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      06-13-2019, 07:57 PM   #227
evanevery
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Drives: iXM60, i8 Rdstr, M4, i7 M70
Join Date: Feb 2012
Location: Wisconsin

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The Line Out Converter, Bluetooth Transmitter, and portable Bluetooth Speaker worked perfectly!

Line Out Converter (LOC): https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Bluetooth Transmitter (rechargeable): https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Bluetooth Speaker (rechargeable): https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I was able to hear the externally generated sound clearly inside the car while driving and there are a few surprises (at least to me)!

There is more than one sound being generated!

1. There is turbine like sound which is generated when the car is at lower RPMs and or in EV mode. This turbine "whoosh/whine" will get louder as the car is put under more load and its pitch will increase as the speed of the car increases. The turbine sound is just like you would expect to hear from an electric car of the future in a SciFi film!

2. There is also a typical engine exhaust sound which is generated if the engine is running. It will be very quiet at low RPMs and become louder and higher pitched as the RPM increases. The engine sound appears to only be generated when the engine is running though (otherwise all you get is the turbine sound).

3. I'm not sure what the rules are as these sounds are "blended", but it appears to roughly follow the amount of power being generated by electricity vs motor. So, at lower RPMs and very low speeds the turbine sound is dominant and then as the speed and power of the car increases the engine sound becomes more prevalent. The approximate transition point appears to be around 3000 RPM. Mostly turbine below 3000 and then mostly motor above 3000.

This is just a rough description of what can be heard if you can bring the external sound inside the car where it can be heard better over the internally generated sound.

It should also be noted that the internally generated sound and the externally generated sound are not at all the same (as I had originally guessed). They are very different. Although the internal sound has no "turbine component", the artificial engine RPM's of the BMW internal and BMW external sounds DO seem to be in synchronization. (The audible dissonance of the BMW internal sound vs the maxhaust/maserati external sound was one of the issues which led me to remove the maxhaust/maserati modules). It may very well be that the internal sound is the same as the external sound except without any turbine component at all.

I'm not sure where I will go from here. The little amp I bought doesn't seem to make any appreciable difference in the volume of the external BMW sound and maybe I will see if I can get more volume out of a different unit.

The basic premise is accurate though. If you tap your harness in a similar fashion, you can switch between sound sources very easily! The sound level in the harness is "speaker level" and the "actuator" under the car is really nothing more than a speaker.

I recommend trying the LOC/BT Transmitter/Portable Speaker test for anyone who REALLY wants to hear what their car sounds like from the outside while it is moving. The way the turbine sound blends into an engine sound is pretty cool. It truly makes the i8 sound very special.

If anyone has any questions or ideas I'ld love to hear them!
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