'72 Amplifier Location.

[Scott S.]

Hi folks. I'm reinstalling the orginal radio in my '72 and I'm stumped on the correct mounting for the amplifier. I'm pretty sure it goes behind the right-hand dash panel but I can't seem to find any existing holes that line up with the holes in the brackets. Can someone please explain how this should look? Or maybe share a picture?

Thanks (I thought this was going to be the easy part!)

[Patrick H.]

Re: '72 Amplifier Location.

Here's my 71:

[Joe L.]

Re: '72 Amplifier Location.

Patrick and Scott-----

Yes, however, this is an installation for a car with U-79 stereo radio. If Scott's car has just U-69, then he would have only the "convector", the device on the right side of the photo. In fact, I think that I can see at least one of the holes for the convector mounting in Scott's photo.

[Scott S.]

Re: '72 Amplifier Location.

Thanks Patrick. Now I'm wondering if the PO gave me the right part...

[Harmon C.]

Re: '72 Amplifier Location.

Scott
The part you have in your photo is for a radio with stero that I have seen used in 73's. The part in the photo plus the radio was all the parts needed in 73.The part on the upper right in Patrick's photo is for a standard radio. The large box on the left in Patrick's photo I do not know what it is but I'm sure Patrick will let me know.
Lyle

[Jack H.]

There are several variable here...

(1) Is the radio a base AM/FM unit or is it the optional FM stereo set?

(2) If the radio is the optional FM stereo, is the car A/C equipped or not?

(3) Do you have the correct radio external components for your year and configuration car?

Your copy of the AIM will show you the approximate mounting location for the components NOT contained within the radio chassis. Early Shark cars like the '72 in question use a 'convector' module on the base radio that mounts to the upper RH brace beneath the dash. One version of the convector works regardless of car configuration.

If you have a stereo radio, consult the AIM under section U79. The convector unit is NOT used and is replaced with an adaptor assy. There are two versions of the adaptor: one for base cars and another for A/C equipped cars. The general mounting location is shown in the AIM.

Last, as technology moved on, the adaptor was simplified for later versions of U79 around the mid/late 70's. The adaptor became a simple, 2-channel convector--a heat sink with DS-501 audio drive transistor(s) on it. Do NOT confuse/mix the various versions of the stereo adaptor!

If you see a car with a convector AND an adaptor under the dash, suspect someone has changed the configuration of the car from base radio to optional stereo radio....

[Eric F.]

Re: '72 Amplifier Location.

Lyle,

I have the same part for my 1975 stereo that Scott has. I couldn't find bolt holes to match either. I thought maybe someone replaced the mounting brackets. Do you know where it would attach under the dash? I checked the AIM but I couldn't tell from the drawing.

Thanks,

Eric

[Scott S.]

Re: There are several variable here...

Hi Jack, thanks for your response. I'll do my best to fill in the blanks:

1. Base radio (U69) according to the info I have from GM on the car.

2. I don't believe that it's a stereo unit. (no "Stereo" markings on it anywhere.) No A/C, LT-1 is the only option.

3. Correct external components? I guess that's the big unknown at this point. I'm starting to think it's not not unless there was some other bracket that was used to attach this convector to the existing holes. (seems pointless)

I don't have an AIM but it's in the mail. I was hoping to get this done sooner but it's so cold in the garage right now that it'll be a while before I get to it anyway!

Thanks for the help.
Scott.

[Jack H.]

Re: There are several variable here...

OK, when you get your copy of the AIM you'll see the only A/C impact comes from the optional AM/FM/Stereo radio and which adaptor is used. U69 is the base AM/FM radio and there is no adaptor only a convector.

The adaptor does FM Stereo channel separation. The convector is simply an aluminum heat sink with a DS-501 transistor installed on it which forms the final audio drive circuit. It's not really an 'amplifier'...it changes voltage waveforms to current waveforms to drive the speaker.

Look at the picture Pat posted. You'll see BOTH an adaptor as well as a convector unit! The adaptor is the larger 'box' that's almost dead center in his photo. The convector is the small 'box' that's all the way over to the right hand side, mounted on the birdcage reinforcing gusset and it's cocked about 12-degrees off dead horizontal.

Now, look at the picture you posted and you'll see two small holes drilled in your reinforcing gusset that are where the car's original convector unit was mounted. When you get your copy of the AIM, you'll see that's where the call out to mount the convector unit points to.

[Scott S.]

Re: There are several variable here...

Thanks Jack. Now I'm convinced that I either have the wrong convector for my radio or the wrong radio and convector for my car. The convector has 2 DS-501 transistors and there is no way that I can position it so that the holes in the mounting brackets align with the holes on the reinforcing gusset. I've even tried reconfiguring the brackets to no avail.

Do you know if there's any way to validate that may radio is a U69 from a '72 Corvette and not something else?

Man! I thought the difficult part was going to be removing and re-installing those nuts on the bottom of the guage cluster, they were a piece of cake compared to this!

Thanks again for the help.

[Jack H.]

Re: There are several variable here...

Ok, as I said earlier in the thread there were bacically two radios for early Shark cars (mono and stereo) and several configurations of them over time. The reason the mono radio (U69) had an external convector was due to the limited space behind the center cluster and designers moved the final speaker drive with its companion heat sink out of the radio chassis to gain space.

When the stereo version of the radio entered production (U79), space considerations required a substantial amount of electronics move out of the radio chassis and the 'converter' was born. This 'box' contained the stereo signal detector and L+R channel separation electronics.

In 1973, integration allowed the stereo electronics to be integrated back into the main radio chasis (ALMOST)... That version of the stereo radio was called U58 and it used a dual channel convector (one heat sink with two DS-501 xsistors, one for each channel). The U58 version of the stereo continued through 1978.

To tell the difference between the different radios, you either have to know what you're looking at or go by the Delco PN and do a look-up using the separate Delco radio catalog(s). The PN is on a paper sticker affixed either to the radio chassis or on the underside of the radio's upper cover.