Adding and additional amp to the OE system

ScottyMemphis

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Hi, I love this forum and just got my Supra last weekend! I am going to be implementing the changes in this thread to improve the quality of the OE system but I personally like a lot of sub bass that I know I won't get even from the best fixes that will give me.

With that being said, I've Googled and Googled, and gone through some threads here but can't answer this simple question:

How can I add an am (RCAs & remote power, specifically) to the OE system? In my old car, an FR-S, this was easy because the head unit had an extra RCA output and a dedicated remote wire, but I know times have changed and that probably isn't an option.

Thanks in advance!
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Hi, I love this forum and just got my Supra last weekend! I am going to be implementing the changes in this thread to improve the quality of the OE system but I personally like a lot of sub bass that I know I won't get even from the best fixes that will give me.

With that being said, I've Googled and Googled, and gone through some threads here but can't answer this simple question:

How can I add an am (RCAs & remote power, specifically) to the OE system? In my old car, an FR-S, this was easy because the head unit had an extra RCA output and a dedicated remote wire, but I know times have changed and that probably isn't an option.

Thanks in advance!
The Stereo AMP seems to be located in driver side of back of trunk. I haven't seen it so I cannot confirm but if it's true and if you know the wiring, it should be fairly simple to add moderate AMP that would not draw too much power from battery.
 

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@JasonO may be able to help you out with this...I believe he added another amp to the OE system.....
 

JasonO

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Hi, I love this forum and just got my Supra last weekend! I am going to be implementing the changes in this thread to improve the quality of the OE system but I personally like a lot of sub bass that I know I won't get even from the best fixes that will give me.

With that being said, I've Googled and Googled, and gone through some threads here but can't answer this simple question:

How can I add an am (RCAs & remote power, specifically) to the OE system? In my old car, an FR-S, this was easy because the head unit had an extra RCA output and a dedicated remote wire, but I know times have changed and that probably isn't an option.

Thanks in advance!
The factory system runs on a fiber bus. You have several options. You can order a Mostbus adapter. This will be between $400 and $900 depending on details. These usually come with a configurable DSP and will give you multiple independent RCAs (or opticals) out. It will also generate a remote out as the BMW Mostbus uses the fiber signal for turn-on now. Be careful as you can completely fuck your car by not following directions as this is the bus a lot of stuff wants to talk on.

The next option is getting a wiring harness that sits between the amp and a nearby signal processor (for the fake vroom vrooms and stuff). I tried to go this route but was ghosted by the company. The Coronavirus maybe played a part, I dunno. This will give you (if compatible), up to but maybe not, remote, full range signal, and sub signal or some bastardization in between.

The other option that may be a bitch but works for BMWs is to get the head unit recoded to the mid-fi system. You lose the graphic eq and only have bass and treble at the factory head unit. This change allows a pair of outputs to become operational and you can run an RCA from the head unit. No clue how to handle this with the Supra or if it works.

The next step is to splice speaker wires and get a good LOC and build your system with amps and limited DSP behind it. This is what I did. You can either pull a 12v signal from under the dash in the passenger side or get a signal generator and program it. I use the generator and once programmed correctly, it works perfectly.

All of the above allow you to keep full factory controls/integration.

The other method is to grab a signal from the speakers and run through an LOC. Then use a full featured DSP and amps and do all kinds of crazy processing. The only issue is you will lose the ability to adjust volumes with the factory system and keep your DSP set straight.

In short the factory DSP changes the eq curve with the volume. If you want perfect DSP corrections at all volumes or multiple curves that YOU not Harman decided based on volume, you will have to lose the factory volume at this time unless you get the MOSTBUS adapter or fairly get creative with gains and can chase your noise floor to zero.

So with all that said, what is your goal? You may not need to do as much as you think to get where you need to be.
 
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ScottyMemphis

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The factory system runs on a fiber bus. You have several options. You can order a Mostbus adapter. This will be between $400 and $900 depending on details. These usually come with a configurable DSP and will give you multiple independent RCAs (or opticals) out. It will also generate a remote out as the BMW Mostbus uses the fiber signal for turn-on now. Be careful as you can completely fuck your car by not following directions as this is the bus a lot of stuff wants to talk on.

The next option is getting a wiring harness that sits between the amp and a nearby signal processor (for the fake vroom vrooms and stuff). I tried to go this route but was ghosted by the company. The Coronavirus maybe played a part, I dunno. This will give you (if compatible), up to but maybe not, remote, full range signal, and sub signal or some bastardization in between.

The other option that may be a bitch but works for BMWs is to get the head unit recoded to the mid-fi system. You lose the graphic eq and only have bass and treble at the factory head unit. This change allows a pair of outputs to become operational and you can run an RCA from the head unit. No clue how to handle this with the Supra or if it works.

The next step is to splice speaker wires and get a good LOC and build your system with amps and limited DSP behind it. This is what I did. You can either pull a 12v signal from under the dash in the passenger side or get a signal generator and program it. I use the generator and once programmed correctly, it works perfectly.

All of the above allow you to keep full factory controls/integration.

The other method is to grab a signal from the speakers and run through an LOC. Then use a full featured DSP and amps and do all kinds of crazy processing. The only issue is you will lose the ability to adjust volumes with the factory system and keep your DSP set straight.

In short the factory DSP changes the eq curve with the volume. If you want perfect DSP corrections at all volumes or multiple curves that YOU not Harman decided based on volume, you will have to lose the factory volume at this time unless you get the MOSTBUS adapter or fairly get creative with gains and can chase your noise floor to zero.

So with all that said, what is your goal? You may not need to do as much as you think to get where you need to be.
Thanks for the detailed response! I think option 1 is the way I want to go. I saw you post about this unit in another thread. Do you know of any posts or videos on how to plug it up to the car? Also, if you plug the car's input into this device, does that mean that the OE amp will no longer be connected? Wondering how this sits alongside the OE system or if it is meant to replace it.

As far as my personal goal, I am an EDM DJ and like a considerably larger amount bass than the OE puts out. I don't like the looks of the proposed solutions in the other thread, such as the Bavsound or OEM Audio solutions.

Initially, my plan was to take my existing 10" JL Audio 10w3 and Phoenix Gold amp add it to the factory system, as is, once I get the 8's sounding better per tadda's amazing instructions. I'm not opposed to replacing the OE subs with my setup but I was planning on tuning the freq very low and using the OE subs for mid bass.

Definitely open to other ideas but I don't think paying 4k like one of the fellas in that thread is going to work for me.

Thanks for your time!
 
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JasonO

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Thanks for the detailed response! I think option 1 is the way I want to go. I saw you post about this unit in another thread. Do you know of any posts or videos on how to plug it up to the car? Also, if you plug the car's input into this device, does that mean that the OE amp will no longer be connected? Wondering how this sits alongside the OE system or if it is meant to replace it.

As far as my personal goal, I am an EDM DJ and like a considerably larger amount bass than the OE puts out. I don't like the looks of the proposed solutions in the other thread, such as the Bavsound or OEM Audio solutions.

Initially, my plan was to take my existing 10" JL Audio 10w3 and Phoenix Gold amp add it to the factory system, as is, once I get the 8's sounding better per tadda's amazing instructions. I'm not opposed to replacing the OE subs with my setup but I was planning on tuning the freq very low and using the OE subs for mid bass.

Definitely open to other ideas but I don't think paying 4k like one of the fellas in that thread is going to work for me.

Thanks for your time!
I honestly don’t know enough. By the time I discovered the MOSTBus solution, I was already done. I could be describing some details on this wrong, but I believe I am mostly right on it.

In looking at the manual, sometimes head unit coding may be required and they allude to a rabbit hole on unknown installs. They do list the Supra as compatible, so if you are interested, I would reach out to them. From what I have read, doing things wrong on the MOSTBus can cause serious issues with the car itself, so talk with them before jumping.
 
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ScottyMemphis

ScottyMemphis

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I honestly don’t know enough. By the time I discovered the MOSTBus solution, I was already done. I could be describing some details on this wrong, but I believe I am mostly right on it.

In looking at the manual, sometimes head unit coding may be required and they allude to a rabbit hole on unknown installs. They do list the Supra as compatible, so if you are interested, I would reach out to them. From what I have read, doing things wrong on the MOSTBus can cause serious issues with the car itself, so talk with them before jumping.
Thanks for the response Jason :)

Will keep digging and post back here when I come up with something.
 

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Supra Audio Amp, ASD Amp, and System Diagram

I recently had the panels off in the cargo area and also did some further investigation into the OE audio system wiring and component layout ...Here is what I have gathered so far which might or might not be helpful...I don't have pin designations yet but our system and components are identical to that of BMW's...

OE Audio Amp and ASD Amp location:

Amplifier.jpg


Harman Audio Amp and Active Sound Design Amp Location and Mounts:


Supra HK Amp and ASD lettered.jpg


Audio Amplifier Connections:

Amplifier  3 with labels.jpg


Harman Audio Amp p/n 2622901:

Amplifier part number.jpg


ASD Amp Connection:

ASD pins.jpg


Supra Audio System Diagram:

AMP ASD Diagram Supra.jpg


Active Sound Design Description:
Active sound design description 2.jpg
 
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ScottyMemphis

ScottyMemphis

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☝This could not have been more timely. I had my car at the shop today and they are putting an amp and sub in and was able to send them this, as they’ve not worked on a Supra yet. Thanks for posting this!
 

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Here is shop manual instructions on how to get to the amp....It's fairly easy with only 2 panels to remove...

Amp panel a1.jpg

Amp panel a2.jpg

Amp panel a3.jpg

Amp panel a4.jpg

Amp removal 1.jpg

Amp removal 2.jpg

Amp removal 3.jpg
 

tadda

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And while you have those 2 rear hatch panels removed to get to the Amp I would also eliminate the ASD (Active Sound Design Generator / i.e. faux engine noise) from the sound system by simply unplugging it...I got the chance to unplug the ASD module from the Amp today...No codes were thrown and does not affect sound quality in anyway...

You can also disable the ASD module using Bimmercode...

Supra HK Amp and ASD lettered.jpg


unplug ASD.jpg
 

joeyliv

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Anyone have a photo of the wire harness that plugs into the factory amp? I need to know what pins go to what speakers.
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