Old Cars, Modern Radios

[fogdot]

I bought two radios on Ebay. Just AM-FM units that were removed from new cars to install fancy units. No tape players, no CD's no bells and whistles.
One is going in my wife's 72 Stag, and the other in my 60 TR3.
Is there a way to feed the stereo output to a single speaker?
Will anything blow up if I connect the left and right output and run it to the speaker?
Dave

 

[poolboy]

I don't know, but the PO had an amplifier under the driver seat to boost the volumn to the speakers. I connected both speaker wires to one speaker and blew the amplifier's fuse. I don't know if anything like that would happen coming straight from the radio, though.
You say you have 2 radios ?

 

[fogdot]

2 radios, going into 2 cars. 2 speakers, but one in each car.

 

[poolboy]

Yeah, I was just kidding there at the last. Figured you'd have a back-up just in case one got fried.

 

[TR3driver]

Will anything blow up if I connect the left and right output and run it to the speaker?

Very likely, yes. When the two channels are different (out of phase), each amplifier's output will look like a short to the other amplifier. Some amps will put up with that, but most won't.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is there a way to feed the stereo output to a single speaker?[/QUOTE] You can build a simple combining network by adding a power resistor in series with each output. Of course some of the output power will be lost in the resistors, but perhaps that will be OK. If you need more power, you can run the junction of the resistors into an external amplifier.

I've also seen "center channel" speakers with two voice coils (so you can connect one to each amplifier channel), but don't recall where offhand.

 

[PATR8]

I had a modern radio in mine for 7 years, this summer (seems like lots going wrong with my 8 this summer) I noticed my amp struggling but the radio seemed ok, I hit the disk player and nothing happened so I swapped back to radio and drove it like that for a few weeks. I was on the way to the supermarket and I noticed some smell then SMOKE. I grabbed it by the face and it burned my fingers but yanked it out to include the wiring. Took it to the young thumping stereo kid down teh street and he took it apart and my disk was melted inside and the disk motor had been on fire. I have the radio fillling the space right now but will stick to the V8 harmony for now

 

[Dale]

TR3driver knows what he's talking about, but I think if it was me I'd pick up some cheap speakers at Radio Shack or Auto Zone and put one in each door and get the seperation. The Stag may already have facilities in the door for this. The 3 of course is a different prop, but still doable. The TR7s and 8s had the center grill in the dash for a single speaker, but no room for it with all the wires underneath. They were radio ready from the factory and equiped for door speakers. Just my two cents, have fun with whatever you do.

 

[swift6]

Or you could hook up the speaker to one side and use the balance control to push all the sound to that side and forget about stereo sound. If you only have one speaker no need to worry about stereo sound anyway as your not likely to find an inexpensive car stereo speaker capable of simulating two seperate channels through one driver.

Your welcome to try, but sometimes simpler is easier.

 

[TR3driver]

The Stag also has a single speaker grille in the center, although ISTR someone wrote of mounting two smallish drivers under the grille.

However, the 'cubbys' in the back seat look ideal for speakers (as long as you don't have rear seat passengers), and there's a company in England that sells inserts for the purpose that don't damage the original upholstery.

On the '3, I modified the driver's side kick panel to take a speaker, and used a Masonite mounting ring in the existing hole on the passenger's side. Worked reasonably well, but really needed more power than my 25watt (RMS) stereo could deliver. The Miata seats should solve the problem nicely in the 'new' TR, tho.

 

[fogdot]

Lots to think about and try. I was going to go with one channel and the balance cranked over, but wondered what else I could do. I've seen some very small tweeters that may fit in the dash space in the stag.
It's only money.
Dave

 

[PeterK]

Each side of the amp expects a specific resistance from each speaker (normally 4-8 ohm.) If you hook both outputs to one speaker the resistance will be off which may fry the radio. For your needs, look for a dual-voice coil speaker. Try customautosound.com, partsexpress.com, or ebay.

Another approach would be to get a large wire-wound 4-8 ohm resistor and run one side to the resistor and the other side to a single speaker, then set the output to mono on the radio.

 

[martx-5]

Just remember, the TR3 is positive ground. If you haven't already changed it to negative ground, this might be a good time to do it. Either that or you'll have to isolate the chassis of the radio from the body of the car.

 

[fogdot]

OK, the radio is in the Stag. FM is fine, but I get nothing but noise from AM.
Do I put a filter on the alternator, the radio power radio, or where.
Is it as simple as hooking up a filter?
Dave

 

[TR3driver]

Does AM work with the engine shut off? If not, then adding filtering isn't going to help and something is wrong with your radio or antenna.

Hmm, either way I'd look to be sure the antenna base is electrically grounded to the car. A bad connection there can play havoc with reception. Pull the antenna plug out of the radio and look for continuity between the outer ring of the plug and the car body. The receiver should also be grounded, of course.

Alternator noise is usually more of a whine, while ignition noise is more like static. If you are hearing a whine, a filter (capacitor) at the alternator output may help. Beyond that, all I know to do is try it and see. A reasonable quality radio should already have enough power filtering, so adding a power filter (at the radio) won't help. But cheap units sometimes don't have enough.

This is also a good time to check out your spark plug wires. Take both ends loose, and use an ohmmeter or DVM to check the resistance between the terminals. They should all be fairly similar, around 5 to 10 Kohm for the standard wires. If you find one wire much higher than the others, it should be replaced. Check the coil wire too.

I don't listen to AM much, but as I recall the AM performance was acceptable with the Kenwood I had in my first Stag, without any added filters. The (apparently original) AM radio in the second Stag doesn't work at all, so no help there.

 

[fogdot]

OK, some things to check this weekend.
Thanks, Randall

 

[emmett1010]

Hello:
As I recall AM signals required you to asjust the antenna trim.
Usually this was a small screw accessed through the front panel with a small flat tipped screwdriver. It was turned with the radio on a known AM station frequency until maximium volume and clairity was achieved.
Emmett