I have two Xtant 302As rated at 75x2 wrms. I have a single Xtant 301a (300x1 w rms) for my subwoofer, 99.9% chance I'm using a 12w6v2. I will be biamping an old set of MBQ 218.61Qs with the woofer in door and the tweeter mounted in the kickpanel. I may be using an Alpine head, either a CDA7998 or a CDA9815. I like these decks because of their built in adjustible xo points, slopes, 6 channel time delay (more like 5) and parametric equalization and XM. HOWEVER, I do not think the crossovers in the deck will be able to allow me to run a fully active system and I may need to use the passive crossover for my front stage and the only active filtering for the front stage would be to highpass the woofers, which will be lowpass by the MB Quart passives. I feel that even if I could go fully active, I should still use the quart passives to retain the tonal characteristic of the speaker. After all, those engineers spend just as much time designing the xo networks as the speakers themselves. Also, the Xtant amps have selectable crossver points using chips and cards. I also have a Xtant P500a 5 band parametric I could use in 2 and 3 band mode before the signal hits the 302As, but I was wondering if it would be overkill.

On the other hand, since the tweeter in the kickpanel is so close to the woofer in the door, I'm thinking I could just forget about time delaying ALL the speakers and just bridge the 302a and send 300 wrms to each side through the MB Quart passives.

I want a nice sounding, simple install and to do some slap SQ+ shows if I want to. I want a decent center image, tonal accuracy, dynamics and headroom. I also want the car to pound, but I want to mids and highs to keep up. I want to be able to down out some of the engine nose at highway cruising speeds.

I know someone who has built IASCA champ cars using this same Xtantamp/eq setup (using the xtant xo cards), so I can get the car dialed in right, but the whole headunit with the processing has me confused as to what to do or use.


Can anyone help me clear my head. Thanks.




Modified by dc24me at 1:15 AM 4/22/2003

 

If you have the time alignment and the channels available, go active...especially if you want to compete. Get the install right, and a small parametric should be able to correct all problems.

I would suggest you take a look at the score sheet for slap usac and iasca. If it was me, I'd run kick mounted mids and a-pillar mounted tweeters. This will normally yield a higher stage, avoid the rainbow effect, and get a deep stage. You do sacrifice a bit of staging accuracty, but often this isn't where the bulk of your points are earned in competition. With the option of time alignment (if you know which seat the judge will be in) you should be good. Look at people like Steve Head...he has Focal Audiom tweeters in his a-pillars.

Take a look at Scott Buwalda's Nissan 240 - He used Zapco and MBQ QSD's in a similar arrangement. I would highly suggest you get a hold of him...PM me for his email address. He used to have his own site and forum (http://www.concertcar.com) but I believe it has been taken down. He has also parted out much of the car.

What you will need to do is run the tweeters very high...highpass at approx 5kHz. This means that your midbass needs to be linear up to that point as well...I'm not sure if your set is capable.

This kind of setup is a bit of a tradeoff, but kicks are so difficult to get correct that it may get you a bit better results.

Those alpine's will be fine, and you can combo the heads and amps crossovers to get what you need. Keep in mind that if you are committed to competition, they really don't listen to their systems that loud, so I'd choose the control of an active steup over the extra power of bridging.

That's just my $0.02....

 

Thanks for your input this was the kind I was looking for.

I want a simple system. I will not sound perfect, but decent to IASCA/slap standards. Steve Head's Civic and Buwalda's 240SX are much, much beyond what I want to do. They are also using way too many speakers, imho. I'd like to keep the interior as oem looking as possible, since it's car audio, not audio car . I like functionality and the car will remain a daily driver. The most I want to do visible up front is make my own dash kit (out of plexi, blend an oem honda pocket into it and spray it black) and blend the tweeters into the kickpanel. I thought about mounting the tweeters in the A-pillar, but I was concerned about having a gap or void between the midrange and tweeter (layering effect) and also all those reflections off the glass. But I'll think about it some more. I don't want the tweeters to be so in my face, but I have to remember all the extra control I will have because it's all active and time delay, and the fact by amps have independent left and right gains.

Should I use the P500a? or just rely on the internal parametric of the CDA7998?". The P500a has a noisegate too and I know someone who knows how to dial this particular piece. I don't want to make the system more complicated than it needs to.

Are you using time alignment yourself?

 

Rcurley, what is rainbow effect?

I need to enter a competition some day

The 7998 has a max correction of 6db on the parametric eq. To keep a simple system it might be nice to try it out before buying new hardware. My manual does not say, but I think you should be able to time align the tweet and mid seperately if you switch the 7998 to 3 way mode.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vteg &raquo;</TD></TR><TR><TD CLASS="quote"> My manual does not say, but I think you should be able to time align the tweet and mid seperately if you switch the 7998 to 3 way mode.</TD></TR></TABLE>

That is the impression I get from my manual as well so you aren't alone.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dc24me &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for your input this was the kind I was looking for.

I want a simple system. I will not sound perfect, but decent to IASCA/slap standards. Steve Head's Civic and Buwalda's 240SX are much, much beyond what I want to do. They are also using way too many speakers, imho. </TD></TR></TABLE>

Scott's car only uses 5 drivers for SQ - 2 tweeters, 2 midbasses, 1 sub woofer...all drivers are MB Quart, he has 4 subs for SPL. I agree that Steve uses a few more, 8 speakers for sq - two tweeters, two mids, two midbasses, (all Focal) then 10" OZ subs free-air in the kicks. The 4 OZ 12's that are free-air are only for SPL.

While these cars are extreme (both have fully custom dashboards, you can take some design cues from them, and apply them to your car.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">I'd like to keep the interior as oem looking as possible, since it's car audio, not audio car . I like functionality and the car will remain a daily driver. The most I want to do visible up front is make my own dash kit (out of plexi, blend an oem honda pocket into it and spray it black) and blend the tweeters into the kickpanel. I thought about mounting the tweeters in the A-pillar, but I was concerned about having a gap or void between the midrange and tweeter (layering effect) and also all those reflections off the glass. But I'll think about it some more. I don't want the tweeters to be so in my face, but I have to remember all the extra control I will have because it's all active and time delay, and the fact by amps have independent left and right gains.</TD></TR></TABLE>

I would try it out. I think that it will be easier to get the high stage that you want --- I think it's pretty important. Often it's tough to get that high stage with out them. I know Head did an RSX a little while back, and it was all OZ and arc audio if memory serves. He used KP mounted tweeters, but added a second set in the sail panels to help height and width. Regardless, experimentation is the key...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Should I use the P500a? or just rely on the internal parametric of the CDA7998?". The P500a has a noisegate too and I know someone who knows how to dial this particular piece. I don't want to make the system more complicated than it needs to.

Are you using time alignment yourself?</TD></TR></TABLE>

I'm not really up on that Xtant piece.....

Personally, I will not use time alignment, nor do I have any plans to. With my install, I dont' need it because I will have fairly equal pathlengths.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vteg &raquo;</TD></TR><TR><TD CLASS="quote">Rcurley, what is rainbow effect?</TD></TR></TABLE>

When you put tweeters in kickpanels, your stage will sag at the ends...this is most prevalent with soft dome tweeters, but the same can happen with metal ones as well. So your stage height is shaped like a rainbow.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">The 7998 has a max correction of 6db on the parametric eq. </TD></TR></TABLE>

If you need more then 6 dB, your speakers are in the wrong spots...