Bass Bump Headphone Amp – Make:

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The bass bump headphone amplifier is an audio accessory you can build to enhance all of your private music listening. it has enough power to deliver clear sound and punchy dynamics through most headphones, or even a set of small speakers. Custom bass enhancement circuitry allows you to boost the music’s critical low-frequency spectrum to your liking. It sounds better than the headphone driver circuits in most smartphones and mp3 players because it has a lower source impedance and much higher drive current. this means that the sound of your headphones is not affected by factors such as long cables or impedance mismatches. All parts come from RadioShack, right down to the rechargeable battery and external charger. build one and you’ll notice the difference right away.

Reading: Bass bump headphone amp

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i chose the lm386 amplifier chip because it is easy to build: it is widely available, runs on a single power supply as low as 5v, and requires few external components. there are higher performance chips on the market often used in portable headphone amps but a dual power supply would be needed for a more sophisticated op amp circuit making the power and load electronics much more complex . the lm386 works fine and makes things simpler.

The bass bump headphone amplifier does not have a power switch: it is turned on by inserting the coaxial power plug from the battery clip into the coaxial jack connected to the amplifier circuit. in this way, two parts perform 3 functions: power switching (jack and plug), battery recharging (battery plug), and external power for the device (power jack). the plug and connector are very sturdy. for stationary use, you can also power your bass bump from a usb port, using a custom cable which we’ll also show you how to do.

The schematic shows one channel. The left side of the schematic is the input and tone control. The right side is the amp section. The signal comes in from the far left.

The schematic shows one channel. The left side of the schematic is the input and tone control. The right side is the amp section. The signal comes in from the far left.

How It Works

Resistor r8 provides a load for the source device, which reduces noise. the input signal is divided into two branches. the separation between frequencies occurs around 100 Hz, between the conventional mid and low ranges. high-frequency sounds pass through the c6/r3 junction and low-frequency sounds through r7/c5. series resistors r4, r5, and r6 connect the high-pass and low-pass filter outputs, recombining the frequencies. since r5 is a potentiometer, it can be used to control the extent to which the high-pass and low-pass outputs are mixed into the recombined signal. resistor r4 limits the maximum bass “cut” to about 3db, and resistor r6 limits the maximum “boost” to about 13db. note that r4 and r6 are different values ​​because we are more likely to want to “boost” than “reduce”.

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the signal from the filter enters the lm386 amplifier chip u1 through pin 3. resistor r1 provides a ground reference level for the input of the chip. capacitor c1 is a filter to ground any high frequency noise from the source device that travels that far. The chip is powered by a 9v battery or external power supply with the supply connected to pin 6. Pin 4 is connected to ground. capacitor c4 filters power supply noise.

pin 5 is the audio output of the amplifier. This pin adds a DC voltage equal to half the supply voltage (4.5V in the case of battery power, 2.5 in the case of USB) to the audio signal. capacitor c3 blocks this additional dc voltage from reaching the audio output and passes only the ac audio signal. r2 and c2 form a network called “zobel” to ensure a low impedance load at high frequencies and damp oscillations. resistor r9 acts as a reference to ground to prevent c3 from charging up and “bumping” when headphones are connected.

let’s build it!

See also: Sony MDR-NC500D Digital Noise Canceling review: Sony MDR-NC500D Digital Noise Canceling – CNET

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