Audio amplifier for 6 volt, positive ground vehicle

Thread Starter

shortmort37

Joined Jul 20, 2016
18
I have a 1954 Plymouth that's 6 volt, positive ground. I have a shell of a radio that nicely fits the dash, and I'd like to put a bluetooth receiver in it with an audio amplifier, both powered by 6 volts. Any suggestions for me - either to build, or to buy?

Thanks
Dan
 

AnalogKid

Joined Aug 1, 2013
8,297
Could be an all-buy, all-ebay project.

There are many bluetooth receiver modules available that run on either +5 V or +3.3 V. These are very low power, so the 6 V can be dropped to 5 V with a zener diode and a small resistor.

The amp will be more tricky. Even with a 2 ohm speaker (yes, there were such things), you're not going to get much volume with only 6 V to power the amp. Better to use a boost converter module to get you some working room, and then either a traditional linear amplifier module or a Class D switcher.

ak
 

JMW

Joined Nov 21, 2011
122
I have a 1954 Plymouth that's 6 volt, positive ground. I have a shell of a radio that nicely fits the dash, and I'd like to put a bluetooth receiver in it with an audio amplifier, both powered by 6 volts. Any suggestions for me - either to build, or to buy?

Thanks
Dan
DDG 6 to 12 volt converter. There are many available, some even switch grounds.
 

Thread Starter

shortmort37

Joined Jul 20, 2016
18
Thanks for the replies - this sounds promising.

I'm drawing a blank on DDG, though. What does it stand for? Google's not helping 8^\
 

atferrari

Joined Jan 6, 2004
3,766
How the final circuit shoukd be connected when, most probably, the common of the circuit will be 0V?

I find this confusing.
 

Thread Starter

shortmort37

Joined Jul 20, 2016
18
Whether I go with 6V or boost to 12V (the latter seems like my best bet), the body of the car is earth ground. If I isolate the boost, amplifier and speakers from the car, I'll just tie earth ground (+ on the battery) to the + lead of the boost, and the - on the battery to the floating - of the boost. Ground will be relative to the audio circuit itself.
 

JMW

Joined Nov 21, 2011
122
Whether I go with 6V or boost to 12V (the latter seems like my best bet), the body of the car is earth ground. If I isolate the boost, amplifier and speakers from the car, I'll just tie earth ground (+ on the battery) to the + lead of the boost, and the - on the battery to the floating - of the boost. Ground will be relative to the audio circuit itself.
Remember the new radio is neg ground, the antenna ground is +, you will be putting 18 volts where it is least expected. The devices s in the link I posted take this into account, floating the radio. Making the antenna and any mounting issues irrelevant. Don't do anything without one of those converts. Been doing this awhile Mack was pos ground until the mid 70's All 2 way radios until the late 60's were +/- ground . Jumpers were provided. 6/12 were also common until the mid 60s.
 

Thread Starter

shortmort37

Joined Jul 20, 2016
18
No antenna - as I say when I started this thread, I want to put a bluetooth receiver and an amp in the radio shell. No AM/FM (except for the FM coming from my iPod nano). Wouldn't floating everything work with a conventional (and cheaper, probably more powerful) booster?
 

JMW

Joined Nov 21, 2011
122
No antenna - as I say when I started this thread, I want to put a bluetooth receiver and an amp in the radio shell. No AM/FM (except for the FM coming from my iPod nano). Wouldn't floating everything work with a conventional (and cheaper, probably more powerful) booster?
It will as long as you isolate everything. And keep it that way. I don't know how the "boosters" operate. The +/-convertors I used created a completely isolated radio, even though it was mounted to the vehicle frame. It has been at least 40 years since I've done this. The details have escaped.
 
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