[VP Electricity]

So we recently did some testing on the F30 HiFi system. No real surprises, but here's what we found:

First off, here's the electrical signal out of the amp to the stock woofers. Any dips or peaks are NOT due to the acoustic characteristics of the cabin, NOR to the acoustic behavior of the speakers - this is caused by the processing built into the amplifier.

The woofer enclosures for the HiFi are actually different, and deeper, than the HK enclosures, so that's good. The woofers themselves are not as well made nor as nice as the older HiFi woofers.

The actual voltage indicated that the HiFi amp is still working with 12V internally and still lacks any internal power supply. Therefore, the laws of physics say that there is a fairly low limit you can put into a speaker when you're starting with 12V.

Note that the crossover point is a bit higher than the crossover point we found when we tested the F30 HK system. It's pretty similar here to the E9X HiFi system:



Next is the signal to the L and R front door speakers.



The signal to the center speaker is almost identical:



The center speaker isn't created by any kind of DSP processor - it's just L+R, and that's why it really just narrows the stage and decreases stereo separation. Unless you really have some attachment to mono, we still recommend unplugging it as the single biggest upgrade you can do.

Here's the rear speaker signal:



So they are slightly different, but not very. Finally, the signal going TO the HiFi amp:



So that's the balanced signal we work with. Same front and rear.

Any deviations from a flat line in the pic are due to the randomized nature of the pink noise signal we were playing.

Oh, and by the way, if you use an RTA with a mike to test anything in these cars, put the mike by your head first of all, but secondly, RTAs can't distinguish between distortion and clean output with pink noise, so don't misuse a tool

[emoon3]

Ken,

If the underseat woofers are deeper than the HK, do you think the Kickers used in the E90s would work? Any 8 inch woofer that you think would fit?

[VP Electricity]

The kickers are discontinued and I can't get them, so I have no way of knowing. We have tested a few and are going to be offering them in a week or so.

[jetbill]

You recommend unplugging the center speaker on the L7'HK system? If you turn L7 off doesn't it turn off the center speaker? Thanks