The name of VR is VARIABLE RESISTOR variable resistor. The general machine is used to adjust the size of the signal. It is used for volume control, balance on the left and right, high and low knobs on the audio ... all. This component is continuous. The adjustment step (sliding type) is very poor in stability and susceptible to instability caused by temperature and humidity. Please refer to the related instructions of the electronic component books for other. VR is a new product because most human ears are concerned about sound It is slower to detect, but after a period of time, you will feel that the sound of the left and right channels will drift, and the instrument cannot be accurately positioned.After a long time, there will be noise when you rotate the potentiometer. It will get worse and worse, some people blame the East and West, change planes, change lines, and go to the doctor in a hurry. Also in vain. The volume potentiometer can choose general potentiometer, such as ALPS.Noble and so on. Or buy a Swiss Elma rack and add 0.1% Holco precision resistors to form a progressive potentiometer (the rich person ’s choice, this potentiometer is two thousand oceans), or make a progressive volume switch yourself. The advantage of the former is that it is easy to buy, but the sound quality of general commercial products of dozens of yuan is not very ideal, and the error of the two channels is usually not small, which seems to be inconsistent with the spirit of HI-FI; if you buy high-end products, the price is quite The high-end expensive machine is seen here, so the 24k gold plated contact switch is welded with a fixed resistance ranging from 24 to 60 segments to ensure a more stable quality. The latter is a multi-band switch (usually more than 25 bands), welding resistors with different resistances, and mimicking the action of the potentiometer.The advantage is that the error of the two channels is very small, and when using a more advanced resistor, In contrast, the better the sound quality, the disadvantage is that the multi-band band switch is not easy to buy, and the quality is good, the price is not cheap; after a period of time, the contact is easy to oxidize, producing noise. The best is a fully sealed band switch. Of course, there is no doubt that this type of stepping resistor is better than potentiometer. It is generally like Cello, Krell, Mark Livinson, Jadis, MBL ... and the fixed resistance of the multi-stage series switch used by my MATISSE is welded. This design can greatly reduce the size of the parallel type and can have continuous Multi-segment volume switching (generally about 24 ~ 60 segments), the use is no different from traditional cheap VR, but the sound quality is indeed difficult to compare with VR, the disadvantage is that because the series is multi-stage, so the number of fixed resistors is amazing Hundreds cannot be run away, and the error of using ultra-precision resistors must be below 0.1 ~ 0.5%. You can use Holco, Vishy Dale, Philips ... resistors. At the same time, the quality of SW is better, which is why this kind of stuff sells you 3 to 6,000 yuan. You can buy finished products at various fever parts shops. If you use VR that is not the general specification, you must make it yourself. The formula that can be substituted into 20 Log Av can be stepped in about 0.5 ~ 0.8dB per segment. figure 1 100K VR (The unit is Ω. It can be seen from the figure above that the resistance of this potentiometer is in series (referred to as a series resistance progressive potentiometer), its noise is also superimposed, and the signal passes through 25 resistors at low volume.) Figure 1 is a 25-band band switch.If it is not available (or too expensive), it can be replaced by a six-band band switch.For the calculation of attenuation resistance, please refer to the formula in Figure 2 below. 100K VR
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250K VR
0
0
549
15.0K
150
402
174
511
221
634
274
825
348
1.00k
453
1.21k
576
1.82k
715
2.21k
909
2.61k
1.21k
3.32k
1.50k
3.92k
1.91k
5.11k
2.43k
6.81k
3.16k
8.25k
3.92k
10.5k
5.11k
14.0k
6.81k
18.2k
8.25k
22.6k
10.0k
27.4k
12.1k
33.2k
14.0k
39.2k
15.0k
45.3k 
250K VR
R1
R2
R1
R2
100k
0Ω
249k
0Ω
100k
100Ω
249k
1.50k
100k
332Ω
249k
1.91k
100k
681Ω
249k
2.43k
100k
1.00k
249k
3.16k
97.6k
1.21k
249k
3.92k
97.6k
1.82k
243k
4.99k
97.6k
2.43k
243k
6.19k
97.6k
3.16k
243k
8.25k
95.2k
3.92k
243k
10.0k
95.2k
5.11k
237k
12.1k
93.1k
6.81k
237k
15.0k
93.1k
8.25k
237k
20.5k
90.9k
10.0k
226k
24.3k
86.6k
12.1k
221k
32.4k
84.5k
15.0k
221k
39.2k
80.6k
20.0k
205k
49.9k
75.0k
24.3k
182k
60.4k
68.1k
32.4k
169k
98.7k
60.4k
39.2k
150k
97.6k
49.9k
49.9k
121k
121k
37.4k
63.4k
93.1k
150k
20.5k
78.7k
49.9k
205k
0.00Ω
100k
0.00Ω
249k 
