possible solution for aftermarket stereo problems?

[everlast]

So, I too am at the crossroads of the aftermarket stereo that everyone else has run into. I don't want to rewire the car, the factory amp is good enough for my purposes in this car, and I really don't want to rip this car apart to do the work since it has zero squeaks right now, and won't afterwards.

I want to install an aftermarket deck connected to the factory amp. So, here is the problem..

My aftermarket line level outputs are too cold, but the speaker level coming from the deck don't work either. They are not too hot either, they're actually about the right volume. However, they distort easily. The distortion is coming from the HU since it is not seeing enough resistance to develop any power. This is especially true since the decks negative's are floating (not connected to anything.) The deck would normally see an average peak of 4 ohms, of course. ANY load will likely resolve the distortion problem I think.

I bet a lot of people's HU's do this and they assume its the crappy factory amp.

So I'd like to try to put an artificial load on the output stage by attaching a 200ohm resistor across the + / - of each speaker lead, then connect the + to the amp input.

Thoughts? 200ohms should be good? How many watts should the resistor be?

More info on a line adapter like this here:
http://www.tkk.fi/Misc/Electronics/circuits/speaker_to_line.html

(In the paragraph entitled Notes on using the circuit)

[Fetch]

I will be interested in the result of this.....

I did a HU & sub install on my friend's 3 series, and we spliced the low level outs into the bmw amp, and it sounds fine, but the volume is a little low (is that what you ment by cold lol)

I'm about to put the HU & sub from my old car in my e34, and will probably go low level rcas into the bmw amp, unless this turns out well

Thanks :)

[everlast]

I tried my line level RCA's tonight (JVC deck) and found them too quiet, yes. I had to turn it up full volume to get 3/4 volume from the factory amp, and the deck didn't like it very much either.

IDEA: I'm going outside RIGHT NOW and trying this, but I'll use a speaker as the load.. I'll just run a speaker wire to a speaker outside the car to simulate simulating the load. LOL!

Back in a minute.

[everlast]

Damn.

The sound coming from the speaker was not distorted, but touching the input line to the amp, the signal is distorted. I'm guessing that its because the + wire only has the + half of the signal, clipping at 0 when compared to ground (which the amp is doing).

It doesn't distort at low volume though, which doesn't make sense.

Would a line adapter that has a VERY high output stage work? I don't know where the EFF I'd fit it though, since it would need to be in the dash.

This sucks. Maybe i'll buy an iPod and FM mod instead. Too bad.. the JVC deck has the perfect orange light and I carefully dismantled the whole face and painted it black. :(

[Elekta]

search "stereo upgrade" (http://www.bimmer.info/forum/showthread.php?t=2379&page=2&pp=10&highlight=upgrade) and you will find my upgrade. I sent my HU off to www.soundrepair.com to be rebuilt and added an amp under my seat and an EQ in my glove box that has an aux input for an ipod, then adapt the flashlight receiver to an ipod charger.

It turned out sweet and has been for 2/3 years

[gmannino]

What you guys need is a "Adjustable Premium Sound Interface." This will drop your high level outputs from your deck to low level outputs, yet have a trim pod to adjust the output level of the deck. YOu will need to do some level matching but I'm sure most of you can handle that. THere are a few manufactures out there who make premium sound interfaces. Peripheral is my personal favorite but PAC also makes good ones also. Do a search for those.

CHeck out http://peripheralelectronics.com/web/loc.asp, should be the first few products on the list.

[fujioko]

i did the resistor experiment a few days ago. i used 10 ohm 10 watt in series with the speaker level outputs.. no difference. Then i tied another 10 ohm 10 watt reistor across the outputs. The second set of resistors should have divided the output in half ... still suked.

The input impedenze in the trunk amp is 30K OHMS. if you want to continue the resstor exeriment.. then you really wouldent need high wattage reistors. i used the big power resistors because i assumed the amp had a much lower impedence.

[everlast]

I've used a PAC device before, I guess I'll have to do that again. Its just that there is no room for it inside the dash. :(

[gmannino]

Just try the sound interfaces, and tuck that thing away in the dash.