Amplifier fixes
Headphone amplifiers are more complex than people imagine. At base, they are a chain of blocks, USB negotiation, a decoder, a digital–analogue converter, then an amplifier. That’s before design considerations like USB modes, source detection, power supply regulation, soft‐start, and meeting legal legislation. And the designers and builders don’t know what the amplifier will be plugged into, There’s a lot can go wrong, Fortunately, most of what goes wrong falls under a few headings.
I paid, it sounds no better
You are not hearing the wonderful music you think your phone can make. If you are playing some sound out of interest from a website, then you probably don’t care about the quality. But if you paid money to a provider, then downloaded good quality music files, you can be disappointed.
The cause
This may be a source/player/amplifier incompatibility. Since you are interested in this, I assume you know enough about specifications like bitrates and compression. Also you know enough about standards like MPG3 and FLAC. Those are not the issue here. The first issue is that not all players can handle all standards. Then that replay is not as simple as pushing the audio to the amplifier (you wont hear it often nowadays, but players used to stutter). Then the audio stream is decoded. The decoding reacts to music quality. Some cheap amplifiers grind down all sound, whatever the source, to one sample rate (they ‘resample’).
The fix
First, don’t blame the amp. It’s not the fault of a headphone amplifier if you give it a low‐quality signal. Try another player. Read about the format you are downloading, see which players others recommend. Then check the amplifier specification. Is it able to react to your high‐quality sound? There is at least one format (MVQ), which needs to be paid for, so not all amplifiers support it.
Occasional blips
You hear a small blip or pop, every few minutes or so.
The cause
This is almost always because you are using a cheap amplifier and are listening either to files stored on the device itself (not downloaded/streamed). The reason for the pop is not worth explaining here—if you want to know more, look up “synchronous amplifier sample rate”.
The fix
Involves settings, and maybe a dealbreaker. You need to change the settings on your device to run at a base 44.11Hz rate (same as CDs). Most computers run at an industry standard ???. Otherwise, stop playing downloaded music. Or put up with it. Or buy a more expansive amp.
Crackles
You hear a wavering crackle in the background.
The cause
Almost always because of interference from being picked up by the microphone cable. Occasionally, the interference comes from the device itself, through the cables—to check this, try plug the amplifier into other devices,
The fix
Another annoying issue, and enough to stop using the amplifier. It wasn’t just the washing machine, was it? If crackles are continuous, you’ll need to replace the device, amp, or headphones.
Sound is quiet (cause #1): Amp output Limiting
Sound is quieter than the item used without an amplifier.
The cause
Most plugin amplifiers, at any price, are louder than the device. However, amplifier manufacturers may limit the volume intentionally because,
Some manufacturers have reacted to potential EU regulation by dropping output power
Amplifiers may drop the volume with some headphones, to avoid blasting your ears
The fix
Well, the volume is low for a reason. If you do raise the volume, volume controls can become unusable, and the amplifier may start to distort. But them, a low volume can be annoying. And you can sometimes get better sound by playing a loud amplifier quietly. Confirmed that this fix can double the volume of some (usually big manufacturer) amps,
Without headphones, plug the amplifier in. It sounds nuts, but plug an extra cable, 3.5mm plug to 3.5mm socket, into the amp. The cable tricks the amp into thinking a massive load is attached, so the amp jerks up to full volume. Then plug in the headphones.
Plugging headpones/earphones in and out causes volume to drop (quiet sound, cause #2)
Note: you are pulling the headphones out of the amp, not the amp out of the device.
The cause
Most amplifiers try to remember what volume they were working at. Sounds wrong, but it’s true. It’s the amplifier that remembers, then it feeds back to the device. So, for no obvious reason, the device and amp work together to drop the volume a lot.
The fix
Pull the amplifier out of the device then push it back in. If this seems like a design flaw, perhaps it is. But you try to design a device in this way, then figure out how to make it work.
No sound, or sound is quiet/sounds like the amplifier is doing nothing (quiet sound, cause #3)
Especially if any sound is very like the sound of the device using it’s internal amplifier.
The cause
It’s what is called the ‘On The Go’ connection. Have you seen a comment that says, “I bought this [headphone amplifier], the sound was no better. Returning.”. Or “Unimpressive audio”? Or read a review that said an amplifier was good, but the review seemed unconvincing?
This may be an ‘On The Go’ (sometimes it’s called ‘Plug and Play’) connection issue. ‘On The Go’ is a connection mode for USB. It relies on electronics at each end, and a special cable. In this case, the mode is not triggered. So the computer or phone uses it’s own electronics to process the signal. The new amplifier is treated as a cable, and the result is that you hear sound almost exactly like the phone or computer. If you like, tou can do some checks,
If you are on a computer, and you know what I am talking about, check the driver
My computer will tell me if I am using the audio in the computer, or the amplifier. That’s a big help.
If you are using a phone, check the phone supports ‘On The Go’
Some older phones do not. Ways to check,
You may be able to find the name in a list online
Though the adverts are irritating, by far the sane method
Go online and find the specifications for your phone
Spec sheets may not be available for older phones, and short spec sheets will not tell you. An inefficient method, but a definitive result
If you have an Android phone, download an app
There are several checkers available in the Play Store e.g. USB OTG Checker. Personally, I find this very wrong, downloading an app to find data that should be listed in Settings. But, reputedly, the apps work ok
Incidentally, if you do not have OTG support, you can usually add it by replacing the operating system, so‐called ‘rooting’ the phone. This is way beyond what most people would want to try. But I thought I’d mention this solution because the web has a lot of bad advice about this.
The fix
Most people do not know what has happened so return the amplifier. However, you can sometimes coax OTG into working. On the device side, add an extra cable or connection block, Especially try cables or blocks that are USB‐C or USB‐A and labelled ‘On The Go’. Or try using a USB hub. If you have an Apple phone, the forum advice is to use the official Apple ‘Lightening to Camera’ adaptor. This is known to provoke an OTG connection.
Last note: about unwanted behaviour and headphone amplifiers
How often do these oddities happen? Well, This site is not a major or comprehensive tester of HiFi gear. But we do a lot of cross‐testing on different devices and cheap HiFi earphones. We do far more than most reviewers. And we’ve tested a handful of amplifiers. We’ve heard unintended behaviour, in some setups, from nearly all of them. Our experience is that buying from major manufacturers can be more reliable, but will not stop unwanted reactions. Spending more money only works for the ‘occasional blip’ error.
Some examples: On my test computer, I have a cable amplifier which splutters until it is re‐plugged. Another, if I select an unsuitable computer driver, blanks audio (others work). On the test phone, one dongle will not work at all. And one cable amplifier looses ‘On The Go’ (and inserting extra connections wreaks the tidiness of a cable, right?). Given the small size of our sample, but the wide range of our tests, we are saying every amplifier has had difficulties in some combination of equipment.
So my answer is that unexpected behaviours do not happen often, but happens enough to be more than a local failure. Note that this is not the fault of the manufacturer or the retailer. It’s hard to blame the ‘On The Go’ standards, too. OTG is used is used not only for headphones but, as far as I know, it’s original purpose was for printers. It would be nearly impossible to cover every combination of device and headphone.