Friday, July 31, 2015

Review: JBL Xtreme - how much bass can you handle?

The JBL Xtreme (buy from amazon) (not to confuse with the older and meanwhile discontinued JBL OnBeat Xtreme) suddenly appeared in an inconspicuous way without any preceding official announcement. There was just a leak on Youtube and some weeks later it was already available on the european JBL site for pre-order, which I did immediately as I had this particular feeling that JBL might really have an interesting product here. So far it doesn't seem to be available in the US yet, and to tell the truth I have no idea when it is going to be released there and why it hasn't been already released. Update: JBL Xtreme was released in the US on September 1st as well.
Looking back in the history it took JBL a long way to finally come up with some impressive portable speakers after a period with rather underwhelming devices. Although JBL always had great sounding speakers, their portable speakers were rather lacking, including all the old onTour models, the JBL Flip series, JBL Charge, to finally redefining their standard with the JBL Charge 2. The JBL Charge 2 despite having some initial issues is a pretty good sounding portable speaker in some ways even better than all competing models. The cylindric design with 2 opposing passive radiators at the sides was afterwards used for another Harman speaker: the Infinity One. The Infinity One was something like a blown up JBL Charge 2, bigger, with bigger sound and a more premium finish. Now the JBL Xtreme seems to continue with this obviously successful design and looks like a blown up Infinity One, again larger, heavier and more "extreme". Jump in to find out if the Xtreme can really take it to the extreme?

Let's first look at some technical highlights of the JBL Xtreme. The built in amp should deliver 40W according to the spec-sheet, which would be pretty powerful for a compact speaker although in parentheses you can read: "AC mode", this could hint at some power reduction when run from the internal battery. This is not an uncommon approach for Harman/JBL as many of their speakers sounded considerably worse or less powerful when run from battery, many onTour models come to my mind here, but also the Harman Kardon go&play, which sounded much more full-bodied from AC-power and was louder as well, than when run from 8 D-cell batteries. This trick made it close to unsable when portable operation was intended. The Harman Kardon Onyx was not that different and managed to play louder with more bass and less distortion when it was attached to mains. My fear was that the JBL Xtreme could be similar and my hope was that it would at least deliver an satisfactory amount of power even when run from battery, otherwise what's the purpose of an portable speaker if it has to be kept attached for best performance? We will see later how much power is really lost in battery mode or if at all.
Other highlights are a huge 10.000mAh internal battery which is even able to charge 2 external devices at once thanks to 2 separate USB-ports.  The speaker is claimed to be splashproof, it supports multipoint connections to 3 devices simultanously (similar to the social-mode of the JBL Charge 2, just without any additional mode), and finally the Xtreme can be connected to "multiple" other speakers thanks to JBL Connect. Of course we will have a look later how well this really works.

Currently there seems to be a revival of larger portable speakers starting again. Most companies began shrinking their speakers more and more thanks to the overly successful Bose Soundlink Mini and tried to squeeze the most sound out of them with the result that the market is flooded with similar speakers, although still only a couple of these manage a really convincing performance, but people seem to realize now that while some of these might be pretty nice for low level listening at home etc, they are not quite suitable for outoor use where simply more power and loudness is needed. Even a UE Boom which can play quite a bit louder than both a JBL Charge 2 or a Soundlink Mini is simply not good enough sounding to be worth taken to the beach or to the park, a UE Megaboom doesn't sound that much better and speakers like the Bose Soundlink III or even the Infinity One are all struggling at higher levels. I guess only few really want to carry huge boomboxes around with  them where you might even have to add half a dozen huge batteries in order to power them. The Klipsch KMC-3 comes to my mind here, a powerful big heavy boombox which can deliver plenty of sound and loudness, but you will probably think twice if you are really going to take it with you if you already have to carry your large backpack stuffed with beer and vodka, when there is still the long march through the pineta to the beach in front of you.

It needs smaller speakers that still manage some real powerful performance and I think this is where the JBL Xtreme jumps in. It is not really compact anymore as it weighs more than 2kgs and is about the size of a large PET-bottle. But in reality it is still pretty well handleable unlike the Klipsch KMC-3 or non quite portable speakers anymore like the B&O Beolit 15 etc. You can still clamp the speaker under your arm, it will also fit in any backpack, it is just that you won't fit it into your jacket pocket anymore, but some jackets won't even accomodate a JBL Charge 2 and btw. who wears a jacket when going to the beach?

Despite being physically bigger than a Soundlink III an Infinity One or RIVA Turbo X, the JBL Xtreme is not less portable because if you can accomodate one of these somewhere you will easily be able to carry the Xtreme instead as well. None of those speakers is really pocketfriendly either, you will always need some kind of bag to take them with you.
From the first leaked images I rather thought the JBL Xtreme to be just a rebranded and redressed Infinity One with a similar size. Although considerably larger, the form-factor is still very close to the Infinity One with all controls on top, the same lugs at the side edges and all the ports still being located at the back. As the JBL Xtreme is claimed to be water proof or splash resistant the ports at the back are indeed protected by some funky zip, the Infinity One had a more common flap.

The battery indicator migrated to the front at the bottom now so at least you don't need to turn the speaker around to check battery status and unlike the uncommon and a bit sensitive ceramic coating of the Infinity One the JBL Xtreme rather remembles a UE Megaboom now due to its fabric finish. According to the quick guide you can wash the speaker under the tap with running water in case it might have collected some dirt. But the quick guide also rules out to submerge it under water completely. So it is not 100% water proof, but it should withstand any water pour or rain. I went for black, because black was looking simply most neutral although the other colors look cool too.

The JBL Xtreme comes inside a major box containing the speaker, an external charging unit and a kind of carrying or shoulder strap. This strap was missing with the Infinity One, despite being equipped with some similar lugs this time you can finally attach the strap to the speaker and use it double folded for letting the speaker hang from your shoulder or pulled out to the complete length to carry it over the neck, or simply using it as a carrying handle.

I actually like the strap and welcome that it is included now, it makes the handling of the speaker more comfortable, because it is not that easy to grab it with one hand now, because of its increased diameter. This was not that easy with the Infinity One either, but as the Xtreme is even thicker, you can imagine that you'll need really large hands to be able to carry it securely with just one hand, at least the speaker is not slippery thanks to the fabric material in contrast to the Infinity One.

Build quality is really high and the speaker simply feels and looks gorgeous unlike many other speakers that rather resemble an old transistor radio or an old guitar amp from the 60s. With the Xtreme you get the impression of having some weapon in front of you, a kind of sound cannon or something.
I am not quite sure about the durability of the fabric finish and if it might frazzle quickly, but it looks definitely more resistant than the ceramic thing on the Infinity One which scratched easily by just placing the speaker on stone or another hard surface. The fabric might wear out with time as well, for example I would rather avoid bringing it close to some velcro-material although a velcro tape might be indeed a solution to attach other things to the Xtreme, like a second JBL Flip 3 on the back for example, to add a bit of 360° sound...
What I noticed though is that the metal lugs to attach the strap seem to peal off slightly. When I used the speaker with the strap attached more often, I found some residue all around the lugs looking as if the metallic coating was wearing off.

The Xtreme doesn't hide to be rather meant as an outdoor speaker and to be taken outside and placed in some mud, despite the passive radiators being still unprotected. I cannot evaluate the decision about using totally exposed passive radiators again, because on the one hand they look extremely cool when seeing them moving around together with the bass, on the other hand they might be prone to damage if you carry the speaker in your bag together with other hard objects. But the reality and everyday handling of my JBL Charge 2 which has the radiators also exposed showed me that the radiators are pretty insensitive to damage. They might scratch after some time but there is also some additional rubber coating covering the metal part of the radiators which takes a bit more of an effort to really add some visible damage. Also keep in mind that passive radiators are not actual speakers that can be damaged in some way, they are just vibrating weights which are tuned to a resonate with the active drivers at a particular frequency, you just have to be sure not to damage the rubber suspension. It could be perforated by some sharp object and the speaker would lose its air tightness with the passive radiators not working anymore. Therefore I would still suggest to use some additional protection during transport, just for security. Unfortunately no bag is included and it might be hard to find a suitable one. I was able to use one of the XXL lens-bags to fit the Infinity One inside, but so far I have not found anything for the Xtreme except some custom made pouch.

The controls are simple and self-evident. A central power button accompanied by the JBL connect button with the volume buttons spread to the opposite sides of this which makes it easier to find them even in complete darkness. Then you will also find an own bluetooth button and a play/pause button at the other side, which can be also used for receiving or starting calls. Skipping tracks is possible through a double click, but triple click to skip backwards doesn't work just like on the JBL Charge 2. It worked on the Infinity One though. No idea why JBL didn't make it work for the Xtreme as well because skipping backwards can often be desired I guess.

When opening the zip at the back we can have a look at all the ports. You need to push away the zip with your finger or some wire in order to access the ports, as it covers them even when open. Behind the zip you will find the socket for the external power supply. This delivers 19V at 3A which is really powerful, but it obviously rules out any USB-recharging of the speaker as it was still possible with the Infinity One. But even recharging the Infinity One through USB was rather meant as emergency only because it could took a whole day to recharge it completely. Quite unique for a portable speaker, although not what I would call "extreme" are the double USB-ports for charging of external devices. With one device attached the USB-port will deliver 2A, otherwise both ports share the power and deliver 1A each. So far I only charged my iPhone with it and thanks to 2A charging was extremely quick. The speaker has to be turned on to enable charging but as soon as a device is attached and being charged you can turn it off again and it will continue charging until you deattach the device or unplug the USB-wire. Of course charging external devices will suck quite a bit of battery. I noticed that charging my iPhone completely would result in a loss of one or even two dots from the battery indicator. Usually the battery indicator stays off until you touch a button on the speaker, like volume up or down for example, it will also shortly light up on its own when it changes the status from 5 dots to 4 dots etc. But with external devices attached for charging it will remain active whole the time. The battery indicator has to be taken with a grain of salt though. There are 5 dots that drop off until the last dot starts blinking red, but I noticed that it takes quite long until the first goes off, while afterwards it can be pretty quick going from 3 dots to a red blinking one. This was not that different on the JBL Charge 2 or on the Infinity One, but on the JBL Xtreme it seems even more striking. The only thing that makes this even more weird is that if you attach the speaker for charging when 1 red dot was lit, it may happen that the 4th dot will already start flashing after 15 minutes of charging time, then it takes nearly 3 more hours to charge the speaker completely until all lights will go off. I am really not sure what to think about this, just don't take this indicator too serious and rather see it as a very rough guide how much battery is left. JBL claims up to 15 hours of battery life, and of course I tested this with the speaker cranked to maximum. I got 5:15 until the speaker turned off playing my standard playlist that I use for testing all other speakers too. Considering how loud the JBL Xtreme can play and how powerful it sounds, this is a great value falling just 45min short of the 6 hours the RIVA Turbo X would play and at the same time much better than the 1 hour the Beoplay A2 was able to play, which according to Bang&Olufsen should play for 24 hours. Never trust any claims until you haven't proven them by yourself!

Another port we have omitted so far is labelled with "service". This seems to be a standard Micro USB and is probably meant for any future updates. I am not sure why the port is necessary because there is also a JBL Connect app available for iOS and Android devices and according to the descrption of the app updates should be also possible like that. Let's hope JBL will really issue some updates in future as there are still several bugs or simply annoyances that should be worked on.

Now let's turn the speaker on and see what happens. First thing you will hear is some loud and disturbing welcome tone. Unlike with all previous Harman/JBL devices that all played the same tone, this time JBL went for some strange guitar slap, something like "chakaboommm", it is really loud and annoying. If the speaker is not in pairing mode already after the first power on you can force pairing with a press of the bluetooth button, the speaker will then play a repeating guitar tone symbolizing a kind of sonar-like searching. Finally if a device has successfully paired you will hear another guitar-arpeggio not much better than all the other tones. Alltogether I am really disappointed by all these loud and unnecessary tones. I really hope there will be a way how to disable them or at least make them hardly hearable after some future update. As it is now it is simply unacceptable, you cannot turn the speaker on silently or turn it off, as it will play a similar guitar slap again. I really don't know who started this competition for the most hilarious speaker-tones, the most extreme might be the pairing confirmation tone of the Pill XL, which thank godness is no longer with us.

If there has to be a tone in any case then please something subtle and soft like the "click" from Bang&Olufsen. For these tones alone I would willingly degrade the rating of the JBL Xtreme by one mark if we were at school. Putting the tones aside for a moment, you will notice that you can pair up to 3 devices with the JBL Xtreme that can stay connected simultaneously and alternate playback. Each speaker can steal the playback of another speaker. So it might happen that if device A is currently playing while device B receives an SMS, the alert tone will interrupt the playback of device A. You just have to keep that in mind if intending to connect several devices at once. Maybe this is the reason why JBL didn't go for a more aggressive pairing strategy. The JBL Xtreme will never connect to more than 1 device on its own. It is the same as it was with the JBL Charge 2 and many other speakers supporting multipoint connections. It is just Bose with their current speakers that manage an automatic connection to 2 devices at once. With the JBL Xtreme you always have to force any additional connection from the other devices, even when they were already paired before. When the speaker is currently playing and you want to pair another unknown device, simply press the Bluetooth button and the speaker will jump into pairing mode still continuing playback from the current device. In this case there will be no pairing tones etc, which of course is welcome as it won't interrupt the ongoing music.
But it is still a pity that JBL didn't manage a smarter connection policy. After power on the speaker will always look for the latest device that was connected. If that is not present but some other already paired ones, it won't even try connecting to these. Pretty annyoing and it forces you to establish a manual connection directly from those devices by digging into the Bluetooth menu and selecting the speaker from their device list. At least this is the case with iOS devices, I heard rumors that with Android devices the speaker will indeed connect to any of the currently present ones, you just have no influence on which is going to be selected. It misses any logic that only Bose seem to deal with this problem, while other companies simply don't care?
Bluetooth reach seems pretty stable with quite a wide range. It is definitely more reliable than it was the case with the Infinity One. When connection is lost it seems as if the speaker was trying to reconnect when still within a certain timeframe. If this timeframe exceeds, you will have to reconnect manually. A letdown for many might be missing NFC or AptX support. The JBL Xtreme doesn't support AptX. Nevertheless I didn't notice any streaming quality issues so far. I am using an iPhone, thus I have no possibility to use AptX anyhow. But it could be that with other devices the speaker might fall back to some inferior compression Codec which could indeed reveal compression artefacts etc. With an iPhone the audio quality is top notch, and I couldn't notice any difference in sound if attached through auxiliary input or if streamed through Bluetooth.
As with all recent JBL/Harman speakers volume control is mirrored between speaker and iOS devices. There are 32 dedicated volume steps when controlled directly through the speaker and when top volume is reached the speaker will play some strange (a kind of muted guitar) tone. It doesn't do this though when controlled through the iOS device. A UE Boom or Megaboom will always play a loud honk when top volume is reached regardless if you control it through your iPhone or through the speaker. At least Ultimate Ears provides an option to turn off all these tones with their speakers, I hope JBL will do the same. Volume curve is set quite sensibly, you can control the loudness in very fine steps even at low levels, something that was is not possible with the JBL Charge 2, but the lowest volume step could still be a bit softer especially for particular scenarios like listening at the bedside etc.
A problem which may be related to the mirrored volume control with iOS devices could be the fact that the JBL Xtreme always swallows the first 1-2 seconds of a track after playback is started or even when skipping to the next track. This can be pretty annyoing as it is close to impossible to hear the first second of a song now, according to some others this does not happen in case Android devices are used for streaming, therefore I assume it might be a problem with the synced volume, as the song always fades in after the swallowed first second.
Update: This problem with the first seconds of a song missing, was fixed with a recent firmware update, although it still happens that the Xtreme will cut away the intro of a song, when playback is started. This does not occur between track changes, but when there is no playback for several seconds and is started again, the first seconds of a song will still be missing. But this does happen with lots of different speakers as well, JBL Charge 2 did the same thing, and as far as I remember the Bose Soundlink Mini too.
Last but not least the JBL Xtreme has the option of handsfree of course, but to tell the truth, I haven't even tested it yet. It probably works as with every other speaker equipped with handsfree, but I rarely use it at all.
Another thing worth mentioning is the loud hiss you can hear when the speaker is on. There seems to be some higher amound of hiss with most recent JBL speakers, I also noticed it on the JBL Flip 3. The JBL Charge 2 had some hiss as well, and in case of the JBL Xtreme you can easily hear it with the ear closer to the speaker when no music is playing. Many speakers mute any possible hiss when no music is being played, the JBL Xtreme doesn't thus for anyone sensitive to that kind of noise, this may be annoying, although I personally didn't find it that disturbing, you can really only hear it in very silent enviroments with very low volume playback.

"JBL Connect" is a new feature which I would like to elaborate on a bit more in detail. Just skip it, if you are not interested. The Xtreme together with the new JBL Flip 3 are the first JBL speakers to have JBL Connect implemented. According to the quick-guide as well as to the JBL website this feature enables you to connect multiple speakers for either doubling the sound, which is called "party mode" or to create real stereo with one speaker playing the left channel while the other one taking over the right one. Unfortunately in JBL-language "multiple" means two, I was not able to connect three or more speakers at once, just two. But the good thing is, you can connect a JBL Xtreme to a JBL Flip 3 as well, although in this case you will be missing the stereo-option, they will just connect in "party-mode".
The JBL Connect App is really simple and you actually don't need it to use JBL Connect at all, but the app is the only option to switch between party or stereo. It also allows to swap both stereo channels, and it provides you the ability to rename a speaker, in order to be able to distinguish them, otherwise you would have 2 equally named speakers in your list. The app also allows firmware updates to be done, as soon as a new firmware is available, the app will show a new symbol. There was already one update for the Xtreme which fixed some issues, and the update procedure took nearly half an hour but worked without any problems.

Without the need of using an app connecting two speakers is pretty straightforward. Each enabled speaker has an own appropriate button, just press it on both speakers that you intend to connect together and they will jump into an own kind of pairing mode. If one speaker is already playing some music, it will not play any additional tones, otherwise you would hear the same pairing tone you usually hear when Bluetooth pairing is active. The other speaker will of course play these tones, which is a bit annoying. But as soon as both are finally connected, the second speaker will start playing together with the first one. In my case (I am using an iPhone 6) there is some delay and the music can even cut out for several seconds before both speakers really start playing completely in sync. Usually the first one should continue playing when the second one is turned off, although even in this case there might be a short pause, it is just not very smooth overall. I also heard reports from others that it seems to work seemlessly with Android-devices. As soon as both speakers are paired, the second one will simply jump-in without any break. It really might depend on the type of device that is connected to the speaker.
You can control volume through any of the connected speakers or through your streaming device of course, it should always be in sync. Although one speaker acts as a kind of "master" the other one rather being a "slave", also the "slave" can take over the master for playback. Imagine your device being paried and connected to speaker A, while your wife's device is paried and connected to speaker B. If you connect both speakers together now, they will still play as a pair regardless if speaker A is receiving a stream from your device or speaker B some music from your wife's device. Track changes directly from the speaker are only possible through the "master" though.
Usually JBL Connect should not cause any problems but if other nearby Bluetooth speakers or devices are active as well, there might be some interference. An iPhone can be connected to 2 or even more Bluetooth devices at the same time, although streaming can only be switched between 2 of them, older iOS versions didn't have any limit and you could be connected to multiple Bluetooth speakers at once and switch between all of them through the "Airplay"-switch. I have the impression that if an iPhone has 2 simultanous Bluetooth connections active this might also cause some interference with JBL Connect and the music starts to stutter and cut out repeatedly. The worst thing is if both speakers are already paired with your iPhone and you intend to use them with JBL Connect feature, instead they will probably both connect to your iPhone first, then if they finally connect to each other I noticed that JBL Connect can become unreliable as well. The range for JBL Connect is not too long. It should work within 5-6 meters, but can become unstable with obstacles in between, it will be shorter if both speakers are placed closer to the ground and it will be longer if they are hang elevated. Also important may be the position of the streaming device, for better reliability it should rather be placed closer to the master instead of the slave, otherwise interrputions may appear as well.
All together I am not too impressed with JBL Connect in its current status. The functionality is great, but it simply seems to be unstable too often without any obvious reason. If the connection becomes unstable it might help to turn off both speakers and reestablish the connection again. I also had the impression as JBL Connect worked better with two JBL Flip 3 than with two JBL Xtreme or one JBL Xtreme and one JBL Flip 3, so the JBL Xtreme may be the more affected unit.
Unfortunately the JBL Connect app is not that great either and it sometimes takes much too long for the app to discover any connected speakers. It even warns you that no playback should occur during the connection, and in case the speakers are currently playing they may also start stuttering if the app is launched. There should be some improvement to really make this as seemless and fluid as possible, as it is now the JBL Connect app can become a bit frustrating. Just avoid using it as both speakers usually remember the last connection mode anyhow. If both speakers were connected in stereo, the next time they will connect as a stereo pair again, thus no need for starting the app at all.
I really hope for some future update that may improve stability of JBL Connect as the potential is outstanding. Pairing 2 JBL Xtreme as stereo pair gives you a much more impressive sound experience than the playback through just a single speaker. Setting them apart several meters fills the area with a huge sound stage in front of you. But even connecting one JBL Xtreme with one JBL Flip 3 can make sense, just imagine the JBL Flip 3 acting as a back speaker for the JBL Xtreme. This way you can achieve a kind of 360° sound dispersion, just place the JBL Flip 3 at the back of the JBL Xtreme turned around to the other side. The problem with pairing a JBL Xtreme and a JBL Flip 3 together is just volume divergency between both speakers. At very low levels the Flip 3 will be too loud compared to the JBL Xtreme, while at higher levels the JBL Xtreme will be too loud.
I am still not quite sure if connecting "multiple" speakers will really be possible in future, but it would definitely be desirable. Just imagine two Flip 3 connected as stereo pair and another Xtreme acting as a kind of subwoofer. I really hope but I doubt that JBL will get it going. Logitech may produce crappy sounding speakers, but they have all the features one can dream of. Now it's JBL's turn to prove that they really take it serious. I prepared a simple video to demonstrate JBL Connect in action:

Before discussing the probably most important part of how it sounds, let's first have a look at the inner workings of the JBL Xtreme: The 40W bi-amp mentioned at the beginning is driving two 63mm mid-drivers and two 35mm tweeters. The passive radiators have a diameter of 72mm. Thanks to the dedicated tweeters this means that the JBL Xtreme doesn't have to rely solely on full-range drivers to produce both bass and treble, thus the likeliness for intermodulation distortion as it was the case with the Infinity One is minimized, treble dispersion should also be less directional as it is more common with fullrange drivers. In contrast to the Infinity One which also had drivers at the back (although filtered for treble), the JBL Xtreme has only drivers at the front, thus no sound coming out at the back. I am not sure if this is good or bad, but 360° sound would of course be a nice feature to have, I really got spoiled a bit with the close to omnidirectional sound dispersion of the Beoplay A2, I was not that impressed by the claimed 360° sound of the UE Boom or Megaboom as those suffered from treble loss considerably if not exactly one driver was facing the listener. The upcoming Fugoo XL will also provide 360° sound, so you will probably just need to put it somewhere and don't care about re-aiming at the listener anymore, as you should get great sound from all angles. 
When playing the first tunes you will immediately feel the punch in your gut, the JBL Xtreme seems to be a kind of bass factory. This thing is really powerful and heavy sounding. Despite the sheer amount of bass it still has enough refinement to the overall tuning that it simply sounds "good". When listening to a Beats Pill XL, a UE Megaboom, a Soundlink III or many other speakers that come to my mind, you will always have the impression that something is just not right. The Megaboom sounds honky, the Pill XL sizzling and muffled at the same time, the Soundlink III muffled and boomy... But the JBL Xtreme sounds really familiar and right, it is just the huge bass that jumps at you in the first moment. But after getting used to it, all other speakers will suddenly start sounding tinny. The JBL Xtreme doesn't make a secret out of it to be a real outdoor speaker. While many other outdoor speakers even have an own switch labeled "outdoor mode" or something like that, this switch usually does exactly the opposite of what I would expect from an outdoor speaker, it makes them just louder by pulling out the non existing bass even more. Especially outdoors when there are no walls, no ceiling but just the ground that can act as reflective surface bass will be the first thing that gets lost pretty quickly into all directions. At home you can put the speaker in a corner, closer to a wall, you can even make a Mini Jambox suddenly sound "big" when put in a corner, but as a matter of course with the JBL Xtreme this would be counterproductive because you would enhance the already strong hitting bass even more. The JBL Xtreme sounds perfectly rounded especially outdoors standing completely free. You will hear and feel every bass note even from some distance without having to crank the speaker close to maximum. Unlike some other companies JBL has the tradition not to apply any loudness compensation to their speakers. This is not different with the JBL Xtreme, but as the sound is that full-bodied to begin with, it will still manage to sound full-bodied at low levels. Many other speakers that won't apply any dynamic Equalizing will always sound slack and lifeless at low levels until not a particular loudness level is reached. This was exactly the impression I also had with the RIVA Turbo X which didn't manage to impress me at low levels. Other companies apply various kinds of dynamic equalizing, some even manage to overdo it as is the case with the Bose Soundlink Mini. Funny thing is, the Soundlink Mini may even sound fuller than the JBL Xtreme at very low levels, Bose boost bass that much that the Soundlink Mini can start sounding "bigger" than the JBL Xtreme, it is just that if you start increasing volume the Soundlink Mini will gradually start reducing bass again until not really much will remain at levels close to maximum. The difference to other speakers is that the JBL Xtreme keeps the bass level equal up to some certain point which will rather give you the impression as it became more and more bass heavy when turning volume up. Of course from some certain level up the JBL Xtreme will start reducing bass as well (unlike the RIVA Turbo X, which keeps the same level up to maximum) but this level is already pretty high and comparable to maximum volume of all the smaller speakers. The JBL Xtreme starts dialing bass back slightly at levels above 60% below that you still get that crazy bassboost which makes it sound extremely huge and powerful. But even at higher levels it still manages to sound powerful enough to remain impressive. At maximum volume bass reduction is more obvious together with some dynamic processing, but both are much less intrusive than it was the case with the Infinity One, which hardly had any bass left at its maximum volume, while dynamic compression was so strong, that any peaks got lost completely. Analyzing the sound deeper will reveal that the bass does not reach overly deep, it has a strong peak at 75Hz, and rolls off pretty quickly below that. This legendary 75Hz peak can also be found on the JBL Charge 2 and the Infinity One and is probably just a psychoacoustic trick to simulate deeper bass without really the need of any deeper response. The stronger boost at 75Hz obviously tends to mask the missing lower frequencies. The JBL Xtreme rather resembles the sound of a Klipsch KMC-3 or a Beolit 15 than that of speakers in its own class, outdoors you will hardly notice the lower bass advantage of the KMC-3, except when really listening close or with particular tracks that contain lots of low-bass content. Although a Beoplay A2 might reach deeper than the JBL Xtreme, it only really does so at low levels, at higher levels distortion would become too strong and bass reduction is the only way to prevent the drivers to overdrive, which in case of the Beoplay A2 obviously didn't quite work anyhow as seen from my tests. Any track with stronger bass content, especially with electronic drum kicks will distort when played through the Beoplay A2 already at half volume. The same is true for the Sony SRS-X33 or X55, which both pretend to produce an impressive amount of low frequency response, while in reality they both start struggling at any level above half producing ugly distortion which I cannot quite understand how such products could hit the market at all. JBL probably went for this tricky 75Hz-peak tuning as it might be easier to control a driver with a high-Q peak at a fixed frequency than one that is forced to play deeper. This way JBL probably also manage a higher possible loudness level without the sound falling apart. The JBL Xtreme is one of the loudest speakers in its class but doesn't brake any loudness records. It is about as loud as the Beats Pill XL, which was no slouch either, but the Xtreme manages to retain much more and deeper bass than the Pill XL and simply sounds much more impressive regardless of loudness level. Although it has to be said that the Pill XL doesn't apply any obvious dynamic compression at maximum volume and manages to remain still pretty distortionfree, while the Xtreme limits some stronger peaks and compresses dynamics to achieve this loudness. Still the result is much more convincing than that what Beats managed to offer. I am not even talking about all the other speakers in this class, including the Bose Soundlink III, the Infinity One, the UE Megaboom, the B&W T7 etc. which are all simply in a class or two classes below not only regarding loudness level, but also overall sound quality as all lack the power of the JBL Xtreme. Nevertheless the JBL Xtreme could get along with a bit more loudness. A Harman Kardon Onyx Studio is quite a bit louder than the JBL Xtreme, although only when attached to mains. The JBL Xtreme shows hardly any difference in sound or loudness when it's run from battery or from wall power. I had to attach and de-attach it several times to really notice some slight difference.
Maybe the JBL Xtreme is not the best speaker for analytical listening at home, bass can be simply too much, especially if you listen at levels close to half when there is still no bass reduction of any kind applied. For indoor use I found "bass reducer" EQ-setting on the iPhone to be quite helpful for taming the bass a little bit, you still feel the deeper pounding without the boominess. But take the Xtreme outdoors and I have yet to hear a better speaker, the bass is just spot on. Of course you will achieve a higher loudness with the Klipsch KMC-3, but if looking at the size/weight difference between both, this is not a big surprise, not even mentioning that the KMC-3 needs either batteries or an external power bank to be used outdoors. A B&O Beolit 15 will hardly play louder than the JBL Xtreme, although the Beolit 15 manages to retain more bass at higher levels and it will sound quite a bit more restrained than the JBL Xtreme. One of the closest competitors for the JBL Xtreme could be the already several years old Bose Soundlink Wireless System, or the even older Bose Sounddock Portable. Both weigh above 2kg and are larger than the previously mentioned speakers. Listenting to both, I would give the JBL Xtreme the edge in overall sound quality. The Bose will play quite a bit louder, in reality it nearly manages to reach the loudness of the much larger Klipsch KMC-3, but the Bose will sound extremely forced with lots of distortion to reach this loudness, you can hear that it is simply pushed too much. When turned down and matched to the maximum volume of the JBL Xtreme, I would still take the JBL over the Bose as it simply will sound more convincing and more powerful with less distortion and less compression. Having said this, I am still very impressed by the performance of the old Bose design which is dated back 8 years when the Sounddock portable was released.
Of course such a strong overall bass boost doesn't come without problems. Up to exactly half volume I didn't notice any anomalities, but one or two notches above half some slight distortion might creep in. This is especially noticeable with stronger peaks like those from particular bass-drum sounds, I noticed it with many songs. You hear a slight "clicking" sound and the bassdrum won't sound 100% clean anymore. This distortion will go away at even higher levels, probably because bass is started to be reduced. While maximum volume can sound a little forced, the JBL Xtreme will still remain more or less free of stronger distortion effects. It is just this narrow range above half volume where it tries to still remain as full-bodied as possible, but starts struggling a bit. I haven't noticed such problems with neither the JBL Charge nor the Infinity One although especially the latter suffered from strong intermodulation artefacts that were much more obvious than the slight problems of the JBL Xtreme.
So far we only talked about bass as this seems to be the main selling point of the JBL Xtreme, you either love or hate it. My wife hates it as it is too much "humming" for her taste, but she already found the Denon Envaya Mini too bass heavy, thus she might not be the best point of consultation.
I find the entire tuning to be really well done, it is tasteful and refined to really be enjoying, and despite the slightly overdone bass, the Xtreme sounds considerably more convincing than most speakers in its class as it can also cover a much wider loudness range. While most other speakers will already reduce bass or do other funky stuff to achieve a higher loudness, the JBL Xtreme will still go strong. The treble has some nice definition without the metallic character of the JBL Charge 2. It is also less directional than that of the Infinity One, although treble seems to be emitted more to the bottom than to the upper side of the speaker, which is what I would have expected. The Infinity One has the drivers tilted upwards to project sound up, but with the JBL Xtreme you get the clearest treble if you tilt the speaker backwards, so that the area below the JBL logo is aiming towards you. I found this really strange, as the speaker sounds definitely better and  more sparkling if it is placed elevated. If you put it below the treble will rather be chocked at the ground, maybe the engineers had some intention to do exactly as is, maybe treble should be dispersed at the base the speaker is placed on, I am really not sure, but I prefer the sound if the speaker is tilted back, or if I listen to it from below.
I already mentioned that the Xtreme sounds also pretty nice when listened at very low volumes even without any added loudness, it doesn't get the boomy character of the Bose which tends to drown the treble thanks to an excessive bass boost at low levels, while other speakers including the JBL Charge 2 may even become a bit tinny sounding. The JBL Xtreme is definitely not a flat sounding speaker, but it makes lots of fun and doesn't have any colorations that may make it sound unpleasant or weird. It only starts sounding a bit harsh at levels close to maximum. Although no stronger mids-emphasis is visible from the measurements at high levels, some slight resonant coloration becomes pretty obvious with music. Next you can see the frequency response of the entire volume range including the measurement at top volume when attached to mains which is hardly different to the top volume measurement from battery.

Just for the sake of completness the frequency response of the JBL Xtreme (black) directly compared to the Infinity One and to the UE Megaboom below:

I also prepared several videos which you can all see with the following playlist, starting with a general introduction of the JBL Xtreme including a short first and heavily unfair comparison against the JBL Charge 2. Next comes a direct comparison against the Beats Pill XL to make everyone the decision easier of returning their Pill XL after Apple has recalled all units. One indoor and one outdoor video puts the JBL Xtreme against the UE Megaboom, then you will see one video with the JBL Xtreme and Bose Soundlink III side by side and finally the JBL Xtreme together with the Harman Kardon Onyx Studio, a kind of brother to brother competition, as both speakers are maybe even tuned by the same fathers... er... engineers.

My personal verdict: the JBL Xtreme sounds huge and it is what the Infinity One should have been from the very beginning. Putting both side by side makes the Infinity One suddenly look and sound pretty lost, although the Infinity One already managed to stir up the competition quite a bit, the JBL Xtreme finally manages to turn the market inside out. At 299€ (not sure about the upcoming pricing in the U.S) it was released at an extremely competitive price while offering extreme sound quality putting most similar speakers to shame. The JBL Xtreme may be larger and heavier than those, but it still remains prefectly portable and shifts the limits of sound and loudness you can get out of a portable speaker. The strong bass boost may not suit everyone's taste, but keep in mind that this is ought to be an outdoor speaker tuned for outdoor use, where low frequencies are usually drowned away earlier than indoors. The JBL Xtreme is built with a rugged textile finish it is water proof and has an impressive battery life that should allow for more than 5 hours of music when cranked to maximum volume, values that some other portable speakers hardly even reach at whispering levels. I can willingly accept the extra weight and size compared to most competing models priced the same or even higher, because the JBL Xtreme simply outperforms all of them. It is not faithful to the original recording, but is rather tuned for fun and power. If you want a flat sounding speaker, check out the RIVA Turbo X, the JBL Xtreme is rather a party speaker that makes you dance not a speaker that makes you want to lean back and listen to a symphony of Beethoven. Imagine the possibility to pair 2 of these monsters for wireless stereo and you will definitely be the king of the beach.
There are still some slight quirks like the unnecessary status tones which are much too loud or the fact that the first second of a track is swallowed especially with iOS devices. Also JBL Connect is not always 100% stable and would need some update. But I am pretty sure that JBL will sort this out soon, as the JBL Xtreme is obviously easily updatedable through the own JBL Connect app unlike the JBL Charge 2 which caused quite a confusion for most owners who wanted to update their device to the latest 1.4.1 firmware, but didn't get any support from JBL. Let's hope JBL will take it more serious now. I am not quite sure which speaker may become a serious contender to the JBL Xtreme, the closest I can imagine could be the upcoming Fugoo XL, which I hope I will be able to put through its paces when it will finally become available. Until then the JBL Xtreme is hard to beat and already now a classic and certainly one of the few portable speakers that I can really highly recommend without hesitations.

+ huge sound
+ bass, even more bass, did I already mention bass?
+ louder than most competition
+ tasteful overall sound tuning
+ sturdy build quality 
+ water resistant
+ great battery life
+ multipoint pairing to 3 devices at once
+ stereopairing with a second speaker through JBL Connect

- a bit too big and too heavy
- doesn't brake any loudness records
- bass can be a bit overpowering sometimes, especially indoors in smaller rooms
- bass not reaching really deep
- some obvious distortion with strong bass kicks at levels slightly above half 
- sound becomes quite harsh with resonant upper mids at levels close to maximum
- welcome and status tones much too loud, cannot be disabled
- some noticeable background noise
- 1st second of a song is cut-off when skipping tracks (was fixed with recent update)

- No NFC, no AptX support
- JBL Connect not always 100% stable