TDK A33
World's Best Bluetooth Speaker: AC/DC, Waterproof with Microphone
TDK A33 (40.8 oz./1,156g, 9.5 x 3.75 x 2", two 1.5" speakers each driven with 3 watts and one 2.5" woofer driven with 9 watts, two 2.5" passive radiators, built-in 6-AA Ni-MH rechargeable battery, AC or DC power, originally $150 but about $20 used if you know How to Win at eBay in 2025). enlarge.
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TDK's A33 battery replacement instructions. Battery part number EU-BT00003000-B available at Amazon and available at eBay.
Top, TDK A33.
Back (two passive radiators), TDK A33. enlarge.
March 2025, Christmas 2014 Audio Reviews All Reviews
Introduction top
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The TDK A33 is the world's best Bluetooth speaker because it sounds at least as good as the $300 Bluetooth speakers I've heard, it runs on AC power as well as its own included rechargeable battery, it's splash-resistant for use by your pool, it has a built-in mic for use as a speakerphone, it's super easy to use, and it's Bluetooth connection is the best ever. The TDK A33 is so smart that even after being turned off for months, just turn it on and it will reconnect all by itself and start your music playing without you having to make so much as one click. That's what music's all about!
The A33 is also the perfect size: small enough to go with you everywhere, and big enough to fill a large room with big sound at least as well as Bose.
This little thing sounds great, and is perfect for portable music from my iPhone, movie sound from my iPad, or even desktop sound from my Mac.
I bought one of these for myself when I saw it recommend in Consumer Reports' list of the 10 top electronic products of 2013. Out of the thousands of products tested by Consumer Reports, they chose just ten as the year's standouts. Along with TVs, phones and cameras was this TDK speaker, rated as one of the best they've tested, and it's priced at a fraction of those from more heavily advertised brands. For just $150 I couldn't resist, and boy, were they were right!
For $100 or less today, the A33 is an absolute no-brainer for you and everyone on your Christmas list.
It made Consumer Report's best-of again, on page 29 of the December 2014 issue.
This little A33 speaker sounds as good or better than any of the Bose or other bluetooth speakers I've heard, and costs nearly nothing. It's the steal of the year!
It sounds warm and smooth, just like a tube console radio or phonograph. Honest, I first played Christmas music on it, and it sounded just like the radio/phonograph at my mom's house with a 12" speaker and a 10 watt vacuum tube amplifier built by my dad back when he was a kid!
This speaker is all about clean, smooth and mellifluous sound. It's accurate; nothing is boosted to sell well at a retail store. If you want more bass, put it against a wall or in a corner, and for less bass, put it on a table away from any walls.
This TDK uses all the same tricks as Bose: loads of active bass equalization, efficient class-D amplification and tough little drivers and passive radiators in a tough, tight box. It's also got a microphone so you can use it as a speaker phone to receive calls.
It connects via Bluetooth in seconds, and immediately starts playing.
Playing from my iPhone 5, it plays for hours without skips so long as I stay within about 40 feet (12 meters). It's far better than Apple's AirPlay, which always cuts out for me. Connected to my iPod, iPhone or iPad, it's all good!
There is also a 3.5mm AUX input so you can play your TDK cassettes or play your 1/2" masters from your Studer A80 with the right adapters. TDK rates the maximum input of the 3.5mm jack as 2.5V RMS, meaning it's perfect for use with any CD player or other portable device.
It runs about 6 hours on its internal Ni-MH battery. It also runs and charges from AC power with the included 12 V DC adapter. There is a 1A USB outlet for charging other devices, so long as you're also plugged into charging power. TDK says use only their AC adapter, but I'll bet you any standard 12V center-positve AC adapter or car-battery cord works just fine, too.
There is a slide switch to disconnect the battery from discharging, and it will charge regardless of the setting of the slide switch. The only reason to use the slide switch to turn it off is to prevent it from turning on or discharging accidentally.
No worries about turning off the power: just walk away, and it turns itself off after about 20 minutes idle. My only whine is that it beeps if it loses your bluetooth signal. It has a hissy fit, like leaving the cassette door open on a 1990s Mercedes. If you have anyone else in the room as you leave, you'll have to turn it off otherwise it will drive them crazy. The beeping is actually the "Hey, let's connect Bluetooth, dummy" alert, which is useful as you're setting up the first time, but unacceptable later.
If you leave the area, it restarts your music as soon as you get back within range. If it turned off, hit the power button to turn it back on, and it fires your music back up all by itself. Brilliant!
It's splash resistant. Everything is rubberized. Don't dunk it, but if it get splashed at the pool, no worries.
Just as if it ran on tubes, the top gets a little warm as it plays.
It's sturdy plastic, with metal grilles and sturdy rubber feet so it doesn't walk away while playing. If you touch it, you'll feel this little speaker vibrating like crazy cranking out big bass from a tiny box, just like the Bose speakers for double or triple the price. Someone has to pay for those fancy stores!
The volume setting is shown by a 5-segment LED bar graph, but it's more precise than that because the top LED on the bar varies its brightness as you set intermittent levels. I find that volume is slow to adjust on the speaker, but no big deal since we usually adjust the volume from our Bluetooth device. The volume LEDs are behind the buttons, so they tend to hide as you're adjusting the volume. Ditto for the Bluetooth light; it's in the button so you can't see if it's blinking or not as you press the button.
It uses powerful magnets to get all this sound out of such a tiny box — keep it away from your cassettes or CRTs. Measured at the outside of the speaker, I measure 5,000 µT (50 Gauss) maximum, 1,300 µT (13 Gauss) typical. This is about the same or more than a giant subwoofer like the 100-pound, 1 kilowatt, 15" B&W ASW 850 subwoofer, and is because with the A33 we can get so much closer to the magnets than we can with bigger speakers in bigger boxes.
It easily fills a big room with big sound, but as you'd expect from this single speaker, it's in mono. To hear stereo, your head needs to be within less than a foot of the front, as with all of these bluetooth speakers.
TDK A33 with a CD.
Specifications
TDK A33 Connectors.
Size
9.5" wide by 3.75" tall by 2" deep.
Weight
I measure it at 40.770 oz. (1,155.75g).
Drivers & Power
Two 1.5" speakers, each driven with 3 W.
One 2.5" woofer driven with 9 W
Two 2.5" passive radiators.
Power
Built-in 7.2V 2,000 mAh Ni-MH battery (custom solder-tab 6-cell AA pack, part number EU-BT00003000-B).
12V DC input from AC adapter, or 12V car DC cord if you're intrepid.
The 12V DC input seems to work fine with any common 12V, 2A center-positive adapter.
Price, USA
About $20 used if you know How to Win at eBay, March 2025.
$85 for Christmas 2014 at Amazon.
$120 for Christmas 2013 at Amazon.
$150 MSRP.
Bluetooth
Works great with my iPhone 16 Pro Max in 2025.
It's rated for Bluetooth version 2.1 with A2DP, HFP profiles with AAC codec.
Introduction
About 2012.
Quality
Made in China.
See also TDK's A33 Sales Data.
Usage
TDK's A33 manual in many languages.
TDK's A33 Bluetooth Pairing Guide.
Connection
To connect, make sure the Bluetooth button is flashing, which it will the first time you turn it on. Next time you need to connect it will remember your devices. To connect to a new device, just press the Bluetooth button for a few seconds to make it discoverable. If you need a code, use 0000.
TDK's A33 Bluetooth Pairing Guide.
Power & Battery
Just a tap the power button to turn it on or off; a longer press will be ignored.
To mute, tap the power button to turn it off. To restart, just tap the power button. It may be a second and you may hear a Bluetooth connection beep, and it will restart playing right where it left off.
There is no battery gauge. The power LED will change from solid amber to throbbing red just before the battery dies and it turns off. Otherwise there are no other warnings or beeps, just silence.
Full charge of a dead speaker takes 2.5 to 3 hours. Solid red power LED = charging, and it turns off when done. Solid amber power LED = playing.
To charge another device from its USB port, you have to be connected to external power and the speaker needs to be ON (press the power button and see the Amber or Red power LED.
Battery Replacement, March 2025
The 6-AA Ni-MH battery pack (part number EU-BT00003000-B, 7.2V, 2,000 mAh Ni-MH) seems to die after a decade. No worries, it's easy to get replacements at Amazon and at eBay.
TDK's A33 battery replacement instructions.
You'll need a tiny Torx T5 screwdriver to open the bottom hatch. Some batteries include a cheap version of this tiny driver that's not very durable, while I use this professional Wiha tiny screwdriver set.
In March 2025 I bought this particular replacement battery because it actually ha product ratings at Amazon and it includes a basic Torx 5 driver which seems to work fine. This battery plays for 6 1/2 hours, and charges from completely dead in 2 hours and 45 minutes, which is at least as good as the original battery. Bravo!
TDK A33 with stand lowered.
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