Skip to main content

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Can IEMs be as good as full sized headphones? (Read 303767 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Can IEMs be as good as full sized headphones?

Reply #50
Thank you for quoting my review of the JH13Pro below. They are excellent sounding earphones, but for the price, I feel don't warrant the missteps in build quality. Do they sound good? Absolutely. But, one thing that must be taken into account is that Jerry Harvey, a pro though he is, is first of all, marketing a product. It may be true that the drivers themselves, matched up and paired do produce greater headroom and can make for less distortion. But, most people don't have the equipment which will drive these phones without distortion.

I don't have the distortion graphs set up yet, but am working on them. My tests have been done at the amplifier level simply because I don't have the proper equipment (Yet) to produce accurate representations of the sound from the transducers themselves. The JH13Pro induces a heavier load than any earphone I have seen, ever. No dedicated amp I have used with it produces anything even near optimal sound reproduction. At best, there is a massive bass roll off and always, treble spiking. Also, all amps (internal from daps to external, dedicated amps) are generating a lot of thd and imd distortion in comparison to ANY other headphone of any type and calibre.

While I think they are remarkable headphones, I wager that very few, if any have heard them optimally paired and run. My equipment is humble by some regards, but much better than quite a few people's and it gets walloped every time by this headphone.

Just for a reference, the USB/DAC/HEADPHONE AMP review below shows some results of the JH13Pro. Even though it is a cheap amp, its results fall in line with every single dedicated amp I have yet used with the JH13Pro.

Fireye II DAC/USB/HEADPHONE AMP in Reivew - Full Metal Amp -- TouchMyApps

Well, I happened to come across the statement Jerry Harvey made about the advantage to using two drivers per frequency band in his JH-13 Pro.  Here it is:

"The balanced armatures when coupled lower distortion. They also are working much more efficiently because of 2 drivers doing the work. Each driver does half the work which increases headroom. A concert PA system like a L Acoustics line array will have roughly 64 15" speakers,128 8" speakers and 32 2" high drivers hanging in the air. Also 64 18" sub bass speakers. In order to create headroom which is gain before distortion you need the work load distributed across multiple components. Yes you can distort all of the components but the sheer gain to do so would be at the threshold of pain. Headroom equals clean audio when operated at a normal spl. Jerry"

Also, you may be interested in checking out this list of head-fier impressions.  It seems unanimous that the JH-13 is at least in the league of the top ($1000+) full-sized headphones.

http://www.head-fi.org/forums/5911775-post3001.html

This seems beyond FOTM.  Several long-time head-fiers have sold off their huge collections of gear because the 13 has made everything else moot.  Even if you think everyone on head-fi is crazy, it's tough to deny that there's got to be something to all this.  Also, check out the review on touchmyapps.com, below.

http://www.touchmyapps.com/2009/09/30/jerr...-for-your-ears/


Can IEMs be as good as full sized headphones?

Reply #51
This seems beyond FOTM.  Several long-time head-fiers have sold off their huge collections of gear because the 13 has made everything else moot.  Even if you think everyone on head-fi is crazy, it's tough to deny that there's got to be something to all this.


No, it's really not all that hard to deny for people who have been on Head-Fi for a while.  Back in the start of 2008 people were raving about the AKG K701.  Anybody, and I do mean anybody, who made a negative comment about the K701 was greeted with a "you need a proper amp" answer and sure enough the people who purchased all this expensive eqiupment turned around and said the K701 was perfect.  A year later if you mention the K701 people start bashing it.

<edit>

My point it, when reviews of some product on Head-Fi are almost universally positive I always become skeptical.  This becomes even more pertinent to me when it's a very expensive product that only a select few individuals can afford.  There is a ton of curious behavior when it comes to negative opinions of expensive product on Head-Fi.  A lot of times people will simply refuse to accept that somebody can see a product as negative and any negative opinion will be overwhelmed by people who want to defend that expensive product.  I know (via private messages) of people who just have stopped posting negative comments on Head-Fi because they don't care to deal with the hostility towards them and their comments.
</edit>

I am very curious about the JH13Pro though even though it's way beyond what I want to pay for a headphone.

As for the JH13Pro being hard to drive, I don't see why it should be. A 28 ohm output impedance is going to lead to some coupling capacitor induced bass rolloff.  However, after looking at those graphs shigzeo has posted, I wonder if the impedance of the JH13PRO varies a lot over the FR.  Coupled with a headphone jack with a higher than 0 impedance out, this can lead to all sorts of changes over the FR.

Is there something else going on here that I'm not aware of that leads to all these FR changes?  shigzeo - do you have a solid state desktop amp on which you can do a loaded RMAA test?  Something with a near 0 ohm output impedance?

Even test it with a CMOY as that has a near 0 output impedance

Can IEMs be as good as full sized headphones?

Reply #52
Thanks for posting, shigzeo.  Your JH13 review was very well written.  That truly is abysmal amp performance.  What exactly makes them so difficult to drive?  Something other than their low impedance?  What other amps have you tried?

Can IEMs be as good as full sized headphones?

Reply #53
Thanks for posting, shigzeo.  Your JH13 review was very well written.  That truly is abysmal amp performance.  What exactly makes them so difficult to drive?  Something other than their low impedance?  What other amps have you tried?


I have tested it with 5 amps now, 2 which are very cheap: the Fireye series, and 3 other dedicated headphone amps: all portable. This 28 OHM 119db machine is not an easy to drive earphone. Each of the amps are very good, one costing about 300$ USD. I will get a chance to do some more testing on really high end mains amps (I have only tested in on one mains amp so far) and ALL fare the same.

Though the JH13Pro sounds good, I think no one is hearing the true performance of the JH13Pro - no one unless they have a very very powerful amp.

Incidentally, the iPod touch 2G drives a reasonable frequency response with the JH13Pro (I won't yet release the charts simply because I am compiling a list of other portables for output performance comparison only), though it suffers from its usually near-perfect driving character.

Just for reference: here is a small graph RMAA graph of 3 amps driving the same 28 ohm JH13Pro. These fed into the Edirol FA66 (by no means a powerhouse, but a good recorder) via balanced TRS cables and through the amps using a Y-split from Jays of Sweden.

These are preliminary: I decided to do this test early as I wondered about the treble - it seems there are other things I should have asked. Keep in mind that this earphone sounds great, but what it does to any inboard or outboard amp proves that probably 99% of people are not hearing as it should sound:



Also interesting is that the cheapest of the amps did the best in controlling the frequency of the JH13Pro, at least internally. Again, these are taken at an amp level and do not represent what sound comes from the JH13Pro. In other words, they represent how inadequately these dedicated mainstream amps are at driving the earphone.


Can IEMs be as good as full sized headphones?

Reply #54
If it's only the earphones' low impedance that makes them difficult to drive, there are several amps that handle a 28 Ohm load very well; for instance, the mini3, a portable amp, successfully got an "excellent" on the Rightmark Audio Analyzer Test with a 33 Ohm load.  I can't link directly to the measurements, but go to the specifications page and then scroll down to the relevant measurements (I refer to the "high performance" version, as opposed to the "extended runtime" version):

http://www.amb.org/audio/mini3/

The desktop version, the M3, got scores of "excellent" in all categories when driving a 33 Ohm load, and even when driving an 8 Ohm load.

Would you by chance have impedance graphs of the JH13?

Can IEMs be as good as full sized headphones?

Reply #55
If it's only the earphones' low impedance that makes them difficult to drive, there are several amps that handle a 28 Ohm load very well; for instance, the mini3, a portable amp, successfully got an "excellent" on the Rightmark Audio Analyzer Test with a 33 Ohm load.  I can't link directly to the measurements, but go to the specifications page and then scroll down to the relevant measurements (I refer to the "high performance" version, as opposed to the "extended runtime" version):

http://www.amb.org/audio/mini3/

The desktop version, the M3, got scores of "excellent" in all categories when driving a 33 Ohm load, and even when driving an 8 Ohm load.

Would you by chance have impedance graphs of the JH13?


it isn't the low impedance that is doing it. These phones are the only earphones which do this to my amps. I have tried dozens, from 12 OHM to 150 or so in the span of 3 years. For example, the Victor/JVC FX500 is almost picture perfect for both FR and everything else. While it is 16 ohms, it is a dream to drive in comparison.

Can IEMs be as good as full sized headphones?

Reply #56
shigzeo - Looking at the graphs on your Fireye II review, I'm wondering if there is some problem with your test setup that you are not aware of.

Let me point out only my first reason for saying this.  You have posted an loaded RMAA for 64 Ohm DJ1Pro.  According to specs this has a 102 db sensitivity.  Just from the following details I make the following statement.  The 64 ohm impedance is high enough that it will not induce any major (if any) of the effects of a high pass filter (bass roll off) or result in major increases in distortion.  The impedance and sensitivity is also high enough that an amp like the 5V fireye should be able to drive it to headache inducing volumes without distortion or clipping on the part of the amp.  I assume the impedance of the headphone is flat (or nearly flat) across the frequency range.

By this rationale your RMAA for this should be razor flat.  Yet, even with the Fireye II you've got a small bit of bass and treble rolloff and small variations in the whole FR.  Even your Macbook pro seems to have done a better job driving the Ultrasone than the Fireye.

Either that Fireye II is defective, poorly designed, or there is something off in your testing procedure.  Are you sure your Edirol is performing properly?

Beyond that, there is some reason why you are getting such erratic FR with the JH13Pros.  Low impedance headphones can change the FR from flat and increase distortion, but I've never seen anything like what you've found.  Headphones with a wide variation in impedance through the FR range. can also change the FR.

It's not just "hard to drive" because your RMAA measurements are so interesting.  There's a reason and I'd like to know.  I'd test it myself if I had the earphones to figure it out.

Can IEMs be as good as full sized headphones?

Reply #57
Well, I've been testing headphones with much better set ups till last year and I work mostly at a high end audio. Headphones induce these changes no matter the rationale. The test should not change to accomodate a certain headphone and no, there is no problem with my FA66 or the Fireye. Unloaded, both perform flawlessly (well, within reason).

Volume is no problem at all: each of the headphones go far louder than I want to hear - far louder. But, they each induce the signal differently. Headphones, just like speakers are actually very cumbersome on most audio-output equipment. My test procedure isn't out. I have controls taken, unloaded tests taken, and many headphones also taken, all pointing to the fact that the JH13Pro isn't driven properly by most dedicated amps.

I am not arguing that the Fireye is a perfect device. It has severe limitations even when compared with the other amps you see in the RMAA test results. Again, the same setup yields great results (as seen in the DJ1Pro). My test only tests the effects of headphones on amps; in other words, how well an amp can actually pusha  headphone. The JH13Pro is the only one with that poor of results across about 5 portable amps and now two mains amps.

EDIT:
Thank you for the input. I too am perplexed, but again will note that only the JH13Pro acts this way. The kenwood C700 is also harder to drive from the same amps, but nothing in the same class.

Just for reference, you can see the Fireye 1 performing the same tests (though I did not publish the JH13Pro results).
Fireye 1 Portable headphone amp in review - Heavy Metal

shigzeo - Looking at the graphs on your Fireye II review, I'm wondering if there is some problem with your test setup that you are not aware of.

Let me point out only my first reason for saying this.  You have posted an loaded RMAA for 64 Ohm DJ1Pro.  According to specs this has a 102 db sensitivity.  Just from the following details I make the following statement.  The 64 ohm impedance is high enough that it will not induce any major (if any) of the effects of a high pass filter (bass roll off) or result in major increases in distortion.  The impedance and sensitivity is also high enough that an amp like the 5V fireye should be able to drive it to headache inducing volumes without distortion or clipping on the part of the amp.  I assume the impedance of the headphone is flat (or nearly flat) across the frequency range.

By this rationale your RMAA for this should be razor flat.  Yet, even with the Fireye II you've got a small bit of bass and treble rolloff and small variations in the whole FR.

Either that Fireye II is defective, poorly designed, or there is something off in your testing procedure.  Are you sure your Edirol is performing properly?

Beyond that, there is some reason why you are getting such erratic FR with the JH13Pros.  Low impedance headphones can change the FR from flat and increase distortion, but I've never seen anything like what you've found.  Headphones with a wide variation in impedance through the FR range. can also change the FR.

It's not just "hard to drive" because your RMAA measurements are so interesting.  There's a reason and I'd like to know.

Can IEMs be as good as full sized headphones?

Reply #58
There is something really odd going on with the JH13 RMAA.  Maybe it is something with the design or wiring of the IEM that is causing problems with the RMAA test suite?  Perhaps some interaction between the Edirol and the JH13?  I had a similar problem when I borrowed a modified amp from a friend.  Audibly there was no problem.  But RMAA was giving me wild results (10%+ THD, IMD).  I was never able to reconcile what I was hearing with the RMAA results.  I eventually concluded there was some odd interaction between the ADC and amp because I think the testing worked properly with different hardware.  It was a while ago so I don't remember the details.

Do you have a different ADC to test with?  How about just using the stereo in of a computer sound card, even if it's the built in sound card?  If nothing else at least you can see if the results between the computer stereo in and the Edirol are correlated.

Can IEMs be as good as full sized headphones?

Reply #59
Does anyone know what could cause this in a headphone?  What contributes to one being difficult to drive, other than impedance and sensitivity?

Can IEMs be as good as full sized headphones?

Reply #60
Does anyone know what could cause this in a headphone?  What contributes to one being difficult to drive, other than impedance and sensitivity?


Barring the typical problem (e.g. clipping) I've only seen this sort of FR nuttiness when you put together 2 types of devices.
1.  A headphone jack with a high impedance out (e.g. home receiver with a headphone jack powered by resistors off the main amp).
2.  A headphone with wide impedance variance over the frequency range.

Look at this Pio2001's thread on Head-Fi.  However, even those FR changes don't look half as nutty as the FR graphs for the JH13.

Can IEMs be as good as full sized headphones?

Reply #61
Right.  And he's tested a variety of amps, though all Firestone.  I'm not clear on how these measurements are done, so not that I know what I'm talking about, but if there were any other load in series with the earphones, this would have the same effect as increasing the amp's output impedance.

Can IEMs be as good as full sized headphones?

Reply #62
Right.  And he's tested a variety of amps, though all Firestone.  I'm not clear on how these measurements are done, so not that I know what I'm talking about, but if there were any other load in series with the earphones, this would have the same effect as increasing the amp's output impedance.


Yes.  Even resistors in series would do it.

Just from the FR graphs I would conclude the Mac Book pro actually has a lower output impedance than all the other dedicated amps.  It seems there are a lot of badly built headphone amps out there...

Based on specifications Firestone Audio Cute Beyond has a near 0 output impedance, but I don't know if shigzeo has access to that.  Even a CMOY, assuming the output is directly connected to the opamp, has a near 0 output impedance.

I've even tested 25 ohm headphones (Denon D5000,D7000) with a Cmoy and it can drive both with a flat FR.

Can IEMs be as good as full sized headphones?

Reply #63
The brain is an amazing thing.  I can no longer hear myself walk when wearing IEMs.  Bothered the piss out of me the first few days, and then slowly it disappeared.
Rough back of the envelope calc says I've worn IEMs for around 5000 hours, but my brain learned to filter it out way before then.
I even jog with them in.

Same here - I don't notice it much. What I do notice is that I can't really hear the bass when I'm moving. I know it is there but it is obscured by all this low frequency noise that my fine brain is ignoring. And that's what I was referring to when I complained about unstable bass response. I should add that I fully take advantage of the cone of silence created by IEMs and usually listen at very moderate levels.

Can IEMs be as good as full sized headphones?

Reply #64
i don't yet have access to a cmoy, but had one in the past. I will be borrowing more amps later for more reviews. It is intriguing. Remember, those graphs show max down and upswings of up to 6 dbl, so perceived sound effect is much, much less than shown I'll have some more preliminary tests up soon.

Can IEMs be as good as full sized headphones?

Reply #65
shigzeo - could you post an RMAA for the JH13 connected directly to a PMP?  Any player (as long as it measures well unloaded) is fine but if you have access to a Sansa Clip I that would be great.  I am very curious about the results.

I don't think the JH13PRO should be hard to drive.  I suspect something else is going on - I just don't know what!

Can IEMs be as good as full sized headphones?

Reply #66
The clip and the iPod touch 2G have no appreciable differences other than the Clip not performing as well on channel separation (on every hardware I have tested it on). I returned it to its owner for that reason (would take it back when it gets rockboxx)

These tests are not final, but I expect final tests not to change much:



But not all 16 ohm phones are created equally: The FX500 is driven beautifully, though it too is only 16 OHMs. Sensitivity is 100dbl. B2 stands for Bass jumpers set to position '2' in the Fireye 1 which has some bass roll off (as you can see) in the image:


In the last 3 years (since 2006), I have done personal tests with 3 different professional soundcards and about 5 computes with a variety of shielded and unshielded cables following the same respected principles. Amps from Heed, Meier, Xin, Firestone, Graham Slee, Travagan's, and two prototypes. The only phone which has really provided these results has been:

Jerry Harvey Audio JH13Pro
Earsonics SM2

As you can see, the deviation on the iPod touch versus these dedicated amps is far less, but not that good. The Clip fared a bit worse, but held up pretty well. Its Channel separation was worse than the Fireye 1. Official TMA results will go up at the end of the year with all the headphones I can scrounge together, but I won't be changing any hardware or testing methods as these have stood their ground for a long time. Keep in mind, the 'large' swings in frequency response represent only about 6 decibels (which admittedly is a lot), but far less than most people enjoy when they bump up their EQs. Trust me, they only reflect how the earphone stresses the amp, not so much on how 'off' or 'on' it sounds.

cheers

Can IEMs be as good as full sized headphones?

Reply #67
Quote
The balanced armatures when coupled lower distortion. They also are working much more efficiently because of 2 drivers doing the work. Each driver does half the work which increases headroom. A concert PA system like a L Acoustics line array will have roughly 64 15" speakers,128 8" speakers and 32 2" high drivers hanging in the air. Also 64 18" sub bass speakers. In order to create headroom which is gain before distortion you need the work load distributed across multiple components. Yes you can distort all of the components but the sheer gain to do so would be at the threshold of pain. Headroom equals clean audio when operated at a normal spl. Jerry


I've actually read about this on Loudspeaker and Headphone Handbook. Of course, multiple drivers yield more headroom, since the workloads on drivers are lessened! More # of drivers should help IEMs get more SPL w/o clipping, and hopefully more bass to compensate the 'missing 6 dB' effect. However, I believe there's a downside as well when multiple # of balanced armature transducers are coupled together.

I've seen many IEM measurements, but yet to see any multi-driver IEMs with a lower harmonic distortion figure than single-driver IEMs usually have. Moreover, balanced armature transducers are moving-iron transducers, and their distortion figures are very non-linear in their nature. From what I've seen, when these BA transducers were coupled together, the outcome was always more harmonic distortion, mostly at the frequencies where the crossover network takes place. (in turn, more headroom & sensitivity)

Can IEMs be as good as full sized headphones?

Reply #68
Quote
The balanced armatures when coupled lower distortion. They also are working much more efficiently because of 2 drivers doing the work. Each driver does half the work which increases headroom. A concert PA system like a L Acoustics line array will have roughly 64 15" speakers,128 8" speakers and 32 2" high drivers hanging in the air. Also 64 18" sub bass speakers. In order to create headroom which is gain before distortion you need the work load distributed across multiple components. Yes you can distort all of the components but the sheer gain to do so would be at the threshold of pain. Headroom equals clean audio when operated at a normal spl. Jerry


I've actually read about this on Loudspeaker and Headphone Handbook. Of course, multiple drivers yield more headroom, since the workloads on drivers are lessened! More # of drivers should help IEMs get more SPL w/o clipping, and hopefully more bass to compensate the 'missing 6 dB' effect. However, I believe there's a downside as well when multiple # of balanced armature transducers are coupled together.

I've seen many IEM measurements, but yet to see any multi-driver IEMs with a lower harmonic distortion figure than single-driver IEMs usually have. Moreover, balanced armature transducers are moving-iron transducers, and their distortion figures are very non-linear in their nature. From what I've seen, when these BA transducers were coupled together, the outcome was always more harmonic distortion, mostly at the frequencies where the crossover network takes place. (in turn, more headroom & sensitivity)


Your thoughts mirror my findings perfectly. Some BA phones don't offer as much hell to amps, but some like the JH13Pro do. The SM2 from Earsonics is another which I will show later, but these are simple findings on the effects on the amp, not the actual sound which comes from the earphone.

Can IEMs be as good as full sized headphones?

Reply #69
Shigzeo, would you mind explaining or linking to a page that explains the testing procedure you use to measure amps driving headphones?  I'm unclear on it.  Thanks.

Can IEMs be as good as full sized headphones?

Reply #70
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

Can IEMs be as good as full sized headphones?

Reply #71
When I started this thread I was just trying to get a general idea of how IEMs compare to headphones.  I'm not a fan of owning 10 different pairs of headphones/IEMs so I don't want to buy stuff and just put it in the closet, which I have done already..  Compared to full sized headphones it's is also very difficult to demo IEMs and (depending on vendor) return options are limited.


I thought I'd share my experience:

I have a couple of pairs of Sennheiser CX400s as well as a pair of Grado S80's. 

Head to head with the Grados, the Grados win in sound quality.  I forget I have them on my head! (I love my Grados!).  The open backs give the music space to where I feel like I'm listening to speakers and not headphones.

Can I use my Grados at work, while I go to sleep, or mow the lawn?  Nope!  For those things, I used to use my ear buds from my iPod or from an older Sony mp3 player.

So, it's better to compare the CX400s with the ear buds I used to use.  The CX400's blow the doors off the ear buds hands down!

With the CX400s, I feel I get quality sound with great portability.  And it isn't that they don't sound as "good" as my Grados - they just sound different.  But for quality sound in a noisy or highly mobile environment, you can't beat the in ear headphones like the CX400s.

I also found that using foam tips help tone down the boominess and brightness I hear when using the standard rubber tips.


Can IEMs be as good as full sized headphones?

Reply #72
For portable use and for ultra details which are sometimes not audible from big phones (for a variety of reasons), IEMs are phenomenal. 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. However, what even a high-end IEM will not give is the sensation which help your ears experience bass and to a lesser extent, spacial dynamics. That can only be done by sound reaching all parts of the ear, inner and outer.

Still, IEMs have better bone-conducting transfer of sound which helps them recover soem of what they lose out in inherent ability to stimulate the outer ear.

When I started this thread I was just trying to get a general idea of how IEMs compare to headphones.  I'm not a fan of owning 10 different pairs of headphones/IEMs so I don't want to buy stuff and just put it in the closet, which I have done already..  Compared to full sized headphones it's is also very difficult to demo IEMs and (depending on vendor) return options are limited.


I thought I'd share my experience:

I have a couple of pairs of Sennheiser CX400s as well as a pair of Grado S80's. 

Head to head with the Grados, the Grados win in sound quality.  I forget I have them on my head! (I love my Grados!).  The open backs give the music space to where I feel like I'm listening to speakers and not headphones.

Can I use my Grados at work, while I go to sleep, or mow the lawn?  Nope!  For those things, I used to use my ear buds from my iPod or from an older Sony mp3 player.

So, it's better to compare the CX400s with the ear buds I used to use.  The CX400's blow the doors off the ear buds hands down!

With the CX400s, I feel I get quality sound with great portability.  And it isn't that they don't sound as "good" as my Grados - they just sound different.  But for quality sound in a noisy or highly mobile environment, you can't beat the in ear headphones like the CX400s.

I also found that using foam tips help tone down the boominess and brightness I hear when using the standard rubber tips.


Can IEMs be as good as full sized headphones?

Reply #73
I've been using full sized headphones for a long time.


As have I. My first high quality stereo headphones were by Telex, and purchased some time prior to 1962.

Quote
Lately (over the last few years), it seems like just about everybody and their brother is releasing IEMs.


True, and how many of them are OEMed and rebranded is only known by the guilty parties. Compounding this are the facts that they are basically hearing aid technology in a slightly different wrapper, and that people like Knowles Research are openly selling the components on the electronic components market.

If I listed the really pretty good headphones I own and use frequently, this post would be considerably longer. If I added my list of IEMs, it would be longer still.

Quote
I realize there is a large profit motive to do so because of the explosion of portable media devices.


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.

Quote
For a long time I've simply dismissed them as devices that sacrificed sound quality for size and portability.


That seems to be pretty strange thinking to me. IEMs have their small size because they do a smaller job. Instead of filling a room or a earmuff with sound, they focus their efforts where it matters - the ear canal.

Can IEMs be as good as full sized headphones?

Reply #74
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.  )