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[Jeff Lelko]

Hi all,

Anyone here have experience with the 3M Peltor MT Series Headsets?  I'm particularly interested if the connector coming out of them is just a standard 1/8" TRRS plug (where I can use a breakout cable to interface with a variety of equipment) or if it's a proprietary size that must be used with their PTT Adapters.  The price on the headsets is quite reasonable but I'm not keen on paying another 250-300 for a PTT Adapter just to use it.  Naturally the manual doesn't give details other than direction to spend the extra cash on the adapter... 

Thanks!
-Jeff

[brian maddox]

Hi all,

Anyone here have experience with the 3M Peltor MT Series Headsets?  I'm particularly interested if the connector coming out of them is just a standard 1/8" TRRS plug (where I can use a breakout cable to interface with a variety of equipment) or if it's a proprietary size that must be used with their PTT Adapters.  The price on the headsets is quite reasonable but I'm not keen on paying another 250-300 for a PTT Adapter just to use it.  Naturally the manual doesn't give details other than direction to spend the extra cash on the adapter... 

Thanks!
-Jeff

Looks like an 1/8" TRRS to me...   

http://multimedia.3m.com/mws/media/678237O/3m-peltor-mt-series-2-way-headsets-communication-solutions.pdf

[Mac Kerr]

Anyone here have experience with the 3M Peltor MT Series Headsets?  I'm particularly interested if the connector coming out of them is just a standard 1/8" TRRS plug (where I can use a breakout cable to interface with a variety of equipment) or if it's a proprietary size that must be used with their PTT Adapters.

It does say it works with most radios, so that implies it is a standard connector. In the photo it looks more like the stubby TRRS connector used on helicopters, but that wouldn't work with any radio, so it won't be that. I would cut off the connector and replace it with a 4 pin XLR that would work directly with comm systems and build adapters to that for any other gear.

Peltor is generally pretty comfortable for a high noise environment headset.

Mac

[brian maddox]

...
In the photo it looks more like the stubby TRRS connector used on helicopters, but that wouldn't work with any radio, so it won't be that. I would cut off the connector and replace it with a 4 pin XLR that would work directly with comm systems and build adapters to that for any other gear.

Peltor is generally pretty comfortable for a high noise environment headset.

Mac

Looking at all the other photos those look kinda stubby to me as well.  They sell a variety of adapters for it which may be why they say it "works with any radio"...

I second Mac's suggestion.  I'd cut that sucker off and put an XLR on it, then make adapters to fit any use case i regularly encounter.

[Henry Cohen]

The plug is a Nexus connector, and is pretty standard fare for high end radio & intercom agnostic headset offerings. David Clark is another headset OEM that uses them regularly. You then buy the adapter interface specific to your application, be it a radio, fire apparatus intercom, aircraft system tank, Humvee, etc. The interface not only provides the cable with the correct connector but may also contain impedance matching, mic preamp, bias voltage circuitry, headphone amp and battery. In the cast of a two-way radio, the interface also contains the PTT switch.

[Jeff Lelko]

The plug is a Nexus connector...

Perfect, that was the piece of the puzzle I was missing.  I can definitely see the benefit of chopping off the plug and soldering my own on, but I'd rather (and will) do that to a short extension cable so that I don't modify the headset itself, just in case I ever wanted to sell it.  I just needed the right phrase to find what I was looking for!

Peltor is generally pretty comfortable for a high noise environment headset.

I'm glad to hear that you like them Mac.  They're not cheap but seem to be pretty standard issue for field applications that need comm on top of standard ear protection.  These will be put to use for Class B pyro jobs which can get quite loud down on the firing line. 

Thanks for the help with this!  I'd hate to buy a few of these just to realize I can't use them as intended! 

[brian maddox]

Perfect, that was the piece of the puzzle I was missing.  I can definitely see the benefit of chopping off the plug and soldering my own on, but I'd rather (and will) do that to a short extension cable so that I don't modify the headset itself, just in case I ever wanted to sell it.  I just needed the right phrase to find what I was looking for!

I learned a new connector today.  yay me.

Here's what you would need to make the extension cable...

http://www.skygeek.com/nexus-tj-102-in-line-microphone-jack.html

[Scott Holtzman]

I learned a new connector today.  yay me.

Here's what you would need to make the extension cable...

http://www.skygeek.com/nexus-tj-102-in-line-microphone-jack.html

In airplane world we call those U174 connectors.  Bose is one of the most insane vendors with the adapters for their ANR headset tilting the scales at $275.00

I had a chance to try out the AKG ANR headsets at a trade show.  They are by far the most comfortable with excellent noise cancellation.

[Jeff Lelko]

Thanks Brian and Scott.  After rooming with three pilots back in college I caught on pretty quickly that anything aviation related is usually pretty expensive.  Even as an engineer of the aerospace variety, I get why anything related to a life safety situation needs to be held to a much higher reliability standard and as such the cost will increase accordingly.  Even the few bits of fire fighting equipment that I own are very costly for what they do.  That said, I still don't want to spend a few hundred dollars on a cable/adapter that likely cost Bose/3M/etc. a few bucks to make... 

What attracted me to this specific headset is that a variant is available for use with a hardhat.  I've tried headsets with the band behind the head instead of on top, but between the hardhat, eye protection, and occasional Nomex hood I'm wearing it was just too much stuff on my head and it wouldn't stay put!  I think these will work out much better.  Thanks again!

[Lyle Williams]

I think the U174 and friends are much bigger connectors than this one.

[Jeff Lelko]

I think the U174 and friends are much bigger connectors than this one.

Hi Lyle, can you explain what you mean?  I haven't placed an order yet but need to sometime this week.  Thanks!

[Art Welter]

Hi Lyle, can you explain what you mean?  I haven't placed an order yet but need to sometime this week.  Thanks!

Jeff,
I agree with Lyle.
The U-174/U or Nexus TP-120 are a bit larger than 1/4", .281" to be exact, while the photo of the headset looks to be a plug more near to a 1/8" diameter. If you look up the specifications of the radios the headset(s) work with directly, it should give the type of connector used.

Good luck- I recall spending more on adapters to get a PTT mic connector working with a radio for my (former) ultralight trike than I spent for the radio. I have since sold the trike and radio, but retained the adapter.
Just checked to see if the adapter was the same as the Peltor connector, but it was not.

Art

[Jeff Lelko]

Jeff,
I agree with Lyle.
The U-174/U or Nexus TP-120 are a bit larger than 1/4", .281" to be exact, while the photo of the headset looks to be a plug more near to a 1/8" diameter. If you look up the specifications of the radios the headset(s) work with directly, it should give the type of connector used.

Good luck- I recall spending more on adapters to get a PTT mic connector working with a radio for my (former) ultralight trike than I spent for the radio. I have since sold the trike and radio, but retained the adapter.
Just checked to see if the adapter was the same as the Peltor connector, but it was not.

Art

Thanks Art (and Lyle).  This is what kept throwing me off when I was watching product videos on this.  It looked bigger than an 1/8th inch, but not knowing what a Nexus Connector was I couldn't find any clues as to the exact size.  I might try calling the product support line tomorrow just to verify before I buy anything.

[Lyle Williams]

The big TRRS plugs also have military and civilian variants that look so similar but aren't.

[Lyle Williams]

Oh, and I have a listen-only (no boom mic) variant of the Peltor MT.  Good sound isolation but not fabulous audio.

[Jeff Lelko]

Okay, so here's an update.  The headset arrived and the plug is in fact a U174 (or Nexus TP-120...I'm not able to tell the difference, if any).  Just to see what the sound quality is like I rigged up a cable to attach this to the basic 1/8" output from my laptop - no dice.  The audio is very, very quiet to the point that if it weren't for the sound isolation the headset provides I wouldn't be able to hear it at all.  Doing some preliminary searching, my guess is that there's an impedance mismatch.  The headset doesn't appear to need any batteries to work either.  The label on the box says "230ohm dynamic mic J11 helmet attachment".  Does that mean anything to anyone and if so, what else do I need to buy to get these working?  Thanks!

[Art Welter]

Okay, so here's an update.  The headset arrived and the plug is in fact a U174 (or Nexus TP-120...I'm not able to tell the difference, if any).  Just to see what the sound quality is like I rigged up a cable to attach this to the basic 1/8" output from my laptop - no dice.  The audio is very, very quiet to the point that if it weren't for the sound isolation the headset provides I wouldn't be able to hear it at all.  Doing some preliminary searching, my guess is that there's an impedance mismatch.  The headset doesn't appear to need any batteries to work either.  The label on the box says "230ohm dynamic mic J11 helmet attachment".  Does that mean anything to anyone and if so, what else do I need to buy to get these working?  Thanks!

Jeff,


IIRC, the mic and ears are separate pairs of the four conductors.

A 230 ohm dynamic mic is a "low impedance" mic with a moving coil- no phantom power required, simply connect the mic "+" and "-"  to whatever input you are using.

The extremely low level headphone output sounds like it may be bleed through, headphone output connected to the wrong plug terminals. You should be able to read an impedance anywhere from around 8 to 100 ohms on the ear transducers, and if you do a "click test" with a 1.5 volt battery between the  "+" and "-" you should hear a fairly loud click.

Give me a call if you have any questions.

Art

[Jeff Lelko]

Thanks Art, I appreciate the reply!  So based on your recommendation I explored a bit more with my multimeter and the connector going into the headset is not wired in the "industry standard" pinout.  I confirmed this with the folks at Peltor today, and instead of the more common Pin 1-Mic+, 2-Speaker+, 3-Mic-, 4-Speaker-, it's wired so that Pin 1-Mic-, 2-Mic+, 3-Speaker+, 4-Speaker-.  Once I rearranged the cables on my adapter I got noise out of the phones!  Interestingly, the resistance across the mic pins is 248ohm and across the speaker pins is 118 ohm.  I popped open one of the ear cups and in fact each speaker is 230 ohms, given away by the "Peltor HTS-230" marking on the driver.  They're wired in parallel, which explains the 118 ohm reading at the connector.  They seem to work well enough as is, though I might swap out the drivers for a more common lower impedance.  They'd only be $15 and the audio quality I'm sure will be much better.  It'd also be cheaper than an impedance adapter...  So many new things to learn!  Thanks again!

[Art Welter]

Thanks Art, I appreciate the reply!    I popped open one of the ear cups and in fact each speaker is 230 ohms, given away by the "Peltor HTS-230" marking on the driver.  They're wired in parallel, which explains the 118 ohm reading at the connector.  They seem to work well enough as is, though I might swap out the drivers for a more common lower impedance.  They'd only be $15 and the audio quality I'm sure will be much better.  It'd also be cheaper than an impedance adapter...  So many new things to learn!  Thanks again!

Jeff,

Glad you got it going, "when in doubt, ohm it out" ;^).
The relatively high ear transducer impedance may also be indicative of limited bandwidth and high sensitivity, good for speech, probably not "high-fi", but with mortars blowing at 160 dB the original transducers may still be the way to go for clear communication.

If you would like, you could do an A/B test between them and my GK Ultraphones, which are Sony MDR-7506 drivers in Peltor muffs. The 7506 transducers would be more than $15.00, Sony parts individually seem to add up to considerably more than the full unit cost. They are about the most sensitive (loudest) full-range headphone transducers I have experienced, other than my neighbor's Dr. Dre knockoffs that can be heard above traffic from 30' away when he walks by.
Ouch.

Cheers,

Art

[Jeff Lelko]

I think you hit the nail on the head there - giving it another listen the frequency response of these drivers is clearly matched for speech - or at least that's what my ears seem to tell me.  I agree that this may not be a bad thing, especially in high-noise environments.  I'll certainly take you up on the offer to audition the Sony drivers, though it'll probably have to be after the Fourth.  I'll PM you from here, but I really appreciate all the help from you and the others! 

[ProSoundWeb Community]