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1999 Golf GTI 2.slow, 2000 Beetle GLS 2.slower, 2001 Golf GTI 1.8t
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Discussion Starter · #1 · (Edited)
I've been having a bit of fun reverse engineering the factory Monsoon amplifier. I'm just going to drop this here in case anyone's bored. If you have any requests or additional information you'd like to add, feel free to leave a reply. I'll update this post as I compile new information.

After Market Head Units, Manual Amp Remote Turn On Wire, and Parasitic Draw
The factory Monsoon head unit applies a DC voltage to the positive front left output to switch on the amplifier. When the car is turned off, the front left output is grounded to shut off the amplifier.

Aftermarket head units obviously don't supply this DC signal. Speaker level voltage is enough to drive the transistor which turns on the amp, but since most cheap head units don't ground the output during standby the amplifier will most likely stay on after the car is shut off. This can result in a parasitic draw while the car is off.

The best solution for an aftermarket head unit, or to fix a factory Monsoon amplifier with parasitic draw, is to wire up the Manual Amp Turn On circuit. At the same time, the Automatic Amp Turn On circuit should be disconnected to avoid injecting DC voltage on the speaker input and frying your head unit.

Pin 12 on the Grey connector is for the turn-on wire. You'll need to source a repair pin to populate this connector, or hop on over to the parts yard and yank one yourself. You'll have to run this wire all the way up to your head unit amp turn-on wire or tap the accessory wire. You could also reuse the CD changer harness if you don't want to run a wire. If you do run a wire, you might as well run the RCA/Power/etc. for a subwoofer.

In addition to the new turn-on wire, you'll also have to move the turn on resistor from the Left Front speaker signal to the Pin 12 traces. Take the amp out of the car, unscrew the four screws on the bottom of the amp, and pop off the bottom and top covers. De-solder the turn-on resistor and move it to the location indicated in the photo below. A good soldering iron, flux, and needle point tweezers highly recommended.

Preview


Line Level Input
Contrary to popular belief, the Monsoon amplifier will accept line level input. The input is isolated at the first op-amp, which is setup as a voltage follower. Since this circuit is high impedance, any line level input can be used to drive it.

Just make sure you wire up the Manual Amp Turn on mentioned earlier, since line level voltage isn't enough to drive the transistor for the Automatic Amp Turn On. It's also isolated from ground, so the amp also won't turn off after the car is shut off.

RCA connectors can be connected directly to the harness connector at the head unit. The example below uses Mini-Fit JR connectors in-between for cleanliness.

Preview


Crossover
Coming soon.

Speaker compatibility
The amplifier should technically be 2 ohm stable on all channels since the factory rear woofers are 2 ohms. The rest of the woofers/tweeters are 4 ohms.

The tweeters on low-line cars have a high-pass filter capacitor soldered directly to the tweeter. This capacitor is missing on Monsoon equipped cars since the amplifier already has a crossover built into it.

Monsoon Amp Pinout
24 Pin Grey Input Connector
Pin​
DescriptionColorNotes
1​
Right Rear Tweeter +Circuit Not Populated. Hands-free speaker?
2​
3​
4​
5​
6​
7​
8​
9​
10​
MuteCircuit Not Populated
11​
12​
Amp Turn OnNot Connected
13​
14​
Left Rear +White
15​
Left Rear -Black
16​
17​
Right Rear -Black
18​
Right Rear +Brown
19​
20​
Left Front +YellowAutomatic Amp Turn On
21​
Left Front -Black
12​
23​
Right Front -Black
24​
Right Front +Green

23 Pin Green Output/Power Connector
Pin​
DescriptionColorNotes
1​
Left Rear Woofer +Red/Green
2​
Left Rear Woofer -Brown/Green
3​
Right Rear Woofer +Blue
4​
Right Rear Woofer -Brown/Blue
5​
Left Rear Tweeter +Brown
6​
Left Rear Tweeter -Black
7​
Right Rear Tweeter +Green
8​
Right Rear Tweeter -Black
9​
Left Front Tweeter +White
10​
Right Front Tweeter -Black
11​
Left Front Tweeter -Black
12​
Right Front Tweeter +Yellow
13​
Left Front Woofer -Brown/White
14​
Left Front Woofer +Blue/White
15​
Right Front Woofer -Brown/Red
16​
Right Front Woofer +Red
17​
18​
Constant 12 VoltsRed
19​
Chassis GroundBrown
20​
Chassis GroundBrown
21​
Constant 12 VoltsRed
22​
Chassis GroundBrown
23​
Constant 12 VoltsRed

Delco 82452 Audio Amplifier
I haven't been able to find any datasheets online for this chip. I may de-solder one and characterize it, but I haven't the need to yet.
TDA7396 should be a pin-compatible drop in replacement for the Delco 82452 (Coincidence?)

The diagnostics pin is setup to reduce the signal at the op-amp before it's fed into itself. This includes short-circuit protection, thermal overload, etc.
Pin​
DescriptionNotes
1​
IN-
2​
IN+
3​
Vs+12v
4​
? CD-DIAClipping Detect - Diagnostics. Low during error
5​
OUT-
6​
GND
7​
OUT+
8​
STANDBYStandby when Low
9​
Vs+12v
10​
SYNCConnected to all amplifier chips
11​
MUTEMuted when high (5v)

Volkswagen Part Numbers
I have no clue why the Jetta and Golf have different amp part numbers. Perhaps they're tuned differently?
Part NumberDescription
1J6 035 456 CGolf 2 & 4 Doors Monsoon Amp
1J5 035 456 AJetta Monsoon Amp

Front woofers are held in by rivets.
Part NumberDescription
1C0 035 411 E2 Ohm 50W 140mm Monsoon Woofer Rear
1C0 035 411 G4 Ohm 70W 140mm Monsoon Woofer Front
3B0 035 411 E4 Ohm 19mm Monsoon Tweeter Rear (Todo: Confirm Part Number)
3B0 035 411 F4 Ohm 19mm Monsoon Tweeter Front (Todo: Confirm Part Number)

Schematics
Coming soon.

Interesting Stuff
  • Unpopulated circuit for separate front/rear mute.
  • Unpopulated circuit for Manual Mute on pin 10 of grey connector
  • Unpopulated circuit leading to Right Rear Tweeter on pin 1 of grey connector. Perhaps for reducing echo for hands-free calling or navigation unit.
  • Disconnected circuit for Manual Amp Turn On (see earlier section).

Surface Mount Marking Decoding
Brief list of surface mount PCB components.
MarkingDescription
BA14741FLow Noise 4 Channel Operational Amplifier
MAW/RBRSST6838 NPN Transistor
MAZ/RFQSST6839 PNP Transistor
R232SC3356 NPN Transistor
 

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Just came across this while researching the Monsoon system wiring. This is exceptional work, nice job!

I believe my amplifier is causing an intermittent parasitic draw (factory head unit). I currently have it unplugged so no sound. Is there anyway to bypass the amplifier? Not looking for anything fancy, just want some tunes again. I considered buying a new (used) amp off ebay, but not sure I want to roll the dice on another used VW part.
 

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1999 Golf GTI 2.slow, 2000 Beetle GLS 2.slower, 2001 Golf GTI 1.8t
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Discussion Starter · #3 ·
Just came across this while researching the Monsoon system wiring. This is exceptional work, nice job!

I believe my amplifier is causing an intermittent parasitic draw (factory head unit). I currently have it unplugged so no sound. Is there anyway to bypass the amplifier? Not looking for anything fancy, just want some tunes again. I considered buying a new (used) amp off ebay, but not sure I want to roll the dice on another used VW part.
Your factory head unit should output speaker levels. Either connect the speakers directly to the head unit at the amp connectors (using the connector pinout above) or do the manual amp turn on mod.

The speakers on a non-monsoon system have the tweeters connected directly to the speakers, with a passive high-pass filter capacitor. You can just run the same signal for the speakers to the tweeters without much issue.
 

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I have been doing some digging for days now and i can't find some explanation...
Its a 2006 beetle with the monsoon amp.

1.) Where does the rear tweeters are connecting?

2.) Monsoon sound does not have tweeters in the A-pillars. (Are they empty?? - If someone could please confirm this) and there are tweeters and mids installed under the dash into the corners.
There are 4 wires coming up to the dash, 2 for the mid and 2 for the tweeters. I assume 2 tweeters are from monsoon Green connector Pins: 9,10,11,12. But where are the wires coming for the mids ??
here is a picture:
Hood Product Motor vehicle Font Automotive lighting


Thanks!
 

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Great info thank you.

I just stumbled upon the monsoon crAmp in my wagon yesterday. I was shocked to find the monsson amp behind the foam in the left rear storage area while tapping into the reverse trigger. That explains why the system sounds like doooookie done died and then dried in my ears!

After seeing this thread I think it will be very easy to simply just delete the and upgrade that monsoon amp. Using an epicenter would be very simple like this too...

My plan is this:
*run RCA , remote, and power wire
*tap into the 23 Pin Green Output/Power Connector for the speakers
DONE

The tweet wires are not neccicary IF your door speakers have had aftermarket components installed like mine. MIne had the tweet wires cut and a crossover rewired in off the woofer channel. Opposionally, if you system is not hooked up this way you can always bi amp or run the epicenter....

OR it would be easier to use something like a Clarion xr5420.
With an RCA That could be run entirely off the stock wires once you figure out how to re wire one of the three constant power wires and use it as remote turn on.
 

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Discussion Starter · #7 ·
Oh huh, guess I'm going to the junkyard to get a 10 channel amp. Looks like it just adds two mids in the dash.

I've been collecting part numbers and connectors for a guide on using the CD changer harness as a low effort way to wire up the amp and a sub. Other than that I haven't had time to sit down and reverse engineer the crossovers.
 

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Discussion Starter · #8 ·
@XDleader555 Any further progress? Have you looked into the NBC 10 speaker monsoon amp?
Looks like the new beetle convertible is still using the same 8 channel monsoon amp.

To accommodate the additional set of mids in the front, the rear tweeters are wired in parellel with the rear woofers.

Funny how the sticker on the amp states that it's for a Cabrio.
 

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Discussion Starter · #11 ·
@XDleader555 if I was able to grab one of those supposedly true 10 channel gm monsoon amps and was willing to ship it to you would you have interest in taking a look at it?
If I didn't already have a backlog of projects, I would. The amp would probably work as long as you had the right pinout which you can find through service manuals.
What car specifically were you thinking of pulling it from?
 
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