How to choose the resistance value of the potentiometer2021

When we are choosing a potentiometer, we all need to set a resistance value for the potentiometer. The resistance range of the Shengwei potentiometer is between 1K and 1000K. Regarding what kind of resistance value should be customized for the potentiometer, Shengwei Electronic found a post on calculating the resistance of the potentiometer from the Internet for your reference.

Many friends ask me a question when buying a potentiometer: Is it better to use a 50K or 100K? This question is easy to answer but not easy to explain clearly in one sentence.

The good answer is simple: select the resistance of the potentiometer according to the needs of the circuit diagram. If it is much simpler for people who are preparing to build a machine, just select it directly according to the value on the circuit diagram. But there are also many people who change the potentiometer of the original machine or want to use a better one, so the question arises; what value potentiometer is more suitable?

The following suggestions are only user feedback summaries and personal practical experience, and only for the situation of electronic tube machines:

Suggestion: If you understand the circuit, if you are using a tube machine, if you know the gate-drain resistance of the preamplifier tube, then it is more appropriate to choose a potentiometer with a value of about 5 times smaller gate-drain resistance, such as The gate-drain resistance of your pre-amplifier tube is about 250K, so choose a 50K potentiometer. If your gate-drain resistance is 1M ohms, then 250K is more appropriate. What if you don’t use gate-drain resistors? Do you like to use the potentiometer directly and also have the function of gate-drain resistance? Then it is recommended to use a potentiometer with a large resistance value, such as at least 250K or more (500K or more is best). As for why? This is related to the resistance of the potentiometer to ground and the working principle of the tube. Finding relevant information and searching for the function of the gate-drain resistance will know one or two things, and I won't go into details here. However, my personal suggestion is generally to add gate-drain resistance.

Generally speaking, the resistance value above 50K is suitable for the electronic tube machine, but the larger the better. Of course, compared with the previous machines with low output impedance (usually a few hundred ohms), it is possible to use potentiometers above 10K (the principle of impedance matching at the front and rear stages: the front is low, the output is high, and the input is higher. More suitable for signal transmission), there are many abroad The data also shows that it is more appropriate to use a 10K resistance potentiometer for passive front-stage volume control. Some people say that the larger the resistance, the better the signal-to-noise ratio, but from the actual use effect, unless individual circuits and experience, it is not that the larger the better, there will be obvious differences in the sense of hearing, too large resistance The potentiometer will make you feel over-controlled, and the sound tends to lack vitality (in other words: feel the sound is compressed and can't let go). The reason is actually because the potentiometer with too large resistance is more likely to affect the actual attenuation to the ground resistance in the direction of louder volume. Although theoretically there is so much attenuation per gear, it is because of the gate-drain resistance. The reason is that the volume attenuation value will change after the potentiometer is incorporated into the circuit, especially the higher the volume, the more obvious the gear. If the gate-drain resistance is not used, it may be different (the potentiometer has the same effect on the ground resistance part), but also pay attention to the requirements of some pre-tubes for the gate-drain resistance (for example, some tubes require it The resistance of the gate-drain resistance should not be greater than much. It is best to look at the technical data of the front-end tube, which will be explained in the general technical data).