The bottom line:
I may "mod" these earmuffs to enhance NRR. For those with experience in acoustics, any advice on NRR enhancement?
Troubles/how it started: I have 2 sets of Caldwell E-max. Yes, they were cheap with lots of static/noise but I was happy with the ability to hear conversation at such a low price with them. They seem to be less effective at indoor ranges and I always double up in ear protection with them now regardless of my environment.
After about a year (past the warranty time) one set of muffs lost hearing in the right earpiece completely. It had been cutting on and off intermittently for a few months and a pull/push/twist of the knob or wire seemed to help sometimes. The other speaker was working well.
Disassembly:
(sorry about lack of pictures for disassembly, i didn't thin I would post about it) The ear pad pops of very easily with a coin (see the slot on the bottom side) and I'm surprised at how simple/how little there seems to be inside. The flat black sponge you see when looking into the cup is about as thick as 2-3 quarters stacked and probably just serves to keep dust out. Further disassembly (freeing the circuit board) requires you to carefully remove the sponge cap around the microphone and unscrewing a ring around the base of it. I needed to do that in order to have better access to the wires. Also unscrewing the two screws seen in the picture.
The fix: I put batteries in and had the muffs running. In my low-tech way (not an electrical engineer) I pulled/tweaked individual wires until I narrowed down which wires/group of wires would allow the speaker to turn back on when manipulated. There was a lot of hot glue holding the wires to the circuit board and glued at very sharp angles which seemed to stress the connections. With my own hot glue gun empty, I simply melted the hot glue to the group of wires that I thought was the problem, propped them up at a less stressful angle and let the glue harden. The speaker worked, problem solved. However, a week later I began having problems again and found that another source of tension on the wires was in the way I had been folding them up for storage combined with the way the factory assembled the unit with an extra loop of the wire around a metal rod which took up slack. I undid that loop and fed a little more slack on the black wire into the right muff and the problem was gone again.
My greatest surprise was how little there was in the way of the shell!
That's all that stands between you and the sound is the green plastic shell. The only foam/padding present is in the ring that goes around your ear.
So I'm considering cutting slices of foam mat end-pieces that were left over (the harbor freight anti-fatigue mats) and hot-gluing them to the inside of the shell. I'm not too familiar with the mechanics/physics of sound and am unsure if hot-gluing them to the shell would provide such an anchor that it would cause the foam itself to vibrate and thus transmit sound. The foam seems pretty dense (I've pressed a piece up to my ear canal and it decreases sound pretty well). Another alternative would be strips of foam mounting tape although it would cost money.
I recognize one pitfall to avoid could possibly be this: if I didn't secure the material to the shell, it could make contact with the circuits and prevent moisture from evaporating/promoting corrosion. Or some chemical in whatever I add may cause corrosion. So I think I should probably avoid stuffing it with free-floating material. Either way I wouldn't want anything to come in front of the speaker either.
I just love the idea of enhancing something that would spare our hearing/keep us healthier. It makes me wonder if better protection could be easily offered but is reserved for more expensive models only.
This may not be something I'll get to right away but it seems like I should do something if I can.
I may "mod" these earmuffs to enhance NRR. For those with experience in acoustics, any advice on NRR enhancement?
Troubles/how it started: I have 2 sets of Caldwell E-max. Yes, they were cheap with lots of static/noise but I was happy with the ability to hear conversation at such a low price with them. They seem to be less effective at indoor ranges and I always double up in ear protection with them now regardless of my environment.
After about a year (past the warranty time) one set of muffs lost hearing in the right earpiece completely. It had been cutting on and off intermittently for a few months and a pull/push/twist of the knob or wire seemed to help sometimes. The other speaker was working well.
Disassembly:
(sorry about lack of pictures for disassembly, i didn't thin I would post about it) The ear pad pops of very easily with a coin (see the slot on the bottom side) and I'm surprised at how simple/how little there seems to be inside. The flat black sponge you see when looking into the cup is about as thick as 2-3 quarters stacked and probably just serves to keep dust out. Further disassembly (freeing the circuit board) requires you to carefully remove the sponge cap around the microphone and unscrewing a ring around the base of it. I needed to do that in order to have better access to the wires. Also unscrewing the two screws seen in the picture.
The fix: I put batteries in and had the muffs running. In my low-tech way (not an electrical engineer) I pulled/tweaked individual wires until I narrowed down which wires/group of wires would allow the speaker to turn back on when manipulated. There was a lot of hot glue holding the wires to the circuit board and glued at very sharp angles which seemed to stress the connections. With my own hot glue gun empty, I simply melted the hot glue to the group of wires that I thought was the problem, propped them up at a less stressful angle and let the glue harden. The speaker worked, problem solved. However, a week later I began having problems again and found that another source of tension on the wires was in the way I had been folding them up for storage combined with the way the factory assembled the unit with an extra loop of the wire around a metal rod which took up slack. I undid that loop and fed a little more slack on the black wire into the right muff and the problem was gone again.
My greatest surprise was how little there was in the way of the shell!
That's all that stands between you and the sound is the green plastic shell. The only foam/padding present is in the ring that goes around your ear.
So I'm considering cutting slices of foam mat end-pieces that were left over (the harbor freight anti-fatigue mats) and hot-gluing them to the inside of the shell. I'm not too familiar with the mechanics/physics of sound and am unsure if hot-gluing them to the shell would provide such an anchor that it would cause the foam itself to vibrate and thus transmit sound. The foam seems pretty dense (I've pressed a piece up to my ear canal and it decreases sound pretty well). Another alternative would be strips of foam mounting tape although it would cost money.
I recognize one pitfall to avoid could possibly be this: if I didn't secure the material to the shell, it could make contact with the circuits and prevent moisture from evaporating/promoting corrosion. Or some chemical in whatever I add may cause corrosion. So I think I should probably avoid stuffing it with free-floating material. Either way I wouldn't want anything to come in front of the speaker either.
I just love the idea of enhancing something that would spare our hearing/keep us healthier. It makes me wonder if better protection could be easily offered but is reserved for more expensive models only.
This may not be something I'll get to right away but it seems like I should do something if I can.