high-low converter, resistor divider?

azira · 7th March 2004, 07:32 PM

In my old car I had to use a high-low converter to power my sub amp from my rear speakers. My sister wants to do that with her car right now until she replaces her deck. The ones I bought were isolation transformers. Can she just use a resistor divider (basically a 10k pot) to do the same thing? I was thinking that there shouldn't be much of a problem with it, it's significantly larger impedance than the 4-ohm speaker...

maylar · 8th March 2004, 11:32 PM

Line Level Converters (LLC) are available pretty cheap. The problem with a resistor divider is that the speaker outputs aren't ground referenced like RCA line inputs are.

In theory it should be possible to run just one side of a speaker output directly to a 10K ohm amplifier RCA input, using the car ground as the other side. You'll only get 4-5 volts rms, which most amps can handle fine. The only issue is how much noise you pick up in the ground side.

azira · 9th March 2004, 03:54 PM

Ah, thanks for the tip. Nothing in car audio is cheap, it's always way too marked up. I think she settled on an amp that has line level inputs so I guess the problem is adverted. Thanks.

7th March 2004, 07:32 PM	#1
azira diyAudio Member Join Date: Dec 2003 Location: Near Seattle	high-low converter, resistor divider? In my old car I had to use a high-low converter to power my sub amp from my rear speakers. My sister wants to do that with her car right now until she replaces her deck. The ones I bought were isolation transformers. Can she just use a resistor divider (basically a 10k pot) to do the same thing? I was thinking that there shouldn't be much of a problem with it, it's significantly larger impedance than the 4-ohm speaker...

8th March 2004, 11:32 PM	#2
maylar diyAudio Member Join Date: Jun 2003 Location: Connecticut	Line Level Converters (LLC) are available pretty cheap. The problem with a resistor divider is that the speaker outputs aren't ground referenced like RCA line inputs are. In theory it should be possible to run just one side of a speaker output directly to a 10K ohm amplifier RCA input, using the car ground as the other side. You'll only get 4-5 volts rms, which most amps can handle fine. The only issue is how much noise you pick up in the ground side. __________________ dave

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9th March 2004, 03:54 PM	#3
azira diyAudio Member Join Date: Dec 2003 Location: Near Seattle	Ah, thanks for the tip. Nothing in car audio is cheap, it's always way too marked up. I think she settled on an amp that has line level inputs so I guess the problem is adverted. Thanks.