Wiring and subsonic filter?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=29763
Printed Date: July 15, 2025 at 8:13 AM
Topic: Wiring and subsonic filter?
Posted By: charlie101_1999
Subject: Wiring and subsonic filter?
Date Posted: April 05, 2004 at 10:19 PM
I'm going to be running a MTX 895 5 channel in a mountaineer. It's rated at 70 X 4 and 320 X 1 @ 2ohms 12.5 volts.
I'll be pushing (4)5X7 Infinity Kappas and a JL12W3v2 4ohm. How would you wire the 5X7's, I understand how you would wire the sub but I'm lost when it comes to the 5x7's.
Also, the amp has a 85hz low pass fitler, would you suggest a subsonic filter? I checked past post but I'm still confused. Thanks
Replies:
Posted By: DYohn
Date Posted: April 05, 2004 at 10:29 PM
Which model Infinity 5X7 do you have? The reference or the Kappa with external crossover? In general, a subsonic filter can help protect your sub from unwanted DC voltages and can help the amp perform better at low frequencies, but it is not necessary.
Posted By: charlie101_1999
Date Posted: April 05, 2004 at 10:45 PM
They are the Kappa's w/crossovers.
It isn't necessary, but would you recomend one? Thanks again.
Posted By: DYohn
Date Posted: April 05, 2004 at 11:11 PM
The Kappas are 4-ohm speakers. You connect the amp to the crossover, and the two outputs from the crossover go to the woofer input and the tweeter input on the 5X7. They use different sized connectors, so you can't easily hook them up wrong. Your amp is rated at 35 watts X 4 into 4-ohms, so I would recomend wiring your sub for 8-ohms. The MTX sub channel will put out about 75 watts into 8 ohms, which will blend nicely with the 5X7s at 35 watts. Unless you want overpowering bass, then wire it for 2 ohms and be prepared to not hear the 5X7's. :) A subsonic filter is a high-pass crossover usually set below the range of human hearing (less than 18 Hz.) Your amp does not have one built in, so you will have to either buy an external one, build one, or buy a crossover with one built in. Yes, if you can afford one, I recomend one. I run one set to 5 Hz.
Posted By: charlie101_1999
Date Posted: April 06, 2004 at 4:58 PM
Do you have any suggestions on any 2ohm 5X7's?
Posted By: customsuburb
Date Posted: April 06, 2004 at 5:53 PM
I have never seen a 5x7 that is 2 ohm. The only easy way you could get a 2 ohm load out of you amp is to wire 2 speakers to the left front or rear channel and two to the other front or rear channel. Wiring it this way would give you just as much power as wiring one to each channel, but you won't be able to fade and the amp will have a lower damping factor with a 2 ohm load so it wont sound as good.
Posted By: DYohn
Date Posted: April 06, 2004 at 6:04 PM
Ditto to customsuburb. No 2-ohm 5X7s that I know. Wiring two sets to one channel to force the amp to operate at it's 2-ohm rating is not a smart thing to do and will actually gain you nothing. In terms of sound quality, it will only hurt. The Infinity Kappas are good sounding speakers and will operate fine with the 35 watts from this amp, but if you want to push more watts, you'll need a bigger amp.
Posted By: charlie101_1999
Date Posted: April 06, 2004 at 6:05 PM
I guess my question is, what would one do with a 5 channel amp. I thought it was for running front, rear and a sub.
Posted By: DYohn
Date Posted: April 06, 2004 at 6:12 PM
Thatr's exactly what it is for, and it will do a fine job at that.... You have it correct.
Posted By: forbidden
Date Posted: April 06, 2004 at 7:50 PM
Agreed, a 5 channel amp is a dream to work with and can perform beyond most peoples expectations.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: haemphyst
Date Posted: April 06, 2004 at 9:39 PM
As a suggestion, buy another identical 5 channel amp, bridge the bridge them each to 3 channel mode, and then you will have 4 very high power channels, and two remaining mono channels for running a pair of 4 ohm dual voice coil subs. If you are going to do this configuration, though, use one for one SIDE of the car and the other for the other SIDE of the car. This will keep your separation and imaging as high as the deck can put out. Also, with the four channels bridged to two channels, they will be seeing two ohms per channel.
Forget all that drivel... I have to agree with DYohn on this one... Bridging quadruples the distortion rating, and quarters the damping factor, both bad things, indeed. Get more power than you absolutely need to start with, and have somebody THAT KNOWS WHAT THEY ARE DOING install it... and Eclipse does indeed make a wonderful 5 channel amp... the PA5532 is an amazing piece of gear, and not heinously expensive... Your Kappas would SING, then add a good quality sub, and you are done. Also this amp makes more power into the 4 ohm load of the Kappas than the MTX - 70 watts at 4 ohms, versus the 70 watts at 2 ohms of the MTX. <Probably around 40 watts or so at 4 ohms> Forbidden is also correct, a 5 channel amp can be a dream to work with... easy installation, and usually with all of the bells and whistles built right in...
Posted By: charlie101_1999
Date Posted: April 06, 2004 at 10:15 PM
I really appreciate the help guys. I have the MTX already and access to the JLW3v2(free). I haven't bought the 5X7's yet but the Kappa's are what I wanted. I'm trying to build a decent system with what I have already. If a 5 channel could be a good thing, then whats the best way to set this system up. I wanted to have this MTX run everything for now. Could I just run the 5X7's @ 4ohm and the sub @ 2ohms? I this possible? And if it is, is the worst case scenario just running a sub at 320 and 5X7's at 40?
Really, thanks for the patience guys
Posted By: stevdart
Date Posted: April 06, 2004 at 10:27 PM
Yeah, you can run the speakers at 4 ohm and the sub at 2. They don't have to be the same. Good luck with your install!
Posted By: charlie101_1999
Date Posted: April 06, 2004 at 10:30 PM
Thanks, I hope so also.
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