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Topic: Can IEMs be as good as full sized headphones? (Read 304407 times) previous topic - next topic
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Can IEMs be as good as full sized headphones?

Reply #75 –
Quote
Consider this. One marketing report I've seen suggested that the market for add-on loudspeaker/amplifier products for iPods was larger than the entire home A/V component market.


If you combine this wiith my experience with cheap earbuds in the 80s and early-mid 90s, you can understand my skepticism of IEMs.  If you combine marketing, chance for profit, and lack of transparency about technical matters, and consumer ignorance and strange expectation, you end up with an industry where half cooked products are sold for super cooked prices and people assume there is some engineering (versus marketing) reason for this.

However, my opinion is changing.  I recently purchased a Klipsch S4.  I do not like it at all (far too much bass for my taste), but I sense a great potential with IEMS.

Arnold - You can help solve a mystery in this thread.  If you look at some of the later posts you'll see a bunch of RMAA measurements for the JH13 Pro IEM.  Why are we seeing the non-flat FR graphs, even with dedicated headphone amplifiers?  This seems to be something that is localized to this specific IEM.  What is going on?  Is it because it has a passive crossover?
Quote
source --> amp --> y split --> input of measuring device/headphones.


Yes, this is correct.  The Y splitter comes after the amp, not between the sound and amp.

Quote
A hi-end IEM like the JH13Pro will be a great upgrade simply because it doesn't need all the dedicated equipment that a full-size needs in order to sound good, or be driven properly.


Quote
If you ever get the chance, I'd be interested in finding out how the iQube performs with the JH13. It's a very different circuit design, which I'm cautiously optimistic won't have the same problems with the JH13 as other amps. I'd also be interested in hearing about the ALO Rx. (And, you know, every other amp. )


WHOA!  Let's not forget we are on Hydrogen Audio, a forum which explicitly states that claims need to be supported by controlled (blind, volume matched) tests and/or measurements.  Most of the claims of audible differences between, and benefits of, headphone AMPs, DACs, Cables, etc have been made after listening in uncontrolled tests.  All these differences tend to vanish in controlled listening tests.

Whenever people say "X headphone is hard to drive" they are basing such conclusions the faulty data of evaluations made in uncontrolled tests.  The large majority of dynamic (not planar) headphones are not hard to drive and they don't need a special amp or source to shine.  Generally, low impedance headphones are well driven by devices as simple as a IPOD or Sansa Clip.  High impedance headphones MAY need a amp is you are listening to highly dynamic music at high volume levels.  Even then, I suspect a decently made 9V amp should be enough for anything, even up to 600 ohms. 9 volts into 600 ohms is 135mW.  Good luck to your ears at that power level.

If you want to refute this with more examples than the JH-13 Pro measurements, feel free to provide some measurements or controlled listening results.  Even then, there is an explanation for why we are seeing the strange FR of the JH 13 Pro.  I don't think it's simply a matter of "hard to drive."

I'm sorry to be such a stickler about this.  But this is the only audio forum on the net where people are actually skeptical of claims about audio equipment.  I'd like that standard to be remembered and maintained.

Can IEMs be as good as full sized headphones?

Reply #76 –
odigg, I think you misunderstood me.  Since Shigzeo has the JH13 and performs measurements, I was simply asking him to perform measurements on those two amps if he ever had the chance, to find out whether or not they had the same FR problems with the JH13.

Edit:  What I meant by "how they perform with the JH13" was, "how they measure."  I suppose I should've just written that.

Can IEMs be as good as full sized headphones?

Reply #77 –
Quote from: odigg on
Arnold - You can help solve a mystery in this thread.  If you look at some of the later posts you'll see a bunch of RMAA measurements for the JH13 Pro IEM.  Why are we seeing the non-flat FR graphs, even with dedicated headphone amplifiers?  This seems to be something that is localized to this specific IEM.  What is going on?  Is it because it has a passive crossover? )


Measuring IEMs is still controversial, because as far as I know we don't yet really understand what measured FR corresponds to audibly flat response at the eardrums.  Most of the "dummy head" systems I have read about seem to merely imitate the external ear, which makes sense for over the ear headphones, but I don't know how well they imitate the ear canal, not to mention that I believe most of us have wide variations in just how our canals run. 

My IE8's sound "flat" to me, more or less,  with the bass turned all the way up,  and I find no need to equalize their response.  Yet the graphs at Headroom show a 15 db downward slope from 20 hz to 10 Khz.  With the large flange tips they do not sound more than very slightly bass heavy to me.  They do not boom and even deep male voices sound quite natural (except their positioning in the sound field of course).

Some links to actual studies of these matters would be very interesting.  But we should not assume that a measured "flat" response in a magazine equates to an actually neutral sound.

Ed Seedhouse
VA7SDH

Can IEMs be as good as full sized headphones?

Reply #78 –
What we're seeing problems with is the frequency responses of amps when driving the JH13, not the frequency response of the JH13 itself.  For some reason, amps seem to have trouble outputting a flat frequency response when driving the JH13.  The frequency response of the sound produced by the earphones isn't what's being measured.  What's being measured is the signal the amp is outputting.

Can IEMs be as good as full sized headphones?

Reply #79 –
As far as I can comprehend, what shigzeo has discovered is an impedance interaction(impedance bridging) between IEMs and amplifiers:

1. Balanced armatures have very low-Z by their nature. (usually no more than one-digit?)
-> Since input impedance is low, more current is drawn(i.e. current-hungry) from the amplifier where Z is lower. The amplifier(high output-Z) output follows the impedance curve of the BA.

2. You couple 2, 3, or even 6 of these low-Z BATs together with a cross-over network, Z goes up where transducers are joined together; the resulting impedance is extremly non-linear.
-> The amplifier output follows the drastic impedance curve of the IEM, especially if the amplifier has a high output-Z.

Thus if you'd like to drive JH13Pro or any multi-BA transducer IEMs with a close-to-flat amplifier output, you must have an amplifier with the output Z < 0.1 or even lower. Or add a serial resistance adapter to JH13Pro, so that less current is drawn. (adding a serial resistance will raise the input impedance of IEM, lowering the current drawn. However, will raise the ouput-Z of the amplifier as well, underdamping the resonant frequency of the IEM itself)

If anything is wrong with my analysis, you're more than welcome to correct & elaborate it further.


BTW, here's the RMAA result of iRiver H140 with ER-4P(&4S) loaded:


ER-4P has a serial resistor(~20 ohms) inside, so its input impedance would be sufficiently high.(its resonant frequency is intentionally underdamped in order to simulate the ear canal resonance) Since most of DAPs have output Z of less than 10ohms, it wouldn't be so hard to obtain a flat response at their output ends w/ ER-4P.

Can IEMs be as good as full sized headphones?

Reply #80 –
the amp is a measuring device: whether a soundcard, or my Edirol FA66, the unit is a type of amplifier. My measuring device is the FA66

As I stated before

source --> ysplit -->> one to headphones, one to amp or FA66. The advantage of the FA66 is that I can accurately test noise levels whereas the MacBook Pro only tests accurately for frequency response.

Quote from: steaxauce on
Quote from: shigzeo on
Not sure about a specific scientific procedure, but to perform a LOADED test, you must:

source --> y split --> headphones/line to amp.

For UNLOADED:

source --> amp/line


That signal is recorded in an audio application in .wav and sent to RMAA to analyse. Even without RMAA though, after getting used to proper, perfect audio waveforms, you can 'see' the printed information does not match.

If you want a hell of a lot of these tests, anythingbutipod has a huge RMAA loaded test section:
Index of Loaded RMAA tests

Hm, are you sure you wrote that down correctly?  You didn't specify where the measuring device goes.  What I'd think the setup would be for a loaded test is:

source --> amp --> y split --> input of measuring device/headphones.



And for unloaded:

source --> amp --> input of measuring device

If you ever get the chance, I'd be interested in finding out how the iQube performs with the JH13.  It's a very different circuit design, which I'm cautiously optimistic won't have the same problems with the JH13 as other amps.  I'd also be interested in hearing about the ALO Rx. (And, you know, every other amp.  )

Can IEMs be as good as full sized headphones?

Reply #81 –
Good observations. I have noted in earlier tests with the ER4s that the same frequency response does not occur. As you have mentioned, it is likely that is due to the cross over network and a mismatch of Z. Even a dual-balanced armature presents a different load to the amps and as I stated, I have yet to see any amp which isn't negatively affected.

Even adding 75OHM resistance does little to correct the situation, and in the case of certain high-end balanced armature phones, dulls the high frequencies, while for many dynamic phones does little but bring out the bass a bit more since less current is needed and the single ended outputs aren't drained as much.

Quote from: udauda on
As far as I can comprehend, what shigzeo has discovered is an impedance interaction(impedance bridging) between IEMs and amplifiers:

1. Balanced armatures have very low-Z by their nature. (usually no more than one-digit?)
-> Since input impedance is low, more current is drawn(i.e. current-hungry) from the amplifier where Z is lower. The amplifier(high output-Z) output follows the impedance curve of the BA.

2. You couple 2, 3, or even 6 of these low-Z BATs together with a cross-over network, Z goes up where transducers are joined together; the resulting impedance is extremly non-linear.
-> The amplifier output follows the drastic impedance curve of the IEM, especially if the amplifier has a high output-Z.

Thus if you'd like to drive JH13Pro or any multi-BA transducer IEMs with a close-to-flat amplifier output, you must have an amplifier with the output Z < 0.1 or even lower. Or add a serial resistance adapter to JH13Pro, so that less current is drawn. (adding a serial resistance will raise the input impedance of IEM, lowering the current drawn. However, will raise the ouput-Z of the amplifier as well, underdamping the resonant frequency of the IEM itself)

If anything is wrong with my analysis, you're more than welcome to correct & elaborate it further.


BTW, here's the RMAA result of iRiver H140 with ER-4P(&4S) loaded:


ER-4P has a serial resistor(~20 ohms) inside, so its input impedance would be sufficiently high.(its resonant frequency is intentionally underdamped in order to simulate the ear canal resonance) Since most of DAPs have output Z of less than 10ohms, it wouldn't be so hard to obtain a flat response at their output ends w/ ER-4P.

Can IEMs be as good as full sized headphones?

Reply #82 –
Quote
odigg, I think you misunderstood me.

Sorry.  I spent some time on Head-Fi today and probably became overly sensitive to the possibility of wild claims   

Quote from: shigzeo on
As I stated before

source --> ysplit -->> one to headphones, one to amp or FA66. The advantage of the FA66 is that I can accurately test noise levels whereas the MacBook Pro only tests accurately for frequency response.

I'm confused by this.  If you put the y split before the amp then you are changing the signal even before it reaches the amp.  How is this a valid test of the amp?  The headphone load is then on the source, not the amp.  So the amp is only going to amplify the FR deviations by the headphone load on the source.  Many sources have a higher than 0 output impedance so it is expected that the FR will change if you connect the IEM directly to it.

When you tested the Fireye II this should have been your setup

source -> Fireye II -> Y split -> JH13/FA66.

Did you do this?  If not, your measurements of the Fireye II are not valid.  Have I misunderstood what you are doing?

Quote
If anything is wrong with my analysis, you're more than welcome to correct & elaborate it further.

Your analysis is sound.  However, if this is the reason for the non-linear FR then the solution is quite simple.  As you have stated, use a device with a low Z out.  This is the typical output of an opamp, but in the "audiophile" world they've come to see opamps as bad.  So they make complex and expensive solutions without opamps that actually make the amp worse than cheaper, simpler, designs...

If this is the case then the JH 13s are not "hard to drive."  This is actually demonstrated with the RMAA measurements were the IPOD measures better than the dedicated amps.  You just need a device with a low impedance output.  If it were the case that the JH 13s are "hard to drive" then it would perform much worse with the IPOD and improve only with a dedicated amp.  These are not the results of the various RMAA tests.

Can IEMs be as good as full sized headphones?

Reply #83 –
odigg, I know you are only trying to get things straight, but again: source, ysplit, headphones and the opposite line going into the (in your terms) sound measuring tool (Edirol FA66).

As stated from the very beginning, I have been doing this for years with other, better-known colleagues based on reading evidence and experience. And, as you have pointed out yet again, the chain should be set up as I have listed.

Here is another graph:

Output: source (iPod, AMP3, MacBook Pro, Fireye II) feeding (Fireye I, Travagan's Red, Graham Slee Voyager, Heed Canamp)

Ysplit --> one end feeding line in of 'measuring device', another into headphones. For comparison's sake, unloaded tests are also presented.

I don't see how my tests and results could have been misinterpreted so many times, even if we use different language. The results speak for themselves as to the testing chain.

Quote from: odigg on
Quote
odigg, I think you misunderstood me.

Sorry.  I spent some time on Head-Fi today and probably became overly sensitive to the possibility of wild claims   

Quote from: shigzeo on
As I stated before

source --> ysplit -->> one to headphones, one to amp or FA66. The advantage of the FA66 is that I can accurately test noise levels whereas the MacBook Pro only tests accurately for frequency response.

I'm confused by this.  If you put the y split before the amp then you are changing the signal even before it reaches the amp.  How is this a valid test of the amp?  The headphone load is then on the source, not the amp.  So the amp is only going to amplify the FR deviations by the headphone load on the source.  Many sources have a higher than 0 output impedance so it is expected that the FR will change if you connect the IEM directly to it.

When you tested the Fireye II this should have been your setup

source -> Fireye II -> Y split -> JH13/FA66.

Did you do this?  If not, your measurements of the Fireye II are not valid.  Have I misunderstood what you are doing?

Quote
If anything is wrong with my analysis, you're more than welcome to correct & elaborate it further.

Your analysis is sound.  However, if this is the reason for the non-linear FR then the solution is quite simple.  As you have stated, use a device with a low Z out.  This is the typical output of an opamp, but in the "audiophile" world they've come to see opamps as bad.  So they make complex and expensive solutions without opamps that actually make the amp worse than cheaper, simpler, designs...

If this is the case then the JH 13s are not "hard to drive."  This is actually demonstrated with the RMAA measurements were the IPOD measures better than the dedicated amps.  You just need a device with a low impedance output.  If it were the case that the JH 13s are "hard to drive" then it would perform much worse with the IPOD and improve only with a dedicated amp.  These are not the results of the various RMAA tests.

Can IEMs be as good as full sized headphones?

Reply #84 –
Adding serial resistance will not lower the current drawn.  The same current will be drawn, but the voltage will be higher.  The voltage-to-current ratio across the IEM with serial resistance will be higher than the voltage-to-current ratio of just the IEM, so effectively, the amp will have a higher-impedance, lower-sensitivity load, which will make certain amps perform better.  As far as the IEM is concerned however, adding, say, a 70 Ohm serial resistance, while it might lower THD, noise, etc. will effectively make the output impedance of the amp 70 Ohms plus whatever the amp's original output impedance is.  If the IEM's impedance varies widely with frequency, the serial resistance will therefore only skew the frequency response much more.  If you're measuring the effective frequency response of this configuration, your measuring device should be in parallel with the earphones, but in series with the serial resistance; i.e. the Y-splitter should be inserted after the serial resistance in the chain.

Can IEMs be as good as full sized headphones?

Reply #85 –
Shigzeo, the reason people are having trouble understanding your testing procedure is that the language you are using is ambiguous.  You're calling the headphone amplifier your "source" where in audio the word "source" generally designates the CD player/DAC/portable media player/what-have-you, and you're calling your measuring device your "amp."  Sure, it is an amplifier in a sense, but people think you're referring to your headphone amp.  This is what we thought you meant when we read your testing procedure:

"source" such as iPod, MacBook Pro, FA66 analog output, etc. --> Y-splitter --> headphone amplifier in parallel with headphones

Which would be a very odd setup!  I think we are all picturing the same setup, though, which is:

source (as I've defined the word) --> headphone amplifier --> Y-splitter --> FA66 input in parallel with headphones

Can you verify that this is correct?

Can IEMs be as good as full sized headphones?

Reply #86 –
Quote from: steaxauce on
The same current will be drawn, but the voltage will be higher. The voltage-to-current ratio across the IEM with serial resistance will be higher than the voltage-to-current ratio of just the IEM, so effectively, the amp will have a higher-impedance, lower-sensitivity load, which will make certain amps perform better.


I certainly have missed that. Appreciate your input.

Can IEMs be as good as full sized headphones?

Reply #87 –
Well, looking back, I will have to agree that my language was ambiguous. Even so, the same would be true however if I fed the entire thing into a preamp - the frequency response wouldn't change.

I began by saying source merely because the Fireye II is a source, not the macbook. It is a DAC supplying all audio output for the MacBook Pro. But later, I understand why I was misunderstood and am sorry for the confusion. In any case it is as you say:

source (as I've defined the word) --> headphone amplifier --> Y-splitter --> FA66 input in parallel with headphones
or
source (as I've defined the word) --> headphone amplifier --> Y-splitter --> FA66 input for unloaded tests.

Quote from: steaxauce on
Shigzeo, the reason people are having trouble understanding your testing procedure is that the language you are using is ambiguous.  You're calling the headphone amplifier your "source" where in audio the word "source" generally designates the CD player/DAC/portable media player/what-have-you, and you're calling your measuring device your "amp."  Sure, it is an amplifier in a sense, but people think you're referring to your headphone amp.  This is what we thought you meant when we read your testing procedure:

"source" such as iPod, MacBook Pro, FA66 analog output, etc. --> Y-splitter --> headphone amplifier in parallel with headphones

Which would be a very odd setup!  I think we are all picturing the same setup, though, which is:

source (as I've defined the word) --> headphone amplifier --> Y-splitter --> FA66 input in parallel with headphones

Can you verify that this is correct?

Can IEMs be as good as full sized headphones?

Reply #88 –
The only problem with all this is that the JH13 is far from the only headphone with extreme variations in impedance, and yet the others don't have this problem with the amps tested.

Can IEMs be as good as full sized headphones?

Reply #89 –
Quote from: steaxauce on
The only problem with all this is that the JH13 is far from the only headphone with extreme variations in impedance, and yet the others don't have this problem with the amps tested.


Pardon me, but what 'others' do you refer to? Other headphones? Amps? I am very interested in hearing an amp which doesn't fluctuate when driving the JH13Pro - very interested.

Can IEMs be as good as full sized headphones?

Reply #90 –
Quote from: Ed Seedhouse on
Quote from: odigg on
Arnold - You can help solve a mystery in this thread.  If you look at some of the later posts you'll see a bunch of RMAA measurements for the JH13 Pro IEM.  Why are we seeing the non-flat FR graphs, even with dedicated headphone amplifiers?


I believe that is is pretty much standard for headphone amps to provide a moderate source impedance, with 16-32 ohms being a common range. If you load an amplfiier with a source impedance like this  with an earphone that presents a non-uniform load impedance, then of course the response is going to be non-flat.

I'm not sure that this is even a problem.

Quote
This seems to be something that is localized to this specific IEM.  What is going on?  Is it because it has a passive crossover? )



I might imagine that a headphone with a crossover presents a more complex load than one that does not. We see this with loudspeakers. Again, it is not necessarily a problem.


Quote
Measuring IEMs is still controversial, because as far as I know we don't yet really understand what measured FR corresponds to audibly flat response at the eardrums.  Most of the "dummy head" systems I have read about seem to merely imitate the external ear, which makes sense for over the ear headphones, but I don't know how well they imitate the ear canal, not to mention that I believe most of us have wide variations in just how our canals run.


In my travels I found a paper that was provided to people who fit hearing aid earpieces. As I've mentioned before, IEMs are very similar, and may even contain the same components.

The interesting thing about this paper is that it described how to modify various common components of hearing aid earpieces and earmolds so as to aptimize their frequency response for various listeners. There was a strong implication that ear canals varied quite a bit and this affected the perceived frequency response of the earpiece. Apparently there are standard procedures for measuring the user's perception of the frequency response of a hearing aid - perhaps by repeating hearing frequency sensitivity tests.

These days hearing aids seem to include very sophisticated DSPs, and this sort of mechanical modification may no longer be necessary or practiced. But my point is that this paper is evidence that people's ear canals and subtle details of the earpiece can signficiantly affect frequency response.

I know that the human brain is capable of making very strong adaptations to optimize sound quality and intelligitiblity. For example, its not unusual for me to sit down to listen, turn the TV or stereo up at first, and then turn it down as I my brain unconsciously adapts to it.

I think that our natural goal for music reproducers is sound quality that we perceive as natural sound. As our current listening situation becomes more different from being in a familiar and/or preferred music listening situation, the more unnatural it may seem. 

Since headphones short-circuit much of our usual daily listening context, it is more likely that they will sound unnatural, particularly until we "acclimatize our ears" Of course our ears may change very little during this process, its our brain that is adapting. IEMs short-circuit even more of your usual daily listening context, so it is likely that they will seem even more unnatural to us.

An anecdote: I just went on a 8 day camping/hiking/canoeing trip with my wife. I delayed finding my portable CD player in the house. At the last minute I couldn't find it. So, I ran over to RS  (a block away) and picked up a cheap but cheerful protable FM radio. I went upstairs to find my IEM collection, and picked something that I was familiar with. When I got out on the road, I found that one channel of my old reliable IEMs was dead. By then I was well away from urban centers where I would have my choice of good IEMs to purchase. I did find a RS store, and had to pick from their limited selection. Of course the new ones sounded pretty weird. However, after a week out in the woods of listening to them an hour or more a day, they sounded pretty natural.




Can IEMs be as good as full sized headphones?

Reply #91 –
shigzeo - I understand your test setup now.  I have no complaints about your setup.  Your previous diagram looked as if you had put the headphone before the amp.

Quote from: shigzeo on
Pardon me, but what 'others' do you refer to? Other headphones? Amps? I am very interested in hearing an amp which doesn't fluctuate when driving the JH13Pro - very interested.


I think steaxauce is trying to say that there are many headphones with fluctuating impedance.  If you use a low Z output amp the amp measures with a flat FR on a loaded test.  So there is one of two (or both) things occurring in your tests.

1.  The amps you are testing do not have near 0 output impedance.
2.  There is something very different about the JH13 Pro.

Do you have access to an amp you know has a near 0 output impedance?  Just about every (if not every) amp from AMB Labs is like this.  A number of solid state desktop amps are like this as well.  What amps do you have access to.  In one of your graphs is says "red."  Is this the Travagan's red?

Of course, manufacturers of such amps may not provide specifications or may provide selective (e.g. 0.1 ohm at 1khz) specifications.

Also, in a previous message I said a 9V amp should be enough to drive a 600 ohm headphone.  I fixed up my cmoy this morning and tested it with a 600 ohm AKG 240 DF.  This is a very inefficient headphone.  At very loud volumes (to me) I heard clipping.  So my previous statement is incorrect.

I'm not sure if this would happen with a Mini 3 as that amp can swing very close to the rail voltage.  The Cmoy is a very basic design and so maybe a 12 volt supply would do it.  I'd have to test it to be sure.

Can IEMs be as good as full sized headphones?

Reply #92 –
Quote from: shigzeo on
Pardon me, but what 'others' do you refer to? Other headphones? Amps? I am very interested in hearing an amp which doesn't fluctuate when driving the JH13Pro - very interested.

I was just referring to other headphones.  You said earlier on that the JH13 was about the only headphone you've tested that does this, and there are many headphones with wide impedance variations, which makes me think that there may be something odd about the JH13.

The lower the average impedance of the headphone, the more relevant these wide impedance variations become.

Can IEMs be as good as full sized headphones?

Reply #93 –
Shigzeo, have you measured any other earphones that we know have wide variations in impedance, so we can confirm that there is something different going on with the JH13?  Just for reference, headphone.com has impedance graphs of just about every headphone they sell, and many they don't.

Can IEMs be as good as full sized headphones?

Reply #94 –
Fuchinobe-san, whom I mentioned previously to reference W3 measurements, has actually measured the output Z of well-known DAPs as well:
Its output-Z is both relatively high & non-linear.


Quote
You said earlier on that the JH13 was about the only headphone you've tested that does this, and there are many headphones with wide impedance variations, which makes me think that there may be something odd about the JH13 ... Shigzeo, have you measured any other earphones that we know have wide variations in impedance, so we can confirm that there is something different going on with the JH13?

If I am remembering correctly, Triple.Fi 10 Pro from Ultimate Ears also shows a quite similar behavior. Dear Shigzeo, I want to see more RMAA measurements with different IEMs or headphones loaded, too.

Can IEMs be as good as full sized headphones?

Reply #95 –
I went through the IEMs tested on touchmyapps.com, and all of the ones I could find impedance graphs for have pretty much flat impedance.  If another IEM with widely varied impedance has been tested with those amps and has been observed to not have the same problems, something other than the 13's varied impedance is probably causing this, and I'd be interested in knowing about it.  In the mean time, since I don't know of any other mechanism that could cause this, I'm going to say that it's most likely that the Firestone amps have high output impedance and the JH13's impedance is widely varied, and that's the cause.

Can IEMs be as good as full sized headphones?

Reply #96 –
Quote from: steaxauce on
I went through the IEMs tested on touchmyapps.com, and all of the ones I could find impedance graphs for have pretty much flat impedance.  If another IEM with widely varied impedance has been tested with those amps and has been observed to not have the same problems, something other than the 13's varied impedance is probably causing this, and I'd be interested in knowing about it.  In the mean time, since I don't know of any other mechanism that could cause this, I'm going to say that it's most likely that the Firestone amps have high output impedance and the JH13's impedance is widely varied, and that's the cause.


I noticed nothing strange with most of the headphones, but indeed, cross-over laden balanced armatures do the same thing: each and every one have strange results. It isn't as bad with a dual cross over, not all the time, but with more than 2, the impedance fluctuations go mad. I will publish the results later, but now I have a few other reviews to complete which are... games... haha.

Can IEMs be as good as full sized headphones?

Reply #97 –
One point to note is that the impedance of these multi-BA phones (regardless of rating) probably actually dips quite low.  If you look at the UE11 graph the impedance starts out at 10 ohms!  It seems the 18 ohm UE11 rating is quite a fantasy...

I've tested devices with some variance over the impedance range where the lowest impedance is 25 ohms.  Even with a player like a Sansa Clip, they measure flat.

I think every headphone/IEMs has some variance over the impedance range, even if the variances are quite small.  Even so, some players can drive a 16 ohm load without issue.

16 Ohm comparison by dfkt.  Sony devices are also supposed to be able to drive low impedance headphones with a flat FR as well.

However, if you look at output impedance  of the PMPs udauda posted, the UE11s 10 ohms is quite near the output impedance of some of these devices.  This would explain a lot.

If shigzeo was in the USA I would build or buy a Mini 3 and lend it to him for testing.

Also, the Fireye II specifications say it is rated for headphones 32-600 ohms.

I've emailed Jerry Harvey of JH Audio for impedance specifications for the JH 13 Pro.  I hope he replies.

Can IEMs be as good as full sized headphones?

Reply #98 –
Quote from: shigzeo on
Quote from: steaxauce on
I went through the IEMs tested on touchmyapps.com, and all of the ones I could find impedance graphs for have pretty much flat impedance.  If another IEM with widely varied impedance has been tested with those amps and has been observed to not have the same problems, something other than the 13's varied impedance is probably causing this, and I'd be interested in knowing about it.  In the mean time, since I don't know of any other mechanism that could cause this, I'm going to say that it's most likely that the Firestone amps have high output impedance and the JH13's impedance is widely varied, and that's the cause.


I noticed nothing strange with most of the headphones, but indeed, cross-over laden balanced armatures do the same thing: each and every one have strange results. It isn't as bad with a dual cross over, not all the time, but with more than 2, the impedance fluctuations go mad. I will publish the results later, but now I have a few other reviews to complete which are... games... haha.

Then it is indeed the impedance issue.  All you need for flat frequency response, then, is an amp with close-to-zero output impedance, which is not hard to find or expensive at all.  You should get one!

Can IEMs be as good as full sized headphones?

Reply #99 –
I have had a few Sony models and it is true, the models from 2007-present have very little if any problems with frequency response even running low OHM phones. However, my iPod touch, subjected to the same tests with the same tests beats the pants off the Sony overall. 100% flat, lower distortion, wider stereo separation. That is why I was surprised to see the touch thrashed by the JH13Pro.

I have added the FitEars Private 333 to the mix and it ... has another interesting, but not as strange frequency dip. It loses a big chunk of the spectrum from about 8 or 10k to 13k, then comes back strong. The difference is that the FitEars 333 sustains the majority of its signal along 0 decibels rather than way under or way over. I don't have the tests with me now, but I can get a clip again and prove that it tests actually worse than the iPod touch for about 90% of the dynamic phones on the market. Similar to the touch and Sony models, however, it gets spanked by the JH13Pro and the FitEars Private 333.

The 333 is a 3 receiver, 3 driver, 3 crossover machine. The same FitEar company has a prototype 668 with (don't quote me) 6 receivers, 6 crossovers, 8 drivers in it. That, I am sure, will destroy any DAP, even the venerable iPod shuffle 1G (which is remarkable - manages to drive 84 decibels of stereo separation with the FitEars Private 333! and 94 decibels S/N!).

But, after all this testing in the last few years, I have found that the most 'pleasing' sound (noted by comments at headfi) earphones, often drive a hell of a lot of distortion from sources and amps. It isn't always the case, but heavily distorting sources tend to sound softer and in headfi terms, 'musical'. I don't really care for this or that, but it is interesting that people rant about distortion, trashing it, but in the end, they listen to phones which cause heaps of distortion at the source/amp level and love them.

My tests will be published in December and discussed at TMA's small forum (not up yet: should be a good place to host the files too because they will be easy to get at all in the same place).

Cheers.

Quote from: odigg on
One point to note is that the impedance of these multi-BA phones (regardless of rating) probably actually dips quite low.  If you look at the UE11 graph the impedance starts out at 10 ohms!  It seems the 18 ohm UE11 rating is quite a fantasy...

I've tested devices with some variance over the impedance range where the lowest impedance is 25 ohms.  Even with a player like a Sansa Clip, they measure flat.

I think every headphone/IEMs has some variance over the impedance range, even if the variances are quite small.  Even so, some players can drive a 16 ohm load without issue.

16 Ohm comparison by dfkt.  Sony devices are also supposed to be able to drive low impedance headphones with a flat FR as well.

However, if you look at output impedance  of the PMPs udauda posted, the UE11s 10 ohms is quite near the output impedance of some of these devices.  This would explain a lot.

If shigzeo was in the USA I would build or buy a Mini 3 and lend it to him for testing.

Also, the Fireye II specifications say it is rated for headphones 32-600 ohms.

I've emailed Jerry Harvey of JH Audio for impedance specifications for the JH 13 Pro.  I hope he replies.