Re: Mysteries of the (archive)

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In Reply to: Re: Mysteries of the posted by JimL on February 10, 1999 at 15:24:42:

: The TDA1560Q is internally bridged (BTL). The datasheet for this part is available on the web on the philips web site. It's a .pdf file. The "typical" application diagram in figure 6 is exactly what BMW uses. The charge pump caps (C1,C2) are 3300uF.

Duh! You're right. I should have remembered this, but as one gets older the grey matter starts to lose a few bytes. ;-)

: : While in there, did you notice if they happen to have the operation software on a plug-in EPROM?

: I was going to ask you about that. I forgot to write down the part number. THere is a custom control chip made by Motorola for BMW. It's called ZC... something or other. And it's labeled "BMW DSP-1". I assume that this chip decodes the I2C signals coming from the front of the car and tells the DSPs what to do. I think the 56004's are the ROMless parts, but I could be wrong.

I'll have to look it up, but I think you're right. This might open up the possibility of some BMW friendly aftermarket supplier providing software upgrades like Jim C does for the DME.

: I'll open the box again and post the exact part number.
Thanks. Or you can E-mail me if you think this might bore the rest of the message board users.

: Bob, about a replacement sub box. I was looking at the JL Audio Stealthbox for the Audi A4. http://www.jlaudio.com/stealthbox/audia4.html. Do you have anything like this for sale?

Unfortunately not. We have some suitable drivers, to use in a custom box but we don't currently do any enclosures. I'd be happy to work out a design which could be duplicated by a good installer for use with one of our woofers if you'd like. Maybe you could E-mail me a sketch of what's there noe with some key measurements. I'm surrounded by E34's, but I happen to be E39 access-less around here right now.

: How would you recommend mounting a sub in this car? The factory bandpass box sits under the rear deck and fires through two small (approx 3") holes leading into the passenger compartment. The problem is, if I go to one or two 8" or 10" drivers, how do I position them for best sound and least waste of space?

It seems that the factory box probably uses the least useable space, since most of us aren't in the habit of sticking our stuff to the roof of the trunk. A suitable replacement box may be able to even use the existing bandpass holes. My initial thought would be to use a hybrid of bandpass and infinite baffle. Essentially this would be made up of the vented side of the bandpass where you'd logically expect it to be, and the sealed side replaced with "nothing". Essentially replacing the sealed chamber with the trunk volume. A company called ACA has this patented, so it can't be legally used commercially, but it is a viable solution to construct for "personal" use. I am using a simple 10" infinite baffle woofer firing through the ski-bag opening in my E34. It works very well. Tight, clean, goes very low, and I can still fit all the "stuff" required for travel by my 2-1/2 year old and two week old daughters. Unfortunately, BMW stopped putting the Ski-bag opening in E39's unless it had the factory installed bag. It's still safe to cut there though if you consider this an acceptable option.

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