Wiring Audiocontrol LC2i, rear speaker signal vs front speaker signal

[revdoc]

I was recently installing a sub and amp in my 16 FiST and after reading several threads here I thought I had it all worked out. Setup is a Skar VVX 15 with a Skar 800.1 amp in a ported box, Audiocontrol LC2i line out converter. The box basically takes up the entire trunk area but sits below the seat back and package shelf so it's not visible from outside the car. Amp and LC2i are mounted to the front of the box. I tapped the LC2i into the rear speaker wires in the passenger side B pillar as several posts had mentioned.

Once I listened to it, I knew something was wrong. The sub lacked low end extension and sounded a bit muddy. I have had several ported 12" or 15" subs over the years, I am very familiar with how it should sound. Then I remembered the last time I did this in a newer Ford, a 2012 Focus, I had to tap the front speakers for the LC2i signal source because the rears had some serious EQ or crossover applied to them. I know there is the AccuBass function and all that on the LC2i, but I think you are better off to start with the most complete signal you can instead of using the AccuBass to restore what's missing.

The next day I went out and got into the passenger kick panel, there is a large connector (C212) in there with the front passenger speaker wires (white/violet for positive, white/orange for negative). I unhooked my original wires from the B pillar speaker wire and ran them another 3-4 feet up to the kick panel and connected them to the front speaker. WOW what a difference! AccuBass threshold is turned all the way down and the AccuBass knob is all the way down, and I still have full low end extension down to 20 hz (well the box drops off around 32 or so, need to play with the port length).

Just thought I would post this as I have read several of the install threads and many/most of them tap into the rear speaker. If you have time and think you should be getting more bass out of your system, you might rewire it to the front speaker and see if it's any different/better. You probably wouldn't notice this much on a smaller sub or sealed box, or if you don't listen to a lot of deep bass like Decaf remixes. Pics of the system to come, will probably make a new thread for it.

 

[GAbOS]

That is very interesting as I have always heard that there should be no difference front to rear as far as factory EQing goes. I wonder if this is something new with the 2016 and Sync 3 setups.

 

[revdoc]

I don't have real proof other than my ears, but here is my post on FocusFanatics from back in 2012 where I got the info for the Focus: http://www.focusfanatics.com/forum/...adding-amp-base-model-stereo.html#post4169865

I may try playing with my voltmeter and some test tones on a USB stick, see if I can measure the AC voltage output at 20 hz, 30 hz, on up on both the front speakers and rear speakers and compare them. If my theory is correct we should see less voltage on the rear speakers at low frequencies.

 

[GAbOS]

Good call. I am hoping to finally get around to installing my gear this summer. I will be using a PPI DSP myself and would be willing to get the same data you are looking to gather from my 2014 so we can have a definitive answer to this.

 

[revdoc]

Did some testing yesterday and have some numbers that seem to confirm the problem. If anyone wants to duplicate or verify these results the method was fairly easy. All you need is a multimeter capable of measuring AC voltage, preferably digital, and some test tones or a tone generator. I uploaded the tones that I used to Mega and put the link below if you want to use them for a direct comparison. First, make sure you set your volume at 10 and turn off any equalization or balance/fade adjustments on the head unit. Connect your multimeter to the front speaker wire, easy to find on passenger side in the kick panel. Play test tone, write down voltage AC and frequency of test tone. Repeat for each test tone. Then connect the multimeter to the rear speaker wires, easy to find in the B pillar on passenger side. Play test tone, record voltage and frequency, repeat.

SPL Test Tones download

I whipped up a quick chart in Google docs to show the differences more easily. It kind of looks like the front speakers have a highpass crossover around 70 hz, but the rears have that and more, they also fall off above 70 hz. This implies that the difference is not a simple attenuation on the rear speakers, as it would if the curves matched in shape.

2016 Fiesta Speaker out voltage front vs rear

I am going to test an aftermarket head unit next, as a control. It should have a much flatter curve.

 

[chicagoslick]

I am running the LC2I tapped into the left side rear and all is working well. Did you run parallel wires to open channel on LC2i? In my case I ran parallel jumper wires to the right channel from my left input. I am running a sealed enclosure with JL Audio amp and JL shallow mount 12 " sub.

 

[GAbOS]

Did some testing yesterday and have some numbers that seem to confirm the problem. If anyone wants to duplicate or verify these results the method was fairly easy. All you need is a multimeter capable of measuring AC voltage, preferably digital, and some test tones or a tone generator. I uploaded the tones that I used to Mega and put the link below if you want to use them for a direct comparison. First, make sure you set your volume at 10 and turn off any equalization or balance/fade adjustments on the head unit. Connect your multimeter to the front speaker wire, easy to find on passenger side in the kick panel. Play test tone, write down voltage AC and frequency of test tone. Repeat for each test tone. Then connect the multimeter to the rear speaker wires, easy to find in the B pillar on passenger side. Play test tone, record voltage and frequency, repeat.

SPL Test Tones download

I whipped up a quick chart in Google docs to show the differences more easily. It kind of looks like the front speakers have a highpass crossover around 70 hz, but the rears have that and more, they also fall off above 70 hz. This implies that the difference is not a simple attenuation on the rear speakers, as it would if the curves matched in shape.

2016 Fiesta Speaker out voltage front vs rear

I am going to test an aftermarket head unit next, as a control. It should have a much flatter curve.

Need more info! What year car, sync version, wires you used to test, colors are helpful. Test both front and rear or just front?

 

[revdoc]

I am running the LC2I tapped into the left side rear and all is working well. Did you run parallel wires to open channel on LC2i? In my case I ran parallel jumper wires to the right channel from my left input. I am running a sealed enclosure with JL Audio amp and JL shallow mount 12 " sub.

I did jumper the two speaker wires at the LC2i so that all 4 terminals were used.

Need more info! What year car, sync version, wires you used to test, colors are helpful. Test both front and rear or just front?

It's a 2016 Fiesta ST, it has Sync 3.0 with nav, I have never updated it so don't know what firmware revision. I used this link to determine wire colors: http://www.fiestastforum.com/forum/threads/3642-Ford-Fiesta-ST-Speaker-Wire-Colors. I used the white/violet and white/orange wires for the front passenger speaker, they are easily accessed via removing the passenger kick panel and pulling out the big locking connector with 20+ wires in it. I think it's connector C212.

I used brown/white and brown/blue for the rear speaker, just pop the B pillar trim loose then pull the two plastic push pins out and pull the plate they were in out. The wire harness runs through this plate and the brown/white and brown/blue wires are twisted together, should be easy to find.

I tested front and rear. I will admit there is a flaw in the test, I checked my EQ settings afterwards and the Driving Position was set on Driver instead of All, so I bet that's why there is a difference between front and rear. However, there is still a dramatic drop in frequency response after you get below 70 hz even on the front speakers. That is the problem for me currently, I will do a test with an aftermarket head unit and I will also try to test the factory stuff again with the Driving Position fixed.

 

[chicagoslick]

It would not be surprising for the speakers in the car to be choked back to 70hz and above. Years ago prior to all these nice cross over networks and active crossovers from head units, capacitors were used to keep lows from damaging the speakers less than 8 inches. What we most likely hear from the Sony system is "manufactured" lows replicating the original source, and not a true passing of the source. With the factory system we will only be able to do so much. Because there is not much room in this car, I would suggest a sealed enclosure with a 12 inch sub. This will allow you to set the crossover on the sub at 80hz creating a nice bridge between the factory system and the sub. While a 15 inch sub can play at 80hz it is not as effecient at that. It will get muddy. 15's are best crossed over at 50 hz and below.

One other thing I'm curious about is your setting for octave slope. I am set at 24db. Generally 12dB is used, but for the aucustic characteristics of our car it seams like 24 sounds best. This is really a listener preference. 12db seems to make the bass muddier. 24db will tighten it up a little.

You are going about it the right way by using a meter and source recordings. Be careful trusting all of that as the system is tuned by the factory.

What after market head unit are you going to use? If it is not considered an audiophile quality unit, you will have some of the same issues you are experiencing now with the factory system in the car.

Best of luck...

 

[antarctica24]

I was recently installing a sub and amp in my 16 FiST and after reading several threads here I thought I had it all worked out. Setup is a Skar VVX 15 with a Skar 800.1 amp in a ported box, Audiocontrol LC2i line out converter. The box basically takes up the entire trunk area but sits below the seat back and package shelf so it's not visible from outside the car. Amp and LC2i are mounted to the front of the box. I tapped the LC2i into the rear speaker wires in the passenger side B pillar as several posts had mentioned.

Once I listened to it, I knew something was wrong. The sub lacked low end extension and sounded a bit muddy. I have had several ported 12" or 15" subs over the years, I am very familiar with how it should sound. Then I remembered the last time I did this in a newer Ford, a 2012 Focus, I had to tap the front speakers for the LC2i signal source because the rears had some serious EQ or crossover applied to them. I know there is the AccuBass function and all that on the LC2i, but I think you are better off to start with the most complete signal you can instead of using the AccuBass to restore what's missing.

The next day I went out and got into the passenger kick panel, there is a large connector (C212) in there with the front passenger speaker wires (white/violet for positive, white/orange for negative). I unhooked my original wires from the B pillar speaker wire and ran them another 3-4 feet up to the kick panel and connected them to the front speaker. WOW what a difference! AccuBass threshold is turned all the way down and the AccuBass knob is all the way down, and I still have full low end extension down to 20 hz (well the box drops off around 32 or so, need to play with the port length).

Just thought I would post this as I have read several of the install threads and many/most of them tap into the rear speaker. If you have time and think you should be getting more bass out of your system, you might rewire it to the front speaker and see if it's any different/better. You probably wouldn't notice this much on a smaller sub or sealed box, or if you don't listen to a lot of deep bass like Decaf remixes. Pics of the system to come, will probably make a new thread for it.

Nice Save

 

[revdoc]

Ok, found some more info after much web searching. It sounds like it is possible to disable the factory EQ / crossover / DSP with FORSCAN. See thread: http://www.diymobileaudio.com/forum...37121-reprogram-ford-sync-hu-flat-output.html. It is even possible to convert the speaker output from high level to 4V line level outputs, if you were going to run a fully amplified system. This would negate the need for the Audiocontrol LC2i entirely, at least in my case.

In the first part of the thread they mention you can only do this with a Ford IDS scantool, but by end of the thread they say the feature has been added to FORSCAN. I am going to try it out soon and will repeat my testing to see if it works.

Also, the AccuBass feature on the LC2i is supposed to restore the lost low end bass, which is basically what I'm looking for, so I tested it similarly to the way I tested the stock speaker outputs. I cut an RCA cable in half and wired one end to my multimeter, set to vAC. Plugged the other end into the Audiocontrol LC2i output and turned the threshold knob all the way up. This should make AccuBass active at all times. Then I measured the output voltage at 20 hz to 80 hz in 5 hz increments. Then I turned the AccuBass knob all the way up and repeated the test. It does boost the lower frequencies, but it is centered at about 55 hz. Even with maximum gain, it only boosted the 20 hz frequency to 0.198v, while boosting 55 hz way up to 3.33v. So there is still steep roll off down low, in fact it is even steeper with the AccuBass enabled as you can see from the graph.

 

[antarctica24]

Ok, found some more info after much web searching. It sounds like it is possible to disable the factory EQ / crossover / DSP with FORSCAN. See thread: http://www.diymobileaudio.com/forum...37121-reprogram-ford-sync-hu-flat-output.html. It is even possible to convert the speaker output from high level to 4V line level outputs, if you were going to run a fully amplified system. This would negate the need for the Audiocontrol LC2i entirely, at least in my case.

In the first part of the thread they mention you can only do this with a Ford IDS scantool, but by end of the thread they say the feature has been added to FORSCAN. I am going to try it out soon and will repeat my testing to see if it works.

Also, the AccuBass feature on the LC2i is supposed to restore the lost low end bass, which is basically what I'm looking for, so I tested it similarly to the way I tested the stock speaker outputs. I cut an RCA cable in half and wired one end to my multimeter, set to vAC. Plugged the other end into the Audiocontrol LC2i output and turned the threshold knob all the way up. This should make AccuBass active at all times. Then I measured the output voltage at 20 hz to 80 hz in 5 hz increments. Then I turned the AccuBass knob all the way up and repeated the test. It does boost the lower frequencies, but it is centered at about 55 hz. Even with maximum gain, it only boosted the 20 hz frequency to 0.198v, while boosting 55 hz way up to 3.33v. So there is still steep roll off down low, in fact it is even steeper with the AccuBass enabled as you can see from the graph.

I think this, if true, is a major step in the right direction. It certainly gives one the ability to do away with all of the nonsense created by Sony, and not that they have some elaborate history of making great products for the car. They have a 1 or 2 shinning moments in the last 20 years. I am willing to give them credit for portable music in the Walkman. 4 volt out, is definitely in the right direction, and you don't have to use any kits and can keep your display, if that's your thing. But by doing this, you are in effect, doing away with all of the tuning on the vehicle which agreed is junk. What this means is you now have to get something to retune the vehicle with.

GREAT FIND!

 

[chicagoslick]

Ok, found some more info after much web searching. It sounds like it is possible to disable the factory EQ / crossover / DSP with FORSCAN. See thread: http://www.diymobileaudio.com/forum...37121-reprogram-ford-sync-hu-flat-output.html. It is even possible to convert the speaker output from high level to 4V line level outputs, if you were going to run a fully amplified system. This would negate the need for the Audiocontrol LC2i entirely, at least in my case.

In the first part of the thread they mention you can only do this with a Ford IDS scantool, but by end of the thread they say the feature has been added to FORSCAN. I am going to try it out soon and will repeat my testing to see if it works.

Also, the AccuBass feature on the LC2i is supposed to restore the lost low end bass, which is basically what I'm looking for, so I tested it similarly to the way I tested the stock speaker outputs. I cut an RCA cable in half and wired one end to my multimeter, set to vAC. Plugged the other end into the Audiocontrol LC2i output and turned the threshold knob all the way up. This should make AccuBass active at all times. Then I measured the output voltage at 20 hz to 80 hz in 5 hz increments. Then I turned the AccuBass knob all the way up and repeated the test. It does boost the lower frequencies, but it is centered at about 55 hz. Even with maximum gain, it only boosted the 20 hz frequency to 0.198v, while boosting 55 hz way up to 3.33v. So there is still steep roll off down low, in fact it is even steeper with the AccuBass enabled as you can see from the graph.

Nice work revdoc!!!

 

[revdoc]

I messed around with this and got it working Friday night via FORSCAN and a cheap ELM327 cable purchased from Amazon. The cable was identified as a v1.5 by the FORSCAN software, I had read that you need a special switch installed to access the MS-CAN bus with this cable but the one I have appears to work without it.

The important bit is this:
In the ACM module
727-01-01 xx59 F8x8 xxxx - Enables Line Level with Optional Subwoofer (Aux 1) and Front Center (Aux 2) Outputs Enabled*
727-01-02 00xx - Disables Factory EQ Processing
(ACM As-Built)
I only changed the ACM 727-01-02-00xx line, mine was originally 4434, changed to 0034. The difference was immediately obvious. My box is still not tuned as low as I'd like, but it has much more volume at lower frequencies after this. I also noticed if I turned up the volume too high the door tweeters would distort, crackle or pop indicating that the factory crossover or bass cut is not there anymore. I will do some voltage testing soon so I can have empirical evidence to back up my ears, but after listening to it all weekend I am convinced it is a much flatter response now.

 

[Stormy]

Damn. That diymobileaudio thread is formidable. Seems like you have a good grasp on this topic so maybe you can answer a couple questions for me. I also have a '16 with sync3 and Nav.

I see discussion of settings for low level output. Does our HU or ACM physically have low level outputs somewhere that we could tap into as opposed to using an LLC?

I'm assuming the reprogram removes time alignment and everything and not just the curves, right? I was tempted to get a JL Fix 86 but if we can bypass factory DSP I could jump straight into a TWK88 or a PPI 88R fed from a line out or an LLC and save a bundle. Seems like the fix can also cause issues with BT phone use, too. It'd be nice to dodge that bullet.

 

[chicagoslick]

Stormy,

The FiX-86 has not caused issues with the phone for me. I read JL's information about that possibility and then created a specific program setting within the TwK. I have since removed that program in my latest revisions. If you did have issues, JL created a away to tune around it. Not advocating the use of JL equipment, just letting you know that I have not experienced issues with it...Best of luck...

 

[chicagoslick]

Nice work revdoc!!!

Hello revdoc,

What volume level did you have the source unit set at? When I was running my test tones (JL Cal CD) I turn the volume to 3/4 (23 out of 30 volume) and the readings were anywhere from .3-3.4 VAC (coming from the factory speaker wiring). I think the Cal CD runs tones at 50hz, 200hz, 1khz and 8khz. I will check it later tonight and verify that is what I was getting. I am going off of memory.

thanks,

 

[Stormy]

Stormy,

The FiX-86 has not caused issues with the phone for me. I read JL's information about that possibility and then created a specific program setting within the TwK. I have since removed that program in my latest revisions. If you did have issues, JL created a away to tune around it. Not advocating the use of JL equipment, just letting you know that I have not experienced issues with it...Best of luck...

Thanks for the heads up. Honestly, the big draw for me in the savings and simplicity of not needing two units. As I mentioned in the other thread, this isn't a comp system. It's intended to be a relatively simple build to make the sound liveable but not attract negative attention from the wife. Haha. As you know this started as an $80 sub proof-of-concept and has already tapped into my old fires and turned into full upgrade mode. $400 in processors I can barely justify. $800 plus is a definite no go. If I could skip the Fix 86 and just get a TwK 88 it would be a game changer.

 

[GAbOS]

I will be using a PPI 88R and take it to someone to flatten it out using a scope versus a unit to 'auto' flatten out the DSP.

 

[Stormy]

There's a difference in that, though. DSP is flattening out your input signal, removing all the hidden processing in your system that you didn't know about and can't control, giving you a clean sheet from which to tune. Cabin RTA tuning is applying adjustments to compensate for reflections and other modifications to your sound created by the environment. A flat cabin curve doesn't sound good and changes as soon as you add people, road noise etc. Flat cabin curves don't serve much purpose outside of SQ competition AFAIK. I used to compete and I ran 2 banks of audio control EQs, one for flat cabin RTA and one for sound judging and the differences were dramatic. If you plan to compete, get an RTA leveling and smash that curve but if you're not I'm not sure you need/want to do it.