wiring 2 4ohm subs
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=120999
Printed Date: May 13, 2024 at 9:56 PM
Topic: wiring 2 4ohm subs
Posted By: russell2342
Subject: wiring 2 4ohm subs
Date Posted: March 26, 2010 at 9:48 PM
Hi guys I'm working on wiring my subs. I have 2 memphis pr15d4 subs with a cadence TXA 3004 amp. The amp Specs are:
4 Ohm RMS Power: 4 x 75 Watts @ 13.8 Volts
2 Ohm RMS Power: 4 x 150 Watts @ 13.8 Volts
4 Ohm Bridged RMS Power: 2 x 300 Watts @ 13.8 Volts
Frequency Response: 20Hz - 30kHz
Damping Factor: >200 @ 100Hz
S/N Ratio: >100 db
Channel Seperation: >65dB
Minimum THD: <0.05%
Dimensions: 17" x 9.2" x 2.12"
High Speed Mosfet Power Supply
Studio Grade Bipolar Output Stage Transistors
Fully Adjustable 18dB/Octave Crossover
Fully Adjustable Bass and Treble EQ Controls
Adjustable Input Gain 170mV-5V
Ultra Reflective Chrome Top Cover
2 Ohm Stereo Stable
4 Ohm Mono Bridgeable
3 Channel Mixed-Mono Capable
Power and Protection LED Indicators
Full IC Controlled Protection Circuitry
Mute and Soft Delay Circuitry
Lucite Encapsulated Terminals
Whats the best way to wire my subs to get the most power outta my amp? Thanks :)
Replies:
Posted By: i am an idiot
Date Posted: March 26, 2010 at 10:34 PM
Are you using all 4 channels for the woofers? Or are you using 2 channels for Dash/Door/Rear deck speakers? Are your speakers single or dual voice coil drivers?
Posted By: russell2342
Date Posted: March 26, 2010 at 11:22 PM
Im running subs only and want to run the most power available from the amp. They're dvc subs. I only wanna use 2 channels at most
Posted By: ianarian
Date Posted: March 27, 2010 at 3:05 AM
Well, unfortunately you are mismatched to be able to use the amps highest potential. You cant run L+R channels bridged to 2ohm (sub/parallel). Your only wiring options are parallel to 2ohm stereo,(sub/parallel/Lch)(sub/parallel/Rch)- on either front or rear channels, or you can run the subs in series/bridged to both F+R sides. Both options equate to the same, sound wise. Either way, as soon as possible, upgrade.
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This is what I do for FUN!
Posted By: russell2342
Date Posted: March 27, 2010 at 5:13 PM
this is not something i have alot of money in or concerned with upgrading. it is a small system for the family car, thats all. my other system in my truck will be massive. this one is just for some bump not a tremendous amount of BOOM, ya know.
Posted By: i am an idiot
Date Posted: March 27, 2010 at 7:46 PM
I do not understand the statement, "I want to use 2 channels at most" Do you want to run your 4 channel amp as a 2 channel, or do you plan to do something else with the other 2 channels? I really need to know that info to help you.
Posted By: russell2342
Date Posted: March 27, 2010 at 9:49 PM
i am an idiot wrote:
Do you want to run your 4 channel amp as a 2 channel
Correct
Posted By: stevdart
Date Posted: March 27, 2010 at 10:43 PM
If your concern is to get maximum power from the amp, then use just one coil on each sub so that impedance is 4 ohms. Bridge channels 1 and 2 to sub 1 (one coil). Leave the other coil unused. Do the same with the other two channels and the second sub. (The subs are not wired together but used separately with each set of channels.) Should yield slightly more than "just some bump". ;)
------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: nodiggie
Date Posted: March 28, 2010 at 12:04 AM
Correct me if I'm wrong. Those subs are 250/500rms peak. Keep in mind if you wire only one voice coil you are good for 125/250rms max. Your amp (if rms rating is correct) will be pushing 300rms to each sub now using 1 voice coil with lower 125rms rating. If this is true, it will work fine but you will need to take serious care not to over power them and start melting the coil.
------------- Still learning
Kraco
Posted By: i am an idiot
Date Posted: March 28, 2010 at 2:26 AM
Using only one coil of a dual voice coil woofer does not cut it's power handling in half, it is closer to only a 25% decrease in power handling. You next best option would be to wire the voice coils of each speaker in series. Then bridge on speaker per pair of channels for an 8 Ohm bridged load. The amp will not produce as much power this way, but you will be able to sleep better knowing you should not be able to damage the speakers.
Posted By: russell2342
Date Posted: March 28, 2010 at 6:47 PM
speakers are 250/500 peak. So your saying to just use 1 set of coils as if it were a svc and leave the others open, correct? Then wire them, bridged between channels 1 and 2 for 1 speaker, and 3-4 for the second? Thanks for the input guys!
Posted By: stevdart
Date Posted: March 28, 2010 at 10:51 PM
- Already checked those specs, okay
- yes
- and yes
- your welcome
I might be pushing the "by the book" way of doing things (leaving all wisdom up to the great Ohm in the sky), but considering everything in your stated situation it looks like the right thing to do. The RMS of one coil (given that it is nestled together with the heat absorbing second coil) will be close enough to the true power output of the amp in real life playing. I expect that you will build the enclosure to bring the best out of those 15's, and that is where that bit of extra power would come in handy when you want the very low tones to shine. I don't think its too much of a gamble and is certainly the way I would try it first. Set gains of all gear with great care and precision. If it gets smelly turn it off and go to plan B. ;) ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: z03mz03m
Date Posted: March 28, 2010 at 11:05 PM
Yes that is how you could get the most power to each sub.
Your Next best option would then be to wire each VC to each channel on the amp putting out 150w to each sub OR do what Idiot says and bridge the amp and run each sub @ 8ohms. If Idiot is correct about the 25% reduction in power handling when running only one voice coil(250 X .75 = 187.5 watts)then I personally would go with his option of running them bridged @ 8ohms which would give them 150 Watts @ 13.8 Volts and if your car runs @ 14.4 volts then it would be even closer to 187.5 w. I might be wrong about this but I think another advantage of running @ 8ohms would be lower THD which would equal cleaner/tighter bass. But if your looking for max power and are going for the 300w rms just be careful with the gains. 
Another plus to using only one VC is if you do end up blowing them with the 300w setup then you can just switch to the other VC and back down to the 150w setup.
Posted By: stevdart
Date Posted: March 28, 2010 at 11:27 PM
zoomzoom, don't over-complicate it, grasshopper. Don't get too caught up in the ratings numbers, power per volt or the THD. Sometimes common sense for a given situation and specific query prevails. "Just be careful with the gains" means nothing, and your last line is wrong entirely. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: z03mz03m
Date Posted: March 28, 2010 at 11:49 PM
Yes Master... 
I thought I read some were on here that the 2 VC in a DVC sub don't affect each other when blown...but I guess theres more than one way that a speaker can fry? I guess I should find a cut-away pic of one to see the guts and look for that other post. I think it was actually a full time installer that said that.
"Just be careful with the gains" =
"Set gains of all gear with great care and precision."
Posted By: stevdart
Date Posted: March 28, 2010 at 11:53 PM
grasshopper, what is the impedance of one coil?
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: z03mz03m
Date Posted: March 28, 2010 at 11:55 PM
4 ohms Right?
Posted By: stevdart
Date Posted: March 29, 2010 at 12:04 AM
]and&n wrote:
sp;your last line is wrong entirely.
------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: z03mz03m
Date Posted: March 29, 2010 at 12:07 AM
OOOOOOOOOOOOOHHHHHHHHHHHHHHHHHHHHH.........My Bad 
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