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Old 01-11-2018, 06:32 AM   #1
Dennis L Brooks
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Default 68 AM/FM mono radio

Does this radio have just treble/base on the left inside **** --- nothing but tune on the right?

Can I use a single DS 515 convector/amp on it instead of the ds501?

Where do I get speakers that will work with this radio?

It appears to me that it has a blue, green, and black for the speakers - left/right --- with the black being the ground?

thanks

Last edited by Dennis L Brooks; 01-11-2018 at 07:32 AM. Reason: words
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Old 01-11-2018, 08:15 AM   #2
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Quote:
Originally Posted by Dennis L Brooks View Post
Does this radio have just treble/base on the left inside **** --- nothing but tune on the right?

Can I use a single DS 515 convector/amp on it instead of the ds501?

Where do I get speakers that will work with this radio?

It appears to me that it has a blue, green, and black for the speakers - left/right --- with the black being the ground?

thanks
Mine's stereo and a bit different. Green/black for speakers. One channel came from the back of the radio unit the other came from the unit up under the dash. I used an old 8ohm house to test. One inside **** is L/R balance, the other is treble/base.

I got my direct fit 10ohm speakers at http://www.turnswitch.com/

If they have the time they can be very helpful and can probably answer your specific connector questions.

BTW - I am glad I got mine working for nostalgia but in general I just toss a bluetooth can speaker by my elbow on the console and it belts out ten times as much sound and I can carry around my entire music collection in the magic pop-tart on my belt. Zero modifications to the car.
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Old 01-11-2018, 08:40 AM   #3
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not sure about the amp that was in the car from the factory, look up under the passenger side dash it might still be mounted to the firewall
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Old 01-11-2018, 09:11 AM   #4
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not sure about the amp that was in the car from the factory, look up under the passenger side dash it might still be mounted to the firewall

pigfarmer/blue - just have radio - I do not own a c3 --have a 85 c4. Am just tryng to test it. Also plug receptacles had been cut off --- green/black on speaker side of connection is probably same with this one. Just that blue must feed the plug for one speaker.

blue by you -- is yours stereo - as I have no adjustment on the right side for left/right speaker.

I will wire 2 - 4 ohm in series ---speakers measure about 4.0 each.

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Old 01-11-2018, 03:08 PM   #5
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Any radio gurus out there. I still need to know if I can use a single ds515 convect-or/ amp or not instead of the oem ds501. I read that stereo used 2 ds515 instead of the single ds501 on the monos. thanks
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Old 01-11-2018, 08:01 PM   #6
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The 68 radio speaker wires are a different setup than later years. I think the speaker leads go all the way to each kick panel speaker. Another 68 only. Lou.
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Old 01-11-2018, 08:44 PM   #7
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I have my radio out of my 68 on the bench. Can look at it tomorrow evening
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Old 01-12-2018, 02:47 PM   #8
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Early C3 radios and C4 radios were completely different. No wiring color code duplications can be assumed. You need to get wiring diagrams for both systems (as well as electrical specifications) so that you can do this job properly.

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Old 01-12-2018, 03:02 PM   #9
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Early C3 radios and C4 radios were completely different. No wiring color code duplications can be assumed. You need to get wiring diagrams for both systems (as well as electrical specifications) so that you can do this job properly.

OK thanks -- but my question has nothing to do with a C4. I probably will have no use for the 68 vette radio, looks like a decent radio cosmetically and inside --- am just trying to test it before throwing it on the junk shelf.
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Old 01-12-2018, 11:21 PM   #10
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ALL C3 radios have decent value...whether they work or not. If you want to toss it, toss it my way.
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Old 01-13-2018, 07:09 AM   #11
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There's no need to try to swap ds501s. You can still find them.
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Old 01-13-2018, 08:41 AM   #12
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This is not a for sale thread but here are a couple of pics of the radio for verification of a possible vette 68-69. You may be able to tell my intentions before I found out what I think it is. Would readily trade for a 67-72 Chevy/GMC pickup AM/FM which are harder to find but near the same radio.
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Old 01-13-2018, 09:14 AM   #13
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Lots of wiring mods on that piece. The power connector is the three-wire connector having all the splices. The speaker outputs are the two green wires. I believe the blue wires have something to do with convector hookup.

The best thing you could do with that unit would be to sell it to some repair guy as a 'core' unit. Hooking it up incorrectly could just fry it completely.

Output impedance of these early C3 radios was 10 ohms (to each speaker). The only new 10 ohm speakers are those made to be exact replacements for these radios...but they are made just as poorly as the original speakers. You can hook lower impedance speakers up for testing the unit, but you DO NOT want to turn the volume up much as the low impedance speakers would draw too much current and fry the convector transistor (at a minimum!).

Others may have 'better' info on this unit.
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Old 01-13-2018, 10:20 AM   #14
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Well you may be right but there have been no mods on the wires - just the ends cut off before I got it. I extended the cut off ends on the key/ground/panel plug. There should be a yellow/green/blue going to the convector and a green/black eventually going to dual speakers - since this a mono with no adjustment on right **** other than tuning -- it leaves a blue. Someone knows --- could be told by looking inside a similar radio. But no matter. thanks guys

fearless

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Old 01-13-2018, 10:29 AM   #15
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Old 01-13-2018, 12:52 PM   #16
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3 to sink yellow/blue/green, 3 to speakers ----- black/blue/green with black as common ground --- thanks --- now to find a ds501 working transistor --- will use 2 - 4 ohm speakers in series for each side

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Old 01-15-2018, 08:26 AM   #17
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Mine is a mono am/fm and uses a amp, just not a amp like they use today
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Old 01-15-2018, 10:07 AM   #18
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Would be nice to see an inside pic of a mono 68 or newer to see the pin connections for the convector

if 68 --- convector yellow/green/black
to speaker plug blue/blue/green? -- then green/black

if late 69 -- convector yellow/green/blue
to speaker plug black/green/ blue? ---- then green/black

I have no legible model number but I suspect 68 as the 2 blue wires are common on the pins--I suspect left/right speaker with a green ( which green) to plug then -- green/black

There is a 69 for sale on ebay about 10 miles from me and I have asked to look at his -- no response yet

I do have a ds501 mono convector coming and also 2 - 6 ohm resistors to put in series with 2- 4 ohm speakers for testing. I will get to the bottom of this. haha -- a challenge.

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Old 01-15-2018, 05:33 PM   #19
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You can put resistors (of adequate size) in the speaker lines to get better impedance match, but you will lose a proportional amount of volume and it may affect sound quality somewhat. It would be much better to get whatever speakers you use on each side to be wired such that 'total' speaker impedance is nearly equal to head unit output impedance.

For stock radio, the best match for modern speakers would be two 4 ohm speaker wired in 'series'. That would give you 8 ohms on each side. At full volume, you might get a bit of sound distortion as the output transistor would be driven a little higher on current than intended (due to lower speaker impedance), but you will not overdrive the amp to the point of damage. This exact setup is what I have with my stock '71 radio and I have no problem at all with clipping/damage. With 'tweeters' in the dash and the rest coming from the kick panels, the sound is full, rich, and of adequate volume to listen to ZZ Top while zipping down the highway.
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Old 01-15-2018, 06:55 PM   #20
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Thanks 7T1, will keep that in mind for future use. Looks like the bidding on ebay has increased for the 69. Anyone need the link? I am watching it as I could pick it up and save the shipping. I just want to see inside of it.
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