Wiring subwoofers with different ohm voice coils together

TL/DR: 02WS6 did his math wrong. The dual 4 sub will receive 2/3's total power and the dual 2 sub will receive 1/3 total power.



Actually load the amp sees is exactly what impedance is. Load the amp sees is better described as impedance than resistance. We just generally use the term "resistance" because it's easier for people with electronics knowledge to understand and it's much easier to measure/test for. Impedance is a combination of resistance and inductive reactance, and has to be measured by Z = E/I.

The points raised by the elite, all-knowing, super, high-post-count guys haven't mentioned blowing subs. The conversation ranged from a generic "Don't do it. It's bad", to cancellation from running two different subs. Having said that, you are absolutely wrong with your 70-30 statements. Please give me the formula I forgot to mention that you alluded to. Although I didn't mention power levels, because I assumed OP can set his gain levels to avoid blowing either sub, let's break it down so you can learn something (even though I'm a moron because I have under 50 posts):

This will apply to a series-parallel configuration with two 2 ohm loads wired in series, and two 4 ohm loads in parallel with the series 2 ohm loads, so essentially three 4 ohm loads in parallel. I'm not going to use numbers because this doesn't apply to only one scenario, so variables are more appropriate. I'm going to refer to the voice coils as vc2-1, vc2-2, vc4-1, and vc4-2. Vc2-1 and vc2-2 are the voice coils on the dual 2 ohm sub, and vc4-1 and vc4-2 are the voice coils on the dual 4 ohm sub. You should be familiar with the rest of the formula symbols. On to it.

In every parallel circuit, supply voltage is the same across each branch. Vc4-1 is its own branch; vc4-2 is its own branch; vc2-1 and vc2-2 in series represent a single branch.
Therefore, Evc4-1 = Evc4-2 = (Evc2-1 + Evc2-2), or to rephrase, Evc2-1 = Evc2-2 = 1/2(Ecv4-1) = 1-2(Evc4-2)
Current is limited by resistance, and can be different between parallel branches, but is constant in series loads.
Given that I = E/R, and each parallel branch is equal to a 4 ohm load, Ivc4-1 = Ivc4-2 = Ivc2-1 = Ivc2-2
The formula for power is P = I x E.
So, since Pvc4-1 = Pvc4-2 = (Pvc2-1 + Pvc2-2), we can see that power is cut into three, with the dual 4 ohm sub receiving two thirds of total power, and the dual 2 ohm sub receiving one third of total power.

If you want to simplify it, the dual 4's in parallel are a 2 ohm load, and the dual 2's in series are a 4 ohm load.

I think we can all agree that a 2 ohm load draws more power than a 4 ohm load. Roughly twice as much.

I hope that makes sense to you. You can let me know if you have any questions, but you'd probably trust someone with more posts more than you'd trust me.

- Joe

You're still not getting it. Impedance is a measure of resistance for the voice coil not for the entire circuit which is why you can change final resistance it by wiring in series/parallel. Wiring changes what the amp sees not what each voice coil receives. Total circuit resistance is how you wire your speakers together to get a final matched resistance to whichever amplifier you're using. Internal impedance of each voice coil is how the speaker coil itself consumes the power. You cannot externally change this no matter how you wire it up.

Final resistance for the circuit is doubled to 1.3 ohms in your example (which will work for the amp) but this is what each voice coil see's in the circuit.

19873
 
Ignorance and mental gymnastics? I don't think I've displayed either of those. I gave an explanation because some dude doesn't understand basic electrical concepts. That's the opposite of ignorance.

I have given accurate information, and i GUARANTEE inaccurate information blows a LOT more subs than using dissimilar subs.

"Impedance rise" has nothing to do with any of this. It applies to my post just as much as it applies to the 70-30 guy, but you call me out and not him? Oh, because his opinion is the same as yours, regardless of whether or not it is founded on accurate reasoning.

Hide behind your post count, bro, and maybe try a different strain if you're this high strung.

What else you got? I hope it's a new argument, because addressing my counter-arguments would be silly.

Impedance rise, phase angle and group delay have quite a bit to do with this conversation regarding cancellation and the cone of different speakers moving at different rates. Its great that you can demonstrate elementary level arithmetic to calculate a nominal ohm load but you have been given the opportunity to further substantiate your arguement and you have failed to back up your claims.

I'm not hiding behind my post count, I'm calling out your ignorance of fact.

You clearly have a tenuous understanding of acoustics and you would benefit from swallowing your pride and opening your mind to learn.

You are the intellectual equivalent to a wall and I'm not about to sit here and bang my head against it. The more you post the more your lack of knowledge shows so keep it up.
 
Impedance rise, phase angle and group delay have quite a bit to do with this conversation regarding cancellation and the cone of different speakers moving at different rates. Its great that you can demonstrate elementary level arithmetic to calculate a nominal ohm load but you have been given the opportunity to further substantiate your arguement and you have failed to back up your claims.

I'm not hiding behind my post count, I'm calling out your ignorance of fact.

You clearly have a tenuous understanding of acoustics and you would benefit from swallowing your pride and opening your mind to learn.

You are the intellectual equivalent to a wall and I'm not about to sit here and bang my head against it. The more you post the more your lack of knowledge shows so keep it up.
Show me facts behind your claims. I don't think that's an unreasonable criterion. I actually really enjoy learning new things, and I know very little about acoustics. However, I have a decent understanding of physics and a strong understanding of electricity.

I guess if hesitation to accept information without facts makes me ignorant, then color me ignorant, though you have already turned to name-calling because I don't bow down to the forum veterans.

I'll admit when I'm wrong, but not without confirming that I am wrong. So far everyone who is telling me I'm wrong either can't provide proof to their claims or is giving information that contradicts known facts.

02ws6 - you are wrong again. Reread my explanation, and let me know if you need anything further explained. Your numbers apply to a parallel circuit, not a series-parallel circuit like the one i suggested. If you don't believe me, grab some resistors and a multimeter and check it out. I mean that genuinely; you are giving out false information that could potentially cost people their equipment.
 
Another TL/DR for most but feel free to read for some entertainment value:



How? You explained how to wire the subs, not how to change the internal impedance of the voice coils which is impossible. Resistance or load the amp sees ≠ Impedance



You're missing the point but I'll do my best to help you refocus on the actual problem OP is facing if he followed your advice.



Again all you did was tell him how to wire the subs together to provide a complete resistance load to the Amp of 1.3 ohms. The amp should be fine, no one in this thread contested that. I’m contesting how the load is split between the two subs.



Do you know how forums work or just Facebook and Reddit? Forums have post counts and join dates for a reason. Those with higher post counts and who have been members for a longer period of time USUALLY, have seen more crap and are more experienced. I’m speaking in generalizations, I’m sure there are plenty of senior members who are wrong from time to time but I have a feeling they’re wrong less than someone with <50 posts when it comes to car audio. Seeing as this is a car audio forum those post counts mean the more "Senior Members" have contributed a helluva lot more to this place than either of us have and I for one respect that, much in the same way I'd respect it in any other forum. If you don't like it then go hang out on 4Chan, they hate post counts or usernames over there.

I'm not contesting your original response, only that you glossed over one of the main issues of wiring two different impedance subwoofers together:



Correct on all counts - Again my issue is you glossing over the fact that the two wildly different subwoofers don’t get the same amount of power. Just to recap in case anyone forgot

Shallow Mount - D2 - 400W RMS
vs
Standard Mount - D4 - 1200W RMS



I have nothing to contest here, it's all electrically sound except for one formula you forgot to mention. Which you even mentioned above and I highlighted for good measure. "The subs wont get the same amount of power". You're exactly right but then you're not even remembering that you brought it up! How does a current load balance in a perfectly imbalanced circuit? Let's say for example, 2 ohm voice coils vs 4 ohm voice coils? Oh that's right it still follows the path of least resistance so the 2-ohm voice coils will be getting about 70% of the current where the 4-ohm voice coils will be getting about 30%. No matter how you wire the final load the amp sees, you still cannot change how the internal voice coil impedance will consume that power. You've protected the amp, but the lower rated and more sensitive sub will still be getting 2/3rds of the power.

The remaining 30% of the power the amp is producing, is consumed on a sub with a lower sensitivity and a much higher RMS rating. So as OP turns the gain (or volume) up, the P3S will be dramatically louder than the Gothic, if he continues turning the gain to get anything out of the Gothic, 70% of that power will keep going to the P3S until one of two things happens. OP realizes that the P3S will blow before he gets anything worthwhile out of the Gothic or he blows up the P3S trying to get the Gothic to hit. THAT is the gear we all believe he's gonna blow up if he wires it the way you advised, the P3S Sub NOT the amp.

BTW It's a regular P3 not a shallow. 500rms 1000 peak
 
BTW It's a regular P3 not a shallow. 500rms 1000 peak
Don't listen to that guy. He doesn't understand basic electrical theory, but don't listen to me either, because I spent time getting a degree in electronics, when I should have spent time racking up more posts on internet forums.

I had an original P3 back in 2006 or so (rough guess on the year), and I loved it. Good choice!

Let us know how your install goes and how the system sounds so I can learn from it! The other guys will probably call you names if you don't agree with them.
 
Phase angle is a current/voltage relationship. It's not the actual movement of the cone. To apply its effect to SQ gets you pretty deep into the subtleties of sound. Same with group delay.
I'm guessing a guy trying to get some temporary boom in his car doesn't need to be worrying about this stuff.
It's less than ideal, but it will work fine.
 
Of course you can. The amp has no response to what is connected to it other than impedance. Wire the D2 in series for 4 on one output and the D4 parallel for 2 on the other. The p3 will see 1/3 of the power, the PA will see 2/3.
The amp doesn't have separate channels -- it's just two connections to the same channel so anything you connect to one output will be parallel to the other. Also -- subs don't "withstand" the load. They ARE the load.
Don't expect great sound quality, but it will give you some bass until you can get a proper matching pair.

You might have better results just running the Pwr Ac at 2 ohms.
If i was just going to run 1 sub, why the **** would i choose the PA over the RF
 
If i was just going to run 1 sub, why the **** would i choose the PA over the RF

Presumably because it's actually matched to your amplifier's RMS rating. It's 1200 while the P3 is only 600. If you run the Rockford on its own it'll have to be either 2 ohm and very carefully regulated to not damage the subwoofer or 8 ohms at which point you'll be losing out on a lot of volume. Your voice coils just aren't ideal for that sub alone and that amp, but the other subwoofer is.

I'm curious how it'll sound, looking at those subs you've got one with 83.6 sensitivity and the other at 85. They're not THAT dissimilar. I wouldn't expect the movements to be out of sync enough to not add to the volume, but it might be muddy. They definitely shouldn't share an enclosure airspace, but if you're experimenting anyways... My guess is that one will sound better than both together, but there will be a noticeable volume increase with both. Their resonance frequencies are quite different so they'll fight each other on those a little. The PA doesn't list its xmax, but i'll bet it'll look funny in slow motion with them side by side.

1.33ohms should be just fine.
 
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Presumably because it's actually matched to your amplifier's RMS rating. It's 1200 while the P3 is only 600. If you run the Rockford on its own it'll have to be either 2 ohm and very carefully regulated to not damage the subwoofer or 8 ohms at which point you'll be losing out on a lot of volume. Your voice coils just aren't ideal for that sub alone and that amp, but the other subwoofer is.

I'm curious how it'll sound, looking at those subs you've got one with 83.6 sensitivity and the other at 85. They're not THAT dissimilar. I wouldn't expect the movements to be out of sync enough to not add to the volume, but it might be muddy. They definitely shouldn't share an enclosure airspace, but if you're experimenting anyways... My guess is that one will sound better than both together, but there will be a noticeable volume increase with both. Their resonance frequencies are quite different so they'll fight each other on those a little. The PA doesn't list its xmax, but i'll bet it'll look funny in slow motion with them side by side.

1.33ohms should be just fine.
The p3 is a 2 ohm dvc so i could run it parallel to 1 or in series to 4. The kenwood amp says it does 500 rms at 4ohms
I have also accumulated alot more stuff now. The total list is. Amps; Kenwood 9104d ,audiopipe ampi-1300, massive 1200d, jl j2 320.4. : subwoofers; 2 12in fosgate p3s (2 ohm dvc), 2 12in pa gothics(4 ohm dvc ), 1 12in fosgate hx2 (4ohm dvc) , 1 10in punch p2 (8ohm svc) ,1 12in quinn acoustics q12s4 (4ohm svc) and 1 10in kicker c10 (4ohm svc) : Boxes ;1 dual 12 sealed, 1 dual 12 ported, 1 bassworx 12 ported and a single 12 ported....oh yeah and 2 nvx vsp 6x9s in single boxes
 
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