Wiring subwoofers with different ohm voice coils together


SkrillaPyles

CarAudio.com Newbie
Jan 10, 2020
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0
Decatur, tx
I have a kenwood 9104d amp. I did some research on it and it says it does 900 rms at 2 ohms and is regulated down to a lil over 900 at 1 ohm .I had dual 12 punch p3s (2ohm) and wound up blowing 1 of them. my friend gave me a power acoustic gothic. It's a 4ohm dvc. I know it's not good to have subs that have different ohms. .. but since the amplifier is regulated at 1 ohm. So can I run the punch on left at 1 ohm and the gothic on the right at 2 ohm then they would be very close to receiving the same power
 

Popwarhomie

Team Lethal Pressure
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Jan 22, 2010
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Thats a mono block amp. Its internally bridged with 4 outputs. All one channel. No left and right.

Running two different subwoofers causes cancelation issues let alone running two different resistance subwoofers. One will be getting more power than the other.
 
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SkrillaPyles

CarAudio.com Newbie
Jan 10, 2020
7
0
Decatur, tx
Thats a mono block amp. Its internally bridged with 4 outputs. All one channel. No left and right.

Running two different subwoofers causes cancelation issues let alone running two different resistance subwoofers. One will be getting more power than the other.
Yes I know that. How bout if I ran both speakers parallel. That you be 2+2+4+4=12 12÷2=6 then 6÷4=1.5 ohms, if the subs can withstand a 1 ohm load , how come I cant run a 1.5 ohm load?
 

jt4x4

CarAudio.com Enthusiast
Jul 22, 2019
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Yes I know that. How bout if I ran both speakers parallel. That you be 2+2+4+4=12 12÷2=6 then 6÷4=1.5 ohms, if the subs can withstand a 1 ohm load , how come I cant run a 1.5 ohm load?
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.

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
 
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SkrillaPyles

CarAudio.com Newbie
Jan 10, 2020
7
0
Decatur, tx
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.

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 know how to calculate the resistance if each voice coil is the same. But for some reason I was thinking you also had to divide it by # of subs as well then also using the wrong formula, I did not know how to do it with voice coils of seperate resistance. That's why I'm asking. I wasn't saying it like it was fact. I was asking a question about my math because it looked off and it was. as for the cancelation I was wondering about that too because I have already hooked them up in a parallel To my audiopipe ampi-1300. It didnt seem to have a problem with it. And sounded good
 

dragon.breath

Senior VIP Member
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Nov 22, 2007
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The different brands cause cancellation is real. It doesn’t happen in every case, but it does happen. It is basically because of a difference in response times of the cones.
Here is the over simplified version. Say you have two subs. One has a heavy cone, a 2 inch voice coil and a 30 oz magnet. And the second sub has a lighter cone, a 3 inch coil and a 100 oz magnet. Play a single drum beat. Sub 2 is going to move the cone quicker than sub 1. In fact, sub 2’s cone may be returning to rest while sub 1’s cone is still moving out. You end up with phase issues and cancellation.
 

n2audio

OPTIDRIVEN
10+ year member
Dec 29, 2001
5,630
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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.
 
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jt4x4

CarAudio.com Enthusiast
Jul 22, 2019
41
2
ND
The different brands cause cancellation is real. It doesn’t happen in every case, but it does happen. It is basically because of a difference in response times of the cones.
Here is the over simplified version. Say you have two subs. One has a heavy cone, a 2 inch voice coil and a 30 oz magnet. And the second sub has a lighter cone, a 3 inch coil and a 100 oz magnet. Play a single drum beat. Sub 2 is going to move the cone quicker than sub 1. In fact, sub 2’s cone may be returning to rest while sub 1’s cone is still moving out. You end up with phase issues and cancellation.
I'm having a tough time with your logic here. I understand the theory you're running with. However, I would like to see an experiment with numbers to back that theory up.
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. The sound waves/air vibrations have to travel from the speaker to any given point, so maybe the air vibrations would be more in sync by the time they get to the listener/meter.

Playing devil's advocate here, but I also don't like claims without facts to back them up.
 

Bobbytwonames

CarAudio.com Elite
Aug 28, 2018
1,064
-183
I'm having a tough time with your logic here. I understand the theory you're running with. However, I would like to see an experiment with numbers to back that theory up.
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. The sound waves/air vibrations have to travel from the speaker to any given point, so maybe the air vibrations would be more in sync by the time they get to the listener/meter.

Playing devil's advocate here, but I also don't like claims without facts to back them up.
Why not just go try it and see if you like it? Just use your knowledge and make your best educated guess. It might not be ideal, but it might work for now.
 

THATpurpleKUSH

Smoke weed everyday
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Sep 30, 2009
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Banging gears and passing queeers
I'm having a tough time with your logic here. I understand the theory you're running with. However, I would like to see an experiment with numbers to back that theory up.
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. The sound waves/air vibrations have to travel from the speaker to any given point, so maybe the air vibrations would be more in sync by the time they get to the listener/meter.

Playing devil's advocate here, but I also don't like claims without facts to back them up.
This isn't religion, there is no "theory."

We are talking pure FACT regarding cancellation. Overlay 2 different plots from a modeling program like Bass Box Pro and look at phase angle and group delay. The proof is in front of you- measured in degrees of angle and milliseconds.
 

jt4x4

CarAudio.com Enthusiast
Jul 22, 2019
41
2
ND
This isn't religion, there is no "theory."

We are talking pure FACT regarding cancellation. Overlay 2 different plots from a modeling program like Bass Box Pro and look at phase angle and group delay. The proof is in front of you- measured in degrees of angle and milliseconds.
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.
 

02WS6

CarAudio.com Well Known
Jan 12, 2020
170
80
Sacramento
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.
 

Bobbytwonames

CarAudio.com Elite
Aug 28, 2018
1,064
-183
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.
 

Bobbytwonames

CarAudio.com Elite
Aug 28, 2018
1,064
-183
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.
 

jt4x4

CarAudio.com Enthusiast
Jul 22, 2019
41
2
ND
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.
 
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