I'm fighting back the impulse to say this might look interesting if it happened in mid-air!
Ooops, I said it. LOL.
Just don't stand underneath if it does happen.
I understand you, clearly, but across three years of using RC batteries for audio purposes (links can be found here at Head-Fi to evidence this), I've been taking multiple brands and sizes of LiPo batteries down to 3.4V without any evidence of swelling, failure to charge, puffing, explosions, etc. That's my empirical experience with these batteries, but I am certainly willing to concede that I may have been "getting away with murder," so to speak. So, I will look into it, for sure. It won't hurt my run time all that badly to stop taking them below 3.6V, in any case.
Here's the alpha release of my headphone network calculator: http://robrobinette.com/images/Audio/Headphone_Resistor_Network_Calculator.xls
It's an Office spreadsheet created with Libreoffice but Microsoft compatible.
Using my HE-500's 32 ohm impedance and 8 ohms for my amp's load impedance it came up with R2 of 6 ohms and R3 of 2 using "Dual Resistor Network A."
Those resistors give an amp load of 7.9 ohms, headphone input impedance of 1.3 and amp attenuation of 4.2 times more than the headphones alone.
I'm very open to corrections and suggestions. Please don't actually build a network using it until the gurus look it over.
The calculations look pretty good! A few things to improve it though. Label the "Resistor Networks" as what usage scenario it will be for each one. Such as, "For Powerful SS Amp", "For Tube Amp" etc. Second, it would be nice to have the amp's output impedance as an optional calculation for sake of completeness. Third "Headphone input impedance" should be "Amplifier output impedance". Fourth, include the wattage value of the resistor, like 5 or 10 watts, and also wirewound/cement/metal film etc. Lastly, a bunch of pictures aren't loading for me for some reason.
Great work Rob :D
Sort of makes me wonder how Amazon thinks they are going to fly billions of packages around the US using battery-powered, autonomous rotary craft.
Number 1: not sure I see the point of this one!
I suppose if you drive the headphones directly off the amp output, then with a tube amp, it MAY sound better if the tube amp is loaded down to a typical speaker impedance
Number 2: my favourite
Number 3: kinda like a vintage receiver
doesn't really do much unless R2 is 100 or 200 Ohms or some other high value
Number 4: too complicated for it's own good.
but it impresses the neighbours and may even impress the chicks, well, maybe the geeky ones!
I've added most of the suggested changes except changing attenuation and adding resistor watt calculations.
Here's the latest Headphone Resistor Network Calculator: http://robrobinette.com/images/Audio/Headphone_Resistor_Network_Calculator.xls
I really do appreciate your bringing this to my attention. I'd like the batteries to last as long as possible before having to buy new ones and I don't want any fires, either.
I thought you should you be charging at half the rate...say 2.5a or preferably less? Heat and such...