STEAXAUCE

I saw an impedance graph for the UE11 a while back. It was all across the board. They list the impedance as 18 Ohms just because that's what it happens to be at 1KHz, but if I remember correctly the impedance dips much lower and goes much higher than that at certain frequencies. A 9 ohm output impedance would severely throw off the frequency response with a load like that, and if the impedance varies with the amplitude of the signal as well, it could cause harmonic distortion. Anyway, I'm no EE and don't want to sound like I know what I'm talking about, but that could be interesting to explore if you have any multi-way IEMs around.

I posted this on head-fi, too, since so far as I know these haven't been discussed over there by anyone who's heard them, but, you know, I'd prefer to have a discussion about them here. I haven't seen many posts about the SRH750DJ, but I bought them just a few days ago. They're really fantastic for the money. A little background: I recently sold my Edition 9 and will likely be ordering a JH13 or JH16 within a month or two. In the interim, I was planning to rely on my HD25s, but my car was broken into a month or so ago and the headphones were stolen along with my GPS. I wasn't going to buy a pair of headphones for just a few months of use, but I did want have a backup pair that friends could use, that I could use when the risk of loss or damage would be too high for me to bring along the JH IEMs, etc. I went to a music store that had just about every headphone in Shure's line. I wasn't familiar with Shure's headphones. I hadn't read any reviews, certainly hadn't listened to any of them, and wasn't familiar with the model numbers, but as I'm a bit of an audio nut I went straight for the top model they had, the SRH840. These also claimed to be "monitors" where the SRH750DJ claimed to be "DJ headphones," which also made the 840 seem more up my alley. I plugged them into my Zune HD and started flipping around between classical, jazz, rock and R&B. I liked them, but felt they weren't as dynamic and textured as I would've liked; a lot like what killed the HD650 for me, but not as bad. I would've been satisfied with them as an HD25 replacement, though, and would've bought them if the store hadn't had an SRH750DJ for me to try out next. These were much more to my liking. They improved on the 840 in terms of dynamics and detail, had less of a stuffy sound, "better soundstage," and had a frequency balance that was more to my taste (a bit lighter in the mid-bass). They're not perfect--a little rolled off in the deep bass to my ears and not as smooth as some headphones I've heard--but still, even coming from an Edition 9, very listenable. They're also more compact, more comfortable, and probably better looking than the 840 (though their styling is a little out there for my tastes). Since they were cheaper, too, they were a no-brainer. Definitely HD25 beaters as well. It's been quite a while since I've heard any of the ~$300 open headphones that are supposed to be pretty much the top of the line as far as sane people are concerned; the HD650, K701, SA5000, etc. The headphones in that class all had their specific strengths, but each of them had some fatal flaw that made them borderline unusable for certain types of music. The SA5000 was a perfect example. Their incredible detail and dynamics made them my favorite headphone in the price range, but their excessively bright tonal balance made some music sound, just, wrong. The HD650 was my least favorite among these, because while they had a much more balanced sounding and generally tolerable tonal balance than the SA5000, they severely lacked dynamics and detail--that "Sennheiser veil." Those headphones all likely had something they did better than the ~$130 SRH750DJ (again, it's been a very long time since I've heard them), but to my ears, the 750s do everything decently, and in fact do most things pretty well--they've got none of the fatal flaws that made me drop $1100 on an Edition 9 in the first place. After hearing these, I'm going to have to give some serious thought to whether or not this JH13/16 purchase is really worth it.

+2dB at 50 Hz is a very small boost, and I'd guess that "a touch more upper bass" is likely less than 2dB more, just from the way the sentence is written. Who knows, though. We need some impressions!

JH said on head-fi that the 16 had slightly more bass than the 13. Who knows what "slightly" really means, but in that quote from Facebook he says their sound signatures are very similar, so I'm guessing it's a pretty small difference. As for how easy they are to amp, I don't think anyone knows anything that would help us figure that out. So far as I know, no one even knows their rated impedance or sensitivity.

They won't be right-side-up. They really look great, though. Too bad about the sharks being upside down. That's an odd mistake for them to make. I know they don't guarantee artwork, but you should ask if they'll correct that. You paid extra for the mother of pearl, and that's pretty ridiculous for them to get your artwork upside down.

There'd be no problem with using an impedance adapter if the JH16 had constant impedance, but since a lot of multi-driver IEMs--and, it seems, also the JH13--have impedance that varies widely with frequency, an impedance adapter would throw off the frequency response. And if the impedance varies with something other than frequency, like amplitude, you'll be adding harmonic distortion. I don't know that it does, but I have heard that this is the case for a lot of loudspeakers. An impedance adapter is just a resistor in series with your headphones. If you add a 70 ohm adapter, you're effectively adding 70 ohms to the output impedance of your amp.

Amplitude /= peak to peak. That occurred to me a minute ago while I was away. Thanks Justin.

I'm...confused. Lemme figure out what I did wrong with that when I get back. I'm now wondering whether or not I missed a whole lot of physics problems last semester. Wikipedia says RMS for a sine wave is its amplitude divided by sqrt(2). What am I missing?

Justin, I thought RMS voltage was peak to peak/sqrt(2)?

Um, is that good or bad? I'm new here. So far, I only know you guys hate RSA.

I've been looking at the TTVJ Portable and the ALO Rx. They seem very similar from the product pages. Here's a comparison of the specs: _________________ The frequency response appears equally good on both. The maximum output voltage on the TTVJ is listed as 3.29V RMS. ALO lists 7.45V peak-to-peak=5.26V RMS as the maximum voltage output for the Rx in the specs, but "a minimum of 5.25V peak to peak," which is 3.711V RMS, in the product description. Depending on which of these numbers is comparable to the one TTVJ stated, if either of them are, the Rx either has slightly more or substantially more voltage swing than the TTVJ. It may be that the 5.25V peak to peak in the specifications for the Rx is actually supposed to be the RMS value, since 5.25V RMS is almost exactly 7.45V peak to peak. Maximum current is 200mA for the ALO and 100mA for the TTVJ. None of this is really an issue for me personally, as I'll be using it with the JH13. The output impedance is listed as "less than 1 Ohm" for the Rx and "approximately 2 Ohms" for the TTVJ. The output impedance definitely could be an issue for a JH13 owner, as the JH13 seems to have widely varied (and low) impedance, so that higher output impedance could affect the frequency response. 2 Ohms isn't that high, but it's not zero. The THD+N spec is exactly the same for both: .004% @ 1V RMS into 24 Ohms. The broadband noise spec is the same for both: "<10μV RMS, unweighted, integrated over 20Hz - 20kHz" DC offset is listed as <5 microV for the TTVJ and <3 microV for the ALO. The input impedance is listed as 10KOhms for the TTVJ and 40KOhms for the Rx. Depending on your source, this could make a difference. Stated maximum input levels are 5V RMS and 2V RMS for the ALO and TTVJ, respectively. Channel tracking specification is the same for both. I'm wondering whether or nor these use the same volume control. The TTVJ has 3 gain settings: +0db (unity), +10db and +20db. The ALO has gain settings of 1.5x and 6x. The ALO's gain switch is internal, and *I believe* the TTVJ's is external. The dimensions are approximately the same. The sides are rounded on the TTVJ, which I kind of like. I'd expect that to make it more comfortable in my pocket. ___________________ The small differences between the specs of the two are the only differences I can confirm, and specs can be unreliable. If anyone has any other information on the two, particularly on the actual design differences, I'd love to hear about it.

It appears that I posted the WRONG link last night. The correct link, to a page with unloaded measurement data for the headphone outputs of the iPod Touch, Classic and Microsoft Zune, is below: AnandTech: iPod vs. Zune: January 2008 High End MP3 Player Roundup

I guess we can find out the impedance of the lack-of-load used when I find the web pages I referred to, but the outputs were connected directly to the input of the soundcard. The iPod headphone out actually measures very well when it's not driving headphones, as you can see at the web page below: http://img21.imageshack.us/img21/8151/imgp7447.jpg The lineout measures pretty well too, just not as well as the headphone out. I'll let you know when I find those web pages comparing the two.

Ok, I've searched and searched, but I cannot find any pics of "muddy water blue" IEMs. Can anyone link me? Edit: Nevermind, I found it. I finally searched posts made by Sherwood in the JH-13 appreciation thread at head-fi for "muddy water blue."

I use it all the time!

For the people discussing LODs, you might be interested to know that according to several people who've posted measurements, the newer iPods' headphone output measures better with no load than its line out. I'm talking about the 2G-and-later Touches and the Classic. So you're getting better measured performance from the headphone out via a simple mini-to-mini than you you are using a LOD. I'll try to find the pages to post here. I think I found them the first time through links from anythingbutipod. Note that I didn't say that the headphone output sounds better than the lineout, only that it measures better. Personally, I'd guess that they'd be nearly indistinguishable, but if one did sound better I'd expect it to be the headphone out. I'm a big fan of DBT as the only way to substantiate claims about sound quality. Measurements don't prove anything. Anyone with an iPod and LOD want to try some double blind tests?