The Loudest Portable Bluetooth Speakers — Which Sounds Best?

Our vast research project looked at the largest and loudest Bluetooth speakers. We focused particularly on those that sound great but are still portable enough to be taken out for beach parties, boating, patio soirées, tailgating parties, etc.

The market is saturated, to say the least, which is great: there’s something for any taste. Further down in this article, we’ll discuss the good large alternatives that are waterproof, that have “smart speaker” tech to chat with, and some cheaper options. And we have separate articles covering our top picks if you’re looking for a more portable (beer-can sized) speaker, or a speaker that is tiny and completely pocketable. But for most people looking for volume+quality in a portable package, we’re confident in recommending …

Critical Meta-Review of the Kilburn Marshall II: Our Favorite of the Loudest Portable Speakers

We’ve listened to the Kilburn Marshall II (as well as its competitors), but as usual at SelectoGuru that’s hardly enough. Tastes vary, so we read what everyone else had to say about the larger, louder class of Bluetooth speakers as well.

Everyone’s got their preferences, but a small handful of speakers always came to the top of critics’ lists. And we found that the original Marshall Kilburn has been the most consistently loved of by the French or American consumer testing organizations and top audio critics and tech sites. And we found that the update to the Kilburn, the Kilburn II has been widely seen as even better in the reviews by those critics and others.

The Plaudits for the Marshall Kilburn II

In fact, the Kilburn II is one of the only portable speakers to deliver sound at a quality approaching good bookshelf speakers. At middle volumes, there is a richness in the bass end and the vocals sound full and resonant. The sound is detailed and there is a reasonable soundstage for a single speaker. The balance is even — no overwrought boomy bass here — and it stays this way even when blasting out at top volumes. And while some reviewers felt there was a bit of distortion on occasion at top volumes with the original Kilburn, this is no longer at all an issue with the Kilburn II. The speaker goes plenty loud enough to fill a large room or animate an outdoor porch gathering.

The Kilburn II has analog control knobs instead of the buttons found on most other Bluetooth speakers. While we wouldn’t consider this a breakthrough feature, it’s a pleasant throwback. The knobs control volume, bass, and treble, making it easy and incredibly intuitive to adjust on the fly. Other speakers have dedicated apps that do much the same thing, but you’re unlikely to actually open the app and use them much.

If you’re going to watch videos with this speaker, be assured that the audio synced up nicely in tests with Netflix and other video platforms from a laptop and phone (it helps that the Kilburn II uses Bluetooth 5.0).

Battery life is advertised at “20+” hours although results will vary depending on how loud you’re playing your music and other factors. Most tests showed as little as 13-14 hours in real world use. In any case, you’ve certainly got enough juice for an all-day, all-night outdoors party. And the battery meter on the top helps you keep track of how much juice you’ve got — a major convenience that’s rare on such speakers.

The speaker can connect to two devices simultaneously, so there’s no need to disconnect a device if switching between say a phone and a laptop, or alternating control of the music with someone. In tests this worked just fine, with a satisfying fade as it moved to the next unit.

The Drawbacks to the Marshall Kilburn II

The downside of the Kilburn II is that it doesn’t have some of the bells and whistles of some of its large Bluetooth competitors:

• There is no speakerphone function, but consider that you’re more likely to use the speakerphone function on your phone anyhow. Bluetooth speakers are increasingly going without this function, presumably as it rarely got used.
• It is not waterproof, merely resistant to drops of water (IPX2). Sure, nobody usually intends to dunk a Bluetooth speaker, but it’s nice to know that a speaker is rugged enough to survive that. See below for the best waterproof model.
• You cannot pair two of these speakers to create an bigger sound for a larger party. Again, see below for an option from Ultimate Ears that can do this.

The Marshall Kilburn is a bit smaller than most boomboxes of old, but still a chunky feller to carry around; you’re not going to slip it into a pocket or purse. It measures 9.57 x 6.42 x 5.51 inches (24.3 x 16.2 x 14.0 cm) and weighs 5.5 lbs. (2.5 kg.).

For most uses, we think it’s easy to recommend the Marshall Kilburn II as the best of the largest, loudest Bluetooth speakers. But there are other great options below if your needs are different.

F.A.Q. on the Marshall Kilburn II

We’re endeavoring to answer reader questions that have gotten sent in as often as we can; feel free to drop more in the comments section and we’ll do our best.

Is the Marshall Kilburn II worth it in terms of sound/price ratio?

The Kilburn II is an expensive speaker with no frivolous extra features, but absolutely worth it in terms of price vs. sound quality. It’s the top Bluetooth speaker that delivers good home audio system level sound in a portable-enough package that you can still carry around the house or outdoors when you wish to.

There are more expensive Bluetooth speakers out there that are definitely not worth it. The Kilburn II is at the sweet spot for us in terms of what we’d pay for good sound at this size of speaker. But there are cheaper (smaller, more portable) speakers that are also excellent and also absolutely satisfying for home listening; see especially the two cheaper Ultimate Ears recommendations below, as well as our reviews of excellent, much cheaper travel speakers. They are also enough to fill a small to mid-sized space with sound. The Kilburn II just does it a bit better, with more detail and sense of individual instruments — as much as you can expect from a single unit of its size.

Note that there is likely a bit of a brand premium included in the price; you’re undoubtedly paying a bit for the Marshall brand reputation. This made us sceptical at first, as the Marshall Bluetooth speakers are not even manufactured by the same people who make the guitar amps; the name is actually licensed to Zound Industries in Sweden for this purpose. But they’ve done an excellent job with the Kilburn II, and good sound is good sound. We’re happy recommending it.

How loud does the Marshall Kilburn II go?

A universal comment from the reviewers cited above is that the Marshall Kilburn II goes incredibly loud compared to other speakers of its size, and sound great doing so, without losing control or distorting. (It’s advertised with a 100.4 dB SPL at 1M; but this rating is hard to compare meaningfully to other speakers, and in any case what’s important is how they actually sound when they get that loud.) This makes it absolutely suitable for outdoor use or for filling a large indoor space, and when we’ve used it in these situations we’ve never for comfort taken it above its halfway point, except for testing. Note that as photographed above, a large bar/arts/dance space even uses it as its only sound system.

If you need something even louder (as well as bigger and more outdoorsy and waterproof) go for the JBL Boombox 2 or Xtreme 2 reviewed here, or the improved JBL Boombox 2.

Is this a good outdoors/waterproof speaker?

No. While the construction of the speaker is quite solid, it is only rated IPX2, which means simply that the unit can withstand dripping water from directly above. Do not leave it outside when the party is over. Don’t use it as a bathtub speaker or pool speaker. The better choice for loud waterproof speakers is below.

Is this a good home speaker?

Absolutely. The Marshall Kilburn II is a satisfying as main home speaker, even for filling large indoor spaces like an open living room/kitchen/dining room, as well as for connecting to a television or laptop for better sound. (Our top pick for smaller spaces like dorm rooms would be different.)

Since it has a very long battery life, you can then unplug and take it around the house, to a workshop (it can go loud enough to be heard even over power tools), outside, etc.

If you’re looking for a purely home speaker that will stay put in one room (and thus doesn’t need a battery), we’d recommend the Bose Smart Home or Soundtouch reviewed here.

Can I connect the Marshall Kilburn II to a TV?

It’s easy to connect the Marshall Kilburn II to a TV via Bluetooth or mini-in cable (the kind of cable you find on classic headphones). It will in most cases provide fuller, louder, and more detailed front-on sound than a TV’s own internal speaker.

If you’re going to use the Kilburn II with your TV as a permanent setup, use the mini-in input. If your TV has a mini-out port as pictured, get a quality 3.5mm to 3.5mm cable; otherwise get a double RCA to 3.5mm cable.

Modern TVs are often Bluetooth-enabled as well, and in our tests we find no lag in the audio syncing over the Marshall Kilburn II’s Bluetooth 5.0 connection. Push and hold the Bluetooth button on the top of the Kilburn II, and then search to pair a new Bluetooth speaker in your TV’s settings.

How does the Marshall Kilburn II compare to its predecessor Kilburn I?

See our review comparison of the update Marshall Kilburn vs the update to the Kilburn II; in general terms the Kilburn II goes a bit louder and sounds a bit better doing so, and the bass is a bit deeper. The Kilburn was also an excellent speaker, and we previously recommended it. But unless you find a major discount on the original Kilburn, we’d go with the Kilburn II.

Other Picks: The Best Loud WATERPROOF Bluetooth Speaker

No, we’re not suggesting that you listen to music underwater. But if you’re the type of person who might put a portable speaker through a bit of abuse — maybe the odd splash from the pool, spilt beer, or abandonment in the rain — you should get the Ultimate Ears Megaboom 3 instead of our main pick above. Both speakers sound great, and we’ve even done a focused comparison of the MegaBoom 3 vs. the Marshall Kilburn II. But here are the main differences to be aware of:

• The MegaBoom 3 is fully waterproof (for up to 30 minutes submerged) and dustproof (rated IP67), and with its rubberized housing much more able to withstand shocks. It also floats, though you really shouldn’t leave it or any speaker floating in a pool for best results.
• The MegaBoom 3 does not go quite as loud (although its close) or sound quite as great as the Marshall Kilburn, which is not surprising since the Kilburn is bulkier and weighs three times as much. (Bulkier tends to allow for better sound in speaker design.) But the MegaBoom 3 is nonetheless the getting rave reviews for its sound from audio critics and tech sites and we expect that to continue as more weigh in. It offers great 360-degree sound, meaning that it’s designed to be placed in the middle of the action and sound the same from any side. It has the trademark Ultimate Ears evenness of mix and a fair amount of warmth and expansiveness. The bass end is punchy satisfying.
• If you buy two Ultimate Ears MegaBoom 3s you can pair them for an even louder party and for true stereo sound, via the app.
• The MegaBoom 3 is advertised as having a 20-hour battery life and testers found that it generally went for nearly that long at normal listening levels.
• There is a “magic button” that allows for play/pause and skipping tracks directly on the speaker.

If you can budget for two of them, we do think that the ultimate loudest Bluetooth party-on-the-go comes from buying two MegaBoom 3s and using them as a stereo pair. And if you or friends happen to have other Ultimate Ears speakers that work on the same app (that is: Boom, Boom 2, Boom 3, or original Megaboom), they can all be linked together for quite a loud portable party.

Other Picks: The Best, Loudest SMART Bluetooth Speaker

A number of speakers have recently come out integrating Amazon Alexa, Google Now, and even Siri functionality. This allows you to give the speakers voice commands to play certain types of music, check the weather, and even control smart devices in your home. We think that the technology is a bit of a gimmick, or at least not really functional enough at this time to be worth it (especially since you can get a much better experience out of giving voice commands directly to your phone or tablet, thanks to its screen, which helps you along).

That said, for those who do want to venture into the technology, it’s nice to have alternatives to the Amazon Alexa Echo, Google Home, or the (apparently troubled) Apple HomePod. So far, critics have taken a dim view of the sound quality of these speakers. In fact, you’re probably best off getting an Amazon Echo Dot or Google Home Mini for the voice assistant functions, and using our top pick above or your home speaker system for actually listening to music.

But, if you really want an integrated large but fully portable and very loud Bluetooth speaker with some smarts, the Ultimate Ears MegaBlast is the best option; it’s quite a bit like the Ultimate Ears MegaBoom but with built-in Alexa (Amazon’s voice assistant). Audiophile blogs, tech press, and other reviewers laud MegaBlast’s performance as a speaker, which is not surprising considering that Ultimate Ears speakers generally tend to be at the top of critics’ lists (including ours). It can crank out up to 93 dB without distorting and like the Ultimate Ears MegaBoom 3 it delivers 360-degree sound, so it’s designed to be placed in the middle of the party and sound great no matter where you are standing. The sound is punchy and pleasant and the mix is relatively even across all frequencies.

The main complaint is that the Megablast’s functionality as a smart speaker is still a bit buggy. While it has the same Alexa voice assistant that allows you to play your Amazon Unlimited Music (currently no support for Spotify, Google Music, etc.), ask questions, and control your smart home, there is a significant lag in its response and no visual indication when it is on and listening to you. It can fail to restart your music when it’s done answering a question, and the Alexa functionality only works when you’re on WiFi. Also, unlike the Megaboom 3, you are currently unable to pair two Ultimate Ears Megablasts.

Other Larger, Louder Bluetooth Speakers that We Considered (but Not Our Top Picks)

The Bose Revolve and Revolve + are portable options that offer Bose’s typical evenness and excellent clarity, but we slightly prefer the loudness and punchy oomph of our main picks. But check out our full thoughts on those at the link, especially if you have enjoyed Bose speakers in the past.

The Braven 805 has an 18-hour battery and generally reviewers liked how it sounds, but it’s also twice as big and twice as heavy as our main pick.

Fugoo Sport XL — This is a larger version of the Fugoo Sport; also comes in Fugoo Style XL and Fugoo Tough XL options. Fugoo speakers are great for dirty, rough outdoor use, but they’re not the best-sounding speakers for most people’s uses.

All of the Bluetooth speaker choices from JBL got above-average ratings from various commentators, but the praise was not universal, and they are narrowly beaten out by the ratings given to our main picks above. Check out our full coverage of our thoughts on the JBL Charge 4 and Xtreme 2. We think they’re great, they’re waterproof, and they make fine speakers for outdoor parties. Just not quite our top picks in any category. We’ve also noted how the JBL Boombox 2 is quite worthwhile, though it’s much larger. If you’re into psychedelic or romantic music experiences, you might enjoy the lava-lamp-inspired JBL Pulse 4 speaker, which also sounds quite good (and recommended also for dorm rooms).

Marshall has two other large and wonderful-sounding speakers in its portable lineup. See here for our comparison of the Stockwell II and Tufton alongside our top-pick Kilburn II. The Stockwell II sounds wonderful and is more portable, but doesn’t go nearly as loud. The Tufton sounds fabulous, goes quite loud, and has deeper bass, but at that large size and high price we’d go with the JBL Boombox 2 instead, which sounds better at top volumes.

NYNE Multimedia Bass — This speaker has its fans, but most careful critics prefer other speakers above.

We have discussed how the Riva Arena and Concert are good smart speakers that let you connect to Amazon Alexa or Google Assistant, but they’re mainly home speakers with an optional battery that lets you take them on the road.

The Ultimate Ears Wonderboom 2 is a fabulous little waterproof floating wonder, but we overall prefer the other Ultimate Ears options that we discuss above.

Wrap-Up: Our Loudest Bluetooth Speaker Recommendations