[Pwnage1337]

Hello All


I have a 2017 Malibu 7" touch screen.

I am looking for information if anyone has it about the rear mounted amplifier.

About a month ago, i installed a LOC and an amp. it has been working great, until yesterday i got into the car and noticed the sub was hardly playing. I tapped into the 'amplified lines' (the thicker ones) when wiring the LOC. It is my understanding that the thinner wires are the signal from the headunit, and the thicker ones are the amplified signal going back to the speakers.

I am relatively skilled with a multimeter, so i began checking things, starting with the output to the amp. I started with a 50hz test tone, which i used to set the gains initially. Only 5v output to the sub (equivalent to 25w). I had initially set it up for about 700w RMS, so should have been in the neighborhood of 26.5v

Then i checked the voltage of the RCA's to the amplifier, and had around .300v. This seemed low to me.

I checked the input voltage to the Line out converter, and get 2.00V, with a 50hz test tone at 47 volume.

Now the interesting part is when i check the inputs from the head unit into the amplifier, i get the same voltage as the output voltage from the amplifier to the speakers....

IE, the front right speaker positive and negative are 2.0v from the head unit, and are also 2.0v going to the speakers after the signal has gone through the amp. This is equivalent to about 5 watts, so it seems like the amplifier is not amplifying anything.

Does anyone know the estimated output power of the amplifier? I have read it is around 22 watts or maybe 30 watts.

If anyone with a multimeter would be able to check the voltages their car puts out, that would be great. Its pretty easy to backprobe the green connector and get measurements

Any help is greatly appreciated!!

 

[Pwnage1337]

I should add that the radio works fine, all chimes work fine.

The LOC is still powering up the amplifier when the radio turns on, so it seems to be working. From my knowledge, the LOC will take 'high level' inputs and reduce them to a low level signal the amp can use (i think typically 4-8v)

Edit:

2017 LT factory radio frequency response

I tested the output of the factory head unit on a 2017 LT. I used both an oscilloscope and a PC based RTA to measure both signal amplitude and frequency response. Signal into the amp is 2V p-p balanced, 3V with EQ boosted. Input to factory amp Sound Devices USBPre line input Both...

www.chevymalibuforum.com

I found this thread that identifies that the voltage into the amp should be 2.0v. Which is great, that is what i have.

Now need to figure out why i am only getting 2.0v on the output of the amp.........

 

[campb292]

This third line of your first post says you added a LOC and an amp. Did your amp replace the ANC/amp built into the car or are they both running simultaneously with yours powering a sub?

 

[Pwnage1337]

added an LOC to run a subwoofer amp

the amp built into the car is still driving the regular speakers, the amp that i added is powering a sub

 

[campb292]

Under 3000 rpm the ANC unit is functioning in cancel priority mode which makes testing harder. What occurred is pretty typical though; everything seems fine for a few weeks then problems start. The actual service manual from helminc details everything you could possibly need but the alldatadiy version doesn't have the same detail other than the wiring schematics and amp replacement procedure.

 

[Vince Foster]

Hello All






Does anyone know the estimated output power of the amplifier? I have read it is around 22 watts or maybe 30 watts.

If anyone with a multimeter would be able to check the voltages their car puts out, that would be great. Its pretty easy to backprobe the green connector and get measurements

I don't have the skills to test the output power, but it's something I've wondered about. I searched and searched online for what kind of IC amp chips GM uses in their OEM
amplifiers. Could not find an exact answer, but some people say GM uses amp chips from ST Micro TDA7562. If this is correct, it can put out about 10 to 12 watts RMS per channel into 4 ohm. It can probably handle peak power of 20 watts/channel without clipping too badly. This should play reasonably loud with average car speakers, but no super blast level like the crazy subwoofer setups. I have asked a few experts who test car audio gear, and they say they don't bother testing OEM specs because the serious customers always want to replace it anyway. And one guy said that it's hard to hook up OEM gear to the test equipment because of the proprietary connectors.
But the 10 watts/ch figure seems reasonable.

 

[Pwnage1337]

It's very easy to back probe the OEM connector, you don't even need to disconnect it. You can touch the metal pins from the back side with the meter probes

I could take a picture of how to do it, I don't need O scope type readings just a simple ac voltage on the output of the amplifier.

Worst case scenario I'm going to tap the 2V pre amp connection and run it to the amp directly

 

[DrivenDaily]

I have a 2011 LTZ with the Bose system.

A couple years ago I replaced the 4 speakers (2 front doors, 2 rear package shelf) with Rockford Fosgate "Punch". I kept the 2 tweeters in the A-pillars. I lost all of my bass, but at the same time I suddenly started hearing all of the words that Roy Orbison was singing. I even adjusted the 3-band EQ to put the highs all the way down, the mids around the center or lower, and the bass all the way up. Still no joy.

So I bought an 8" RF sealed sub-woofer and a 5-channel 750-watt RF amp. I removed the Bose amp and spliced into the factory wires without cutting off the connectors, then hooked it all up.

I still have to run the highs all the way down, the bass all the way up, but the mids can now be a bit above center. If I turn it way up, the sub will shake the windows so much that the mirror adjusts itself so I'm looking at the back seat. If I go higher than that, my ears start to bleed because there is so much high frequency coming out of the speakers. I haven't found a way to reduce the power of the 4 speakers, so I've learned to not turn it up that loud unless I just really need to hear that song and feel the thumps.

If I were to do it again, I wouldn't get the "Punch" series. I think they're designed to be way brighter than anything else out there, and the blood stains on my shirt collars seem to echo that.

Any suggestions for me or any future readers on what might be a better course of action?

 

[Pwnage1337]

Run a matched component set that have their own crossovers matched to the tweeter and the mid woofer.

Did you put Coaxials in the doors? so you now effectively have a set of tweeters in the doors and in the A pillars?

 

[Pwnage1337]

Update:

I bypassed the LOC and took the signal Pre-factory amp and took it right to the sub amp. The bass seems like it is hitting deeper (maybe the internal amp has crossovers inside?) and it is now working well as it should......

 

[DrivenDaily]

Run a matched component set that have their own crossovers matched to the tweeter and the mid woofer.

Did you put Coaxials in the doors? so you now effectively have a set of tweeters in the doors and in the A pillars?

Here are the speakers, with the round 6½ inchers in the front and the 6x9 inchers in the rear. The round speakers are not coaxial. The 6x9's have a separate tweeter in the center with a built-in crossover.

I thought that I still had the stock A-pillar tweeters connected, but seeing what came with the round speakers, I now recall that the new tweeters were used to replace the stockers. I had originally ordered 6¾" round speakers for the front, but returned them and got 6½" speakers instead.

Looking at my orders from 2020, I also now realize that the sub is not 8", but 10"! The amp driving the whole system is a Rockford-Fosgate R2-750X5 with a 4-gauge wire and two 100A circuit breakers (resettable) to protect it. There are two breakers because there's one at the front battery like usual, and another at the rear where I installed my old Red Top Optima and a voltage-controlled dual-battery isolator. I'll eventually remove the battery now that I have a proper SUV to get out on the weekends and don't need the second battery for anything, but I'll keep the breaker just to protect from a short back there.

Rockford Fosgate P165-SE Punch 6.5" 2-Way Euro Fit Component Speaker System with External Crossover (Pair)

Rockford Fosgate P1692 Punch 6"x9" 2-Way Full Range Speaker (Pair)

Rockford R11X10 10-Inch 200 Watt Single Loaded Enclosure

The only original items still in use are the HU, the wiring from the HU to the original Bose amp (which was bypassed), and wires to the front speakers. There is new wire from the RF amp to the rear speakers and to the new sub, but I chose to use the stock wires to the front speakers just for simplicity's sake.