Phono Preamp Buyer's Guide
If you didn’t know, you can actually hear the music on your record without any electricity at all. If you are in a quiet room and turn the speakers down to zero, you can actually hear the music playing as a thin, tinny version of itself. That’s what’s being translated into electrical signals by the stylus and cartridge. Still, the strength of that electrical signal is very, very weak and before you can enjoy the music loudly and proudly, it needs to be amplified.
That low-level signal needs to be carefully amplified by a separate component known as a “phono preamp”. The signal strength that goes into the preamp is known as “phono level” audio and what comes out is known as “line level”. The line level standard is what audio equipment amplifiers or any other audio equipment expect to receive.
OK, so why not just use any old preamp? Well, thanks to various issues around the technical nature of vinyl record pressing itself, the audio frequencies encoded in the vinyl are distorted in a very specific way. A phono preamp is designed to undistort that standardized distortion so that the frequencies come out “flat” before they get processed more by subsequent components.
Many lower-end record players have a built-in preamp, but for the most part they are “switchable”, which means that you can turn them off and use an external preamp instead. Why would you want to do this? Well, not all preamps are made equal. The quality of the signal could be degraded from what the turntable itself naturally produces. You may find, therefore, that at a later stage you can get better audio from your existing record player just by using another preamp.
If you have bought a higher-end unit the chances are that it won’t come with a preamp at all! So in that case you have to buy a preamp and them some active speakers or a separate amplifier and passive speakers.
Given that most vinyl fans are going to have to deal with the issue of preamps at one point or another, this short guide will highlight the main questions you’ll have to deal with when picking out your very own preamp.
Here is a pretty big one that has started so many online fights – tube preamps.
Tube preamps are an alternative to solid state preamps. What’s the difference? Well, solid state amps use silicon transistor components such as those in your iPhone to process and amplify the signal. They’re digital devices. Tube preamps, on the other hand, use analogue tubes and valves to do the same job.
The main argument is that putting the warm and analogue signal from a record player through a digital preamp defeats the purpose of the whole thing, but there are two sides to every story.
Tube amps do have “clipping” or volume cutoffs that are smoother and less jarring. They are also more resistant to voltage spikes and other electricity weirdness that can damage or cause malfunctions in solid state digital gear. Some people also feel that they have a wider dynamic range, but hearing that difference is not always easy.
On the other hand, they are physically fragile, power-hungry, and comparatively expensive.
Solid state preamps clip more sharply and distort the sound more often at high volume levels. Transistors will also pick up radio interference from, for example, GSM cellphone transmissions which come over as clicks and buzzes on the speakers.
That’s not actually such a common problem and solid state amps are by far the most popular since they cost much less, are hardier, and more reliable. When they do break, however, it’s often cheaper just to throw them out, whereas tube amps can often be repaired for less than the price of a new one.
Solid state units are also smaller, lighter, and can withstand travel. So if you want to move your audio equipment around often, you’ll have to take extraordinary care if it uses tubes.
Preamps come at lots of different price points and, generally, the more expensive they are the better they will sound. Your preamp is one component in an overall audio system where each device has its own positive or negative effect on the audio quality.
Generally you want to match components so that they do not cause performance bottlenecks. What does this mean? Well, there’s no point in having a $1000 turntable and then pairing it with a $50 preamp. Whatever amazing quality you are getting from that player is lost after it has been through the cheap amp. The final sound quality can only be as good as the weakest component in the chain.
There is a mild exception to this. You may want to buy a better turntable for now, and then use cheaper downstream components with the idea that you’ll upgrade them over time. That’s fine and understandable, but of course in the long run it will cost you more than simply waiting until you have the budget available for the components that you want.
Form of a Bear
It’s very important that you not only pay attention to the specifications of a preamp, but also to its physical dimensions. Some are designed to go into a rack or stack system. Many tube amps have to be free-standing to accommodate the tall tubes. This can look great, but if you don’t have the space for it that’s a problem.
Make sure that the preamp you are looking at has inputs that match the connector type on your turntable, and that it has outputs that are compatible with the amp or active speakers you want to connect it to. As far as possible you do not want to resort to adapters or other modifications. Every extra piece you add into the chain can be the cause of sound quality issues.
While most record players use a moving magnet (MM) cartridge, you’ll sometimes run into ones that use the more expensive and supposedly superior moving coil (MC) type of cartridge.
How much better MCs are is a talk for another day, but if you have one you need a special sort of preamp that can amplify the MC’s much weaker signal. The nature of such amps is also too much to talk about here; the bottom line is make sure the cartridge and preamp you have will work together.
Pay attention to what the preamp lets you control. Is it more than you need or less? Only you can decide, but be sure that you know what knobs you are allowed to turn.
There is one important thing to remember when taking ownership of your preamp. It can take two or so weeks before it starts to deliver its promised quality. The capacitors in particular need some time to form their “anodic films”. This only applies to preamps that use electrolytic capacitors though; those that use solid ones should be perfect out of the box.