[abizzle]

I am getting ready to install three Infinity Kappa 1000W 10” subs and I have a question about the wiring and ohm load. I have an Infinity Kappa One K amp and although it is a mono amp, it has two sets of sub connection terminals.

I had already done some research on the different wiring options and the resulting ohm loads, and I was prepared to set all subs at 4 ohms and wire them series/parallel for a final ohm load of 2.3 with all subs getting equal power. My personal preference would be an even ohm load, but I understood why that is not possible with an odd number of subs… or so I thought.

I was reading the Amazon comments for my sub today and one guy claims to have achieved an even 2 ohm load by setting one sub at 4 ohms and connecting it to one of the amp’s terminals and then setting the other two subs at 2 ohms and series wiring them into the amp’s other terminal. He claimed that since the amp terminals were internally paralleled the two 4 ohm loads would work out to an even 2 ohms with each sub getting equal power.

Since I don’t fully understand the purpose for two terminals on a mono amp, I have no way of knowing if what he says is true.

Can someone explain?

 

[SloVic]

All the negative and positive terminals are the same circuit inside the amp. Just treat them as one when trying to figure out the total end resistance.

 

[nyquistrate]

Since I don’t fully understand the purpose for two terminals on a mono amp, I have no way of knowing if what he says is true.

Can someone explain?

The purpose is only to make wiring easier. If you have a "bank" of multiple subs you have more terminals to fit all the wire on.

I was prepared to set all subs at 4 ohms and wire them series/parallel for a final ohm load of 2.3 with all subs getting equal power.

I'm not sure how you get 2.3 Ohms from a series/parallel of (3) 4 Ohm subs? Perhaps you meant 2.6 Ohms?

IIRC the switch on those subs aren't EXACTLY 2 or 4 Ohms? There's some amount of play. So I would expect a different final impedance from the series string vs single sub string in that Amazon post. You could measure to verify but that's still a DC nominal measurement. You be the judge but if the subs are sharing air space then I would parallel them all.

 

[abizzle]

The purpose is only to make wiring easier. If you have a "bank" of multiple subs you have more terminals to fit all the wire on.




I'm not sure how you get 2.3 Ohms from a series/parallel of (3) 4 Ohm subs? Perhaps you meant 2.6 Ohms?

IIRC the switch on those subs aren't EXACTLY 2 or 4 Ohms? There's some amount of play. So I would expect a different final impedance from the series string vs single sub string in that Amazon post. You could measure to verify but that's still a DC nominal measurement. You be the judge but if the subs are sharing air space then I would parallel them all.

You’re correct. I had 2.3 in my head, but the Crutchfield drawing showing the series/parallel wiring scheme says 2.7.

I haven’t seen anything about the switch not being a true 2 or 4 ohm. Maybe Infinity does something similar to their smaller speakers where they are actually 3 ohms because they factor in the resistance of the wire?

Each sub will have its own chamber with .80 cuft of airspace. If I parallel wired them, the resulting ohm load would be 1.3 and I don’t believe that amp is stable below 2 ohms. Even at 2.7 the amp will be putting out 850 RMS and the subs are rated at 450 RMS. I’d prefer the amp to run as cool as possible. I’m actually a little apprehensive about how hard three subs are going to slap. I’ve never had more than one.

I really appreciate the detailed response!

 

[nyquistrate]

The leg of the circuit with sub 1 & sub 2 in series will add to an 8 Ohm load. That will draw less current (half) than the single 4 Ohm leg of sub 3 by itself. Also, subs 1 & 2 will be sharing the voltage potential across sub 3 by itself, cutting the voltage to sub 1 & sub 2 in half. So sub 3 will be working much harder than subs 1 & 2. I would choose a different wiring scheme or amp. I’ll look into the switch.

 

[dumdum]

You shouldn’t wire anything like the above pic, it won’t give the same power to each driver, and the guy who said he did just that is wrong also…

3 is a really odd number unless you can run a 1 ohm stable amp

Put bluntly you have the wrong subs for your amp

With three subs you need either all subs in parallel or all subs in series

So 4ohms a sub is either 12 ohms or 1.33

2 ohms a sub is 6 ohms or 0.667

That’s it for three subs to get the same power to each driver 👍🏼 You can’t series/parallel 3 coils and get equal power to each ever

 

[abizzle]

You shouldn’t wire anything like the above pic, it won’t give the same power to each driver, and the guy who said he did just that is wrong also…

3 is a really odd number unless you can run a 1 ohm stable amp

Put bluntly you have the wrong subs for your amp

With three subs you need either all subs in parallel or all subs in series

So 4ohms a sub is either 12 ohms or 1.33

2 ohms a sub is 6 ohms or 0.667

That’s it for three subs to get the same power to each driver 👍🏼 You can’t series/parallel 3 coils and get equal power to each ever

Wow that’s surprising! I’ve never known Crutchfield to publish errant info, but I trust your expertise. I’m so far into this build and over budget unless I can sell a couple of components. I’m not cool with a 1.3 or 6 ohm load, so I’ll downsize to two subs. Luckily I have only purchased one sub and a single sub enclosure. I was planning to buy the other two subs and the three sub enclosure on Friday.

I really wanted to run three, but I’ll make due with two and come up with another plan for later.

Thanks for saving my sanity and my pocketbook!

 

[nyquistrate]

Three won't give you much more than two anyway.

 

[abizzle]

The leg of the circuit with sub 1 & sub 2 in series will add to an 8 Ohm load. That will draw less current (half) than the single 4 Ohm leg of sub 3 by itself. Also, subs 1 & 2 will be sharing the voltage potential across sub 3 by itself, cutting the voltage to sub 1 & sub 2 in half. So sub 3 will be working much harder than subs 1 & 2. I would choose a different wiring scheme or amp. I’ll look into the switch.

Thanks! I want this done right, which means each sub has to get equal power and the total resistance has to be within the specs for my amp without going over 4. Two subs will ruin my hearing and beat the block up just fine for now.

‘Preciate the help!

 

[SQ_Bronco]

That diagram makes my head hurt.

anyway you could always just buy a 4th sub and make it an even 4 ohms or sell the 3 10’s and buy 2 12’s.

 

[abizzle]

That diagram makes my head hurt.

anyway you could always just buy a 4th sub and make it an even 4 ohms or sell the 3 10’s and buy 2 12’s.

I could do a lot of things, but it’s time to finish this build and start enjoying my car and this weather. I have a simultaneous soundproofing project in progress and I haven’t driven my car in almost 3 weeks. You know as well as I do… the build is never done it’s only complete.

 

[gijoe]

Honestly, I would just ditch the 3rd sub for now. Doubling displacement (doubling subwoofers) only gives a 3dB increase in output, when the power stays the same. A 3rd sub would only give you 1.5dB more output than two subs, if the power is the same. You can get an amp that is 1ohm stable and the problem is solved, order another sub and the problem is solved, or just use 2 of the subs you have.

 

[miniSQ]

Lots a miss-leading info so far so tread lightly with it.

i am not sure how a speaker can be either 2 ohm or 4 ohm.

But if i was you i would wire it at 4 ohms and follow the crutchfield wiring diagram to end up at 2.7 ohms.

I would NOT mix and match the settings on the 2 drivers, and i would NOT use only 2 of them. Use all 3.

There is no need to "end up with" an even number on the impedance. it is what it is...can't mess with physics

 

[abizzle]

i am not sure how a speaker can be either 2 ohm or 4 ohm.

The Infinity Kappa subs have a switch allowing you to select 2 or 4 ohms.

Are you saying @dumdum is incorrect in his statement about equal power distribution? The only ohm loads that allow for equal power distribution with three subs are 0.67, 1.3, 6, and 12. None of those work for me.

The goal is not to end up with an even load. The goal is to have power distributed equally to each sub and maintain a load within the specs of the amp without going over 4. The Crutchfield diagram will not allow for that.

 

[miniSQ]

The Infinity Kappa subs have a switch allowing you to select 2 or 4 ohms.

i know what it says and that its a switch. I just don't know how it works. I can see if it was 1ohm or 4ohm. or if it was 2 ohm or 8ohm. But 2 or 4 is confusing to me. Once i figure that part out i will look at what dumdum said.

 

[gijoe]

The Infinity Kappa subs have a switch allowing you to select 2 or 4 ohms.

Are you saying @dumdum is incorrect in his statement about equal power distribution? The only ohm loads that allow for equal power distribution with three subs are 0.67, 1.3, 6, and 12. None of those work for me.

The goal is not to end up with an even load. The goal is to have power distributed equally to each sub and maintain a load within the specs of the amp without going over 4. The Crutchfield diagram will not allow for that.

Wait, what? I must have missed something. Those subs have a switch to choose between 2 and 4 ohms?! Are they dual voice coils with a switch to short one voice coil?

 

[cman]

Lots a miss-leading info so far so tread lightly with it.

i am not sure how a speaker can be either 2 ohm or 4 ohm.

But if i was you i would wire it at 4 ohms and follow the crutchfield wiring diagram to end up at 2.7 ohms.

I would NOT mix and match the settings on the 2 drivers, and i would NOT use only 2 of them. Use all 3.

There is no need to "end up with" an even number on the impedance. it is what it is...can't mess with physics

Some Infinity & JBL subs have the weird switches where they can be DVC and 2 or 4 ohm final instead of a dual 4 ohm sub being 2 ohm (parallel) or 8 ohms (series) final impedance.

But I agree there is some misleading info in here...

You do not need an "even ohm load" to the amps... but you do need an even ohm load across each sub... unless you know the amp is overbuilt i would not go lower than the recommended impedance..maybe 1.75 but 1.5 is the absolute lowest i would risk.. and its still that, a risk.


I think you should get two good subs.... two 12's in a proper enclosure will get loud as $hit... maybe get two subs with more excursion and power handling and a larger amp.. It wont make a big difference from two 12s with the setup you proposed.. but 3 is just kind of silly...

I've used plenty of subs with enough excursion where one 12 will shake my car like crazy... and i use sealed boxes.. LOL

 

[cman]

i know what it says and that its a switch. I just don't know how it works. I can see if it was 1ohm or 4ohm. or if it was 2 ohm or 8ohm. But 2 or 4 is confusing to me. Once i figure that part out i will look at what dumdum said.

I still have not figured it out after years.... all i know is they make custom voice coil windings to do it

 

[cman]

The Infinity Kappa subs have a switch allowing you to select 2 or 4 ohms.

Are you saying @dumdum is incorrect in his statement about equal power distribution? The only ohm loads that allow for equal power distribution with three subs are 0.67, 1.3, 6, and 12. None of those work for me.

The goal is not to end up with an even load. The goal is to have power distributed equally to each sub and maintain a load within the specs of the amp without going over 4. The Crutchfield diagram will not allow for that.

Impossible with 3 subs.. you will be at 1.33 ohms with them on 4 ohm mode and in parallel... the alternative is series where the impedance doubles so you would be at like 12 ohms or something silly high..

you would need four subs to get to 2 ohms... or just use two subs and call it a day.

 

[miniSQ]

I still have not figured it out after years.... all i know is they make custom voice coil windings to do it

My guess was they have a D4 sub, and the switch bypasses one of the voice coils. Kind of makes me twitch to think about it.