Can I wire my amp like this?
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=59870
Printed Date: May 12, 2025 at 4:47 PM
Topic: Can I wire my amp like this?
Posted By: action1978
Subject: Can I wire my amp like this?
Date Posted: July 22, 2005 at 11:40 AM
I am planning on runnning a 12" Punch P3 in a 4th order bandpass enclosure that is tuned down to about 30-40Hz. I was considering adding a pair of 8" subs as components to supply higher freq bass. (I am new at this so feel free to comment on that idea) Here is my question... I was thinking I could run a 4 channel amp and bridge the front channels to one sub, and the rear channels to the other. Then for the RCA input I could run 2 right signal cables to the front and 2 left signal cables to the rear and have two bridged subs in stereo. Has anyone ever done this or heard of doing this? Are there any complications I should know about if I plan on doing this?
Replies:
Posted By: sedate
Date Posted: July 22, 2005 at 11:57 AM
You'd have better results using a 15" and 2x8"... it'd give you better frequency response in the manner you are discussing.. especially as a 15 will play significantly lower than a 12.
Either way, don't bother unless you can put the 8's in kick panels or at the very least the back deck. All in the trunk like that doesn't really work... muddy, muddy bass.
You will also need to seperate the frequencies the woofers are playing, for that, you'd need either an extremely nice 4 channel with lotsa options, like the JL 300/4 or a signal processor, although I'm not totally sure what to recommend here.
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"I'm finished!" - Daniel Plainview
Posted By: Blowntweeters
Date Posted: July 22, 2005 at 11:59 AM
i have seen a setup with 1 12" sub and 2 8" subs and it was wired the same only thing i can think of is make4 sure the amp you get has crossover control for the front and the rear so you can set them how you want for the 12 and the 8's
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1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700
Posted By: action1978
Date Posted: July 22, 2005 at 12:08 PM
Thank you. This is all going into my 1996 4runner. Thus no trunk. I was planning on centering the port of the 12 facing backward and putting the two 8" in the back facing up for forwards on the right and left. I agree putting them in a trunk that way would be stupid. Its too late for a 15" my speaker is purchased and enclosure is almost done. As far as the crossover goes, I am using all rockford amps. I plan on using the T5002 for the 12" DVC which will run 500watts. For the two 8" inch I was going to use the P4004. Will these amps provide me with the proper crossover options that you speak of? Thanks,
Posted By: Blowntweeters
Date Posted: July 22, 2005 at 12:52 PM
i think it does not 100% on that if you already have the amp just look if it has controls for the front and another set for the rear you are in good shape ------------- 1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700
Posted By: sedate
Date Posted: July 22, 2005 at 1:10 PM
Uhh. Hmm.
Blowntweeters, I think he needs to run like.. say.. 60-200 hz off the 8's and 60 and below off the 12. 60 and below is easy with any amp... now a variable subsonic filter and a lo-pass filter that will jump up to 200hz.. that is a little harder to find.
The T5002 will work for the 12. It looks like there is a built in subsonic filter@28hz.. which is fine normally, but given what you are trying to do I would say is less than ideal. I'd defeat it if you can. I'm not sure if you'd hear a sonic difference w/o the subsonic filter though given the driver is only a 12. Again, a 15 is much more ideal for this sort of application.
The P4004 can't run that frequency spread nativly.. You can do 60hz and up, but not 60 - 200 and I really don't think you want 8's playing much above 2 - 250hz..
You might be able to do some fancy xovering with your deck.. like.. run a low pass from 200hz with your HU and then a hi-pass from like 60 and up on the amp..? Of course, I'm not really sure how you'd do that with your deck and still retain a signal for the 12 in the first place.
I don't know what to tell you, other than you should start looking at signal processors and find one that you can run your bass output to, then will divy up the signal for your two amps. I'd recommend something but I'd hit up this board if I was looking for something like that.
------------- "I'm finished!" - Daniel Plainview
Posted By: action1978
Date Posted: July 22, 2005 at 1:38 PM
Okay, I don't think I described this correctly. I want to run the T5002 (2 channel) to the 12" bridged. I want to run the P4004 (4 channel) to the 8"subs. When I said the front channel to one sub and the rear channel to another i meant the front and rear channels of the P4004 sent to the two 8's. The T5002 could be set up for 60Hz and below and the P4004 set to 60 to 200 Hz. I would not need to set up the front and rear of the P4004 seperatly as the front channel of the P4004 would be bridged to the left side 8" and the rear channel to the right 8". That is how I would input the RCA's so the front and rear channels become bridged left and right channels. Does this make sense? Again, thank you for the help.
Posted By: sedate
Date Posted: July 22, 2005 at 2:39 PM
action1978 wrote:
the P4004 set to 60 to 200 Hz.
Right, I understand what you are trying to do. What I'm telling you is that the P4004 amplifier, as I can see it here, simply isn't going to be able to do what you need to ask of it properly run to 8' speakers from it. It needs a 'Band pass' crossover.. both lows and highs cut out of the signal. That amp, like most amps, isn't capable of doing that, only a hipass or a lowpass, not both at the same time, which is what you need.
action1978, what I'm trying to tell you here is that what you are doing is a very high-end style install. You are trying to dedicate mid-bass speakers, which, in any car, almost *always* REQUIRES a signal processor to actively mix up the signal before being shuttled off to what is usually multiple amplifiers.
If you *want*, you can run the same signal to both, just x-ing the 8's over a little higher than the 12'... that will make all the speakers play just fine. However, they won't be playing the frequencies that would be most ideal given the drivers you have.
I think any audiophile would find that producing truly awful sound.. at least.. truly muddy, inaccurate, garbage.
Without the ability to dedicate a frequency BAND, in this case, about 60 - 200hz, doing what you are doing is simply a waste of time. You would be much better off just running the 12 or the 8's.. not the same frequencies to both. That'd be really silly.
Granted, however, it would be a bit louder.
That is just *my* take on what you are trying to do. ------------- "I'm finished!" - Daniel Plainview
Posted By: action1978
Date Posted: July 22, 2005 at 3:18 PM
I think blowntweeters thought I was trying to run both the 8's and 12's off the 4 channel amp. I understand now what you mean about having high and low pass cut offs on my crossover. I guess a signal processor is what I am going to go for. I am shooting for a very high end style install. And this is the first time I have ever done it myself. Sedate, you are very helpful thank you. Maybe I could email you all my plans and you could help me make sure it turns out a high end install and not garbage. I have a ton of questions.
Posted By: Blowntweeters
Date Posted: July 22, 2005 at 3:37 PM
yes i did first think that you where planing on running all three subs with the 4 channel amp sorry about that
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1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700
Posted By: action1978
Date Posted: July 22, 2005 at 6:04 PM
Hey Sedate, If I ran a Hifonics ZX1000 to the 12" sub, and ran a Hifonics ZX4400 to the two 8's would that give me the adjustment I need?? Is this a better brand since RF seems to not be what it used to be?
Posted By: sedate
Date Posted: July 23, 2005 at 5:17 AM
No no. Its not the amplifiers that are bad... well.. I'd go with something other than Rockford stuff, but that's just me. I mean, there isn't anything wrong with the amps, its the crossovers ON the amps. Very few amplifiers, in fact, none that I can think of off the top of my head, have built in crossovers capable of doing what you are trying to do. Save esoteric total system amplifiers like the DaVinciI can't think of anything that would do that straight from the amplifier... even the crazy crossovers on the JL Audio Slash amps aren't quite up to the task.
Looking at the Hifonics here I do not believe so... the amp lists a subsonic filter, but doesn't specify if it is variable or not, and I would imagine if it was, it would *definately* be delineated, given the rariety of that particular feature.
Tell ya what.. I actually do not offhand know of an off-the-shelf product that will do what you want. I keep thinking of AudioControl stuff and they have little modules that you have to interchange.. like take apart the thing and change around stuff on the circuit board itself... to change around the xover points that you would need.
Read this thread ... one of the most serious gear-heads on this board got me onto the whole bi-amping thing.. not precisely what you are trying to do, but the principle of running a very specific signal to your drivers is explained real well.
Now, *another* option open to you, and one that would probably be a heckuva lot cheaper, would be to design or purchase PASSIVE crossovers to filter your signal for your 8's. You could run a low pass at like 200hz off the amp, then run that to a passive outboard crossover that would cut it again below 60hz or so.
This would of course not be as elegant as a actively crossed system, but, it would be *much* easier.
Read about that here.
Post back with any questions. ------------- "I'm finished!" - Daniel Plainview
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