### Resistor color code

A resistor is the most important electrical component in almost every electronic circuit, it can limit current to any load such as led, transistor, opamp, etc. We must read resistor color code if we want to know the resistive value, tolerance, temperature coefficient. Resistors have different color bands (3,4,5,6) the more color bands the more resistor's information.Now let's start with 3 bands resistor color code.

The above resistor has only 3 bands First digit, Second digit, and multiply. A 3 bands resistor color code has fixed +/-20% tolerance that means if color code value is 1,000 ohms the real life resistive value may be +/- 200 ohms.
4 band resistor color code

A 4 bands resistor color code has tolerance value color strip, the resistor on an above picture has 5% tolerance. This type of resistor uses in a regular circuit such as television,radio,washing machine.

5 bands resistor color code

A 5 bands resistor color codes have third digit color bands.
1(first digit) 0(second dig…

## This bass boost diagram is easy to build and work well, I made it because people asked me the schematic diagram of bass boost diagram on my youtube channel.

The circuit has 9 dB gain@40 Hz that mean you will get good bass performance even you play music to a small speaker.
Why this circuit doesn't look like circuits on the internet?

Almost every circuit on the internet uses R/C filter between pre-amp and power amp stage to bypass high frequency to a ground and that seems audio signal being amplified and bypass to ground. I think it wastes pre-amplifier gain, the more gain preamp stage the more distortion to the audio signal, so I use a capacitor to send more negative feedback to pre-amp negative input when the frequency higher than cut-off frequency, capacitor impedance(resistance) higher when frequency lower and that make negative feedback decrease when frequency lower.

An op-amp distortion lowers when negative feedback higher, that mean high-frequency distortion lower when you use this circuit because frequency over cut-off frequency's total harmonic distortion being suppressed around 20 DBs more than normal R/C filter.

The C5 cap can be replaced with MKP type or polystyrene film cap with 1% Precision for the best result.

List of component:
potentiometer = 10 kilo-ohms
IC1 ne5534 (you can use another opamp that pin compatible to the ic)
R1,R6 = 1 kilo-ohms
R2,R3 =10 kilo-ohms
R4,R5 = 4.7 kilo-ohms
C1,C3 = 2.2 uf 16 volts
C2,C4 = 47 uf 16 volts at least (no more than 100 uf)
C5 = 0.1 uf
C5 value can be change depend on your listening behavior
0.1uf = + 15dB(gain = 6 times)@159 Hz and + 17.84dB(gain = 7.8 times)@80 Hz and then + 19.39dB(gain = 9.33 times)@40 Hz good for very small speaker, 2 way car speaker
0.2 uf = + 15dB(gain = 6 times)@80 Hz  good for small speaker
0.4uf = +15dB(gain = 6 times)@40 Hz   good for someone that love deep bass boost and big speaker

See testing video