can i make a EQ box for a cell phone headset?
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Posted on Aug 07, 2006 07:30 pm
fortymile
Member Since: Jan 18, 2003
i have the darndest time finding a headset i like. but i found one today that fits so comfortably and is so compact, that i doubt i'll find anything more comfortable. this thing:
www.radioshack.com/sm-bod...pi-2104724.html
is amazing. and it also sounds like crap.
the midrange is way up there, like an old time telephone. i got to wondering if there was a way to build a small 3 band EQ and just put that in line between the phone jack and the headset jack. use the proper jack, you know, so you can run a cord from the phone into the box and then plug the headset into the box.
is this possible? i mean, i don't know how those headsets work. i assume that the signal that travels down the cord amenable to electronic signal modification, as is. but there are two pathways in that cord, i guess: your mic and your incoming audio.
i dont know. if anyone has any ideas on whether this is possible, i'd be so into building a tiny EQ unit by myself from parts at radioshack. some schematics and components perhaps. or maybe buying a little EQ box, if i can find one, and then modifying it to serve this purpose...
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Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 07, 2006 10:15 pm I would assume you can. I have never liked the sound of most headsets either. I just recently switched to a Motorola Razr and ended up with the top end Jabra Blue Tooth headset and it sounds great. But it isnt cheap either. It doesn't crack up in the wind and in my case it has a deeper insert for people like me with some hearing loss. And it is comfy as all get out as well.
But back to the EQ thing. I would imagine it would have to be very low level input as well as low level output.
Aug 08, 2006 01:31 am bluetooth i will have in the future for sure. but not now.
wow, do i have my work cut out for me. i wouldn't know, offhand, how to make this thing low input and output. i'd have to think about that.
would a three band EQ consist of a little circuit made up of, like, three variable resistors? if i decide to do this, i'll look into it in depth, but this is what occurred to me today. don't know if i'm even on the right track with that.
very good chance i might just buy a tiny 3 band EQ, if i can find such a thing, and then modify it.
Aug 08, 2006 01:51 am store.efunctional.com/eq-50.html
3.5 mm plug. dang. i guess i can just buy an adapter at radio shack, perhaps.
anyway, if i knew how to modify this, this would do the trick. noize, can you shed any light on what i'd need to do to make sure i don't blow anything up? the input level stuff. impedence. that's all new to me for the most part. and a headset has audio coming into it and also audio headed back out to the phone. that is something i cannot think around. i need to understand what to do about that, because since this is not one-way up the wire, i guess i gotta be careful all around so that i don't send a hot signal back to the phone. or a weak one.
arghh, am i biting off more than i can chew? if i only knew more in this area, this would be a fun project
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 08, 2006 08:24 pm forty, I'll take a look and see if I can dream a mod up for it a little later. I gotta run back to work for a bit right now.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 08, 2006 09:02 pm Well, with the tiny wires that most of the headsets use, ya you could be biting off more then most of us with big shaky fingers can chew.
But indeed, you would have to do some serious wire re-rigging. It would require that you tap the headset line to have the output output signal from the phone go to the EQ box, then the heaset feed line wouls simply be seperated to go directly to the phone jack input. It can be done best by building a seperate connector piece that would plug into the phone with a normal micro TRS jack. Then you would split that into one jack carrying the phone output to go to the EQ box and the other jack to connect to the bypass jack rig that the actual headset would plug into. This portion of the connection converter would have one jack again connecting to the output of the EQ and the other jack connecting to the plug that bypassed the Eq box input, which is carrying only the headset return signal. The other end of that splitter cabel would connect to the headset jack itself with the earpiece signal coming from the EQ box and the mic portion going to the other plug of course.
Sounds kinda complicated, but it could be done.
Aug 09, 2006 07:25 pm thanks, diemusik. that circuit's easy; even i could build that!
noize, i think all you're saying is that you cut open the headset cord and find two wires in there. one carries audio to the phone, the other carries audio from the mic back to the phone. and you're telling me to route only the ear-audio through the EQ, right?
but listen, there's been a change of plans. but i can still use that idea, possibly. see, i took that headset back and got another one. this one has perfect sound quality and is comfortable, but this one's too quiet. can't use it in the jeep. but i have a small headphone amplifier (runs on AA batts) that i would like to wire in, now, to boost the level in my ear.
if the EQ idea will work, as you say, then this will work too, via the same kind of wiring setup, as far as i can tell.
if you clarify one thing, i'll be able to understand what you're saying: how does the headset work--how many wires are inside? i see that the plugs have two rings on 'em, yet headsets are not generally stereo devices. am i to assume that inside that cord there's one wire that carries speaker audio to your ear, and another which carries microphone audio back to the phone? if so, i can see how you would do this. though i'll prolly have to ask you a bit later how to build those bypasses. i could figure something out myself, but it seems like you really know exactly how to do it.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 09, 2006 09:24 pm forty, actually what I was describing would just be a splitter type set up. One end with the jacks to go from the phone to the EQ for the earbud, and one line goin straight to the other connecter for the mic input. and that inturn is joined at the female jack on the other end by the output of the EQ connection. I can draw a quick line drawing of it in paint or something for you so you can see what I mean if you dont get the idea yet. Let me know and I'll wip one up.
Aug 09, 2006 09:30 pm yeah, i dont get it. because i don't understand how a headset cable carries the signals. i need to understand that before i can understand what you mean. are there two seperate wires in there or something? how does a normal, unaltered headset both handle incoming audio and send outgoing audio to the phone? two wires in there?
yeah a line drawing might help too if you feel like it
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 09, 2006 09:40 pm Heck, I wipped up jsut asimple quick one to give you an idea.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 09, 2006 09:51 pm It works like any other TRS jack set up. You have your common wire to both in and out signals, which is probably the sleeve, but dont quote me on that. Then you have your output line which odds are is the ring. And finally you have your input line which is probably the tip. The sleeve and tip are the ones that carry the current value or signal. So what you will do is essentially split the sleeve into two common lines, one going to the EQ along with the ring line. The other common split will run all the way to the female jack with the tip line. Then your output will connect as shown with again the common and ring on the other end.
Aug 10, 2006 01:45 pm OH! i see. if i buy some actual female jacks i don't have to slice into the cord itself and i can experiment directly with the ring, sleeve, and tip simply by changing which of the posts i'm connecting the wires to.
that sounds a bit dirty the way i worded that.
i didn't think of doing it this way. this allows me to split up the signal and git 'r done. thanks noize!~
Aug 10, 2006 06:35 pm omg why. why why why.
noize, today i bought and returned two headsets. (a total of five so far: every one has sucked beyond belief). as i was taking the last one back, i decided 'hell, i could make one of these.'
see, the last one i bought and returned was just a mic and an 'adapter' for any set of headphones. it was 2.5 mm jack and wire that go into the phone itself, then a wire leading up to one of those 'dangly' mics. then a female jack in the top of the dangly mic that allowed you to plug any set of earphones INTO the dangly mic. i knew it wouldnt work in stereo--i dont think any of them do, since a phone signal is mono-- but i figured i could test all my headphones to find a set with good freq response, and that's why this was the best option for me. AND since it moved the whole setup over to 1/8 jacks--post microphone--it would let me add in my headphone amp on the correct side of the circuit, just by plugging it in.
but it turned out my phone is not stereo compatible, and the adapter itself is, because it's made for phones with built-in mp3 players. (hence there are three stripes on the jack, and my phone don't like dat). there was no sound in my headphones at all, not even in one ear as i expected.
so i went to radio shack. my new idea was to take one of my old 5 dollar single earbud with dangly-mic headsets and chop off the earbud and then just wire a female 1/8 jack in its place. then i would just plug my ipod earbuds into that jack and i would be good to go.
this did not work. why not? i think i tried two different kinds of jack: one was mono, and one was stereo. for each, i put the 2 little wires from inside the original headset (where i lopped off the earbud) onto the posts of the female jack. in all possible configurations. i still never heard anything. no sound. i figured this setup, if i got the wires connected to the right posts, would at least send a mono audio signal up to ONE of the two earpieces. why the hell wouldn't it? any idea?
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 10, 2006 07:08 pm forty, I have a breadboard here made for trying stuff like that. I will give it a shot with one of my older phones and see if I can figure it out.
I wonder if using the stereo headphone with the TRS jsack might have somthing to do with it?
Aug 10, 2006 08:34 pm i dunno. i just wanna make sure i put down here what's going on so it's clear. lemme try again, better organinized
1. my phone has the little 2.5 mm hole. it is not stereo capable, so the only plugs that work in there have two little black stripes: TRS: tip ring, and sleeve. (i was sold a 'three stripe' headset today. it didnt work at all)
2. im trying to take a cheap 2.5 mm dangle-mic single-bud headpiece, plug that into the phone, and then wire SOME KIND of female socket/hole/acceptor thing in the place where the earbud would usually be. this is the point at which the whole contraption has to 'jump' from 2.5 mm to 3.5 mm (1/8"), and i'd plug a normal pair of earbuds in there. not trying to get stereo out of it, mono will be fine. and i'm just trying to connect those two tiny tiny little wires inside the cord up to the different posts on the female thing. and it doesnt work, but i dont see why it wouldnt.
ok that is all.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 10, 2006 08:50 pm I wonder if there is not enough current going down the wire to supply audio to both of the buds. As it is possible the jack is trying to feed them both. and it should still be mono the way you are doing it. I wonder if by chance it is shorting out?
The earbud piece should only have 2 wires, and those should go to a simple TS connecter. I wonder if by chance the possative and negative got mixed up. That might hinder it as well.
Just thinking out loud now.
Aug 10, 2006 09:27 pm the wire the earbud used to be attached to indeed has just two wires. the female little jacks i'm trying to use have three posts. one of the jacks says its mono and the other says its stereo. i tried to connect the two little wires to two of the posts, in all possible permutations.
the earbuds plug is tip ring sleeve, as earbuds are stereo devices. i am trying, with the female jack, to connect wires to, say, the tip (usually that's left mono, i heard) and the sleeve (usually ground or whatever?)
when you plug the 1/8" earbuds plug into the jack the PLUG itself will be calling for current from different places within the female receptacle. even the 'ring' will be lookin' for power. but as there are only two wires coming into that receptacle from the phone and one post is left unpowered, i figured as long as i connect it up so that power goes to the tip and the sleeve, the ring can go screw itself. i'm trying to leave that sucker unpowered.
keep in mind, i've tried all the permutations as far as connecting it to two of the three posts. and i took care not to short it out. (unless my body can do that, as sometimes i just would press the wires against the posts, to test them)
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 10, 2006 09:51 pm Well it sounds like you did it the right way. Indeed the sleeve shoudl be the common wire and the tip should be left and the ring should be right. The only thing that would make a differance would be common and signal wires being reversed and it sounds as though you have covered that twist. A single earbud should indeed work just fine as it is small enough to not draw too much current.
I would say if you have a multi meter to try and see if you can read any voltage at all through those two wires. It will probably be very small but there should be some small votage present. If you can set it to read millevolts that would probably be proper. And as well if y9ou can read current it would more then likely be in milleamps or microamps. Either way, you should see some signal on the wires. If not it might be a bad jack or wire.
Aug 11, 2006 12:32 am actually i've been plugging in a SET of earbuds. is it wrong to do that?
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 11, 2006 05:51 pm No that shouldn't effect it as it will only send the signal down one of the poles depending on which you have hooked up, tip or ring. If you are hooking both up, try just one of them.
Have you double checked since monkeying with the wirng to make sure it still works OK with just a plain old headset?
I'm bringing my breadboard to work in the morning and will see if I can encounter the same problem or if it works out for me. What model phone is it by the way? I will see if I can find a spec on the output of the thing.
Aug 11, 2006 07:54 pm this is a samsung a670
the guy at radio shack thought my idea should work too. breifly he wondered if the extra length in the earbud cord might be contributing to resistance. but we tossed that idea. only other thing i can think of is that i bought the wrong jack. i wasnt sure what kind i needed, but one says mono and one says stereo and i've tried 'em both.
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 11, 2006 10:30 pm I'm bafled then for sure. If it still works with the regular headset then I dont have any idea why it wouldn't work doing what you are trying.
Aug 12, 2006 03:26 am thats ok, thanks nozie.
haha i mean noize. damn beer.
you rock with all your help and all
Noize2uCzar of MidiAdministrator
Since: Apr 04, 2002
Aug 12, 2006 06:21 pm LOL, thats a good one forty, if you had any idea how many times I catch myself typing my name that way from jjust plain going to fast. I've done it coutless times on myspace and not caught it before sending the OK on it.
And ya, yer welcome. If I think of anything I will let you know.
Aug 13, 2006 05:18 pm :)
