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Discussion Starter · #1 ·
When installing an external amp, using the factory head unit, do you need load resistors across the output so that the head unit thinks it's driving speakers?

Apparently some head units, when they don't sense a speaker load, turn the sound off. So you need a resistor (maybe 8 ohms?) across the output to trick the head unit into thinking there are speakers. But I can't find any information about this for the Crosstrek.
 

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I've never hard of that. The only time you'd want to drop a resistor is to:

1. Simulate a speaker within a set of speakers run in series. This closes the circuit but keeps its overall impedance within specs.
2. Increase the impedance of the circuit to permit the use of, for example, a 2 ohm speaker on a circuit anticipating 4 ohms of resistance. If you only burn 2 ohms, you'd be sending back to much power and fry the amp. Drop in a 2 ohm resistor and your good to go.

Regardless, from a head unit perspective, your amp (or line out converter) is the speaker load. So no, you don't need to do that.
 

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Discussion Starter · #3 ·
I don't know why the head unit amp would distort with a high impedance load, but from Crutchfield -

"Factory stereo systems are getting smarter and smarter these days — which unfortunately makes adding aftermarket amplifiers and processors more difficult. Often, the most convenient place to get audio signal is from a factory amplifier's output, which shuts down or distorts when the speakers are disconnected. Kicker's KISLOAD4 smart radio interface solves this issue by providing the resistive load the amp needs to operate properly, and passing the signal along without any distortion or loss of power."
 

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When installing an external amp, using the factory head unit, do you need load resistors across the output so that the head unit thinks it's driving speakers?

Apparently some head units, when they don't sense a speaker load, turn the sound off. So you need a resistor (maybe 8 ohms?) across the output to trick the head unit into thinking there are speakers. But I can't find any information about this for the Crosstrek.
Yes possibly. With newer systems they have circuits that expect a certain load. You can use these to help.
 

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I guess I have something new to learn about. I truly don’t understand why AudioControl, in this case, is telling me. The sentence structures are OK, its the potentially misleading information that I question:

1. Why would a head unit suddenly decide to emit damaging frequencies because a speaker is disconnected? If it’s by design, good god, why?

2. If it’s sending a distorted signal… well, it must have an impedance load or else you’d never know about it and if it really is, you have other problems that a resistor won’t fix.

3. If it’s mute, then I guess you don’t have speakers or a measuring device and therefore, no load so you wouldn’t know about it.

4. All device inputs (amp, line out converter, speaker, etc) create a load on the circuit. My own amp‘s input impedance specs at 10k. Even speaker/rca wire adds measurable resistance. How would a desire to increase the demands on the head unit by requiring more output power to compensate the signal for loss created by adding more resistance be of benefit?

5. How exactly does a resistor stabilize a signal and why is it acceptable for a properly functioning head unit send an unstable signal?

6. In regards to AudioControl having specified that it applies to Subaru (with Starlink); Starlink runs through the telematics unit (another source of resistance) and if these things are supposed to be installed for the benefit of audio reproduction, in association with Starlink, it could only effective if installing after the telematics unit, for the front speakers only.

At least “they make a charming bracelet“. I bet they could be used as toe warmers as well.

If there really is something valid about these things, I really do want to understand. Until then, these things are no more than
306207


Regardless, for your installation purposes, I never had them and it worked fine. Additionally, AudioCotrol even states:

"IDEAL FOR OEM NON-AMPLIFIED (NO EXTERNAL AMPLIFIER)"

Edit: if these things are so important/valued/valid, why can I only find one manufacturer?


P.S. While firmly against DSPs for non-competition purposes, especially in a vehicle as opposite of soundproof as the XV is, there is value to the product. I just want to find the value for this product.
 

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Discussion Starter · #6 ·
I agree. I can't see why there would be distortion with a high impedance load. Or why they would deliberately shut off the sound if speakers are not attached - especially since any amp upgrade (including a manufacturer's own upgrades) will have a high impedance load.
 
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