers.

 

What if I were to put a resistor in-line with the speaker to bring the impedence to 10 ohm??

~Rich

 

Rich, your original 68 radio amplifier is designed for 10 ohms period. You WILL fry the big ancient DS501 transistor 'can' on the heat sink sooner or later. You can probably get away 8 ohms if it were a 74-6. But on an original 68 radio - definately stick w/ the 10 ohms (well maybe 8 ohms) - see the post above that provides you with GM part#. That's the best speaker option you have.

GM is the only source I know of anymore for 10 ohm speakers (radio shack doesn't offer 8 ohm car speakers anymore). Every GM speaker I've seen is clearly stamped w/ the ohm rating. If your new ones from Zip aren't marked "ACDelco" or "GM" and don't say "10 ohms" - they are almost certainly not 10 ohms. Probably 4 ohms but an outside chance they are 8 ohms.

You can get 'em at any GM dealer or a variety of online sources. I just bought a pair for around $25 ea from a guy (small Corvette parts dealer) I mail order all my GM parts from for my Corvette - email me and I'll put you in touch if interested (he accepts CCs) or go to your local GM dealer or whatever.

-------------------

Matt you sound like you know your stuff... I don't mean to hijack this thread but I have a couple few questions you might be able to help with and may be relevant to this thread...

I'm contemplating building a custom pair of speakers for a mid C3 w/ the dual DS-501 transistor stereo amp. The 662 factory 'upgrade' speakers are about as good as it gets for drop-in replacements, they are the correct 10 ohm speakers and all of that. But while way better than the originals - still not an ultimate hi fi speaker even for a vintage 68-76 amp. (FYI the later amps especially 74-76 are I think a lot better than earlier amps).

As you probably know these mount under the dash facing up and focusing on the windshield glass. THeir baskets are open and explosed to the dash and ultimatley footwells below...

As you know nice separate drivers exist including 8 ohms. Again for an original amp I was thinking of putting together a 4X6 plate w/ cutouts for say a 4" driver and a 1" tweeter and a crossover. THoughts...? Any idea how much better this might be over the ACDelco 4X6 10 ohm given an amp that puts out a couple few watts on a good day?

The other question applies equally to ACDelco 4X6s or a 'custom' speaker and that is enclosures for the face up dash speakers open to the bottom... I was toying w/ the idea of a 4X6 foam baffle and some polyfill in there. No it's not a serious rigid enclosure but perhaps it would be better than an 'open' speaker...? Or is it worth the trouble?

Crutchfield offers XTC Foam baffles in 4X6 w/ either a 3.5" depth or shallow 2.5" depth. The guages on the passenger side probably force the 2.5" depth.

And given a baffle like this - worth cutting a small hole in bottom or not?

I know there are other options like kick panels or rears but right now for this particular project only the original dash mount 4X6 location is an option. And the speaker needs to be at least 8 ohms. Those are THE constraints for this project.

thanks!

 

8 Ohms= Home Audio
4 Ohms= Car Audio

 

Just wanting to be clear. You want to replace the current dash speakers, correct? You are considering either a dash replacement OR putting a pair in the kick panels? You have written that the speakers Zip sent you are oblong. With that I think they sent you a set that is intended to replace the dash speakers. I would call them to confirm that the speakers they sent will work with your stock radio... The major vendors all seem to sell mostly the same parts, so it is likely that Zip sent you what the other vendors (MidAm, CC, etc...) would also sell you for a stock replacement. However, you have received some expert advice in this thread from others, so heed their advice and confirm everything.

Years ago I put a set of separates in my '77 Corvette with an aftermarket radio. I think I had 4" mid ranges in the kick panels and tweeters on a plate in the dash locations with the cross-overs stuffed behind the radio. Sound was pretty good that way...but that likely won't work easily with a stock '68 radio...

 

I have a 68. There are no dash speakers. There are 2 4x10's in the kick panels. This was only like this for 68-69 I beleive. The speakers are a perfect fit....they even come with the mounts riveted to them. They are an exact replacement except for the ohm rating.

 

Only true as a generalization today in the aftermarket consumer industry. Not true of all eras or market segments. Many home audio speakers have been produced w/ ohms ranging from 4 to 16. Many automakers have implemented 8 or 10+ ohm systems over the decades.

Doh! That is correct - disregard the 662 # GM speaker above - that's for 70+ dash mount. Still the 10 ohms is correct for an original 1968 radio. If it's a GM speaker the 10 ohms should be clearly stamped on the magnet (along w/ the GM part#). I think you could probably get away w/ 8 ohms but I wouldn't go below that for an original 68 radio. I know the phone droids at Zip know nothing but surely they have a 'tech' line. Or I can put you in touch w/ my source for GM stuff - not trying to plug his business but he does know his stuff and you'd be talking to HIM not a phone droid and he's into COrvettes.

 

Sent you an email for your guys contact info.

Thanks for the help.

~Rich