In this article we look at the signal chain of a turntable and systematically examine which parts can be possible answers to the question “Why does my turntable sound distorted?”. Of course, we don’t leave it at that but also try to minimize the distortions wherever possible.
Distortion vs. hum vs. noise
To begin with, we need to agree on what exactly distortions are. Colloquially, we often summarize all effects that sound somehow annoying as distortion. Because different effects arise in different ways, they require different remedial measures. That’s why it’s important to clearly separate the terms. So let’s first start with what distortions are not.
Hum
Hum usually occurs when the frequency of the power grid couples into the signal chain. Depending on the country, this signal is 50Hz or 60Hz and sounds like, well, a hum. This interference signal is typically independent of the actual signal. So you can hear it even if the stylus isn’t touching a record at all. If you would like to learn more about reducing hum, I recommend this article.
Noise
The most common noise sources are amplifiers. Of course, manufacturers attach great importance to keeping noise as low as possible. In practice, however, you can only minimize this effect and never eliminate it completely. Like hum, noise is typically independent of our desired signal and occurs permanently as well. Noise is similar to the hissing sound that occurs when your inflatable doll has a leak.
Distortion
According to Wikipedia’s definition, distortion is “…the alteration of the waveform of an information-bearing signal…”. Yeah, uhhm, totally!? But what does that mean in real life? In contrast to hum and noise, there is no additional interference signal which adds to the desired signal. In case of distortion, the desired signal itself is changed. Attention nerds: we’re talking about creating harmonics that, depending on their characteristic, can potentially be annoying.
The signal chain of a turntable
To systematically answer the question “Why does my turntable sound distorted?” let’s look at the signal chain of a typical turntable. It starts with the record and ends with the speaker. Since cables are more prone to hum than distortion, I will ignore them hereafter.
The record as a source of distortion
Dirty record
On the record, the audio signals are pressed into the surface and are therefore exposed to the environment. Scratches, dust and also dirt such as fingerprints can accumulate here and lead to distortions. The simplest countermeasure is of course to handle it carefully in order to protect the record from contamination as best as possible. An anti-static brush can remove loose dust before each play.
Worn record
When scanning the record, the stylus slides through the groove of the record and creates friction. This friction causes the diamond tip to mill the pressed signals every time it is played. This effect is minimal and the durability of records is impressive. Nevertheless, a record is subject to wear and tear and therefore does not last forever. Since the shape of the pressed signals changes when it wears out, we are dealing with distortions here. To check whether distortions come from the record, you can compare it with another, preferably new one. Sometimes records can also have errors when pressed. Then a new copy will also sound distorted. Since this is rather the exception, I would like to mention it here just for the sake of completeness.
The stylus as a source of distortion
The stylus samples the signals from the record with its diamond tip and passes these signals on to the cartridge in the form of mechanical vibration. Since the shape of the signals can also be altered here, let’s look at the two most likely reasons.
Dirty stylus
The stylus scans the surface of the record and collects all possible dirt and dust. You can use a special anti-static brush to remove loose dirt and dust from the tip. A magnifying glass can help you get a closer look.
Worn stylus
The tip is made of diamond or sapphire, for good reason: it should be as stable as possible and wear little. However, it is not possible to do so without wear and tear, which is why the stylus eventually wears out after a few thousand hours. To check, take the cartridge out of the tonearm and check the tip for irregularities using a watchmaker’s magnifying glass.
The cartridge as a source of distortion
In my opinion, the most important part when it comes to why your turntable sounds distorted is the cartridge. Since it mechanically connects the stylus to the tonearm, crucial settings such as tracking force, anti-skating and alignment are effective here. Let’s look at them one by one.
Tracking force too low
The tracking force ensures that the stylus can perfectly follow the shape of the pressed signals. If it is set too low, the stylus loses contact with the groove and begins to bounce. This is an obvious alteration of the waveform and is why it is such an annoying form of distortion. This effect typically occurs with loud passages, as this is where the amplitude is highest. To remedy this, adjust your tracking force properly. I’ll describe how to do this in this article.
Anti-Skating set incorrectly
Insufficient adjustment of the anti-skating as well as too little tracking force will cause the stylus to bounce in the groove. In this article you will learn how best to do this and perhaps already answered the question “Why does my turntable sound distorted?”.
Cartridge misaligned
In order to sample the signals from the groove true to the original, the stylus must be aligned exactly parallel to the groove. Since the tone arm performs a circular movement over the record, an angle inevitably arises between the stylus and the groove, the so-called tracking angle error. By properly aligning the cartridge, you can eliminate this angle error in two spots of the record’s radius. In all other positions there remains a more or less large tracking angle error, which leads to more or less severe distortions. The choice of these two points and their implementation are therefore an essential step towards reducing distortions. I will also address this in a separate article.
The phono stage as a source of distortion
Depending on the system installed (MM or MC), the phono stage has a high or even higher gain. Although these amplifier stages are designed to produce very little distortion, clipping can occur under certain circumstances. As we already know, the level of MM systems is significantly higher than that of MC systems. If you connect an MM system to the MC input, the amplifier will be overdriven, which will result in significant distortion in addition to the high volume of the signal. If the phono amplifier (regardless of whether it is internal or external) has an MC input, pay attention to connect only MC cartridges here.
The power stage and the speakers as sources of distortion
In the final section we look at the last two possible answers to the question “Why does my turntable sound distorted?”. I’ve summarized them because there’s basically not much to say about them. A defective power amplifier always sounds bad, regardless of whether it is driven by a turntable or another source. It’s the same with the speaker. With amplifiers, the relays at the output can often become dirty and thus produce a scratchy sound. This is particularly the case when listening at low volumes for a long time. At high volumes, the contacts “burn free” again, which makes the remedy very easy and quite entertaining. Your neighbor will definitely understand this factual explanation and share your enthusiasm. Just believe…