What else can old speakers do? I found one for the Bluetooth, one for 2.1, and one without a plug. The best sound quality is the one without a plug

tidying up the storage room, three dust-gathering speakers were pressed under the cardboard boxes. One is a Bluetooth mini speaker bought in 2016, which cost over 100 yuan back then. Now the battery is dead, but it works at low volume, but it automatically shuts down when the volume drops below halfway. A 2013 2.1 speaker set with a desktop unit, two small satellite boxes with a subwoofer, and after the desktop retired, it had been crouching at the bottom of the cabinet; and a pair of bookshelf boxes taken from an old amplifier, made of large wooden blocks with only two red and black terminal posts on the back, not even a power plug. Listed on Xianyu, no one asked about the 30 yuan free shipping for Bluetooth, no one wanted the 2.1 version, I took photos of the bookshelf box and posted it in a circle, and a friend replied, "This thing doesn't work even when plugged in, why keep it?"

Last week, when I installed speakers for the TV, I pulled out the 2.1 and plugged it in. It turned out to be the thickest sound among the options, and I got excited, so I tried all three speakers one by one. Here's the conclusion: all three have been saved, and the best sound quality is the one that "doesn't make noise even when plugged in." Let's talk about each one.

Step

: First, identify which type of box you have. Whether the amplifier is inside the box is the dividing line

tinker, you need to figure out which type of speaker you're talking about, otherwise even checking tutorials won't get it right. There is only one criterion to judge: whether the amplifier circuit is inside the box.

Bluetooth portable speaker, battery, amplifier, and speakers all packed into one plastic case, with USB power ports—this is the extreme of 'integration.' The dead end is usually not the speaker, but the battery. Type 2.1 and 2.0 computer speakers are 'active speakers' with a 220V plug, volume knob and a 3.5mm or RCA input port on the back, and a built-in amplifier—this is the most durable type. The secondary cabinet of the bookshelf case and old amplifier is a "passive speaker," with only red and black terminals or two wires—one red and one white—without a power port. It doesn't make noise on its own and relies on an external amplifier to push it—a friend said it "doesn't work even when plugged in" is actually untrue, as it has no power connection at all.

three types of boxes have completely different roles: Bluetooth handles batteries, active ones get work, passive ones provide amplifiers. After all the trouble with the wrong prescription, I started by thinking about the bookshelf case using Bluetooth speakers, studying the positive and negative terminals for a long time, and only then realized what was missing was an amplifier.

90% of Bluetooth speaker issues lie in the battery; plugging in to extend life is the easiest way to do so

the Bluetooth speaker's symptoms are very typical: it can play at low volume, but automatically shuts down once the volume exceeds half; Charging overnight, unplugging the cord in half an hour and then running out of power; Everything works fine with the charging cable plugged in. Three symptoms point to the same thing—the battery is old, the current required by the amplifier can't be pulled at high volumes, and when the voltage drops, the machine automatically shuts down on protection.

the easiest way to keep the phone alive without disassembling it: use it as a "plug-in speaker." The charging cable is plugged in year-round, charging and letting go while charging, with the battery only as a buffer. I put it on my study desk to connect to the computer, with a 3.5mm audio cable plugged into the AUX port. The desktop doesn't have Bluetooth, but it's fine since the cable is only half a meter long. After two weeks of this practice, it was very stable. If you have a dusty old tablet converted into an electronic photo frame or control screen, with the speaker sound as soft as mosquitoes, pairing it with a Bluetooth speaker as an external speaker is a good way to put everything to use.

two red lines need to be clarified. First is swelling. If your fingernail presses the speaker casing, it becomes soft, the edges lift, or it doesn't stand steadily on the desk. Stop using it immediately. Continuing to charge a lithium battery swelling is a gamble on safety. When I previously upgraded my phone's camera, I specifically checked how to handle battery swelling, and it still applies the same way: the speaker softens, the edge lifts, stop using . Don't worry. Second, don't disassemble the battery yourself and switch to direct supply. There are tutorials online where you remove the lithium battery and get a USB 5V direct power circuit board. It looks simple, but in reality, it traps both sides: the lithium battery is 3.7V, the USB is 5V, and the direct supply depends on whether the board can handle it; some boards have battery testing, but once unplugged, the device won't power on, so you have to solder a false voltage to connect it. If you have a multimeter or can solder, ignore me—ordinary people's time isn't worth the price. Thirty yuan desktop speakers are everywhere.

really want to tinker with changing the battery, that's fine. Buy a 3.7V lithium battery of the same size, make sure the protection board matches the original, and don't short-circuit the solder joints. But my advice is: plugging in is enough to keep you alive, so why bother?

old 2.1-inch speakers are underrated treasures; connecting them to the TV feels more grounded than thousand-yuan soundbars

the 2013 2.1 speaker set, two satellite speakers plus a subwoofer, with the amplifier and volume knob integrated into the subwoofer. This kind of box is indeed rustic in a newly renovated living room, but its sound foundation lies in: the subwoofer is a solid speaker chamber, much better than the two downward-facing speakers on TVs today.

the TV is the most convenient position. My TV has a 3.5mm headphone jack, and one audio cable solves it; if your TV only has optical or ARC ports and no headphone jack, don't give up quickly. Just a dozen yuan to buy a digital-to-analog converter (DAC), optical input, red-white RCA output, and speakers will still work. After connecting, there's a level pitfall you need to get right: when the TV's headphone jack output level is low and the speaker volume can't be raised, first set the TV volume to 80% as a reference, then use the speaker knob to make fine adjustments. If you reverse the order, the whole device might feel broken. I went through this section one by one in the of the article on connecting TV external speakers, so I won't repeat it here.

the placement is just one thing: don't stuff the subwoofer into the cabinet compartment. At first, I stuffed the cannon into the cabinet to keep it neat, so the sound was so muffled it felt like being through a quilt. I took it out and placed it on the floor or in the open cabinet shelf, and the bass was instantly clean. Also, the 2.1 satellite box cable is usually one or two meters long, which is just right to place on both sides of the TV. Don't force it to stretch out, as regular extension cables can easily introduce background noise.

besides TVs, it connects to computers and Switch-type game consoles, all plug and play, and the 3.5mm port works well. Wired direct connection doesn't compromise in sound quality, and even the best Bluetooth codec still uses lossy compression. If you store lossless music on your home NAS, I still reserve wired for listening to music. I've written about of connecting speakers to NAS.

passive speakers may look the worst, but in fact, speakers are the most valuable—thirty amplifier boards save the day

focus on those bookshelf boxes. Its reputation as "no sound even when plugged in" is a misconception; passive speakers are meant to be pushed by people. After the old amplifier broke, the case was left behind. Both the speaker and wooden enclosure are excellent—the wooden enclosure resonates much less than the plastic shells of today's hundred-yuan Bluetooth speakers, and the speakers are decent in size. That's why I say the best sound quality is its confidence.

reviving it, there are only three things: a 2.1-channel Bluetooth amplifier board, a power adapter, and two speaker cables. I bought the ZK-TB21 amplifier board, around 30 yuan. The board has Bluetooth, two speaker output ports, a subwoofer port, a volume knob, and a remote control receiver. Don't buy the wrong power supply—this type of board requires a 12V to 24V DC power supply. I just grabbed an unused 12V 2A adapter from the drawer and used this pair of small bookshelf boxes to make do. If the box is large, go to 19V or 24V for more power margin. Connect speaker wires to terminals, paying attention to positive and negative terminals: red to red, black to black. If you connect them backwards, the sound will be empty; if both are reversed, you won't be able to tell the difference. So, as usual, press red to turn positive and black negative.

total cost: 30 yuan for the amplifier board, a few yuan for speaker cables, and an idle power supply. That's 35 yuan, which turns a pair of bookshelf boxes into living room speakers with Bluetooth + wired dual input. You can switch between TV, phone, or NAS player, and the sound quality is noticeably thicker than the new Bluetooth speaker I bought for 150 yuan. If you have a 2.0 passive box, the gameplay is the same—just buy a stereo amplifier.

two pitfalls along the way: misreading the power supply voltage and burning the board, and the huge power difference between the speaker and amplifier board—a small amplifier board producing a loud speaker produces soft sound, while a large amplifier pushing a small speaker can easily cause distortion. For home use, you don't have to worry too much about the sound; a board rated for tens of watts paired with a bookshelf case is sufficient.

retired smart speakers don't just stand idle—broadcasts and doorbell reminders are hidden posts

to mention the fourth category: smart speakers you have replaced at home, such as the Xiaoai Speaker Play. It works as soon as it powers on, so there's no battery issue. Most retirements are because you bought a new one with a screen. Don't throw this out—it has two legitimate positions at Mijia.

First, be the loudspeaker at home. In the Mi Home app, set up automation, and select this speaker by performing an action. There's an option called 'Play specified text'—whatever you enter, it reads accordingly. I paired two lines: when the doorbell is pressed, it says "Someone rings the doorbell," and when the washing machine ends, it says "The clothes are done." If there are elderly people at home who never hear the doorbell, this feature is especially useful; The smart doorbell can also be linked directly to the speaker box in the doorbell plugin settings. Second, as a Bluetooth gateway, connect Bluetooth sub-devices like temperature and humidity meters into Mijia. There are many smart devices home , and an old speaker placed in a signal blind spot serves as a backup. I've written about this feature in detail in this article about Bluetooth gateways. Even if the manufacturer shuts down one day, it can still be downgraded to just use as a regular Bluetooth speaker—no loss.

three speakers are assigned to their designated seats, following this order

Looking back,

looking back, the hardest part wasn't the hands-on practice, but figuring out what each speaker was missing. What Bluetooth lacks is a good battery—plug in and get around; 2.1 lacks nothing, but what it lacks is finding a device to connect it to; Passive ones need an amplifier, which costs thirty yuan to make up for it. The order of judgment is just three steps: First, check if there is a power port on the back. If there's a USB port, it's a Bluetooth box; if there's a 220V plug, it's an active box; if it's only a terminal, it's a passive box. Next, check whether the symptoms are in the battery or the interface; Next, the type is matched with the position.

when it's really too late to save it, throw it away: if the Bluetooth speaker is confirmed to be swollen, send it directly to the battery for recycling, don't treat it like ordinary trash; The speaker unit of a passive box can be disassembled and sold; good wooden boxes are still available in the second-hand market. Of the three of mine, the Bluetooth one stayed in the study, the 2.1 model was in the living room with the TV on the phone, the bookshelf box and amplifier were placed in the bedroom to connect to the NAS and listen to music—none of them were idle.