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ACM: High-Level vs Low Level - What you need to know!

SoundsGoodStereo

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I understand most people know about this configuration in ForSCAN and most have an understanding of what it does.
But I believe there is one BIG misconception that you need to understand.

When you switch from "high-level" to "low-level" in ForSCAN, this is related to voltage, not input/output types. On your amplifier, DSP, etc, you still have to use the "high-level" inputs, you cannot just solder on RCA plugs and run into the low-level inputs of your amplifier. All factory radios (Regardless of ACM settings) output Differential Balanced Outputs (High-Level) and only aftermarket radios with RCA connections output Single Ended (Low-Level). There is no such thing as "low-level" in these trucks, just a lower voltage on the outputs.

ForSCAN code: 727-01-01 = External Variable=4 Volts (Not "Low-Level")

If you use "low-level" inputs on your amplifier, you will not have any type of noise rejection, to better explain, here is D'Amore Engineering explaining the differences in RCA / Signal along with John Myer from the Kicker team.

Any questions, please feel free to reach out to me and I can guide you in the right direction.


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RandyBobanders

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Appreciate the information. I'm curious why Ford would have the option to set the outputs to 4v? Is that just to match the input range of an external amplifier they sell such as the kicker sub upgrade package? In what circumstance would a user want to use FORScan to change the outputs to 4v? I guess maybe if the normal output voltage was higher than the amp/DSP's speaker-level inputs can handle? Or maybe it would extend the max volume level on the radio before clipping occurs - e.g. if it normally clips at level 21, cutting the output voltage to 4v might let it get up to level 27 before clipping?
 

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Appreciate the information. I'm curious why Ford would have the option to set the outputs to 4v? Is that just to match the input range of an external amplifier they sell such as the kicker sub upgrade package? In what circumstance would a user want to use FORScan to change the outputs to 4v? I guess maybe if the normal output voltage was higher than the amp/DSP's speaker-level inputs can handle? Or maybe it would extend the max volume level on the radio before clipping occurs - e.g. if it normally clips at level 21, cutting the output voltage to 4v might let it get up to level 27 before clipping?
Im the one that came up with the FOrscan change 7-8 years ago. Ford put in the acms for the Mustang Shaker system. Along with turning the output to 4 volts you can turn time alignment off and processing. You get a unclipped output to max voltage. I made a video with an Oscope showing it. I came up with it for the guys with sony sound so you could remove the sony amp. It also work in the mustang with taking out the shaker amp. Since its 4volt already you just had to turn the processing off int he ACM. They had it on in the ACM and DSP

This does NOT APPLY to 21 F150 ACMs or the new ACMS with the new style connectors. 2020 Super Duty is one that has the new ACM.
 
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SoundsGoodStereo

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Appreciate the information. I'm curious why Ford would have the option to set the outputs to 4v? Is that just to match the input range of an external amplifier they sell such as the kicker sub upgrade package? In what circumstance would a user want to use FORScan to change the outputs to 4v? I guess maybe if the normal output voltage was higher than the amp/DSP's speaker-level inputs can handle? Or maybe it would extend the max volume level on the radio before clipping occurs - e.g. if it normally clips at level 21, cutting the output voltage to 4v might let it get up to level 27 before clipping?
As Jesse said, it was for external amplifiers in the trucks/cars.

The only reason to ever lower input voltage is due to your amplifier not being able to handle the voltage, which is extremely rare since it's a high-level input into the amplifier.

Another case is for a very abusive customer who does not listen... Then you can ensure no clipping when he turns it all the way up on his new music, but for 99.9999% of people, having it clip earlier ensures they have enough volume over "clipping" on older music since it's recorded at a lower volume. So Pink Floyd, all the way up to 30 will be fine where a new Drake song would want to be at the clipping point of the radio 18-21.
 

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As Jesse said, it was for external amplifiers in the trucks/cars.

The only reason to ever lower input voltage is due to your amplifier not being able to handle the voltage, which is extremely rare since it's a high-level input into the amplifier.

Another case is for a very abusive customer who does not listen... Then you can ensure no clipping when he turns it all the way up on his new music, but for 99.9999% of people, having it clip earlier ensures they have enough volume over "clipping" on older music since it's recorded at a lower volume. So Pink Floyd, all the way up to 30 will be fine where a new Drake song would want to be at the clipping point of the radio 18-21.


Are there any Changes that you can make with forscan that will improve the sound quality
of the 7 speaker system in a 2021 XLT(not B&O)? can you bypass the equalizer?
 

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All processing is in the DSP. None in the ACM. You can turn the ANC off that typically helps. The processing in teh DSP is set to teh vehicle. There is a defualt setting I do not know the result of that.
 
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SoundsGoodStereo

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Are there any Changes that you can make with forscan that will improve the sound quality
of the 7 speaker system in a 2021 XLT(not B&O)? can you bypass the equalizer?

The best and most cost-effective way to get better sound in your truck is to install the Custom Made Door Access Block Off Plates. This will improve the door speaker performance and reduce the "boomy" performance you have now.
 

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The best and most cost-effective way to get better sound in your truck is to install the Custom Made Door Access Block Off Plates. This will improve the door speaker performance and reduce the "boomy" performance you have now.
I have already added those and was very impressed at how much they improved the sound. I am also going to add a " AudioControl ACM-4.300" amp, and possibly new speakers. Just wondering if there are any changes worth making with Forscan.

Thanks for the reply
 
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SoundsGoodStereo

SoundsGoodStereo

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I have already added those and was very impressed at how much they improved the sound. I am also going to add a " AudioControl ACM-4.300" amp, and possibly new speakers. Just wondering if there are any changes worth making with Forscan.

Thanks for the reply
Awesome!! When you add the new amplifier along with the proper Zen A2B integration, it will eliminate all of the factory sound processing and provide you with the perfect output to amplify.
 

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Awesome!! When you add the new amplifier along with the proper Zen A2B integration, it will eliminate all of the factory sound processing and provide you with the perfect output to amplify.

Is there a way bypass the factory sound processing with out using the Zen A2B? I have the base 7 speaker setup( no B&O ) in a 2021 XLT.
 

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SoundsGoodStereo

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Is there a way bypass the factory sound processing with out using the Zen A2B? I have the base 7 speaker setup( no B&O ) in a 2021 XLT.

Oh, non-amplified!! That one is very simple. Turn off the factory EQ in ForSCAN and utilize a hand-crafted t-harness from an amazing company :D to provide you with the signal + speaker wires.
 

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Oh, non-amplified!! That one is very simple. Turn off the factory EQ in ForSCAN and utilize a hand-crafted t-harness from an amazing company :D to provide you with the signal + speaker wires.


Thanks

Can you tell me the codes to change in Forscan to bypass the equalizer?
M truck is a....

2021 F150 XLT Crewcab
7 speaker (no B&O)
12" touchscreen

Thanks
 
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SoundsGoodStereo

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In the ACM, you change this to EQS Flat EQ

Ford F-150 ACM: High-Level vs Low Level - What you need to know! ACM
 
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SoundsGoodStereo

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Thank You,

I have been unable to find this info anywhere else.
You're welcome! We specialize in upgrading the stereo systems in these trucks, so it's important for us to find these little details.
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