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Stereo Amplifier and Ohms question. #5429222 05/14/20 03:30 PM
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krismoriah72 Offline OP
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This question is for my Polaris RZR stereo.

I have just blown my 2nd Subwoofer amp, was not installed by me..

My RZR has 4 separate speaker boxes 1) Overhead 2) 10 inch Sub 3) Two 8 inch Subs

The Overhead has a head unit and a 4 channel amp powering the overhead speakers, A line out that goes to a Monoblock amp that powers the 3 subwoofers.


I figured out yesterday why i have blown 2 Subwoofer amps. The 10 inch sub is wired at 2 ohms, and both 8s are wired at 2 ohms so that would equal to a .67ohm load correct? (All 3 subs are dual voice coil 4ohm)

Again this is a monoblock amp. 1 out supplies the 3 subs.


The way the sub boxes are located and separate, wiring them in series or parallel would be a nightmare..if not impossible

Question 1) If i leave the 10 wired at 2 ohm, and switch the 8s to run 8ohm.. will the amp be unstable? What are the pros and cons? WIll the 10 be under driven?

In a perfect world i should probably have three single voice coil 4 ohm subs instead of three dual voice coil subs..but that is not what the installer did..and i want to use what i got for now.

Question 2) Would it be wiser to just unhook the 8s and run the 10 at 2 ohm until i decide to change subs/and or amp?

,*I am getting the same amp for free from the installer, since this one is blown he is going to exhange it..so i will have a monoblock for awhile.

This is the stats of the amp.

Number of Channels: 1
Frequency Response: 20Hz - 20KHz
2 Ohm RMS Power (14.4V) Per Channel: 1 x 600W
4 Ohm RMS Power (14.4V) Per Channel: 1 x 400W
4 Ohm RMS Power Bridge (14.4V) Channel: N/A
Input Sensitivity: 0.2-5V
Low Pass Filter: 40Hz - 3KHz



Question 3) If at a later date i want to throw more money at it- a 2 channel amp with all 3 speakers at 4 ohm better? Or can i keep the same amp and run all 3 subs at 4 ohm off of a monoblock?

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429238 05/14/20 03:54 PM
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DriveHard Offline
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Really we would need more details on the capability of the subs to answer correctly.

It sounds like the subs are all in parallel right now? If that is the case, they all have connections going back to the amp...so it should be easy enough to change it to whatever arrangement you want.

Ideally for that amp you want to have a 2 Ohm load to get the most out of it.

Guessing all three speakers are dual 4-ohm units from the way you describe?

First thought would be to wire it as shown below. That should let your amp see a 3 ohm load, and allow the 10" to take the brunt of the work.

IMG_2446.jpg

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Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429249 05/14/20 03:59 PM
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samven Offline
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You say that wiring them in series would be difficult. How are they wired now? Do you have separate wires from each box back to the amp. If so take the 2 + from the 8'S and tie them together and the 2 - from the 8'S together. Take the + from the 10 and tie it to the - pair of the 8's. Hook the + from the 8's to the + amp connection and the - from the 10 and tie it to the amp -. The 8's in parr will give you 2 ohms and the 10 in series with the 8's will give you 4 ohms. No more blown amp.

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429265 05/14/20 04:19 PM
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krismoriah72 Offline OP
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Yes wiring them other than how they are now would be alot of work. Its a polaris RZR so the 10 inch sub is under the dash, and the 8s are in separate pods near the footwells one on each side.


Each box has its its own wiring.


As it is now.

10- wired at 2ohm
8 wired at 2 ohm
8 wired at 2 ohm

all 3 joined into 1 pair and hooked to the monoblock.

capability of the subs to answer correctly.

10- Power Handling (RMS/Peak): 350 / 700 watts
8s - Power Handling (RMS/Peak) 300/900 watts



If i wire the 8s at 8ohm each instead of 2ohms each... and leave the 10 wired at 2 ohms... will that be a happier place for my amp? or do i delete the 8s for now?

Re: Stereo Amplifier and Ohms question. [Re: samven] #5429276 05/14/20 04:32 PM
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krismoriah72 Offline OP
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Originally Posted by samven
You say that wiring them in series would be difficult. How are they wired now? Do you have separate wires from each box back to the amp. If so take the 2 + from the 8'S and tie them together and the 2 - from the 8'S together. Take the + from the 10 and tie it to the - pair of the 8's. Hook the + from the 8's to the + amp connection and the - from the 10 and tie it to the amp -. The 8's in parr will give you 2 ohms and the 10 in series with the 8's will give you 4 ohms. No more blown amp.


I drew that out and it looks like the 10 will be grounded out? Take the + from the 10, and tie it to the - of the 8s and hook the - from the 10 to the - of the amp..

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429292 05/14/20 05:02 PM
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wag123 Offline
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Instead of wiring each of the sub woofer speaker's two 4 ohm voice coils in parallel at each speaker, wire them in series at each speaker, this nets you 8 ohms for each speaker. If you then connect all three of them them in parallel at the amp, the amp would see 3 ohms. If your amp is rated to drive a 2 ohm load you will be good to go.

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429339 05/14/20 06:17 PM
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samven Offline
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Drivehard posted a good diagram as I was typing. It does not matter if you start with the 8's or the 10 connected to the + just follow his diagram unless all your wires are connected in the boxes and you only have a single lead coming back to the amp then you need to go into each box and wire or switch for the highest ohms allowed. Even if you wire the 8's to a higher load but leave the 10 at 2 ohms the final load will be under 2 if they are in parallel and the way speakers work the 2 is just calculated at an individual freq, that load changes dynamically as the freq in varies so at times your load drops well below 2. the lower the freq the lower the impedance through a coil.

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429615 05/15/20 06:25 AM
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krismoriah72 Offline OP
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Thank you guys for clarifying. Its an odd situation to have 3 sub boxes but with the size constraints of a sidebyside the installer had no choice.

Final question-

If all 3 subs are 4 ohm SVC instead and they are all tied in together is that a final 4 ohm load?

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429634 05/15/20 07:01 AM
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DriveHard Offline
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Originally Posted by krismoriah72
Thank you guys for clarifying. Its an odd situation to have 3 sub boxes but with the size constraints of a sidebyside the installer had no choice.

Final question-

If all 3 subs are 4 ohm SVC instead and they are all tied in together is that a final 4 ohm load?



No

The sum of the currents through each path is equal to the total current that flows from the source. You can find total resistance in a Parallel circuit with the following formula: 1/Rt = 1/R1 + 1/R2 + 1/R3 +... If one of the parallel paths is broken, current will continue to flow in all the other paths.

So the answer is ~1.33 Ohms which would most likely make for a grumpy amp.

Even moving your two 8's to 8 ohms and keeping everything in parallel will still make for a grumpy amp at about the same 1.33 Ohms


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Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429648 05/15/20 07:18 AM
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DriveHard Offline
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another possibility is finding an amp that is 1 Ohm stable...often class D.

I have no connection to this company, but NVX has proven to dyno quite well for the price...and be 1 ohm stable.

https://www.amazon.com/NVX-Monobloc...Y2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

https://www.amazon.com/NVX-Monobloc...ds=nvx+amp&qid=1589545368&sr=8-3

Only problem is they are digitally noisy, and if you listen to FM radio, the EMI from the amp can interfere with a weak FM station.

Last edited by DriveHard; 05/15/20 07:25 AM.

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Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5429850 05/15/20 11:59 AM
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The_Nuke Offline
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If this were my hardware, I’d wire one 4 ohm VC from each of the 8” subs in parallel to each other to give me a 2 ohm load, to which I’d wire in series with the 10” sub’s DVCs wired in parallel to each other (2 ohm result), leaving a final impedance of 4 ohm for the amplifier to power.

Yes, that means 2 VCs from the 8” subs (one each) will NOT be getting power, and that’s fine with me, don’t need them to.

Yes, that means I have to buy a bigger amp to push more watts since I’m at 4 ohms in the end, and I’m fine with that too. That’s actually what I prefer over 2 ohm or 1 ohm loads.


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Re: Stereo Amplifier and Ohms question. [Re: The_Nuke] #5430037 05/15/20 04:33 PM
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krismoriah72 Offline OP
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Originally Posted by The_Nuke
If this were my hardware, I’d wire one 4 ohm VC from each of the 8” subs in parallel to each other to give me a 2 ohm load, to which I’d wire in series with the 10” sub’s DVCs wired in parallel to each other (2 ohm result), leaving a final impedance of 4 ohm for the amplifier to power.

Yes, that means 2 VCs from the 8” subs (one each) will NOT be getting power, and that’s fine with me, don’t need them to.

Yes, that means I have to buy a bigger amp to push more watts since I’m at 4 ohms in the end, and I’m fine with that too. That’s actually what I prefer over 2 ohm or 1 ohm loads.


Ok So the 8"= Parallel + of one to + of the other. - of one to - of the other.

10"= Series + to the - of the 8" and - to the + of the 8" ?

That looks like the 10 will be in reverse? or does it not work that way?


As far as amps- im limited on space as its a sidebyside, and it has to be marine grade since its mounted under the hood, it sees a little water, dirt, dust, mud etc.

Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5430079 05/15/20 05:30 PM
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The_Nuke Offline
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Originally Posted by krismoriah72
Originally Posted by The_Nuke
If this were my hardware, I’d wire one 4 ohm VC from each of the 8” subs in parallel to each other to give me a 2 ohm load, to which I’d wire in series with the 10” sub’s DVCs wired in parallel to each other (2 ohm result), leaving a final impedance of 4 ohm for the amplifier to power.

Yes, that means 2 VCs from the 8” subs (one each) will NOT be getting power, and that’s fine with me, don’t need them to. If

Yes, that means I have to buy a bigger amp to push more watts since I’m at 4 ohms in the end, and I’m fine with that too. That’s actually what I prefer over 2 ohm or 1 ohm loads.


Ok So the 8"= Parallel + of one to + of the other. - of one to - of the other.

10"= Series + to the - of the 8" and - to the + of the 8" ?

That looks like the 10 will be in reverse? or does it not work that way?

As far as amps- im limited on space as its a sidebyside, and it has to be marine grade since its mounted under the hood, it sees a little water, dirt, dust, mud etc.


Yes on the 8”s.

On the 10”, you’re using both voice coils, so do + to + and - to - which yields parallel VCs and a 2 ohm load overall for the 10”

Now to wire the 2 ohm 10” (DVC) in series to the 2 ohm 8” (SVCs):
1) do + from 10” to - on 8”;
2) do - on 10” to - on amp;
3) do + on 8” to + on amp.

Clear as mud?

BTW, that will split the amp’s RMS watts 50/50 between the 10” DVC combo and 8” SVC combo. So the 10” sub gets half, and each of its voice coils gets 1/4 of the RMS watts. And each 8” sub also gets 1/4 of the RMS wattage since half was sent to the parallel combo of SVCs.

There are many other ways to wire these up. I like this one because it makes figuring out how much of the amp wattage each speaker gets easier.


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Re: Stereo Amplifier and Ohms question. [Re: krismoriah72] #5430122 05/15/20 06:18 PM
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The way that I told him to wire it will give a more balanced sound output and frequency response from all of the subwoofer speakers. The impedance change in any one of the subwoofers over its frequency range will not affect the sound quality and frequency response of other subwoofers. Also, if he blows one of the voice coils in any one of the subwoofers, the other two subwoofers will continue to function the same without it.

Re: Stereo Amplifier and Ohms question. [Re: wag123] #5430343 05/16/20 12:30 AM
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Originally Posted by wag123
The way that I told him to wire it will give a more balanced sound output and frequency response from all of the subwoofer speakers. The impedance change in any one of the subwoofers over its frequency range will not affect the sound quality and frequency response of other subwoofers. Also, if he blows one of the voice coils in any one of the subwoofers, the other two subwoofers will continue to function the same without it.


Your way would also give each sub a third of the power the amp is putting down the channel. That may or may not be a good use of the power available.

In my case, I probably would have gone the el-cheapo route on the 8" subs so I could spend a little more on the 10", and so I personally would want the 10" to get more of the amp's watts as opposed to the 8" subs...but that's me, I'm a weird duck. crzy


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