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Author Topic: 3M Peltor MT Series Headsets - Anyone with Experience?  (Read 4778 times)

Jeff Lelko

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #10 on: May 21, 2017, 04:05:25 pm »

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!
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Art Welter

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #11 on: May 22, 2017, 11:36:30 am »

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
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Jeff Lelko

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #12 on: May 22, 2017, 05:01:01 pm »

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.
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Lyle Williams

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #13 on: May 22, 2017, 05:12:02 pm »

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

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #14 on: May 22, 2017, 05:14:50 pm »

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

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #15 on: June 10, 2017, 07:20:57 pm »

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!
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Art Welter

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #16 on: June 12, 2017, 11:45:34 am »

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

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Jeff Lelko

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #17 on: June 13, 2017, 09:39:26 pm »

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!
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Art Welter

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #18 on: June 13, 2017, 10:58:23 pm »

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
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Jeff Lelko

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Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #19 on: June 14, 2017, 06:40:57 pm »

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! 
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ProSoundWeb Community

Re: 3M Peltor MT Series Headsets - Anyone with Experience?
« Reply #19 on: June 14, 2017, 06:40:57 pm »


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