Wiring subwoofers with different ohm voice coils together

Just my .2c FWIW from a low voltage electronics guy.

Can you? Sure.

Should you? Probably not.

P3S is a shallow mount, 400W RMS sub - Dual - 2 Ohm.

Gothic is a standard mount, 1200W RMS - Dual - 4 Ohm.

You can hook them up but you'll probably blow your P3S before you can get anything worthwhile out of the Gothic. Regardless the P3S will be pushing much harder overall than the Gothic at any gain level. The amp might be ok, depending on how you wire the subs together but you'll still be over driving one sub while barely powering the other. That is without taking into effect the possibilities of cancellation/phase/resonance and other points brought up by others way more experienced than myself.

In any other thread this would be considered an Apples and Oranges comparison. So again I say,

Can you? Sure.

Should you? Probably not unless you don't care about SQ at all or the very high likelihood of blowing up your remaining P3S.
 
This is absolutely theory until FACTS are presented. A modeling program isn't the same as real FACTS (since we are capitalizing that word for some reason). FACTS come from experiments, not simulation. Again, if there are any (proven,) facts, I'm genuinely interested in the subject. "Proven facts" is redundant, but apparently appropriate for the audience.

You are the experiment. So, go do it and let us know how it works out for you.
 
Buy me the gear and I will test it.

I didn't make any claims or declare facts, so I don't have anything to prove.

Well, you sound like you want a UL tested experiment. That will not happen here. People are telling you the pros and cons of doing it. Now, it's up to you to take their advice and give it a shot. The advice you want is something that people on here wouldn't do. Trying to wire everything as close to 4 ohm would probably be the safest route, but, not the loudest. Going under one ohm would most likely cost you gear. The safest best would be to trade your dual 2 ohm sub for a dual 4. Then, wire to one ohm.
 
Well, you sound like you want a UL tested experiment. That will not happen here. People are telling you the pros and cons of doing it. Now, it's up to you to take their advice and give it a shot. The advice you want is something that people on here wouldn't do. Trying to wire everything as close to 4 ohm would probably be the safest route, but, not the loudest. Going under one ohm would most likely cost you gear. The safest best would be to trade your dual 2 ohm sub for a dual 4. Then, wire to one ohm.
This isn't my thread, bud. I don't need UL; any fact-gathering experience would be fine. I'm giving this person my opinion as well. I'm not sorry for disagreeing with you or your buddies.
 
Given the theory that cones move at different rates, they still have to react to the sine wave being delivered to the voice coil. If the cone reacts any fraction of a second behind the signal getting to its terminals, the cone will eventually either catch up with the signal or move in the complete wrong direction. I think it will catch up and move on-point with the signal. So that leaves a split second where they subs might be out of phase (unnoticably).
Also, given your theory is accurate, your two subs will always be a different distance from you, so you could argue that the different distances could actually make your subs sound louder by being ever-so-slightly out of phase.

Agreed. It's a reinforcement/attenuation/SQ problem, not so much SPL.
 
This isn't my thread, bud. I don't need UL; any fact-gathering experience would be fine. I'm giving this person my opinion as well. I'm not sorry for disagreeing with you or your buddies.

No one is stopping you from giving your opinion, you're just giving a bad one which has been confirmed by the overwhelming responses from senior members of this board vs your one opinion favoring that he try it.

To provide some context that I think others would agree with: Someone coming to this board asking if he can run a 2 Ohm and 4 Ohm sub (his friend gave him) together doesn't sound like someone who has any budget for gear. Based on that alone I think most of the people in this thread are trying to help him from blowing up any more gear than he already has.
 
No one is stopping you from giving your opinion, you're just giving a bad one which has been confirmed by the overwhelming responses from senior members of this board vs your one opinion favoring that he try it.

To provide some context that I think others would agree with: Someone coming to this board asking if he can run a 2 Ohm and 4 Ohm sub (his friend gave him) together doesn't sound like someone who has any budget for gear. Based on that alone I think most of the people in this thread are trying to help him from blowing up any more gear than he already has.
I'm also trying to prevent him from burning any equipment; the difference is that i provide facts with my opinions. I beg you to contest my first response, which actually provides PROVEN electrical theory, a claim that none of the counter-arguments can make. If he wires his **** as i suggested, he isn't any more likely to break down that he would be with two dual-4 subs; in fact he is safer at 1.33 ohms than at 1 ohm, provided the subs can handle the power.

"Senior members" suggests you are drinking the koolaid. Define a "senior member". Someone with more posts? Someone who signed up longer ago? Tell me how either of those criteria make someone more knowledgeable. I'm not going to try to talk myself up, but i would also worship post-counts if i didn't have anything else to offer.
 
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Another TL/DR for most but feel free to read for some entertainment value:

I'm also trying to prevent him from burning any equipment; the difference is that i provide facts with my opinions.

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

I beg you to contest my first response, which actually provides PROVEN electrical theory, a claim that none of the counter-arguments can make.

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.

If he wires his **** as i suggested, he isn't any more likely to break down that he would be with two dual-4 subs; in fact he is safer at 1.33 ohms than at 1 ohm, provided the subs can handle the power.

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.

"Senior members" suggests you are drinking the koolaid. Define a "senior member". Someone with more posts? Someone who signed up longer ago? Tell me how either of those criteria make someone more knowledgeable. I'm not going to try to talk myself up, but i would also worship post-counts if i didn't have anything else to offer.

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:

It's doable, but they subs won't get the same amount of power. If your amp is stable down to 1 ohm, then it doesn't care how you get there; it only cares about the load it sees at the speaker terminals.

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

Having said that, I don't know where you came up with that formula for calculating parallel loads. If all parallel branches are the same resistance, you can use the formula Rt = Rx / Rn ; Total resistance equals the value of each branch divided by the number of parallel branches. If each branch is a different resistance, then you use the formula Rt = 1/(1/R1 + 1/R2 + 1/R3 ....).

In your case you could technically use either formula, but let's go with the latter:
Rt = 1/(1/4 + 1/4 + 1/2 + 1/2);
Rt = 1/(6/4);
Rt = 2/3 ohm, or roughly 0.67 ohm, which is lower than your amp can handle.

Your best bet would be to wire the dual 2-ohm sub in series to create a 4-ohm load, then wire all three 4-ohm loads in parallel. Thereby, Rt = 4/3 = 1.33 ohms.

As stated by others, having two different subs or sub with different impedances will not give you ideal results, acoustically speaking, but if you wire them correctly, it is far from impossible.

Bear in mind, I'm just some guy on the internet, as is everyone else who provides advice in forums. The information I gave you is electrically correct, but follow it at your own risk. If you didn't know how to calculate total resistance, you might be better off either keeping it simple (get two of the same subs) or paying someone to do it for you.

On a side note: I don't know how running two subs in phase with eachother would create any cancellation. I would love to hear the theory behind it.

Hope that helps.
- Joe

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.
 
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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.

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.

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
 
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



Since you know everything, explain how impedance rise will deliver precisely 2/3 of the amps power to one sub and 1/3 of the amps power to the other sub.



Your level of ignorance and mental gymnastics are astounding.
 
Since you know everything, explain how impedance rise will deliver precisely 2/3 of the amps power to one sub and 1/3 of the amps power to the other sub.



Your level of ignorance and mental gymnastics are astounding.
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.
 
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