Shaker pre-amp signal measurements

I checked the pre-amp signals of my 400a system and found them to be in range of RCA line level. This is just confirming what we expected.

The range is 0.04 volts at 20% volume to 1.53 volts at 80% volume (and 3.1 volts at max volume) with a CD audio source.

I used a female Molex 34690-0160 plug to connect to the harness that feeds into the amp.
http://www.mouser.com/Search/ProductDetail.aspx?R=34690-0160

I took my measurements from the #7 and #8 pins, which represent the front left signal.

These voltages are on the weak side so I'll be using an Audio Control Matrix Plus up front to boost their strength before a cable run to the trunk area. It's going to take about a week for the Matrix Plus to get here. I'll let you know how it goes.

In the mean time I'm feeding my system by summing the factory amp signals. Here are my components:

Front speakers: Focal PS 165 F3
Rear deck: Focal PC 165
Sub: JBL CS-110LGTW
Amp: Alpine PDX V9
DSP: Audio Control DQ-61

The DQ-61 is adding some hiss at low volumes. I'll be eliminating it from the system along with the factory amp. I think I'll want another DSP or at least an equalizer to replace it, but I'll tackle that after I hear whether I get a clean sound from the Matrix Plus.

So you could just pins 7 and 8 BEFORE the amp and feed them to an MS-8 ? Cleaner source signal than using the speaker out wires AFTER the amp? Lost any fucntionality bypassing the factory amp?

neozeric said:

So you could just pins 7 and 8 BEFORE the amp and feed them to an MS-8 ? Cleaner source signal than using the speaker out wires AFTER the amp? Lost any fucntionality bypassing the factory amp?

Click to expand...

I don't expect any lost functionality bypassing the amp, just a cleaner signal. The amp does have noise cancellation inputs, however I don't believe those are in use for a GT. I don't notice a difference with them unplugged.

Yes, the signals going into the amp seem suited for an MS-8, which advertises 2.8V as the max line-level input voltage.

However, I'm not sure there's enough room up front to mount an MS-8. The wires are so thin that extending the run to the rear does not seem wise. So I'm going to start by mounting an Audio Control Matrix Plus under the kick panel to boost the signal. If that provides a clean enough signal to the rear I'll look into an MS-8 or similar (starting with an Audio Control EQX I have sitting around).

I'll have to figure out a way to put the MS8 nearby . I will be following this, let me know what you find out

I have my MS8 sitting in a box until you audio wizards figure it out ;)

I yanked out the factory amp today!

I used an Audio Control Matrix Plus to boost the signal enough to make it to the rear where an old-school Audio Control EQX feeds it to an Alpine amp.

It definitely sounds cleaner. Probably not worth it to most people, but I'm glad I did it.



Here's the outgoing factory Shaker amp.




Getting ready to mount the Matrix Plus to the factory amp bracket. I used 3M Strip Calk for anti-vibration.




Audio Control makes a single channel version of this called the Overdrive. It's much smaller and less expensive. Not a bad option if you want to control front/rear fader from your EQ or DSP.




It fits!


I used Molex plugs from mouser.com so I didn't have to cut my wires.



The factory remote amp turn-on signal is 6v. I used a PAC TR-4 Remote Turn-on Module as a 12V relay. This was soldered to pin 1 of the C2385B connector, which also provided the 12V power and ground.



:cheers: Thanks to Heinocerous and ThirtyThreePointThree for the amp diagrams and info on the molex connectors: http://www.mustang6g.com/forums/showpost.php?p=404864&postcount=41 and http://www.mustang6g.com/forums/showpost.php?p=428577&postcount=1



My setup:
Audio Control Matrix Plus
Audio Control EQX
Alpine PDX-v9
Front speakers: Focal PS 165 F3
Rear deck: Focal PC 165
Sub: JBL CS-110LGTW
Tuned with a UMIK-1 and WinMLS.

Wow h65, great work and attention to detail. Thanks for sharing!

Great write-up and pics! One question - did you run all new wiring to the speakers from the amp in the trunk?

Did you lose anything from sync with removing the factory amp?

NewTekBuzz said:

Wow h65, great work and attention to detail. Thanks for sharing!

Click to expand...

Bryman said:

Great write-up and pics! One question - did you run all new wiring to the speakers from the amp in the trunk?

Click to expand...

Yes, I ran a pair of 18 AWG 9-conductor speedwire bundles from amp to the speakers. I ran new wires up the A-pillars to the tweeters and used the existing wires that go into the doors.

neozeric said:

Did you lose anything from sync with removing the factory amp?

Click to expand...

No functions lost on my GT, however this would eliminate the EcoBoost noise cancellation and possibly the fake engine noise.

I like that this brought back my separate rear channel signal. This keeps the Sync tones, commands and calls isolated to the front. My previous setup had used signal summing from the front channel to feed all speakers. It had bothered me having the Sync blips and dialogue fill from the rear deck. It was louder than it needed to be and too immersive.

h65 said:

Yes, I ran a pair of 18 AWG 9-conductor speedwire bundles from amp to the speakers. I ran new wires up the A-pillars to the tweeters and used the existing wires that go into the doors.




No functions lost on my GT, however this would eliminate the EcoBoost noise cancellation and possibly the fake engine noise.

I like that this brought back my separate rear channel signal. This keeps the Sync tones, commands and calls isolated to the front. My previous setup had used signal summing from the front channel to feed all speakers. It had bothered me having the Sync blips and dialogue fill from the rear deck. It was louder than it needed to be and too immersive.

Click to expand...

I havn't quite had the time to sit down and review the wiring diagrams here, but assuming my quick glimpse is correct.


You've removed the factory amp, and your circut path is like this.


Factory Signal Level Molex connenctor -> Aftermarket Molex connector -> Male RCA -> Matrix Line Driver -> Standard RCA -> Processor/amplifier -> Speaker Wire -> Aftermarket Molex connector -> Factory Speaker level Molex Connector -> Factory Speaker wire -> Crossovers -> Aftermarket speakers

With a second circut path for the remote wire only with the pac module?

With the setup this way, you're getting adequate voltages without any signal summing at all, and this didn't require pulling out the factory headunit to get behind it?


Sounds fantastic if you never had to open up the dash.

The other question I had, is during your testing were all 4 speaker outputs (front l/r and rear l/r) all full range signals? No factory roll off at higher volumes for the low frequency?

And I assume there were no resistors anywhere inline between the factory amplifier and the midrange speakers or tweeters or you would have mentioned having to bypass/remove them?

Cream Puff said:

I havn't quite had the time to sit down and review the wiring diagrams here, but assuming my quick glimpse is correct.


You've removed the factory amp, and your circut path is like this.


Factory Signal Level Molex connenctor -> Aftermarket Molex connector -> Male RCA -> Matrix Line Driver -> Standard RCA -> Processor/amplifier -> Speaker Wire -> Aftermarket Molex connector -> Factory Speaker level Molex Connector -> Factory Speaker wire -> Crossovers -> Aftermarket speakers

With a second circut path for the remote wire only with the pac module?

With the setup this way, you're getting adequate voltages without any signal summing at all, and this didn't require pulling out the factory headunit to get behind it?


Sounds fantastic if you never had to open up the dash.

Click to expand...

Correct. Never had to get behind the dash. Everything is accessible from the left kick panel. The factory amp takes an RCA-level signal. You could hook up a DSP right to them instead of the Audio Control Matrix Plus.

I have not ruled out going with a Helix DSP, but for now I'm liking the old-school feel. I added an Epicenter today.

The gains on my amp are all set to the lowest setting.

My signal path is very much like what you mentioned except I'm using new wire from the amp to the crossovers under the driver's side seat then new wires to the kick panel area to meet up with the ones that feed the doors.

Cream Puff said:

The other question I had, is during your testing were all 4 speaker outputs (front l/r and rear l/r) all full range signals? No factory roll off at higher volumes for the low frequency?

And I assume there were no resistors anywhere inline between the factory amplifier and the midrange speakers or tweeters or you would have mentioned having to bypass/remove them?

Click to expand...

I don't have spectrum analysis from the factory signal or amp. I assume they are playing with the signals since that's so common these days. I'll measure for rolloff when I get a chance to open things up again. I'll generate some signals and check the voltages.

I measured for clipping using a DSO NANO and found a perfect sine at all volume levels. I'm only moderately confident in my readings... but it sure looks like the factory unit has no distortion at max volume.

I found no resistors in the factory wiring.

h65 said:

Correct. Never had to get behind the dash. Everything is accessible from the left kick panel. The factory amp takes an RCA-level signal. You could hook up a DSP right to them instead of the Audio Control Matrix Plus.

I have not ruled out going with a Helix DSP, but for now I'm liking the old-school feel. I added an Epicenter today.

The gains on my amp are all set to the lowest setting.

My signal path is very much like what you mentioned except I'm using new wire from the amp to the crossovers under the driver's side seat then new wires to the kick panel area to meet up with the ones that feed the doors.

Click to expand...

I'm going to try going straight to the amps with no processor or line driver, the alpine pdx's that im using pull rated power as low as 0.2v input so it should be alright. Considering their max input voltage is only 4v, the 3 from the factory HU might do it.

Can you list the part numbers you used for the molex connectors.. and which is signal side and which is output side.. thanks very much

Did you notice a big difference with the epicenter? I used to love those things back in the day