Question about partially using passive xover

[beezel]

This isn't quite PG related, but you guys have proven to be very knowledgeable about everything car audio related.\

I'm thinking about replacing my HU with the Pioneer PRS-80, which has a 3way active xover network. I, unfortunately, have a 3way passive MBQuart stage and a sub, which makes it a 4way. I only have 1 zx450 and 1 zx500 for amps, so that's only 2 channels for my 3way, meaning at some point I have to use my passive xovers.

My question is this: Can I safely use my mcx335 that is a 3way passive and ONLY use it to xover my 8"s and 4"s? I'd be running my "front" channel into that, and my "rear" channel directly to tweeters. Also, am I losing any protections by putting my tweeters directly on my rear channel?

I've mocked up a diagram of my "ideal" setup.
https://docs.google.com/drawings/d/1B08 ... ITKCg/edit

Note that due to the x-overs available on the HU, I have to use the passive between the MID-LOW and MID-HIGH, forcing the tweets onto their own channel.

Thanks!

[ttocs]

most passive cross overs need to have all the speakers hooked up to get the correct freqs that it is designed to block and allow to pass. Not sure about your quarts in particular but for the most part only hooking up part of it will change the freqs it is crossing over.

[Eric D]

With the equipment you have at hand, I know I personally would run the ZX450 stereo bridged into the Quart passive network. Then run the ZX500 on the sub as you planned.

This will get you 250W+ a channel to the 3-way, which will easily be able to drive the drivers with authority.

[Audiophiliac]

IIRC, that MBQ crossover is bi-amp capable, yes? There should be some jumpers you can move to allow you to use one set of amp channels for the midbass, and one set for the mids and tweeters. You could go that route and just send a high pass from the HU into the 450, and use the front channels for the highs and the rears for the lows.

BUT, my preference, if I were you, would be to run the 450 bridged and use the passives as is. The extra power will gain you more than going partially active IMHO.

[Audiophiliac]

Dang it! Eric beat me to it. More power is more better.

[beezel]

With the equipment you have at hand, I know I personally would run the ZX450 stereo bridged into the Quart passive network. Then run the ZX500 on the sub as you planned.

This will get you 250W+ a channel to the 3-way, which will easily be able to drive the drivers with authority.

I believe that is how i have it now - assuming stereo bridged means front channel L+ and R- to left input on the xover, and rear channel L+ and R- into right input on xover, with it setup without bi-amp jumpers.

It does sound good - the nerd in my wants full active control. I guess the real solution would be adding a zx250 or something for the tweeters, and ditching the passive network entirely. I guess that gives me a path to work towards.

[ttocs]

bridging the amp would mean you use the pos left and neg right of the front, and the same for the rears.

[beezel]

bridging the amp would mean you use the pos left and neg right of the front, and the same for the rears.

Right, but that would be a mono-bridge. I was asking for clarity on the stereo bridge. Thanks though.

[ajaye]

bridging the amp would mean you use the pos left and neg right of the front, and the same for the rears.

Right, but that would be a mono-bridge. I was asking for clarity on the stereo bridge. Thanks though.

what ttocs said is how you'd achieve a stereo bridge. The amp's front L+R would be bridged to one mono channel. The rear L+R bridged to the other channel. Your front inputs on the amp should only be fed with one side of the stereo signal, the rear with the other.

[davewaibel]

dont ditch the tweeter protection of the crossover to go active on the tweeters.....other wise the nerd in you will be shopping for tweeters....as running active is likely to kill these without warning-

[Audiophiliac]

Let me throw another option out that may be a little out of the box, but follow me. You can run the 8s active on the ZX500, using a highpass from your HU and the lowpass on the amp to create the proper bandpass or by sending a bandpass from the HU. Then send another highpass to the front half of the ZX450 (or full range from HU and use the HP on the amp), using the passive for the 4" and tweeters, and bridging the rear channels of the ZX450 to your sub. What 12W6 do you have? Old school? Or v2? If it is the old school dual 6 ohm version, you will have plenty of power.

Just a thought. Having more power and losing the passive for the 8s might improve your midbass noticeably. If there really is an issue using the 3-way passive without the midbass connected, find the proper MB Quart 2-way and use it.

But if you really want to go 4-way active, you would need another amp and either a different HU or an outboard processor with 4-way capability, time alignment, and probably some EQ options. Good luck! Sounds like a nice setup either way you go!

[Eric D]

Before you consider getting a ZX250, consider a ZX450 instead.

Then use one ZX450 for the left, and one for the right. You can choose to bridge them, or not, and you get the most configuration options, plus true dual mono for the best stereo separation.

[mrblack]

Originally post by davewaibel
dont ditch the tweeter protection of the crossover to go active on the tweeters.....other wise the nerd in you will be shopping for tweeters....as running active is likely to kill these without warning-

I don't necessarily disagree with this post, but I would like to add that I've been running my tweets driven directly from my M44 without any further protection using my processor's active digital crossover for years and years without a single problem. I guess it comes down to the install because you're right, a little blip of turn on noise could be killer in this situation. Some have recommended a small fuse be wired inline with the tweet when driven directly from the amp. I've never had an issue however so I figured why bother? And once you hear a system with a quality active crossover you'll never allow yourself to go back... Unless SQ really isn't your goal and all you're in for is to make your ears bleed. Then I guess power is all you should consider.

The best way I can describe the difference I heard in moving from using passive crossovers to active digital would be a dramatic increase in impact and an amazing amount of definition in the decay of the highs, it's truly one of the most audibly impactful changes I've made over the years to my system. And mind you I actually dropped the amount of power going to my components when I made this change, going from an M100 to an M44, and even with roughly half the power going to the component set the change was more than worth it.

Lastly, I have no experience with your specific head unit, but the quality of the deck's built in active crossover is something else that should be considered in your final decision.

[audiophyle_247]

Few passive crossovers require all connections to maintain freq cutoffs, most run each section inside in parallel not series, so the speaker impedance makes the difference not if you have all of the speakers connected or not. I'd run the tweets & 4's off the passive, then the 8's & subs active, if you can.

[ajaye]

Before you consider getting a ZX250, consider a ZX450 instead.

Then use one ZX450 for the left, and one for the right. You can choose to bridge them, or not, and you get the most configuration options, plus true dual mono for the best stereo separation.

I like this option a lot actually, very good suggestion. I had an old Kenwood KA 7300 integrated amplifier that was marketed kinda using this concept, dual mono amps with independent power supplies in one unit to combat "dynamic crosstalk," also makes pinpointing faults a little easier. I miss that bad boy.