Looking for help re. floating ground adapter use. I own a 1969 Lincoln Mark III with a factory premium sound 5 wire (grounded) 4 speaker system. As the car has 7,000 documented original miles I want to retain the factory radio/8 track and wiring but increase the fidelity.
Is it possible to use the Scosche floating ground adapter in reverse to back-feed into a Line Output Converter RCA signal from the two rear (common ground) stereo speaker wires, then into a modern 2 channel bridged amp to power hi end replacement rear speakers? Thanks in advance for any help
Is it possible to use the Scosche floating ground adapter in reverse to back-feed into a Line Output Converter RCA signal from the two rear (common ground) stereo speaker wires, then into a modern 2 channel bridged amp to power hi end replacement rear speakers? Thanks in advance for any help
Hi tsmith1315,
Thanks for the reply. Yes, single ground for the two rear speakers so it's an unbalanced speaker level load that I'll be feeding the amp . I'm thinking I'll have to run the signal through a transformer isolated passive stereo direct box, then through a line output converter to the amp to power then power the rear upgrade speakers?
Here's a couple of photo's of the car. It's a time capsule. Still has the original tires.
Thanks for the reply. Yes, single ground for the two rear speakers so it's an unbalanced speaker level load that I'll be feeding the amp . I'm thinking I'll have to run the signal through a transformer isolated passive stereo direct box, then through a line output converter to the amp to power then power the rear upgrade speakers?
Here's a couple of photo's of the car. It's a time capsule. Still has the original tires.
That's it!!! Wow, brings back memories. That's a huge 2-door car!
It shouldn't be a problem to run a common ground signal into an amp. A simple 2 resistor voltage divider would probably work well enough (and that's the essence of a line out converter). In other words, no need for a floating ground provisions here.
Motor noise is likely to be a problem in this situation, and either a ground loop isolator (just a pair of 1:1 transformers) or a line-out converter that has ground loop isolation built in will probably be necessary. You may find amplifiers that will accept the speaker input as-is and not have such issues.
Unless you're going to be connecting some other source, I wouldn't spend too much on replacement speakers. That enormously huge factory AM/FM/8-track seriously lacks in the sound quality dept, and anything beyond a modest upgrade will be wasted. That rear deck is pretty skinny, aren't the speakers 4x10 or thereabouts?
Honestly- if it was me, I would leave it as is. It's too sweet to mess with.
It shouldn't be a problem to run a common ground signal into an amp. A simple 2 resistor voltage divider would probably work well enough (and that's the essence of a line out converter). In other words, no need for a floating ground provisions here.
Motor noise is likely to be a problem in this situation, and either a ground loop isolator (just a pair of 1:1 transformers) or a line-out converter that has ground loop isolation built in will probably be necessary. You may find amplifiers that will accept the speaker input as-is and not have such issues.
Unless you're going to be connecting some other source, I wouldn't spend too much on replacement speakers. That enormously huge factory AM/FM/8-track seriously lacks in the sound quality dept, and anything beyond a modest upgrade will be wasted. That rear deck is pretty skinny, aren't the speakers 4x10 or thereabouts?
Honestly- if it was me, I would leave it as is. It's too sweet to mess with.
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Tim,
Thanks for your advice. I hear you about not messing with it brother. I believe what I have in mind won't alter the fabric or integrity of the car at all and, for that reason, I don't want to add another source.
The front speakers are 4X8 and I have no intention of r/p them or fiddling with the front circuit. The rears are actually 5 1/4" and I was going to r/p those with the same size Arum Cantus with 2" voice coils. They should slip right in the factory holes.
The factory 8 track amp puts out a "whopping" 4 watts per channel @ 8 ohms. I figured I could boost the rears to 37.2 watts each (75 @ 4 ohms) to drive them and adjust the response with the factory fader. Not looking for a thunder wagon. Just a bit more response/fidelity working with the limited options available in order not to overturn or abandon the factory OEM setup.
I'd store the stock speakers and everything would be completely reversible (no cutting, mods, same harness, etc.) I'd just route the rear speaker wire into the transformers / LOC / amp to power just the Arum Cantus. So what your telling me is no matter what, if I move forward, floating ground aside, I'll still need to add those devices mentioned.
Many Thanks,
Emil
Thanks for your advice. I hear you about not messing with it brother. I believe what I have in mind won't alter the fabric or integrity of the car at all and, for that reason, I don't want to add another source.
The front speakers are 4X8 and I have no intention of r/p them or fiddling with the front circuit. The rears are actually 5 1/4" and I was going to r/p those with the same size Arum Cantus with 2" voice coils. They should slip right in the factory holes.
The factory 8 track amp puts out a "whopping" 4 watts per channel @ 8 ohms. I figured I could boost the rears to 37.2 watts each (75 @ 4 ohms) to drive them and adjust the response with the factory fader. Not looking for a thunder wagon. Just a bit more response/fidelity working with the limited options available in order not to overturn or abandon the factory OEM setup.
I'd store the stock speakers and everything would be completely reversible (no cutting, mods, same harness, etc.) I'd just route the rear speaker wire into the transformers / LOC / amp to power just the Arum Cantus. So what your telling me is no matter what, if I move forward, floating ground aside, I'll still need to add those devices mentioned.
Many Thanks,
Emil
Looking at amps, take note of what input voltage it will accept. The amp may work without adapters.
If you want to go ahead and get a LOC instead just to be sure it will work together, find one that has ground loop isolation built in, and you won't need anything other than the LOC.
Does it have the automatic headlight dimmer? I don't see the sensor, that may have come along in 1970. It looks like the hidden headlights are even working.
BTW- just so you don't have to wonder or risk your own life to find out: It will do 130mph without a fuss. Maybe more, but that's where my manhood ran out.
If you want to go ahead and get a LOC instead just to be sure it will work together, find one that has ground loop isolation built in, and you won't need anything other than the LOC.
Does it have the automatic headlight dimmer? I don't see the sensor, that may have come along in 1970. It looks like the hidden headlights are even working.
BTW- just so you don't have to wonder or risk your own life to find out: It will do 130mph without a fuss. Maybe more, but that's where my manhood ran out.
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Hi Tim,
I found a used Diamond D300.2; in super shape, asking price $80. Older model without the speaker level inputs, just RCA's so the LOC is required but at that price I can't kick. Looking at a PAC LP7-2 LOC with remote turn on so I'd only have to run one power cable from the front to back which is very attractive to me.
Do you know if the LP7-2 has GL isolation? Not sure if it uses transformers, can't find a diagram of it's innards.
My mark doesn't have the auto dimming option. Everything functioned with the exception of the center toggle of the drivers side 6 way seat. The forward/aft function worked but the up and down didn't. The interior of that switch has 2 poly rockers that hold pins that depress the contacts to activate the motor functions. One of the rockers was broken.
Unable to find a replacement switch, I joined the two halves of the rocker together, reinforced the sides with flat metal splints using JB weld to join and encapsulate the repair. Works better than new! God bless JB weld. This is a common fail point on these switches. I posted some pic's of the process and finished product for anyone interested.
You're a better man than me. 130MPH is not a speed I'll be entertaining in the future but it's good to know it'll do it. With 500 fp of torque the car is deceptively powerful. Only drinks NON ethanol fuel of the proper octane. Many thanks for sharing your expertise!
I found a used Diamond D300.2; in super shape, asking price $80. Older model without the speaker level inputs, just RCA's so the LOC is required but at that price I can't kick. Looking at a PAC LP7-2 LOC with remote turn on so I'd only have to run one power cable from the front to back which is very attractive to me.
Do you know if the LP7-2 has GL isolation? Not sure if it uses transformers, can't find a diagram of it's innards.
My mark doesn't have the auto dimming option. Everything functioned with the exception of the center toggle of the drivers side 6 way seat. The forward/aft function worked but the up and down didn't. The interior of that switch has 2 poly rockers that hold pins that depress the contacts to activate the motor functions. One of the rockers was broken.
Unable to find a replacement switch, I joined the two halves of the rocker together, reinforced the sides with flat metal splints using JB weld to join and encapsulate the repair. Works better than new! God bless JB weld. This is a common fail point on these switches. I posted some pic's of the process and finished product for anyone interested.
You're a better man than me. 130MPH is not a speed I'll be entertaining in the future but it's good to know it'll do it. With 500 fp of torque the car is deceptively powerful. Only drinks NON ethanol fuel of the proper octane. Many thanks for sharing your expertise!
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