tweeter crossovers

[antennahead]

Can someone verify for me the crossover situation with the Top Hi Fi/Carver system in the Z4 M? I have been doing some research trying to find the answer, and have conflicting info. Some refer to the amp as having active crossovers. I personally think the crossover is passive and just happens to be inside the amp........... sounds good to say "10 channels", nice marketing.

This is from BMW's training PDF on the Z4 systems:

"The tweeter has a diameter of 26 mm and a fabric cap or calotte. The maximum load capacity is 25 W. The tweeter (high-range speaker) covers a frequency range from 4000 Hz to 20,000 Hz. The frequency range of the high-range speaker is set by means of a capacitor"

Another poster on another site said the capacitor was inside the back of the tweeter ................. not sure about that. I know it is not wired inline between the plug and the tweeter itself. If not inside the back housing then I think it is inside the amp (passive). If it is inside the back housing then removing/replacing the tweeter would result in a full range signal (or 100hz and up if sourced off the mid signal) being sent to an afternmarket tweeter.

Any definitive information here would be greatly appreciated. Thanks

John

[elerner61]

Well on my Top Hifi/Carver system there definitely aren't any capacitors on the Tweets. I know because I actually added caps to prevent any possible "turn-on" damage to my tweets when I installed my JBL MS-8.

With regards to the BMW doc that mentions caps on the tweets, I remember reading that twice or so and then realizing it was not in reference to the Top Hifi system.

From my experience with the MS-8 install using the stock wiring the crossover is definitely in the Top Hifi amp. Passive is my guess since I haven't come across any documentation on being able to control/adjust the crossover.

Why the interest in the stock crossover situation?

[antennahead]

Originally Posted by elerner61

Well on my Top Hifi/Carver system there definitely aren't any capacitors on the Tweets. I know because I actually added caps to prevent any possible "turn-on" damage to my tweets when I installed my JBL MS-8.

With regards to the BMW doc that mentions caps on the tweets, I remember reading that twice or so and then realizing it was not in reference to the Top Hifi system.

From my experience with the MS-8 install using the stock wiring the crossover is definitely in the Top Hifi amp. Passive is my guess since I haven't come across any documentation on being able to control/adjust the crossover.

Why the interest in the stock crossover situation?

I think when they say "set/controlled by a capacitor" they could be referring to the passive crossover in the amp, assuming that info is correct, that the top hi fi/Carver system amp has passive crossovers in the amp. Also the capacitor reference is mentioned under the "stereo" section. But later in the Top Hi Fi/Carver section they say "tweeter the same as the stereo", so I do believe they are controlling all tweeters in their Z4 systems via passive capcitor. Another poster on another site mentioned the cap being in the tweeter, but seeing how thin the original tweeter is, no way IMO there is a cap under the back casing of the tweeter. I replaced the mids and tweets with the BSW stage one upgrade. The system while now more detailed, has a frequency bump compared to stock that I intend to dial down via an inline cap on the tweeter (simple first order crossover 6db per octave). I was just curious as to how the OEM was handled. The more you know about the OEM system, the better you can tweak upgrades and replacements.

[elerner61]

Originally Posted by antennahead

The more you know about the OEM system, the better you can tweak upgrades and replacements.

Agreed. My last piece of "education" is that the supposed "Digital" connectivity between the HU and amplifier is analog line level signal from the HU to the amplifier and a digital control signal between them that actuates volume, balance, fade, etc... on the amplifier.

There is much "folklore" (such as digital from HU to amp) surrounding the different systems from year to year. Another example is digital vs. analog for the CD changer signal path to the amp.

[antennahead]

Originally Posted by elerner61

Agreed. My last piece of "education" is that the supposed "Digital" connectivity between the HU and amplifier is analog line level signal from the HU to the amplifier and a digital control signal between them that actuates volume, balance, fade, etc... on the amplifier.

There is much "folklore" (such as digital from HU to amp) surrounding the different systems from year to year. Another example is digital vs. analog for the CD changer signal path to the amp.

Interesting

[elerner61]

Have you seen this doc? (attached). I stumbled upon it about a month ago. For all I know it was from you!

It's really a shame that a good amount of thought went into the system, and it sounds the way it does.

[antennahead]

Originally Posted by elerner61

Have you seen this doc? (attached). I stumbled upon it about a month ago. For all I know it was from you!

It's really a shame that a good amount of thought went into the system, and it sounds the way it does.

Yep, I've had that one saved in my Z4 files for some time

I can say that since the stage one upgrade, and after the cap is added to the tweeter, along with some more graphic EQ tweaking and fader tweaking, the system is sounding pretty darn good now. I removed the front baffles on the Carver subs, removed the rubber cabinet liner, and totally sound deadened the cabinet, then replaced the liner .......... as well as placing deadening material on the front baffle around the woofer. This improved the sound and eliminated all resonances and rattles from the sub. I intend to do the same with the kick panel woofers as well. When I replaced the mids I also sound deadened the door panels. All in all the combined tweaks have made a nice difference.

[elerner61]

Originally Posted by antennahead

as well as placing deadening material on the front baffle around the woofer....combined tweaks have made a nice difference.

You know, I hadn't intended to do that but it does make sense to take the extra time and make the effort. I've got a good amount of Brown Bread left over from my Miata installs. I'll do the front woof compartments and the doors when I put in the CDT drivers I've got (if I can find the time/get my ass in gear).

Thanks for the idea!

[antennahead]

Originally Posted by elerner61

You know, I hadn't intended to do that but it does make sense to take the extra time and make the effort. I've got a good amount of Brown Bread left over from my Miata installs. I'll do the front woof compartments and the doors when I put in the CDT drivers I've got (if I can find the time/get my ass in gear).

Thanks for the idea!

I think it will improve things and knock down the resonances inheirant in the factory setup