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Discussion Starter · #1 ·
Hey all...been a minute since I've posted, but I've got a question maybe someone could help me with.

I know hi/lo converters are used to convert speaker level connections into RCA connections. My question is...can the same unit be used in reverse (RCA to speaker level)?

I ask this question simply because with some OEM systems, there's an external amp being used. Running the regular speaker outputs from an aftermarket HU would be sending a signal stronger than the OEM HU was producing to the OEM amp, in turn...creating a situation for distortion to be created really easily.

I was thinking the low level outputs could be utilized in a set up like that, then you wouldn't have to worry about, right?

Feedback is greatly appreciated.
 

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Hey all...been a minute since I've posted, but I've got a question maybe someone could help me with.

I know hi/lo converters are used to convert speaker level connections into RCA connections. My question is...can the same unit be used in reverse (RCA to speaker level)?

I ask this question simply because with some OEM systems, there's an external amp being used. Running the regular speaker outputs from an aftermarket HU would be sending a signal stronger than the OEM HU was producing to the OEM amp, in turn...creating a situation for distortion to be created really easily.

I was thinking the low level outputs could be utilized in a set up like that, then you wouldn't have to worry about, right?

Feedback is greatly appreciated.
That is called an amplifier... :D

BMW and VW are the two manufacturers that I personally know of that use an OEM HU with a OEM amp with analog inputs. In those two particular cases the OEM amp also can accept high level signals from aftermarket HU without the need of any special device like what the one that you are talking about.

These OEM amps can take high level inputs from aftermarket HU just because their input stage is actually LOCs. The problem is that there are no OEM specs available to clearly determine the technical levels of high level input (max voltage/power) that these OEM amps can safely take. It can be possible to determine/guess those input levels somewhat based on what the OEM HU output levels and topology are -for example, BMW OEM HU analog outputs are generally 5V differential- but nothing like definitive OEM specs.

That's the real issue.

My recommendation is to find out the kind and voltage/power level of the OEM HU analog outputs by measuring them and then determine yourself if the aftermarket HU that you are planning to use is within those measurements and type.
 

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Discussion Starter · #3 ·
That is called an amplifier... :D

BMW and VW are the two manufacturers that I personally know of that use an OEM HU with a OEM amp with analog inputs. In those two particular cases the OEM amp also can accept high level signals from aftermarket HU without the need of any special device like what the one that you are talking about.

These OEM amps can take high level inputs from aftermarket HU just because their input stage is actually LOCs. The problem is that there are no OEM specs available to clearly determine the technical levels of high level input (max voltage/power) that these OEM amps can safely take. It can be possible to determine/guess those input levels somewhat based on what the OEM HU output levels and topology are -for example, BMW OEM HU analog outputs are generally 5V differential- but nothing like definitive OEM specs.

That's the real issue.

My recommendation is to find out the kind and voltage/power level of the OEM HU analog outputs by measuring them and then determine yourself if the aftermarket HU that you are planning to use is within those measurements and type.
I know the OEM amps take a high level input (in most cases), but...the question is the wattage coming off the head unit itself. In most cases...the wattage output of an OEM head unit is below 10 watts. Most aftermarket head units have wattages starting around 15 watts up to about 24 watts.

I know when I first put my head unit it (output of 22 watts rms) and I had the factory speakers in, I could barely turn the thing up past 10 without getting a lot of distortion. The OEM speakers are designed to handle the 45 watts rms that the OEM amp is feeding them. After replacing the OEM speakers with the Infinity Kappas (which are rated to handle up to 75 watts rms), distortion is only an issue if I crank the volume up louder than I care to listen at, so basically...distortion isn't an issue for me any more.
 

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Even if the headunit has an amplifier and makes, say 12 watts, watt is a measure of power power, you want to be looking at voltage. Power is derived from current, and voltage, current can't be made with a high impedance input, so if the headunit puts out 12 watts into a 4 ohm load then it's putting out. around 6.9V RMS. into a 10K ohm load like an amp per say (arbitrary number) then the headunit is actually putting out .005Watts ;)

Don't look at watts, look at volts.
 

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Discussion Starter · #6 ·
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