View Full Version : Active Crossover question
03-13-2012, 11:16 PM
Hey guys, just a quick question here. I plan on switching my setup to active crossover soon and I was wondering if I necessarily needed to buy an outboard DSP like an MS-8 to handle the crossover and Eq, or if could just take out my passive crossovers, and then run my tweets and mids off of 2 separate amps with built in digital crossovers and EQs or run the limited EQ from my headunit instead.
It seems like many high end amps nowadays have these things built in to them. I know technically an active system is when the crossover is before the amp, but is it basically the same thing if you just have a good enough amp? I just don't want to spend an unnecessary $500 on a DSP and double up on things I already end up having.
03-14-2012, 11:04 AM
You can run an active crossover with seperate channels for each speaker if you want. There are plenty of options for an active setup, but it depends on the goal you are looking for and what to expect from the equipment you purchase. You could spend as little as $300 on a Sundown SAX-100.4 which is capable to run an active setup by itself with no external crossovers. It will get loud depending on the speakers you use, and could sound quite nice, however you probably won't win any SQ awards. Even if you get a DSP with internal Crossovers and EQs, you still might not win SQ awards, because your car might not be an ideal listening environment.
So for advice, I would recommend you find out what sound you are looking for. Once you find that sound, by equipment to get you there. One of the reasons I want to go active, is so I can turn my tweeters down a notch. Mine sit way up in the A-pillars, and can be a bit harsh when the mids are getting to their sweet spot. I don't plan on competing at all, much less for SQ.
Why So Cereal?
03-14-2012, 11:14 AM
Yes,u can run active from the amp but it's MUCH easier to do it from A capable HU with built in crossovers and a built in DSP
03-14-2012, 11:18 AM
active capable decks are the way to go, it makes life so much easier.
03-14-2012, 11:43 PM
Great, thanks for the input. I'll probably end up getting a new h/u that can play CDs and run an active crossover. On that note, I may end up going 3-way active eventually and would need something that can handle all the channels as well as my subs.
If I run active in the front with a 4-channel amp (like 110-150/ch) , could I still use my current 5 channel amp (55x4 on the speaker channels) to power my subs and send a little power to the 6x9 co-axials in the rear (and run the xover to the 6x9s from the 5-channel sub)? Would this defeat my front soundstage or just serve to round it out? If I did it this way I would still have 2 unused channels in my old amp. Any suggestions as to what to do with these? I have two unused 5 1/4 speaker enclosures in the rear doors...again the question of defeating the front soundstage arises
To sum it up:
1) can I get away with buying 1 good 4-channel amp for the fronts, and then utilize my old 5-channel amp (Memphis Belle) to run the rear coaxials (and possibly rear door components) and sub? Is this type of setup even advisable for an sq build?
2) instead, should I ditch my rear speakers and old amp altogether, and just get a mono channel amp to run the subs (or maybe just 1 good 5-channel amp?)
Thanks for your time; It seems like with every answer comes more questions..
03-15-2012, 01:17 AM
One more thing...If I were to get like a Pioneer DEH-80prs with active crossover on 3 channels, eq, time alignment etc, would this make any of these features on whatever 4-channel amp i decide to go with redundant?
Also, if I had a 4-channel amp running the front, could it accept 2 of the crossover inputs from the h/u for the highs and lows, or is it one input per amp?
Sorry; all of these technical aspects are pretty new to me :)
03-15-2012, 09:35 AM
If your gonna spend money on an active h/u, get a clean sounding 4 channel and bridge it at the correct ohm load and run the rear speakers off the h/u rear speaker outputs.
03-15-2012, 09:54 AM
I'm looking at something like an Arc Se4200 which is 110wx4 @ 4 ohms or 400wx2 @ 4 ohm bridged. I thought with active crossover it was good to have one channel going to eack speaker of the component rather than bridged to the set. Or would the Helix 85wx4 be better for my purposes? I'll be running a set of HAT Clarus comps.
03-15-2012, 10:54 AM
Sorry, this is how I run my set up. You are correct about yours, though. Run each individual amp channel to each speaker. The Arc amp will have plenty of headroom, which is good. The Helix, would be a good choice as well. All depends on how much you want to spend on amplifier.
03-15-2012, 10:57 PM
If you want a 4-way active setup you're going to want a DSP for the most versatile solution. If you want to do it all at the head unit you need something like a Pioneer P99RS for $1199 retail or look for discontinued head units along the lines of the Clarion DRZ-9255. A standalone DSP like the Rockford 360.2, Audison Bit One and its siblings, or the JBL MS8 will work on any head unit.
03-15-2012, 11:19 PM
Why not just use your current 5 channel amp? If you are getting a active hu then you could use it for the front stage and sub. Run your rear speaker off the hu if you want them. If you want more power just get a two channel amp for your mids. Then you can use now extra channels for the rear fill.
03-17-2012, 12:38 AM
That does sound like a good option...Maybe I could start with the two channel and eventually upgrade to a bigger 5-channel if the power is an issue. It may not be though, I'm not sure, I've never run it active. I was leaning towards eventually replacing my current amp mainly because I've run it for several years and I'm feeling like something new, particularly in the sub power department.
Or maybe I could just sell my old amp, get the Audison AV 5.1k, and run my rear coax from the h/u. :)
03-17-2012, 11:24 PM
Why do you want to go active?
If you have a good set of components with a bit of thought put into the passive crossovers, you'll be chasing ghosts for a while trying to get a better sound. Time alignment is neat, but the level setting and EQing is a major PITA and, from experience, you'll never really be satisfied.
In my honest opinion; keep things as simple as possible and use high quality equipment. Outboard DSPs all have their quirks and active capable HU's are all terrible (the affordable ones anyway). My favorite systems have always been the more simple ones. Against my own better judgement, I've tried the active thing a couple times and always went back to passive x-overs and an analog EQ. Wish they made a simple box that only did time alignment, I'd buy that in a heartbeat.
03-18-2012, 10:07 PM
Thanks for the tip; I plan on upgrading to a Pioneer DEH-80prs or maybe even the P99rs, so I'm definitely with you on the keeping it simple philosophy. I also assume that these built-in crossover h/u's don't fall into the category of "crappy" although I'm still a bit of a newb at the more technical end of audiophelia, so you tell me. The 99rs does auto-EQ and time-alignment and then allows you to tune afterwards to personalize the sound, so I shouldn't need any additional EQs, crossovers or DSPs. The 80prs isn't quite out yet but the specs are pretty impressive for the price-range.
With the ability to tune everything from the h/u, and the added benefits of more flexibility and power in active mode, I don't see any reason not to (except for the cost). I like to tinker with the tuning anyway, so I don't view that aspect of active crossover as a burden, especially if the auto-tuning feature offers a good reference point.
I am of the mindset that I would rather spend more and buy once and gain the flexibility to change the sound setup easily in the future, rather than get something that might be feasible for the short-term but won't hold up to long-term upgrading if I decide to switch my setup.
Thanks again for the feedback.
Why So Cereal?
03-18-2012, 10:38 PM
The Pioneer 80PRS and 99RS are both great HU's no doubting that. Pioneer has always had the ability to make some nice high end active HU's. Some people say they are "hard to use" but it took me all of about 10 minutes to figure out how to use my 880 (similar to the 80PRS, just older); so I'd say that ease of use is a plus with them. The independent L-R EQ, Xover points, and slopes they both offer are great additions in helping with level matching the sides to each other.
I was in between the 80 and the 99 for a minute (http://www.caraudio.com/forums/head-units/534541-pioneer-deh-80prs-vs-pioneer-dex-p99rs.html), so I decided I'd pick up a nice "lower line" active deck to try out and see if it was enough for me or if I desired more. By chance, I ran into the 880 for a little more than my budget so I went ahead and picked it up. After using it for a little bit now, I decided I couldn't really justify the $1,300 for the 99. The only reason I'd see to grab a 99 over the 80 is if you plan to run a fully active 3 way front stage plus subs and even then, there are other alternatives. For what you'd pay for that P99RS unit, you could grab an Audison Bit One, JBL MS-8, RF 3Sixty Unit or maybe a Mini DSP for your tuning and active needs and still spend a good bit less. I'm definitely with you on the enjoying of tuning part and spending more once to get what you like. That's why I was seriously considering the P99RS as well. Both would make fine choices just depends on what you're willing to spend for what you get and how you intend to use it.