# What is inside your Monsoon Amp? [Answers inside]



## phatvw (Aug 29, 2001)

I dissected my Monsoon amp today and here is what I found inside:
Monsoon parts:
- 1 double-sided PC board
- 8 'Delco' 82452 11-pin chips with shared heat sinks
- 12 741 op-amp chips (surface mounted)
- 4 2200uF electrolytic capacitors
- 14 small electrolytic capacitors
- 2 small transformers (wired as single coils??)
- 2 rectifier diodes
- 1 small signal diode
- 16 transistors (surface mounted/small-signal)
- tons of surface mounted resistors and capacitors

Monsoon circuit board:
http://www.parts4vws.com/image...n.JPG
Monsoon power and signal cables:
http://www.parts4vws.com/image...2.JPG
I could not find any real data on the Delco chips but google hits on the keyword Delco turned up links to Bose/Delco/Monsoon amplifiers, so I presume they are the same type of power amplifier chips that are used in Bose/Delco car audio amplifiers. Can anyone confirm this? The only other markings on the chips were "W880Q0109" which are probably date codes.
After a cursory examination of the circuit, this is how I think the Monsoon system operates. I didn't break out the multimeter and oscilloscope, so much of this is simply guesswork. I would appreciate comments from folks more knowledgeable than myself.

Monsoon system operation:
- The OEM or aftermarket headunit has a built-in amplifier which supplies a high-voltage signal to the Monsoon amp. The OEM headunit has a 10amp fuse, so obviously it doesn't have that much power output.
- The monsoon amp accepts a high-level signal and converts it to a low-level signal. This is accomplished through a voltage divider and a 741 op-amp chip operating as a buffer for each of the four channels.
- The remaining 8 741 op-amp chips are used in 4 2-way crossovers. Each crossover filter is probably 12db or 18db per octave.
- The output of all 8 crossover filters are sent to individual Delco 82452 chips and then on to each individual speaker. This makes the Monsoon a true "bi-amped" setup as all 8 speakers have their own amp chip.

Comments:
I don't understand why the designer chose 741 op-amps for the crossovers. There are much better op-amp chips out there specifically designed for audio that probably do not cost any more.
As for the claim of a 200 Watt system? It is highly possible that each one of those 8 Delco 82452 chips is a 25-watt amplifier, but somehow I doubt it. The heatsinks just aren't large enough to dissipate that kind of heat. That and the fact that my Monsoon hardly gets warm even when playing full blast leads me to doubt the 200-watt claim. In fact I am not even certain that the 82452 chips are amplifier chips at all, so who knows.
Anybody who has any more technical knowledge about the Monsoon amp, please speak up. I am very curious to know what those Delco chips are!
Related threads:
http://forums.vwvortex.com/zerothread?id=1442853
edit: added comment about Delco keyword on google and related threads


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## flashback (Nov 23, 2003)

*Re: What is inside your Monsoon Amp? [Answers inside] (phatvw)*

haah... informative post.... i've sorta been wondering about that mystifying amp in my car that i'm about to throw out in a couple days..... i can't comment on any of the techy stuff that you know, however i'd say the monsoon amp puts out a relatively high signal for most stock car audio systems.... either that or the monsoon speakers are hella sensitive.. i remember someone posting about comparing the amp to their head unit which was putting out ~20 watts rms x4, and he found that the monsoon amp was actually louder than his head unit alone, so i'd give it some credit... probably arround 25-30 watts rms x4, that' 200 watts' is the same bs rating that all crapy amp companies give their amps, i'm guessing its the 'max/peak output', and ya i'm also supprised that the amp runs as cool as it does, however it has a high level signal comming in, so that probably results in less stress on the amp as apposed to rca's being used on otehr aftermarket amps


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## genixia (Feb 8, 2002)

*Re: What is inside your Monsoon Amp? [Answers inside] (flashback)*


_Quote, originally posted by *flashback* »_ ya i'm also supprised that the amp runs as cool as it does, however it has a high level signal comming in, so that probably results in less stress on the amp as apposed to rca's being used on otehr aftermarket amps

No, that wouldn't make any difference to the amount of heat generated.
We don't know anything about those Delco amplifier ICs. What we do know is that the rear woofers in the monsoon are rated at 2ohms. This is so the monsoon can provide lots of power without requiring a step-up power supply. A lot of OEM amps will contain a step-up power supply, and even with a 90% efficient switching PSU design that's still 20W of heat on a 200W amplifier. I suspect that this may be part of the reason that the monsoon 'runs cool'.
Also remotely possible is that the Delco ICs are digital amplifier chips which would be very efficient. That would surprise me however, as I would expect Delco (the 'Monsoon' brand owners) to be shouting about it if they were. Too much marketing potential.


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## theguero (Aug 10, 2001)

*Re: What is inside your Monsoon Amp? [Answers inside] (genixia)*

When I used to use the Monsoon system, mine got very HOT! But that made sense being the Subs and rears were 2 ohm speakers.
In the New Beetle, the setup is little different from the other three. In the NB, there are only two tweeters. They are mounted in the dash right next to the 3.5" midrange speakers. The SUBS were in the doors and the rear speakers were full range 2 ohm.
I thought it was OK for a stock system. If I had to do it over again, I most likely would not change it. If I was buying a NB today, I would wait for the 2005 so I could get my new TDI with factory XM.
I went to my local dealer yesterday and got to play with the XM in one of the 04 limited edition Satellite Blue units. It was exactly like I expected it to be. Same dot matrix display that mine had back in 01 with scrolling text. Of course it has the MP3 CD player too.
On thing I noticed was they got rid of the CD changer connection in the trunk and instead added a built in AUX input. So no Phatobx... But I can see the usfullness in an AUX input too.
But it still had the same Monsoon sound. Very agressive mids and highs that really hurt my ears. The midrange and tweeters are pointing right at the windshield. So it reflects off the glass and is very painful.


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## phatvw (Aug 29, 2001)

*Re: What is inside your Monsoon Amp? [Answers inside] (theguero)*

More info on the Delco amps:

_Quote, originally posted by *tancrede* »_
Hi Dan ! I bought the amplifier on e-bay and tested it (with a voltmeter and an oscilloscope) before installing it in my car. At the present time, it is used only for the rear speakers; the radio drives the front speakers directly. My car was not originally equipped with the Delco amp.
I can aswer some of your questions. There are 8 amplifiers (IC # 82452) in the Delco. The two subwoofers are driven by the same 82452. Of the remaining 7, each drive one speaker (total= 9 speakers). Each 82452 is powered by 12 volt, so you wont get more power from the Delco than from the radio in the dash for equal impedance. Since the subwoofer (according to my Buick dealer) are different (9 speakers system VS 6 speakers system)(somebody mentioned in the text in 2004 that they are 2 ohms instead of 4), you will get more power regardind the subwoofers. At 12 volts for an impedance of 4 0hms without distortion the max RMS power is around 16 watts. The power drawn from the Delco is around 0.75-1.0 Amp. It automatically senses when the radio is turned on (presence of 6 V dc on each of the wire at the output of the radio) and hence should be fed by a 12 V present at all times. The 11 IC in the Delco are quadruple op-amps. The are low-noise 741 (improved). I have all the frequency response in JPEG if you want them.
Were you able to find more info on the 82452 ? The transformer we find in the Delco are RF chokes to prevent noise produced by the alternator to reach the amplifier. The speaker in the front in the center plays mono (R+L), as the subwoofers in the back. The all have a specific part of the audio bandwith, with slopes of either 18 or 24 db/octave. I spent a lot of time studying the Delco; I'm happy if it could be used by somebody.
Pierre


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## pwnt by pat (Oct 21, 2005)

*Re: What is inside your Monsoon Amp? [Answers inside] (phatvw)*

I would be very suprised if the monsoon amp had 18 or 24db/octive crossovers as that those kinds of slopes require lots of parts.
Also, I'd be willing to bet 200w is the "max power" rating of the amplifier, with the actual being 100wrms, or ~16.67wrms per channel. makes sense.
why the rear woofers are 2 ohms is a mystery to me? to change the crossover point perhaps? certainly not to achieve more power out of the rears...


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## phatvw (Aug 29, 2001)

*Re: What is inside your Monsoon Amp? [Answers inside] (pwnt by pat)*

Nah, the crossovers are not that complex. Here is a 4th-order 2-way crossover with input buffer. You'd only need two of these (2 stereo channels) for the Monsoon:









There are easily enough parts on the board to support something similar. Keep in mind that these 741's are 14-pin so they actually have 4 op-amps per chip:











_Modified by phatvw at 5:31 PM 11-7-2007_


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## pwnt by pat (Oct 21, 2005)

*Re: What is inside your Monsoon Amp? [Answers inside] (pwnt by pat)*

I'm digging more into this, perhaps looking into monsoon upgrade options. I'm hoping maybe I'll be able to swap the opamps, play with crossover frequencies, and squeeze a little more out of the monsoon system.
OPamp information:
http://beta.octopart.com/Rohm__BA14741.pdf
Something I've noticed, the entire board and every component is coated in a laquer. My guess is to prevent condensation. I'm heating up the soldering iron to burn it away so that I can use the multimeter and see what goes where.


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## craigsaid (Sep 7, 2005)

*Re: What is inside your Monsoon Amp? [Answers inside] (phatvw)*


_Quote, originally posted by *phatvw* »_
I don't understand why the designer chose 741 op-amps for the crossovers. There are much better op-amp chips out there specifically designed for audio that probably do not cost any more.


741's are going to have an extremely high bandwidth and are amazingly stable. I'd take a guess that this is a switching amplifier so any component's resistance to oscillation is a +


_Quote, originally posted by *pwnt by pat* »_
Something I've noticed, the entire board and every component is coated in a laquer. My guess is to prevent condensation. I'm heating up the soldering iron to burn it away so that I can use the multimeter and see what goes where.

Have you tried just stabbing your meter leads through the coating? We conformal coat all our boards where I work. So if I'm doing a service return I have my DMM leads filed down to a SHARP point so i dont have to take the coating off except around the section that needs to be reworked.


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## pwnt by pat (Oct 21, 2005)

*Re: What is inside your Monsoon Amp? [Answers inside] (craigsaid)*

you can poke through but for the smd resistors and caps, you can't.


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## Stratus2003 (Sep 27, 2003)

*Re: What is inside your Monsoon Amp? [Answers inside] (pwnt by pat)*

great info guys - question - I really want to run the line out of my HU into the monsoon amp - from what I've read it only accepts speaker level inputs - is this true - I really don't want the source going through two power amps (HU and Monsoon) Can it be done (aftermarket HU line level into Monsoon amp)? The THD on my HU (Blaupunkt Monte Carlo MP34) amp section is 10% - this is scary!
If the answer is an absolute no - what's most cost effective HU unit you guys recommend that matches the dash lights and has a clean amp out spec (I don't need fancy HU - I run everything flat)


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## phatvw (Aug 29, 2001)

*Re: What is inside your Monsoon Amp? [Answers inside] (Stratus2003)*


_Quote, originally posted by *Stratus2003* »_great info guys - question - I really want to run the line out of my HU into the monsoon amp - from what I've read it only accepts speaker level inputs - is this true - I really don't want the source going through two power amps (HU and Monsoon) Can it be done (aftermarket HU line level into Monsoon amp)? The THD on my HU (Blaupunkt Monte Carlo MP34) amp section is 10% - this is scary!
If the answer is an absolute no - what's most cost effective HU unit you guys recommend that matches the dash lights and has a clean amp out spec (I don't need fancy HU - I run everything flat) 

The low-end Kenwood amps with MP3+CD are a direct match with OEM lighting. AND using the speaker-level outputs sounds great. C'mon this is a car with road noise, not a studio. Going through an extra amp isn't really that big a deal. If you can really tell the difference in an economy car like a Golf, then Bravo!










_Modified by phatvw at 8:46 PM 12-18-2007_


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## Stratus2003 (Sep 27, 2003)

*Re: What is inside your Monsoon Amp? [Answers inside] (phatvw)*

thanks for the quick response (funny you mention studio - I'm a recording engineer) I should just remove the whole stereo system and listen to the Miltek (lol) funny how when I'm bored I look for things to spend money on.


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## pwnt by pat (Oct 21, 2005)

*Re: What is inside your Monsoon Amp? [Answers inside] (phatvw)*

just run the speaker output on the head unit into the monsoon amp. that's how it's designed to run.


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