2004 VW R32 Install - NOT DIAL-UP FRIENDLY

**R32 JUhl** · 02-19-2005, 10:44 PM

Great news everyone! We beat the "impossible to resolve" Monsoon issue. My carputer's outputs are running directly into my Monsoon amp and working as VW originally intended. The secret: VW is sending a 1/2 battery voltage DC signal on the speaker wires that tells the amp to power up. There is no typical, designated trigger wire to tell the amp to turn on because the speaker input signal is carrying it. So we have the system working. We're stealing the 5V signal from the Opus and as you can imagine, there's a little bit of noise on it. But we're working on a filter to clean out the noise. News as it develops!

The 5V has to go into the left channel to get the amp to power up. We fed it into the left channel common. I used a 10k ohm resistor in series to drop the amperage, just in case - I didn't want to overload the amp. For the record, the Monsoon's Head Unit speaker A/C outputs are virtually identical to the carputer's!

**shakes** · 02-19-2005, 11:02 PM

awesome! glad to hear you got it working!

One thing ... did you mean to say you put a 10k resistor in series with the amp or did you mean parallel? Having a resistor in series with another load (the amp in this case) will supply the same ammount of current (amps) to both the resistor and the load, but different voltages. So you will have a voltage drop across the resistor and you won't get the full 5v to the amp.

Putting the resistor in parallel to the load will supply the same voltage to both but different currents. In this senerio the resistor acts as acurrent limiting resistor (though the current draw of the other load should be known, and the value for your resistor should be calculated so it is able to limit the current as you wish)

I'm not sure how well you know electronics so I don't mean to offend.

**ppgt94** · 02-20-2005, 12:01 AM

Originally Posted by R32 JUhl

Great news everyone! We beat the "impossible to resolve" Monsoon issue. My carputer's outputs are running directly into my Monsoon amp and working as VW originally intended. The secret: VW is sending a 1/2 battery voltage DC signal on the speaker wires that tells the amp to power up. There is no typical, designated trigger wire to tell the amp to turn on because the speaker input signal is carrying it. So we have the system working. We're stealing the 5V signal from the Opus and as you can imagine, there's a little bit of noise on it. But we're working on a filter to clean out the noise. News as it develops!

The 5V has to go into the left channel to get the amp to power up. We fed it into the left channel common. I used a 10k ohm resistor in series to drop the amperage, just in case - I didn't want to overload the amp. For the record, the Monsoon's Head Unit speaker A/C outputs are virtually identical to the carputer's!

That's great news. Good work. Are you running the sound card outputs directly into the Monsoon black box? I thought that the factory headunit was a preamp? Did you replace it with another preamp? If not how loud is the sound you get now compared to when you had the factory headunit?

**R32 JUhl** · 02-20-2005, 08:56 AM

Originally Posted by shakes

awesome! glad to hear you got it working!

One thing ... did you mean to say you put a 10k resistor in series with the amp or did you mean parallel? Having a resistor in series with another load (the amp in this case) will supply the same ammount of current (amps) to both the resistor and the load, but different voltages. So you will have a voltage drop across the resistor and you won't get the full 5v to the amp.

Putting the resistor in parallel to the load will supply the same voltage to both but different currents. In this senerio the resistor acts as acurrent limiting resistor (though the current draw of the other load should be known, and the value for your resistor should be calculated so it is able to limit the current as you wish)

I'm not sure how well you know electronics so I don't mean to offend.

No offense taken! And electronics is an area I have a slight knowledge in - mostly automotive applications - so even your explanation leaves me scratching my head. It made perfect sense when I did it. I'll have to digest what you've said and figure out my next step. Thanks Shakes!

**R32 JUhl** · 02-20-2005, 09:05 AM

Originally Posted by ppgt94

That's great news. Good work. Are you running the sound card outputs directly into the Monsoon black box? I thought that the factory headunit was a preamp? Did you replace it with another preamp? If not how loud is the sound you get now compared to when you had the factory headunit?

I'm still learning about BTL (bridge tied load)... but from what I understand, the pre-amp in the HU is not responsible for increasing the gain level on the speaker outputs, but is instead responsible for introducing the 1/2 battery DC voltage signal under the A/C speaker outputs on the positive and common sides of the speaker outputs.

I cannot tell a difference in the sound level between the factory radio and the carputer now that I've introduced my own power-on signal. I didn't use equipment as sophisticated as the Monsoon pre-amp and the pre-amp I built didn't work for this circuit, so I left it out. Anyhow, the short version of the story is the HU put out 300mV at full volume of white noise. I measured a peak of 300mV from the carputer, too. So, as the saying goes - "Close enough for 'gubment' work!"

**R32 JUhl** · 02-20-2005, 06:15 PM

Originally Posted by shakes

awesome! glad to hear you got it working!

One thing ... did you mean to say you put a 10k resistor in series with the amp or did you mean parallel? Having a resistor in series with another load (the amp in this case) will supply the same ammount of current (amps) to both the resistor and the load, but different voltages. So you will have a voltage drop across the resistor and you won't get the full 5v to the amp.

Okay, here's the idea. When doing the testing, I put the resistor in series just in case the Monsoon amp wanted to pull a lot of amperage. The voltage would have gone low, immediately. I didn't want to overload the amp because I wasn't 100% certain about what I needed to feed in - I was simply hypothesizing based on what I read with a meter, not a scope. The amp is not drawing any current - it's not acting like a load. So the 5V input is simply an input into a logic circuit - CMOS? To prove that, I input the 5V into the amp without any speakers powered and I was able to read that 5V signal on every speaker input terminal (positive and common) AND the amp was powered up. It's time for a nap! But I'm planning on installing a 7805 voltage regulator into the power leads of the amp to see if I can get a cleaner power source and eliminate the slight noise issue I have at the moment. If that doesn't work - capacitors!

EDIT: The voltage regulator didn't address the issue - to the capacitors!

**bergeron76** · 03-05-2005, 10:18 PM

J -

It was great seeing your install today! Your install is much more impressive in person. The pics here just don't seem to do it justice.

I'm really looking forward to the Atlanta meet on the 19th.

Cheers,
CB

**Osiris** · 03-05-2005, 10:25 PM

Originally Posted by bergeron76

J -

It was great seeing your install today! Your install is much more impressive in person. The pics here just don't seem to do it justice.

I'm really looking forward to the Atlanta meet on the 19th.

Cheers,
CB

Aint that the truth.

Sorry i couldnt make it guys but i had an emergency.

**Rafster** · 03-05-2005, 10:48 PM

Hey R32,

That is one of the nicest installs I have seen yet. I almost busted a nut when I saw it. Awesome job. BTW, who is that in your avatar?

Peace,

Rafster

**Oswald** · 03-06-2005, 03:02 AM

Originally Posted by R32 JUhl

Just an update on converting the carputer line level outputs to make them more acceptable for the Monsoon amp... I applied too much voltage to the pre-amp solution I was testing and the smoke escaped from it so now the electricity has no smoke trail to ride on.

Another pre-amp should be here by the end of the week and I'll be more careful with this one! Nonetheless, it appears I have a solution for adapting the computer's line-level audio outputs into a Monsoon amp. I had four seconds of success while the first unit held the smoke in as long as it could.

Hey, haven't read through the whole thread yet but thought that this might be of use. I did with my iPod, not quite the same mod as this, but sort of along the same lines and it works pretty well, I also have a creative Audigy 2 sound card with aux outs on it and that went through fine.

http://forums.vwvortex.com/zerothread?id=509131