Calculation RMS Power for a Subwoofer... For a woofer which is not built yet. Only design is ready.

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kulomer

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Is there anyone who can help me to calculation RMS power for a subwoofer? I have designed the subwoofer. It is not built yet.
I need to know which datas I need from which parts and what will be the formula :)
For example , I have VC details , cone details, I need to multiply with what :)

I appreciated for any help in advance...
 
If you gave some specifics about the build I'm sure a few people on here could give you a ballpark #
Thanks for your answer Haunz..
Everyone please see details in the below

15''
Magnet: 1x Y30 FM and 1x Y35 FM
Spider: 255x76 x2
Wire: Flat CCA 0.40x0.70
Winding Height:60
Possible XMAX (one way) :35
Washer thickness: 20
VC weight: 106gr
VC OD: 81
Cone Weight: 180-200 gr
Effective Height of Cone: 85 (-10 is OK)
 
I would run it at slowly increasing power levels and monitor voice coil temp to find your safe operating limit.

Thanks for your reply Mr. MetalHeadJoe :)
We don't have these parts physically in hand. So do you think there is anyway to calculate approximate RMS ?
 
In the modeling design phase power handling is estimated out of experience. How did you get this far without that?
Thanks for your reply.
We got all of these from our experience. Of course we have a target/aim for RMS. But I need to find a formula to calculate for getting most accurate result for RMS. Any advices ? Appreciated..
 
Wire: Flat CCA 0.40x0.70
Winding Height:60
Coil specifications that matter, that you would need to use to have one wound at least, are inner and outer diameter, and wind width. Number of layers and gauge of wire would be useful as well. Former height and thickness you would need to know as well.

Anyway, good way to estimate thermal power handling of your coil is 100W X diameter (in inches) X layers. Generally speaking 3" 4 layer coil subs will hold 1200W more or less indefinitely. This may go up or down 20% depending on the specifics but it should get you in the neighborhood of what to expect.

As far as mechanical power handling that's largely dependent on the box and application. If you don't have experience building with whatever suspension you plan to use you're going to have to just guess and be prepared to rebuild it stiffer if you wind up with it breaking prematurely.
 
Coil specifications that matter, that you would need to use to have one wound at least, are inner and outer diameter, and wind width. Number of layers and gauge of wire would be useful as well. Former height and thickness you would need to know as well.

Anyway, good way to estimate thermal power handling of your coil is 100W X diameter (in inches) X layers. Generally speaking 3" 4 layer coil subs will hold 1200W more or less indefinitely. This may go up or down 20% depending on the specifics but it should get you in the neighborhood of what to expect.

As far as mechanical power handling that's largely dependent on the box and application. If you don't have experience building with whatever suspension you plan to use you're going to have to just guess and be prepared to rebuild it stiffer if you wind up with it breaking prematurely.
Thank you very much. This is very helpful. I appreciate your help Hispls. This means a lot to me.
 
Thank you very much. This is very helpful. I appreciate your help Hispls. This means a lot to me.
If this is a production run I would suggest real world testing. Connect woofer to a signal generator, 50hz sine wave. A safe "rating" would be if the speaker will survive this for 8 hours. Once you exceed "continuous" thermal power handling it will fail very quickly.

If you rate your subs this way you will know anything that comes back with a burnt coil was abused.

As far as mechanical power handling who can say? Put your 15" sub in a 10 cubic foot sealed box tuned to 40hz and try to play it at 10hz and it'll likely break mechanically at under 500W. Build suspension as stiff as you can without sacrificing whatever performance/efficiency/TS parameters you're shooting for. If you're talking about 500W or less rated sub mechanical power handling shouldn't be a big worry, as you go up from 1200W you'll need to consider more that users will do very stupid things with them and then claim it's your fault.
 
If this is a production run I would suggest real world testing. Connect woofer to a signal generator, 50hz sine wave. A safe "rating" would be if the speaker will survive this for 8 hours. Once you exceed "continuous" thermal power handling it will fail very quickly.

If you rate your subs this way you will know anything that comes back with a burnt coil was abused.

As far as mechanical power handling who can say? Put your 15" sub in a 10 cubic foot sealed box tuned to 40hz and try to play it at 10hz and it'll likely break mechanically at under 500W. Build suspension as stiff as you can without sacrificing whatever performance/efficiency/TS parameters you're shooting for. If you're talking about 500W or less rated sub mechanical power handling shouldn't be a big worry, as you go up from 1200W you'll need to consider more that users will do very stupid things with them and then claim it's your fault.
Once we receive the sub, this is what we will do. I will also share that info here.
I think we will have them in 2 months.
 
If this is a production run I would suggest real world testing. Connect woofer to a signal generator, 50hz sine wave. A safe "rating" would be if the speaker will survive this for 8 hours. Once you exceed "continuous" thermal power handling it will fail very quickly.

If you rate your subs this way you will know anything that comes back with a burnt coil was abused.

As far as mechanical power handling who can say? Put your 15" sub in a 10 cubic foot sealed box tuned to 40hz and try to play it at 10hz and it'll likely break mechanically at under 500W. Build suspension as stiff as you can without sacrificing whatever performance/efficiency/TS parameters you're shooting for. If you're talking about 500W or less rated sub mechanical power handling shouldn't be a big worry, as you go up from 1200W you'll need to consider more that users will do very stupid things with them and then claim it's your fault.
This bobbin I made by myself.
4” VC
6 layers
So is this 1200W hispls ?
 

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This bobbin I made by myself.
4” VC
6 layers
So is this 1200W hispls ?
Most 3" 4 layer coil woofers we use will hold up to 1000-1200W continuous.

4" 6 layer should = 4x6x100 (2400W) or somewhere in that neighborhood. Bear in mind, if you are not using top quality coils the adhesives that hold the coil together may fail before that, if that former isn't very thick you may have issues with bubbling from outgassing (this is particularly a concern with flat wire) or breaking mechanically under extreme pressure conditions. Pushing your product to failure may well reveal a weak point in your materials/design/manufacturing.

Build up some subs with that coil and start testing. I'd say with a 4" 6 layer coil and stiff suspension your sub should be pretty indestructible up to 1600-1800W even buying off-the-shelf from China.
 
Most 3" 4 layer coil woofers we use will hold up to 1000-1200W continuous.

4" 6 layer should = 4x6x100 (2400W) or somewhere in that neighborhood. Bear in mind, if you are not using top quality coils the adhesives that hold the coil together may fail before that, if that former isn't very thick you may have issues with bubbling from outgassing (this is particularly a concern with flat wire) or breaking mechanically under extreme pressure conditions. Pushing your product to failure may well reveal a weak point in your materials/design/manufacturing.

Build up some subs with that coil and start testing. I'd say with a 4" 6 layer coil and stiff suspension your sub should be pretty indestructible up to 1600-1800W even buying off-the-shelf from China.

Thanks for your reply.
We use EP200 and some other adhesives from US. We work with Hernon and CP Moyen.
For serial production, we use glue from China and Taiwan.
For bubble problem, yes we know that very well. We also had some solutions for that.
So for the calculation RMS, you count layers just only one side of the VC, correct? or you double that, because it is circle?
 
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