Crossover opinions solicited

[zhandax]

I am trying to decide whether to recap the stock crossover on the 540 or just change it out for the individual MBQuart crossovers (that came with the speakers). I imagine most people have simply done one or the other. Has anyone heard both and care to give an opinion? Mine has the amp and 10 speaker setup.

Simply upgrading to an Eclipse head unit has made an unbelieveable difference. I have not installed the new speakers yet. The CD changer was dead on delivery, and I removed it to install an XM tuner. I plan to use the changer cable to send the XM signal to the head unit AND (since I discovered that my amp does not support speaker level input) I plan to use the remaining conductors to send line level outs to the amp (will use a common ground). 10 pins on the CD connector works out just right and it appears i can get a connector for the dash end of the cable on Mouser.

If opinion sways toward re-caping the factory crossover, does anyone have a list of the caps in the crossover? Even if opinion leans toward the Quart crossovers, this may be a useful reference for owners who do elect to keep the factory crossover if anyone happens to have the list.

[Ross]

MB Q has ostensibly spent some time optimizing the X-over for their speakers and the BMW x- over would likewise be expected to be set-up for what is in place from the factory.
I think it would be counter productive not to use the MBQ especially if they are already provided. BTW I have four surplus MBQ x-overs if anyone needs them.

[Tiger]

Go all the way... upgrade the amp to aftermarket unit. Run new speaker wires to each location and use the crossovers that comes with the speakers.

Using common ground in a floating ground system leads to sound quality problems.

[zhandax]

I am fairly commited to using the existing cable until I hear cross-talk. I can't help but think that an engineered (German automotive, not like I would trust any of the Windoz jocks I work with) shielded cable installation will be superior to any set of cables I string from the dash to the trunk.

This is to connect a PPI PC450 for the mains and a PPI PCX2200 for the Quart sub. I don't think anyone can fault the hardware I just need advice tor the connections preferably without the big jumble of cable from the dash to the rear like I had in the 528.

I will drop in the speakers next. That, in preparation for the amps, is the point I have a deadline for signal cabling

[Tiger]

Yes, I have done it already... zero problem with shielding... oinly the RCA must be a good wire.

[zhandax]

So you are in favor of the jumble of wires from dash to rear?

[pingu]

Speakers and crossovers are designed to work together so if you're not using the appropriate cross-overs then you're not doing your new speakers justice.

By "recap", do you mean changing the capacitors on the cross-over? If so then that's only part of what you'd probably need to do. Unless a cross-over is for a fairly cheap and basic pair of speakers, the cross-over will probably also have inductors and you'd need to change the inductance of these too.

Regarding the BMW wiring, the stock wiring on mine is twisted pair for the loudspeakers (not that louspeakers are particularly sensitive to interference but it's good to see that BMW have used sensible wiring).

[zhandax]

Tiger, how good a wire is enough? I used monster cable on the 528 and they were almost a half inch diameter per channel. That is the jumble of wires I want to avoid. Do I need to be more concerned with voltage drop or interference? Is Cat5 too small a gauge to avoid voltage drop? Is Cat5 available in anything heavier than 24 gauge?

Pingu, that is what I term 'recapping'. I did not bookmark the threads, but a few people recommended replacing the stock crossover capacitors with polypropylene. Since none of the posters to those threads have chimed in here, I think I will stay with the Quart crossovers.

[pingu]

Crossovers usually use unpolarised (i.e. they can handle AC unlike normal elecrolytic capacitors, which must be connected the correct way round) electrolytics. Electrolytic caps are cheaper than polypropylene caps.

Electrolytic capacitors have a higher internal resistance (real capacitors, unlike theoretical capacitors, have a small amount of resistance - it's as if you have a small resistor connected in series with a perfect capacitor) than would polypropylene capacitors of the same value.

Replacing electrolytic caps in a crossover with poly caps might improve the sound but might also make the treble too bright (because the reduced resistance of the poly caps will let too much treble through to the tweeter). I'd go for an easy life and leave the crossover alone - sounds like you've got your hands full with the wiring!

[attack eagle]

not to mention your factory amp is unlike those used on the 93 and earlier cars with a large passive array and 4 channel inputs. I think it is a 5 channel actively xover amp.