[Culverin]

well, the title says it all.
why the heck do IEMs have such low impedance?

though i'm a relative newbie here. from what i've picked up, if you have higher impedance, then your source does not have to as "clean". It is because IEMs have such a ridiculously low impedance that many/most DAPs hiss with them right? And that when you add a volume control or inline volume attenuator (same thing? but different from electronics standpoint right?), this colors the music and takes away from the original.

So then what is the point? The equipment that stage musicians use to receive the signals can't possibly be perfectly crystal clear since they are wireless right? so wouldn't they too benefit from IEMs that are slightly higher in impedance, thus a cleaner output?

 

[ckhirnigs113]

I heartily agree. I hate hiss, and it seems logical to raise the impedance. -CK

 

[kramer5150]

I've always wondered this too... So many of us here suffer from hiss and noise... what kind of OP-amp circuits are in those wireless belt-packs used by gigging musicians? Surely they can't be as hissy as some of the worst amps I have heard... or are they?

I think low impedance balanced armatures are carry over from the hearing-aid industry. Where, they use small watch batteries in a very low voltage amp circuit.

My dad has a tiny hearing aid, no larger than a UE-10.... its got a mic, volume knob and a small amp inside. So, they are designed to run on miniscule amounts of power.

UE and Shure use various knowles armatures....
http://www.knowlesacoustics.com/know...category_id=30

 

[swt61]

My guess is because their average customer wants to play them straight from a DAP without an amp. We're not the majority consumers here, you must remember that.

 

[kuden]

Quote:

Originally Posted by swt61 /img/forum/go_quote.gif My guess is because their average customer wants to play them straight from a DAP without an amp. We're not the majority consumers here, you must remember that.

i think he means that for example if you buy an E500 and as an average customer would want to play them straight from a dap , you'll get hiss . though i believe that's got somewhat more to do with sensitivity , the shure for example got 36ohm impedance and grados got 32ohm

 

[Febs]

Quote:

Originally Posted by kramer5150 /img/forum/go_quote.gif I've always wondered this too... So many of us here suffer from hiss and noise... what kind of OP-amp circuits are in those wireless belt-packs used by gigging musicians? Surely they can't be as hissy as some of the worst amps I have heard... or are they?

Bear in mind that musicians using wireless systems are doing so while performing in a situation where the ambient background level is probably in the range of 100-115 dB. Though the IEMs provide some isolation, the hiss would have to be pretty loud to be noticeable over the background. I've never noticed any hiss in my Shure wireless IEM system. That does not necessarily mean it's not there, but if it is there, it's not loud enough to be an issue for me.

 

[majkel]

The answer is simple. IEMs are intended for portable devices which have low voltage supplies. For higher impedances you need more voltage to deliver the same power to the driver. On the other hand - who uses IEMs in silent environments? Wherever is loud, hiss is inaudible so this is not a problem.

 

[shigzeo]

it still is a problem. i cannot listen to um2 with meizu m6 or ipod shuffle whilst on the bus as it hisses so much. the bus buy golly is quite loud - the major reason i purchased canal phones and then iems. i think the stage monitor answer was the best yet, but ask westone why their new 3 - designed for music listening not stage performances is still 27 ohm? and senstive as rot.

iem manufacturers could take down the sensitivity and still have excellent sounding phones for portables. remember that most dap portables outside the sony, kenwood and all md players have powerful inboard amplifiers that will do well even with loads of 40ohm+ - a reason that the q-jay is intriguing.

 

[apnk]

Quote:

Originally Posted by majkel /img/forum/go_quote.gif The answer is simple. IEMs are intended for portable devices which have low voltage supplies. For higher impedances you need more voltage to deliver the same power to the driver. On the other hand - who uses IEMs in silent environments? Wherever is loud, hiss is inaudible so this is not a problem.

I don't think so. I had the Etymotic ER4p's and they are 27ohm and they dont hiss with a lot of daps, if they do it's very soft. Every dap can power them, it's not like they should make every iem 120ohms then I would agree.


EDIT: Ok I am confused I read shigzeo post above this one and he says that the UM2 is 27ohms just like the ER4p but it hisses??? BTW I agree cause I had the Um2s before.

 

[nfsu]

Quote:

Ok I am confused I read shigzeo post above this one and he says that the UM2 is 27ohms just like the ER4p but it hisse

It might be due to theirs sensivity:
ER4p 106 dB/mW
UM2 119 dB/mW
I think IEMs have low impedence because of they are design to on-stage performance. There no one pays attention to hiss and with low impedence only a little power is needed to drive them, so battery lasts longer.

 

[apnk]

Quote:

Originally Posted by nfsu /img/forum/go_quote.gif It might be due to theirs sensivity: ER4p 106 dB/mW UM2 119 dB/mW I think IEMs have low impedence because of they are design to on-stage performance. There no one pays attention to hiss and with low impedence only a little power is needed to drive them, so battery lasts longer.

Oh duh! Thanks for the info, I forgot about that.

 

[PetCed]

Still the hiss is not from the IEM, it's from the noisy source. MEIZU M6 and iPods has a bad S/N ratio and therefore you get a lot more hiss with sensitive IEMs with these players.

 

[Culverin]

Quote:

Originally Posted by PetCed /img/forum/go_quote.gif Still the hiss is not from the IEM, it's from the noisy source. MEIZU M6 and iPods has a bad S/N ratio and therefore you get a lot more hiss with sensitive IEMs with these players.

yes, but that's my point.
how clean can a stage pack that receives wireless signals be?
and even regular earbuds don't hiss. and they only have slightly more impedance.

the only thing that makes sense to me so far is kramer's comment on the drivers/armatures being a leftover from making hearing aids. but now there are enough IEMs that surely somebody would make a slightly higher impedance model that won't hiss. isn't the principal the same as why there are 600 ohm DT880/990's?

 

[nfsu]

I think that's why Shure inculdes level attenuator to higher models of their IEMs.

 

[PetCed]

Quote:

Originally Posted by Culverin /img/forum/go_quote.gif yes, but that's my point. how clean can a stage pack that receives wireless signals be? and even regular earbuds don't hiss. and they only have slightly more impedance. the only thing that makes sense to me so far is kramer's comment on the drivers/armatures being a leftover from making hearing aids. but now there are enough IEMs that surely somebody would make a slightly higher impedance model that won't hiss. isn't the principal the same as why there are 600 ohm DT880/990's?

Changing the also changes the sound charactistics of the speaker. It's an impedance you'll change and impedance reacts on frequency.