What's wrong? jacking mic and headphones for Frankenstein headset

March 8, 2013 7:26 AM

I really want to combine my headphones with my microphone so that I can use it as a headset on my home phone. So I got a 3.5mm splitter and a 3.5mm to 2.5mm adapter so that I can plug the mic and headset together, then reduce it to 2.5mm so it can plug into my phone. It doesn't work. Why? More details inside...

I did all this and I can hear calls great over the headphones, but sadly the microphone is not feeding through at all. I tried switching plugs, and I've tested the mic on my computer so it is not faulty. Clearly since I can hear callers the headphones are not faulty so I suspect that it may be a problem with the jack or splitter....

I have used a cheap crappy headset/mic combo on my phone and that works - but that is what I was trying to replace so I can still make and hear calls easily when my kids are happily playing (and making noise). I also wanted to do it this way so that if a component breaks I can replace it... of course since the components don't seem to be playing together well it's kinda a mute point.

I'm kind of at a loss as to what is wrong - shouldn't it just work?

posted by cheesyburgercheese to technology (15 answers total)

Nope. The headset that worked has a "stereo" plug where one channel is headset and the other channel is microphone in.
posted by Ferrari328 at 7:53 AM on March 8 [1 favorite]

The thing with splitters is that both "legs" go back to the same parts of the plug. A microphone/headphone plug actually has some extra contacts to give the headphones a different connection than the mic. You can read about that on Wikipedia.

I can't find it in 2.5mm, but this is the 3.5mm version of what you need. (Note the extra black lines on the plug. Each line splits out another "wire").
posted by Nonsteroidal Anti-Inflammatory Drug at 7:54 AM on March 8 [1 favorite]

Ah. Here is a 3.5mm to 2.5mm TRRS adapter that will adapt each of the connections on the "combiner" in my previous comment. Your current adapter is probably missing the extra contact and most likely wouldn't work.
posted by Nonsteroidal Anti-Inflammatory Drug at 7:59 AM on March 8

Spreading the knowledge, it's moot in that phrase and not mute.
posted by pemdasi at 8:04 AM on March 8

Unfortunately, the adapter that NSAID links (as well as the only other one I could turn up) appears to be the wrong way around for what you need -- they're 2.5mm female to 3.5mm male, and it sounds like your phone has a 2.5mm jack, so you need a 2.5mm male connector at the end of your adapter chain.

However, NSAID is correct in that "TRRS" is the magic word you want to search for. Headphone jacks and connectors in general (whether 1/4", 3.5mm, or 2.5mm) tend to be classed as:
TS (Tip/Sleeve) -- carries ground and 1 audio channel -- 1 ring on the connector
TRS (Tip/Ring/Sleeve) -- carries ground and 2 audio channels -- 2 rings on the connector
TRRS (Tip/Ring/Ring/Sleeve) -- carries ground and 3 audio channels -- 3 rings on the connector

What you want is TRRS because you need to carry two channels of headphone audio plus one channel of mic audio. Normally a mic will have a TS connector because it's mono, and headphones will have a TRS connector to carry stereo sound. Stereo headsets need TRRS to carry those three channels together.
posted by McCoy Pauley at 8:11 AM on March 8 [3 favorites]

What you want is TRRS because you need to carry two channels of headphone audio plus one channel of mic audio.

But OP also needs to combine inputs, and I'm not sure there's a (commercially-available) TRRS splitter that pulls 1 channel from the mic input and pushes 2 audio channels out to the headphones. I think the idea to modularize the setup for easy replacement of individual parts is good in theory and not really feasible in practice.
posted by carsonb at 8:32 AM on March 8 [1 favorite]

Well, the push/pull aspect is handled by the device itself (the phone, in this case). As I read the OP's description, they just want to get the microphone and headphone onto a single 3-channel (i.e., TRRS) 2.5mm connector that plugs into the phone's 2.5mm jack. All that's needed from the adapter is to combine those three channels (2 for the headphones, 1 for the mic) into the one plug. The 3.5mm adapter that NSAID links in their first post appears to do that job -- the real problem is converting that 3.5mm male TRRS to 2.5mm male TRRS, since I can't seem to find any adapters that do that.
posted by McCoy Pauley at 9:09 AM on March 8

they're 2.5mm female to 3.5mm male, and it sounds like your phone has a 2.5mm jack, so you need a 2.5mm male connector at the end of your adapter chain.

Ooops, that's correct.


Here's a TRS 2.5mm male to 3.5mm female adapter. It's missing the second R (ring) connector, so it wouldn't give you stereo sound, but then telephone isn't stereo anyway.

It's been a while since I've worked with mono cables, but I believe stereo plugs are backwards compatible (as it were) with mono plugs. If not, you might need to also add something like a 3.5mm mono to stereo adapter to the chain. Any thoughts on that idea, McCoy Pauley?
posted by Nonsteroidal Anti-Inflammatory Drug at 9:43 AM on March 8 [1 favorite]

Generally you can mix-and-match plugs and get the smallest number of channels supported by both, but the problem is going to be which channel gets dropped. I saw that TRS 2.5 M to 3.5 F adapter, but I suspect that it would give you both channels of stereo output and drop the mic channel, which doesn't help much.

I guess I see what you're getting at with the mono-to-stereo adapter, but it depends what channel the phone expects to see the microphone on. If it only uses channel 3 on TRRS for microphone, then bringing the mic in on channel 2 doesn't help.

I find it hard to believe there's no such thing as a TRRS 3.5mm F to 2.5mm M adapter, since that would solve all the problems here, but I haven't been able to turn one up yet. Otherwise, this is going to turn into a massive, semi-functional tangle of adapters.
posted by McCoy Pauley at 9:58 AM on March 8

Ok, I think I started things off wrong with that TRRS splitter. You'd need TRRS for stereo, so an iPhone will give you that, but this is just a regular cordless phone. Based on the Amazon picture of the recommended headset, the phone has a 2.5mm TRS jack. The extra ring is a red herring.

Instead of a "splitter" as referenced by the OP (functionally a multiplier), what's really needed is a functional splitter, like this guy, right? Throw in the 2.5mm to 3.5mm TRS adapter, go to the true splitter, throw in a mono adapter for the headphones, and bob's your uncle.
posted by Nonsteroidal Anti-Inflammatory Drug at 10:16 AM on March 8

Thanks for the discussion so far, I'm afraid it doesn't look like we will be able to have a consensus on if it will work or not because I didn't even think about the phone dropping a channel, too.

Correct me if I'm wrong here:

Ideally if I can find a 2.5mm M to 3.5mm F TRRS adapter I should try that with a 3.5mm TRRS splitter and hopefully the phone won't cut out the mic channel. Jes?

This appears to be a suitable TRRS 2.5mm -> 3.5mm TRRS adapter...

If I paired that with this or this I have the greatest chance of things working, right?

Or do y'all think I might be better served trying to replace the mic with this and deal with having the mic hardwired into the adapter?

I'm kinda afraid now that the phone is a wildcard that even if I get all the bits and pieces lined up right that it still just might not work anyways.

I'd love to see more opinions but thanks so much for the feedback I've already gotten. I'm understanding the different plug and channel demands better now.
posted by cheesyburgercheese at 11:39 AM on March 8

NSAID makes an excellent point -- the phone is going to be designed for a one-sided headset anyway, so the jack is going to be 2.5mm TRS, not TRRS. (One channel for the earpiece out, one for the mic in.) So I, at least, have been chasing in unnecessary circles.

In that case, the following should work:

1) 3.5mm stereo to mono adapter (TRS female, TS male), to plug the headphones into, as linked by NSAID in this post.

2) The 3.5mm to 2.5mm Headset Buddy adapter from Amazon that you link to just above.

Plug the mono-converted headphones into the headphone arm of the Headset Buddy, plug the mic into the mic arm of the Headset Buddy, plug the 2.5mm TRS connector on the Headset Buddy into your phone handset, and Bob's your only-slightly-jury-rigged uncle. Only question is whether you'll get audio in both sides of your headphones or only one -- that depends on whether the stereo-to-mono adapter splits the mono signal to both stereo channels, or only passes it through to one. But I'm pretty confident it will work.
posted by McCoy Pauley at 12:25 PM on March 8

I'm with NSAID and McCoy Pauley; telephone is mono, and your phone almost certainly has a TRS, not TRRS plug. The Headset Buddy alone will get you most of the way there--the microphone will work, and you'll at least hear sound in your left ear. (The right channel is transmitted on the Ring, which you wont have in a mono plug.) The Headset Buddy may or may not connect the right channel to the left channel internally, but by the absence of complaints in the Amazon reviews, I'm guessing it does. Given that, you should be good to go with just that one piece. If not, adding a mono-to-stereo adapter will do the trick.
posted by yuwtze at 1:09 PM on March 9

Ordered the stuff up (how have I never shopped at monoprice before?!) and just waiting for it all to get delivered. I'll update once we try it all out. Thanks [fingers crossed/]
posted by cheesyburgercheese at 5:49 PM on March 11 [1 favorite]

sorry so long to get back but basically.... it kinda sort works really poorly.

I think that it's just too much to cobble together and have abandoned hope at making it work. When the new components were all strapped together I was able to hear caller, but my audio was unreliable and pretty much undecipherable.

I tried a different idea of trying to search out a portable phone with a 3.5mm jack - but that beast is elusive, as well. For some reason 2.5mm seems to be standard on home phones.

To be honest after all this work probably the best set up is just to use a VOIP service running thru wifi on a cheap cellphone, ipod, etc... or just use a regular cell phone to begin with.

(Most) of the components won't go to waste as I can still use them for skype so long as I don't mind being tethered to my PC.
posted by cheesyburgercheese at 7:48 AM on May 10