#1
I'm a senior in an engineering magnet high school and for my senior design project I'm designing a pair of headphones for people who are hard of hearing. To cut to the chase, one of my innovations is a potentiometer on each cord leading up to the ear that can provide individual ear volume control, on top of the volume set coming from the device (iPod, mp3, whatever). So if the iPod is set at its maximum volume (OW) and for whatever reason in hell they want it louder, how exactly would I set to doing that? I know the potentiometer would have to be connected to the inner wiring, but I'm sketchy as to the details. My headphones are going to have to have a premium audio driver so that they can handle the high volumes and remain clear. Can anybody provide any feedback and/or critique? I'll take help!!! Please? haha

I'm not sure how well I explained any of this, so if you CAN help me but aren't certain of the design, please ask for clarification. Thanks!
#2
unless you design what is generally referred to as an "amplifier", you're going to have to conjure up the extra wattage with magic. Potentiometers either resist current, or do nothing. they cannot make something louder. It's not like you can just draw in an eleven with a sharpie.
#3
haha ^^^ my ipod goes to 11!!!

yea, now, if you wanted to turn it all the way up and cut the volume from there, because they go pretty loud. well.....depending on the headphones you use. choose wisely young padawan.
#4
I like the idea of putting pots on the individual phones. Thanks to the glory of loud, blasting metal, I'm going deaf in one ear more than the other. Since I have a musically trained ear, the volume differences drive me CRAZY. Sweet idea there, TS.


[Ima steal the pot idea ]
#5
Thanks Jim!!! Glad you dig the concept!

And spazz, could you elaborate on this amplifier?

I forgot to mention... with these individual volume controls for each ear, they're going to be... errr... how to say it. I'll diagram it. Hold on.


Ok here goes...


Lets say you have the iPod on 80% volume, but your left ear has a few more dead spots than your right and you can't hear as well. So instead of throwing the finger to your right ear and increasing the volume, you reach up to the individual volume control on your left ear and crank it up. Easy as that. Here's a diagram explaining.




Now here's the part I forgot to explain. These headphones should also help those with sensitive hearing. I have a friend who had surgery on his jaw as a kid, and his hearing has never been quite right ever since. He complains that he can't listen to headphones without immediate headaches because the volume is just too harsh on his ears. What you may not know is that the iPod volume isn't a very steady increase. It goes more in plateaus than anything else, and unfortunately, it goes from soft, to null. There isn't much of an inbetween, and that's where this applies to him. I want to make the individual volume controls sensitive to their home position. If they start at 1 (the lowest) then they can only increase the volume. Now if they start at 10, then theoretically they can only decrease the volume... right? Unfortunately it isn't so. Since I explained earlier that the iPod volume plateaus, then by decreasing the volume of the individual ears, it'll only return the volume to that odd volume point of either being a little bit too loud, or nonexistant all together. What I'd like to achieve is to reach that same awkward point with the individual controls at 10, and then reduce sound from there. Do you follow? Here's a diagram not really explaining much at all. Just a visual reference.




Soooo... is this possible? What do you think? And also... if this ends up working (god willing) would this be a product of interest to you? Thanks
#6
Ok, start being more technical and stop using the term ipod so much. The ipod falls into the category of signal generating devices that have a 1/8" stereo output. I think a lot of portable listening devices have some sort of stereo balance control built in (but I don't think balancing it to one side will result in all that much gain anyways).

Like it was mentioned, a potentiometer will not do anything to make the sound louder, it can only dull the sound. Pots are just used to control the current from a source, its just a resistor that can change. You would want a stereo headphone amplifier to do this (unless you plan on having your headphones run on magic).

So this idea is far from revolutionary, just build a tiny little opamp based stereo headphone amplifier in an small tin or something, and have individual volume controls before the outputs of both of the channels. I think that will be enough to get you an A.
#8
Chill Axe, I'm using the term iPod so much because everyone gets the gist of what it is, and has at some point in their life seen one. And I understand I need an amplifier, but I was hoping somebody could elaborate on just how to use it and or buy one.
#9
Ok coming back to the topic...

I need a miniature preamp to increase the sound levels... does anybody know where I can buy such a device? The only preamps I can find are larger... I need something small, only needed to increase sound minimally (just headphone speakers)
#10
If you are making this yourself, just look for a schematic of a headphone amp. I am thinking you just need to make a small stereo amp using an opamp IC for each channel. I don't know off the top of my head an opamp that runs off of 9v DC and is more suited towards lower distortion. Heck you may even need only one opamp (there should be some that have 2 amp stages in 1 IC). Just build a simple amplifier based around that and put a logarithmic pot before each stage so that it is able to act as a master volume for each channel.