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Seeking some system design opinions...

Posted: Tue Mar 08, 2011 7:31 pm
by Lowcountrypsulion
Hey everybody. I'm currently building a false-floor setup for the trunk of my Si and I am trying to decide how to best utilize the components that I'm using. So, I am officially soliciting advice about which direction to go with the design. Here's the signal chain back to the crossover:

CD player out to PLD-1 back to one EQ215 out to an AX406A out to an M25 and M44. All of my PG processors are first-generation (white powder coat with blue and gold graphics) and my Quart components are 12-year-old MB Quart Reference series.

Here's where I am somewhat stumped. I could go several different directions, but I've narrowed it down to three possible scenarios. Here we go:

Scenario 1: (No rear fill) Use the AX406A in 2-channel, 3-way mode using one pair of channels on the M44 for the Quart tweeters, the other pair of channels for the 5 1/4" mids, and bridge the M25 for the Punch 12. This would effectively eliminate the Quart passive crossovers. Although, I would still want to use the tweeter protection circuit built into the passive Quart unit. This would provide approximately 55 watts per tweeter and mid (the M44 is rated at 55 per @ 13.8 volts).

My question about this scenario is which provides better crossover function: the AX406A or the passive Quart units? I'm guessing the AX406A.

Scenario 2:(No rear fill) Use the AX406A (or the AX204A) in two-way mode and bridge each pair of M44 channels to each component set thus utilizing the passive Quart units. This would provide approximately 160 watts per component pair and 140 watts from the M25 for the Punch 12. To me, this sounds like a lot of watts for the passive Quart crossover to handle, but maybe they can handle it.

Scenario 3: (Yes rear fill) Use the the AX406A in two-way mode sending the high pass to the front channels of the M44 and the low pass to the M25 bridged to the sub. Then use the band pass capability of the AX204A sending the band pass signal to the rear channels of the M44 for the rear fill. This setup would continue to utilize the passive Quart crossovers but only provide 55 watts to each component pair.

I know this system is a low-wattage system, but that's what I'm going for; a low-power, old-school, sound quality setup. I'm also actively avoiding serious upgrades to my electrical system in the process. My progress on the installation is slow, but I'm getting there. I will definitely post pictures.

I know that everyone on this Phorum is experienced and knowledgeable so any advice would be greatly appreciated. And if I overlooked another option, let me know! Thanks in advance!

LowcountryPSULion

Re: Seeking some system design opinions...

Posted: Wed Mar 09, 2011 6:11 am
by smgreen20
I like the first choice. Those tweets would be fine with 50 watts going to them. The only reason I would see for keeping/using the passive xovers is to keep the possibility of DC away from the tweeter. And unless you're going to be driving everything into clipping I see no need for the Quart xovers.

Also the front would be plenty loud that even people in the back seat will hear it. That's how I'm set up and my kids/friends hear it all just fine.

Re: Seeking some system design opinions...

Posted: Wed Mar 09, 2011 10:31 am
by Lowcountrypsulion
smgreen20 wrote:I like the first choice. Those tweets would be fine with 50 watts going to them. The only reason I would see for keeping/using the passive xovers is to keep the possibility of DC away from the tweeter. And unless you're going to be driving everything into clipping I see no need for the Quart xovers.

Also the front would be plenty loud that even people in the back seat will hear it. That's how I'm set up and my kids/friends hear it all just fine.
Thanks, smgreen20. I appreciate it. I was definitely leaning toward scenario 1 primarily because I have never used rear fill speakers in any installation, but I was briefly considering it now. It is plenty loud without them. Plus, they're factory 6x9s and the Quarts blow them away. Ltr

Re: Seeking some system design opinions...

Posted: Wed Mar 09, 2011 6:23 pm
by kg1961
smgreen20 wrote:I like the first choice. Those tweets would be fine with 50 watts going to them. The only reason I would see for keeping/using the passive xovers is to keep the possibility of DC away from the tweeter. And unless you're going to be driving everything into clipping I see no need for the Quart xovers.

Also the front would be plenty loud that even people in the back seat will hear it. That's how I'm set up and my kids/friends hear it all just fine.

i agree!! the quart don't need alot of power im going to run my old 3 way set up with 100rms tried it in the house and man is it loud and clean

Re: Seeking some system design opinions...

Posted: Mon Mar 14, 2011 2:45 am
by ludeboost98
Personally i would go with scenario 2 . Just because i have alot of experience with the quart speakers and with that series i would stick with the quart crossovers . The pg crossover is nice but a litlle harder to accurately set the crossover point . Being that your components are 12yrs old i wouldnt want to see you fry the tweeters . On that series the titanium tweeters dont have a butyl surround like in the q and premiums so you cant quite set the crossover points as low . Thats just me . Those crossovers should be able to handle that power just fine . food for thought

If you can get a pair of premium crossovers you can bi-amp them and still split up your channels . i may be able to track a set down for you .

Re: Seeking some system design opinions...

Posted: Mon Mar 14, 2011 8:00 am
by stipud
My vote is definitely for scenario 1 as well. The AX can very accurately set the crossover frequency because they use fixed chips (or you can build simple resistor networks), so it would be difficult to cause damage. You'll definitely want to set the gains using an oscilloscope, or at the very least a multimeter. An RTA would also help you get the levels between the midrange and tweeters correct, but your ears should be OK for this. I'll bet the tweeter gains will be much lower than the midranges (which should be getting the full power of the amp).

Re: Seeking some system design opinions...

Posted: Tue Mar 15, 2011 3:32 am
by Lowcountrypsulion
stipud wrote:My vote is definitely for scenario 1 as well. The AX can very accurately set the crossover frequency because they use fixed chips (or you can build simple resistor networks), so it would be difficult to cause damage. You'll definitely want to set the gains using an oscilloscope, or at the very least a multimeter. An RTA would also help you get the levels between the midrange and tweeters correct, but your ears should be OK for this. I'll bet the tweeter gains will be much lower than the midranges (which should be getting the full power of the amp).
Thanks, Stipud and everyone else who commented. I appreciate the feedback. I've already talked to my local shop (Custom Car Stereo) and they agreed to RTA it when it's completed. Given the combined amount of gain adjustment between the PLD-1, EQ215, AX406A, and the M44 and M25, I was going to have my hands full tuning it without the benefit of an RTA.

Thanks again!