The MHsoft calculator doesn't let me type in my panel density. Does anybody here know where the calculations / formula's are online for panel absorbers?

I am just finishing my partitions, and thought I may as well seal off sections that would make the wall double as a panel absorber. The 1/2" drywall is not the same as plywood, so it would be different.

The density is an issue : would the studs be considered in the panel density since there would be a few studs per 'panel' and the 'panel' (drywall) would extend to the next 'panel' Seems different, but while the wall would look normal, it would possibly be a selective treatment as well.? I would assume so.

The formula for panel absorbers would be appreciated. I know the Axial fundamental, and I would aim to make the partition-traps around that fundamental. They would be a bit different to create an overlap and have a wider range.

This could delay the renovation a day or two, but could be an effective approach and broadband will still be used.

thanks again
GCJ

There's a freeware program called "Porous absorber calculator" or some such, written by Chris Whealy. I have no idea how accurate it is, or if it's even possible to determine absorption only from density. But no harm in trying it.



Now hold on there a moment. "Density" is a property of rigid fiberglass and equivalent materials. That has nothing to do with membrane panel traps. Maybe you mean "mass," which is part of the calculation. And that is definitely an included parameter in the MhSoft calculator.

--Ethan

Now hold on there a moment. "Density" is a property of rigid fiberglass and equivalent materials. That has nothing to do with membrane panel traps. Maybe you mean "mass," which is part of the calculation. And that is definitely an included parameter in the MhSoft calculator.

Ethan - I meant the mass per meter squared. So with Drywall the weight is known, but with the studs, should their weight be included in the panel mass on MHsoft?

It is all guesswork. My point was why not try to make a panel trap out of the wall to roughly target the range of concern. Time will tell, but I am optimistic of how the partition walls will improve the sound vs the concrete block.

No, you'd ignore the stud weight because they are anchors where the drywall doesn't flex.

--Ethan

Ethan

I was going through the MHsoft calculations for various panel mass inputs. It turns out that in my room my axial modes would be 39Hz and 53Hz. As a result, a single layer of drywall will not target these areas of concern. So I am thinking of using 2 layers with the Green Glue to adhere them. Also, I will make the cavity's dimensions different to stagger to resonance to get a bit more bandwidth.

I thought 1 layer of 1/2" would perform well, but it wouldn't according to the calculations. I was concerned with 2 layers causing problems, but it appears that's what is needed.

Do you think 2 layers will cause a problem in the midbass? I will have quite a bit of Broadband in place.

I forgot to ask something on the previous - sorry. With MH soft, I started to break down the volume of the trap to help me get dimensions I want. That is assuming volume is what matters.

If I have a similar volume (but different depth, length and height) will he Trap still be similar (resonance) to the simulated traps on MH? It is a bit of work on the calculator, but that seems to work to get the numbers that allows the trap to fit in this space.

In the above, the entire rear wall with 1/2" drywall would be one trap. Seems unusually large for a trap, but when you want to trap 39Hz, I guess that is the requirement.

GCJ

I have no idea, sorry. The only panel traps I'm familiar with are the ones in my article from EM magazine.

--Ethan