[Alistair330]

In order to correctly plan my future Audio install I need to understand the following issue!

Does the BMW Professional Head Unit (Basic 6 Speaker package) have a fixed EQ Curve?

i.e. We all know that the base HU setup with NO external OEM amp has a horrible EQ curve applied to compensate for the poor BMW speakers and lack of tweeters.

My Question: is this EQ curve constant or is it volume dependant (Dynamic EQ)?

i.e. When the volume control is turned up or down does the EQ cure change (Dynamically) to increase or decrease bass and treble?

This is often a feature referred to as “Loudness” on HU menu’s and simply increases or decreases bass and treble at low and high volumes accordingly to suit the human ear. (Humans are less capable of hearing bass and treble frequencies at low volumes and are more suited to mid-range frequencies, such as the human voice). At higher volumes, humans hear bass and treble (high/low) frequencies better thus Dynamic EQ’s alter the frequency accordingly. Bass and treble enhanced at low volumes but reduced at higher volumes.

Again, the question is: Although the Professional HU may not give you the option of “Loudness On/Off” as other HU’s do. Does it however automatically apply this?

Unfortunately I do not have a frequency RTA or I would be able to test myself, although I know that several people on this forum do!

Your answers and theories would be much appreciated!!

[taibanl]

Fixed. Look in the sticky. There is a link to vp-e's measurements

[makkan00]

Hmmm, interesting.
Why can't you get it coded to hi-fi to get rid of that equiliser settings?

[Alistair330]

I did initially try to get the HU coded but after several failed attempts at getting UK BMW dealers to even admit it was possible, I gave up.

Also, the cost of a coding was likely to cost the same as the buying a processor to remove the EQ which is the route I'm going down, however 'most' Processors (including the Alpine H650 I have) are very susceptible to varying EQ cures......... Which is why I'm asking the question about the Professional HU.

[Alistair330]

...... If I cannot get the Processor to work as I would like. I will look further into the Coding option.

Do you know of any UK dealers that have successfully coded Professional HU's to Hi-Fi in the UK? (I'm in the Midlands area).

[makkan00]

What year is your car?
And do you have built in bluetooth to HU?

I guess you need to read UK threads but more carefully to have easy answer for your question on coding.

[Alistair330]

My car is a 2007 (Manufacture date: Oct 2006).
It has the Professional head unit but NO Bluetooth etc......

I've done some more digging on the Hi-Fi Coding threads, but there is still one thing that confuses me:

If I get my HU coded to Hi-Fi, I understand that the high level speaker outputs are converted to Low Level signals (Same as RCA phono outputs on an after-market HU) and the full frequency range is retored (Front and Back) with the horrible BMW EQ removed!!!!

My question is: as my HU doesn't have RCA outputs, I assume the Low level output is provided via the existing speaker wires?

If so, how do I now connect the HU up to my 4 channel amp? This has inputs for Low Level RCA's or High Level Speaker wires.

Do I use a LOC? or will this try to convert the already Low level output from the HU to an even lower outout?

Or can you buy speaker to RCA conectors that do not lower the output as a LOc does?


Suggestions/Help greatly appreciated!!!

[Alistair330]

P.s. My Amp is a Alpine PMX-F640.

I also have a 2 channel Alpine Amp I intend to use for the Subs.

Spent nearly 2 full days ripping my car apart (Boot and back seats out etc...) to install the Alpine H650 processor and although the rear speakers are difinitly improved since being fed with a full signal, having to use the Alpine remote to controll everything is just hopeless!!

I've calibrated the H650 with the HU volume at various levels and then tried to alter the volume via the OEM HU and it instantly distorts heavily and quality is greatly reduced!! YOU DEFINITLY NEED TO LEAVE THE HU VOLUME CONSTANT, despite what others have claimed. Also the volume of the PDC (although working) is very low (too low).

As a result the Alpine H650 processor is coming out and I am going to try the Hi-Fi coding route again!!

So again an answer to my previous post and details on who can carry out the Coding would be greatly appreciated!!

[ctuna]

Maybe you should look in the coding section to.
If you are a bit of a hacker you might be able to do the coding yourself,
for the price of a 100 dollar US cable and a lot of reading.

[VP Electricity]

Guys, please remember that recoding isn't it - once you recode, you still need to get to the wires for the signal, which means either:

- pulling the head unit and using the Technic Stereo harness to "bring" F and R back to the trunk along with new woofer wires (unless you're disconnecting the rear speakers, you don't want them to remain connected to the R HiFi 5V output signal)

- grabbing the F outputs and the F door speaker wres underneath the seats and running them back to the trunk along with new woofer wires (what our L1 and L2 packages do with our Musicar harness).

This is why we don't mess with recoding with our packages. I have recoded my own car (but to Top HiFi so I could use the DA2