However knowing about the Knowles filter mods, I'd just get an hf series and roll filters, instead of spending more on the 4 series.
edit: added "to" before Rin.
Edited by shotgunshane - 2/15/14 at 9:54am
Actually, I've been planning to make a post here about the difference between the ER4 and HF5 that I am hearing for a few days now. I got the HF5 about a week ago because I love the ER4 and wanted a cheaper IEM with a similar sound to use as my "beater" pair for using out and about. Now, I heard an HF2 a couple of times before and found them very impressive sounding during both auditions. I also compared an HF2 I borrowed from a friend to my ER4 before and found HF2 a bit brighter and perhaps a little more 3D sounding, with more depth to the soundstage, but also less detailed in the mids, more rolled off in the bass and harsher, less controlled in the highs than the ER4. This time around, having an ER4 and an HF5 here, I also feel that, apart from slightly more controlled highs and noticeably more resolution in the midrange, the ER4 also has a more natural timbre and a cleaner, clearer bottom end. I like Jazz music a lot and the saxophone is one of my favorite instruments. The sax sounds absolutely gorgeous through the ER4 to my ears with amazing resolution and a spot-on timbre, but is significantly less realistic sounding through the HF5 - somewhat "plasticy" and muddy. Don't get me wrong, HF5 still does an admirable job reproducing the sax and most other real instruments as well, but it just doesn't quite have the realism of the ER4. Also, while ER4 has pretty much the tightest, cleanest, most controlled low end that I've ever heard in headphones, HF5 has a somewhat boomy and muddy bass in comparison. I can't say HF5 is actually muddy, but its low end does strike me as a bit bloated and slow sounding when AB'ed against the ER4. So, overall, while HF5 is very good for the price, I think ER4 is a clear step up in sound quality and fidelity, although I understand that some will prefer the HF5 because of its warmer, more "fun" sound.
None are completely linear. The closest is the pfe112, and I can tell you that with the stock pfe112 tips inserted normally, I get just as much bass with my ety inserted deeply. It may not be 100% linear still, but I also firmly believe none of the graphs are completely accurate for two reasons. First, the bass is so dependent on fit, seal and depth and also so much more finicky in general than other IEMs that the test 'heads' or 'ears' they use to measure them would have to be perfectly fit/sealed, etc. Second, I'm guessing none of the measurements are with modded tips. Not that it's necessary, but it does raise the bass further. Thirdly! I can't find that many graphs of the er-4s that are A) accurately portrayed as what you hear (linear line matching linear hearing) and B) that also have other popular models to compare to.
I find the en.goldenears graphs to match the sound of every headphone/earphone i've ever tried perfectly to the hertz practically. But they don't have an er-4s that I can find, except in accudio when selecting the er-4s "mode" there is a small graph sample. And the bass is only slightly rolled off until very low.
Anyhow, I think this is getting into nitpicking on details. I don't mean that in a bad way. But I don't think anyone "hear" said the er-4s was the best sub-bass reproduction out there. But rather that they are what we consider the most accurate earphone "overall" with excellent bass. I don't believe a few db of bass rolloff around 30-40hz or even a few db up to 80hz can be considered worse than the 90% of earphones out there with 10db treble rolloff past 10khz or huge spikes and dips throughout the range. Anyhow, each person hears what he hears, and it may truly not sound the same from one person to the next. Some people hear sibilance in a specific earphone when others don't, even on the same material with the same tips. I for one hear plenty of sub bass for an accurate realistic sound. I get the full realism I haven't found in other sets.
If that isn't the case for you the solution is easy... look for another IEM. :) haha. But seriously. Or buy a c5 and turn on the bass boost. That makes the sub bass very prominent. Just some thoughts.
Extension is only part of the equation though. ER4 may not have a great extension, but it more than makes up for it with the excellent quality. Most headphones are less controlled, slower and less detailed in the lows than the ER4 and even though they may have superior extension, the higher quality ER4 bass sounds more natural.
I think he's adding 6. According to this golden ears graph, it is -5db at 50hz and -10db at 20hz, but again 20hz is more felt than heard and goldenears adds 6db to "compensate" for the lack of speaker feel (the effectiveness/accuracy of this method has been widely debated). So if you don't use the 6db boost than the goldenears graph shows the er-4s to be perfectly flat all the way down to 40hz with only a 5db loss at 20hz which is the limit of hearing. That puts 30hz around 2.5db low. That's very accurate.
There's nothing wrong with that if you prefer it (I go back and forth) but accuracy-wise the non 6db boost is the most technically accurate. That doesn't mean technically accurate sounds the way you want it to. That's why they probably add the 6db to account for most people who might want that extra bass because of the lack of speaker "feel".
It's sort of like saying when you go to an IEM you're losing the feel but not the frequencies. Adding more volume in the frequencies might make you think it's more like a speaker, but it's not really adding "quality", because the feel was missing, not the frequencies.
I think we all need to remember that technical accuracy isn't the end all though. If someone doesn't like the lack of feel and really enjoys the 6db boost or more to "compensate" than more power to them if that makes them enjoy the music.
As for my tip mod. Here are the non-modded tips inserted as deep as possible.
They were already pretty deep, and I'm not sure if you can tell, but these are even deeper and sound incredible. So far no problem having the tips more exposed either...
Lastly, I've tried a butt-load of IEMs and compared as many as possible to the golden ear graphs. I find their graphs to be extremely accurate in their curve related to the actual sound of the IEM give or take the 6db rule.
That make sense as one of the first things you read on Purrin's site is that his measurements are just a hobby and not a serious measurement.
I don't believe in it either, but I wish there were actually a way to recover the "feel". I just find that boosting the bass only half works by giving you a sort of "impression" of the feel, but not really the feel.
Funny you mention this, as a friend of mine just picked these up and I snagged a listen. I had admittedly low expectations but they were nonetheless far exceeded. The 9927 sounds really really good (accurate) especially for $7. In fact, I would definitely put them in the same realm as the RE0, possibly higher if I can get a little more time with them and roll some tips.