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      03-21-2010, 05:13 PM   #14
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Drives: E92 335i
Join Date: Mar 2010
Location: UK

iTrader: (1)

So what did we learn today?

The E92 boot liner is a lot more of a pain to get in and out than the E46!

Not sure I have set the amp gain up correctly. I used the method of using a multimeter. I calculated that I should be seeing 19V out each channel at 3/4 volume on the head unit (90W RMS per channel amp into 4 ohm).

Set it up with a 1000hz test tone. Turned off all crossover, etc. Got all 4 channels to around 19v. Put in a 50hz test tone and saw 26v, clearly too much.

The gain controls on this Vibe amp are highly sensitive!

Slightly concerned about temperature of amp. Went out for a drive (30 minutes of loudish music). Came back and put my fingers through the CD changer hole onto the amp and it was very warm. This is probably normal as it is tiny, but I am a little bit concerned by it at the moment.

System sounds really good. LHS subwoofer is blown I think. At high volume levels I can hear speaker clipping, which is a nasty noise. Cannot hear it from the RHS sub. . . .think either gain is slightly higher on LHS, or LHS woofer is damaged.

When I put my head in the middle of the car, it sounds balanced, so assume damaged LHS woofer.

Can anyone help with gain setting? There are 4 of them! One per channel. When I was setting it up, the tinyest movement would result in 3 or 4 volts change, so it took a while. Then when I changed the tone, it was all wrong. Doh!

I eventually just set them all at the same angle, which sounded good at 3/4 volume on head unit. By angle, I mean the angle of each gain screw on the amp looked the same. But if the gain controls are so sensitive that a tiny movement can change 2 or 3 volts output, could my gains all be different now meaning I am getting different volumes to each channel??