February 2014 ~ AmplifierCircuits

LM4910 Stereo Headphone Amplifier

Circuit description:

LM4910 belonging to the Boomer series of National Semiconductors is an integrated stereo amplifier primarily intended for stereo headphone applications. The IC can be operated from 3.3V ans its can deliver 0.35mW output power into a 32 ohm load. The LM4910 has very low distortion ( less than 1%) and the shutdown current is less than 1uA. This low shut down current makes it suitable for battery operated applications. The IC is so designed that there is no need of the output coupling capacitors, half supply by-pass capacitors and bootstrap capacitors. Other features of the IC are turn ON/OFF click elimination, externally programmable gain etc.

Circuit diagram:

Circuit diagram of the LM4910 stereo headphone amplifier is shown above.C1 and C2 are the input DC decoupling capacitors for the left and right input channels. R1 and R2 are the respective input resistors. R3 is the feed back resistor for left channel while R4 is the feed back resistor for the right channel. C3 is the power supply filter capacitor. The feedback resistors also sets the closed loop gain in conjunction with the corresponding input resistors.

The IC is available only in SMD packages and care must be taken while soldering.

The circuit can be powered from anything between 2.2V to 5V DC.

The load can be a 32 ohm headphone.

Absolute maximum supply voltage is 6V and anything above it will destroy the IC.

A logic low voltage at the shutdown pins shut downs the IC and a logic high voltage at the same pin activates the IC. Original aritcle sourse circuitsproject.com

Battery-powered Headphone Amplifier

Description:

Some lovers of High Fidelity headphone listening prefer the use of battery powered headphone amplifiers, not only for portable units but also for home "table" applications. This design is intended to fulfil their needs and its topology is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-B arrangement. Output power can reach 100mW RMS into a 16 Ohm load at 6V supply with low standing and mean current consumption, allowing long battery duration. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability.

Battery-powered Headphone Amplifier Circuit diagram

For a Stereo version of this circuit, all parts must be doubled except P1, SW1, J2 and B1. Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to maximum resistance and Trimmer R3 to about the middle of its travel. Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output. Switch on the supply and measure the battery voltage with a Multimeter set to about 10Vdc fsd. Connect the Multimeter across the positive end of C4 and the negative ground. Rotate R3 in order to read on the Multimeter display exactly half of the battery voltage previously measured. Switch off the supply, disconnect the Multimeter and reconnect it, set to measure about 10mA fsd, in series to the positive supply of the amplifier. Switch on the supply and rotate R6 slowly until a reading of about 3mA is displayed. Check again the voltage at the positive end of C4 and readjust R3 if necessary. Wait about 15 minutes, watch if the current is varying and readjust if necessary. Those lucky enough to reach an oscilloscope and a 1KHz sine wave generator, can drive the amplifier to the maximum output power and adjust R3 in order to obtain a symmetrical clipping of the sine wave displayed.

Technical data:

Output power (1KHz sinewave):

16 Ohm: 100mW RMS

32 Ohm: 60mW RMS

64 Ohm: 35mW RMS

100 Ohm: 22.5mW RMS

300 Ohm: 8.5mW RMS

Sensitivity: 160mV input for 1V RMS output into 32 Ohm load (31mW)

200mV input for 1.27V RMS output into 32 Ohm load (50mW)

Frequency response @ 1V RMS:

flat from 45Hz to 20KHz, -1dB @ 35Hz, -2dB @ 24Hz

Total harmonic distortion into 16 Ohm load @ 1KHz:

1V RMS (62mW) 0.015% 1.27V RMS (onset of clipping, 100mW) 0.04%

Total harmonic distortion into 16 Ohm load @ 10KHz:

1V RMS (62mW) 0.05% 1.27V RMS (onset of clipping, 100mW) 0.1%

Unconditionally stable on capacitive loads

Class-A Headphone Amplifier

This circuit is derived from the Portable Headphone Amplifier featuring an NPN/PNP compound pair emitter follower output stage. An improved output driving capability is gained by making this a push-pull Class-A arrangement. Output power can reach 427mW RMS into a 32 Ohm load at a fixed standing current of 100mA. The single voltage gain stage allows the easy implementation of a shunt-feedback circuitry giving excellent frequency stability.

The above mentioned shunt-feedback configuration also allows the easy addition of frequency dependent networks in order to obtain an useful, unobtrusive, switchable Tilt control (optional). When SW1 is set in the first position a gentle, shelving bass lift and treble cut is obtained. The central position of SW1 allows a flat frequency response, whereas the third position of this switch enables a shelving treble lift and bass cut.

Before setting quiescent current rotate the volume control P1 to the minimum, Trimmer R6 to zero resistance and Trimmer R3 to about the middle of its travel.

Connect a suitable headphone set or, better, a 33 Ohm 1/2W resistor to the amplifier output.

Connect a Multimeter, set to measure about 10Vdc fsd, across the positive end of C5 and the negative ground. Switch on the supply and rotate R3 in order to read about 7.7-7.8V on the Multimeter display.

Switch off the supply, disconnect the Multimeter and reconnect it, set to measure at least 200mA fsd, in series to the positive supply of the amplifier. Switch on the supply and rotate R6 slowly until a reading of about 100mA is displayed. Check again the voltage at the positive end of C5 and readjust R3 if necessary. Wait about 15 minutes, watch if the current is varying and readjust if necessary.

P1          : 22K  Dual gang Log Potentiometer 
R1          : 15K 
R2          : 220K
R3          : 100K
R4          : 33K 
R5          : 68K 
R6          : 50K 
R7          : 10K 
R8,R9       : 47K 
R10,R11     : 2R2 
R12         : 4K7
R13         : 4R7
R14         : 1K2
R15,R18     : 330K
R16         : 680K
R17,R19     : 220K
R20,R21     : 22K
C1,C2,C3,C4 : 10µF/25V 
C5,C7       : 220µF/25V
C6,C11      : 100nF
C8          : 2200µF/25V
C9,C12      : 1nF
C10         : 470pF
C13         : 15nF
D1          : LED
D2,D3       : 1N4002 
Q1,Q2       : BC550C 
Q3          : BC560C  
Q4          : BD136   
Q5          : BD135   
IC1         : 7815
T1          : 15CT/5VA Mains transformer
SW1         : 4 poles 3 ways rotary Switch 
SW2         : SPST slide or toggle Switch

Mobile Car Stereo Player TDA1554

Using a mobile phone while driving is dangerous. It is also against the law. However, you can use your mobile phone as a powerful music player with the help of a stereo power amplifier. This does away with the need of a sophisticated in-dash car music system. Most mobile phones have a music player that offers a number of features including preset/manual sound equalisers. They have standard 3.5mm stereo sockets that allow music to be played through standard stereo headphones/sound amplifiers. Nokia 2700 classic is an example.

Mobile Car Stereo Player Circuit Diagram

A car audio amplifier with 3.5mm socket can be designed and simply connected to the mobile phone output via a shielded cable with suitable connectors/jacks (readymade 3.5mm male-to-male connector cable is a good alternative). Fig. 1 shows the circuit of car stereo player. It is built around popular single-chip audio power amplifier TDA1554Q (IC1). The TDA1554Q is an integrated class-B power amplifier in a 17-lead single-in-line (SIL) plastic power package.

IC TDA1554Q contains four 11W identical amplifiers with differential input stages (two inverting and two non-inverting) and can be used for single-ended or bridge applications. The gain of each amplifier is fixed at 20 dB. Here it is configured as two 22W stereo bridge amplifiers. The amplifier is powered from the 12V car battery through RCA socket J2. Diode D1 protects against wrong-polarity connection. LED1 indicates the power status.

Stereo Jack :

(a) 3.5mm stereo socket and (b) 3.5mm Stereo Jack

Connect stereo sound signal from the 3.5mm headset socket of the mobile phone to audio input socket J1. When you play the music from your mobile, IC1 amplifies the input. The output of IC1 is fed to speakers LS1 and LS2 fitted at a suitable place in your car. Electrolytic capacitor C5 connected between pin 4 of IC1 and GND improves the supply-voltage ripple rejection. Components R2 and C4 connected at mute/standby pin (pin 14) of IC1 eliminate the switch on/off plop. The circuit is quite compact. A good-quality heat-sink assembly is crucial for IC1. Fig. 2 shows the stereo socket and stereo jack.

Proposed enclosure

Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Small dimensions of the power amplifier make it suitable for being enclosed in a plastic (ABS) case with vent holes. Signal input socket, speaker output terminals, on/off switch, indicator, fuse holder and power supply socket are best located on the front panel of the enclosure as shown in Fig. 3.
Author : T.K. Hareendran - Copyright : EFY

Stereo Amplifier Circuit Diagram with TDA7052

BTL Stereo Amplifier Circuit Diagram with TDA7052

2/02/2014

Amplifier Circuit 2W

Amplifier description:

This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone output. Of course, in most cases you will have to make two boxes to obtain stereo. The circuit was deliberately designed using no ICs and in a rather old-fashioned manner in order to obtain good harmonic distortion behavior and to avoid hard to find components. The amplifier(s) can be conveniently supplied by a 12V wall plug-in adapter.Closing SW1 a bass-boost is provided but, at the same time, volume control must be increased to compensate for power loss at higher frequencies. In use, R9 should be carefully adjusted to provide minimal audible signal cross-over distortion consistent with minimal measured quiescent current consumption; a good compromise is to set the quiescent current at about 10-15 mA. To measure this current, wire a DC current meter temporarily in series with the collector of Q3.

Amplifier circuit diagram:

Amplifier circuit partlist:

P1----------10K

R1----------33K

R2----------33K

R3----------33R

R4----------15K

R5----------1K

R6----------1K

R7----------680R

R8----------120R-1/2W

R9----------100R-1/2W Trimmer Cermet

C1 ----------10µF-63V

C2 ----------10µF-63V

C3-----------100µF-25V

C4-----------470µF-25V

C5-----------47pF-63V

C7-----------470µF-25V

C6-----------220nF-63V

C8-----------1000µF-25V

D1-----------1N4148

Q1-----------BC560C

Q2-----------BC337

Q3-----------TIP31A

Q4-----------TIP32A

SW1---------SPST switch

SPKR--------3-5 Watt Loudspeaker

Mini Portable Guitar Amplifier

Guitar Circuit description:

This small amplifier was intended to be used in conjunction with an electric guitar to do some low power monitoring, mainly for practice, either via an incorporated small loudspeaker or headphones. The complete circuit, loudspeaker, batteries, input and output jacks can be encased in a small box having the dimensions of a packet of cigarettes, or it could be fitted also into a real packet of cigarettes like some ready-made units available on the market. This design can be used in three different ways: Loudspeaker amplifier: when powered by a 9V alkaline battery it can deliver about 1.5W peak output power to the incorporated loudspeaker. Headphone amplifier or low power loudspeaker amplifier: when powered by a 3V battery (2x1.5V cells) it can drive any headphone set type at a satisfactory output power level or deliver to the incorporated loudspeaker about 60mW of output power. This configuration is useful for saving battery costs. Fuzz-box: when powered by a 3V battery (2x1.5V cells) and having its output connected to a guitar amplifier input the circuit will behave as a good Fuzz-box, showing an output square wave with marked rounded corners, typical of valve-circuits output when driven into saturation.

Guitar amplifier circuit diagram:

Guitar amplifier partlist:

R1__________22K 1/4W Resistor
C1__________10µF 25V Electrolytic Capacitor
C2__________100nF 63V Polyester or Ceramic Capacitor
C3__________220µF 25V Electrolytic Capacitor
IC1_________TDA7052 Audio power amplifier IC
J1,J2_______6.3mm Stereo Jack sockets (switched)
SPKR_______8 Ohm Loudspeaker (See Notes)
B1_________9V PP3 Battery or 3V Battery (2 x 1.5V AA, AAA Cells in series etc.)
Clip for PP3 Battery or socket for 2 x 1.5V AA or AAA Cells

Technical data:

Max output power: 1.5W @ 9V supply - 8 Ohm load; 60mW @ 3V supply - 8 Ohm load
Frequency response: Flat from 20Hz to 20kHz
Total harmonic distortion @ 100mW output: 0.2%
Max input voltage @ 3V supply: 8mV RMS
Minimum input voltage for Fuzz-box operation: 18mV RMS @ 3V supply
Current consumption @ 400mW and 9V supply: 200mA
Current consumption @ 250mW and 9V supply: 150mA
Current consumption @ 60mW and 3V supply: 80mA
Quiescent current consumption: 6mA @ 9V, 4mA @ 3V supply
Fuzz-box current consumption: 3mA @ 3V supply

Crowbar Speaker Protection

Description

Crowbar circuits are so-called because their operation is the equivalent of dropping a crowbar (large steel digging implement) across the terminals. It is only ever used as a last resort, and can only be used where the attached circuit is properly fused or incorporates other protective measures.

A crowbar circuit is potentially destructive - if the circuitry only has a minor fault, it will be a major fault by the time a crowbar has done its job. It is not uncommon for the crowbar circuit to be destroyed as well - the purpose is to protect the device(s) attached to the circuit - in this case, a loudspeaker.

There's really nothing to it. A resistor / capacitor circuit isolates the trigger circuit from normal AC signals. Should there be enough DC to activate the DIAC trigger, the cap is discharged into the gate of the TRIAC, which instantly turns on ... hard. A TRIAC has two basic states, on and off. The in-between state exists, but is so fast that it can be ignored for all intents and purposes.

The BR100 DIAC (or the equivalent DB3 from ST Microelectronics) is rated for a breakdown voltage of between 28 and 36V - these are not precision devices. Needless to say, using the circuit with supply voltages less than around 40V is not recommended, as you will have a false sense of security. The supply voltage must be higher than the breakdown voltage of the DIAC, or it cannot conduct. Zeners cannot be used as a substitute for lower voltages - a DIAC has a negative impedance characteristic, so when it conducts, it will dump almost the full charge in C1 into the gate of the TRIAC. This is essential to make sure the TRIAC is switched into conduction.

The TRIAC is a common type, and may be substituted if you know the specifications. It's rated at 12A, but the peak current (non-repetitive) is 95A, and it only needs to sustain that until the fuse (or an output transistor) blows. A heatsink is preferred, but there is a good chance that the TRIAC will blow up if it has to protect your speakers, so it may not matter too much. The 0.47 ohm resistor is simply to ensure that the short circuit isn't absolute. This will limit the current a little, and increases the chance that the TRIAC will survive (albeit marginally). Feel free to use a BT139 if it makes you feel better - these are rated at 16A continuous, and 140A non-repetitive peak current.

The peak short circuit current will typically be about 90A for a ±60V supply, allowing ~0.2 ohms for wiring resistance and the intrinsic internal resistance of the TRIAC, plus the equivalent series resistance of the filter capacitors. That's a seriously high current, and it will do an injury to anything that's part of the discharge path. Such high currents are not advised for filter caps either, but being non-repetitive they will almost certainly survive.

Construction & Use

Apart from the obvious requirement that you don't make any mistakes, construction is not critical. Wiring needs to be of a reasonable gauge, and should be tied down with cable ties or similar. C1 must be polyester. While a non-polarised electrolytic would seem to be acceptable, the circuit will operate if the capacitor should dry out over the years. This means it will lose capacitance, and at some point, the crowbar may operate on normal programme material. This would not be good, as it will blow up your amplifier!

Make sure that all connections are secure and well soldered. Remember that this is the last chance for your speakers, so it needs to be able to remain inactive for years and years - hopefully it will never happen. The circuit doesn't have to be mounted in the amplifier chassis - it can be installed in your speaker cabinet. Nothing gets hot unless it operates, at which point no-one really cares - it just has to save the speakers from destruction once to have been worthwhile.

Remember that the crowbar circuit absolutely must never be allowed to operate with any normal signal. A perfectly good amplifier that triggers the circuit because of a high-level bass signal (for example) will very likely be seriously damaged if the crowbar activates. To verify that no signal can trigger it, you may want to (temporarily) use a small lamp in place of R2, and drive the amp to maximum power with bass-heavy material.

A speaker does not need to be connected. If the lamp flashes, your amp would have been damaged. If this occurs, you may want to increase the value of C1. Note that bipolar electrolytics should never be used for C1, because they can dry out and lose capacitance as they age. This could cause the circuit to false-trigger.

Origianl article sourse learningelectronics.net

70 Watt Guitar Amplifier

Guitar Amplifier description:

Guitar Amplifier parts list:

R1______________18K 1/4W Resistor

R2_______________3K9 1/4W Resistor

R3,R6____________1K 1/4W Resistors

R4_______________2K2 1/4W Resistor

R5______________15K 1/4W Resistor

R7______________22K 1/4W Resistor

R8_____________330R 1/4W Resistor

R9,R10__________10R 1/4W Resistors

R11,R12_________47R 1/4W Resistors

R13_____________10R 1W Resistor

C1_______________1µF 63V Polyester Capacitor

C2_____________470pF 63V Polystyrene or Ceramic Capacitor

C3______________47µF 25V Electrolytic Capacitor

C4______________15pF 63V Polystyrene or Ceramic Capacitor

C5_____________220nF 100V Polyester Capacitor

C6_____________100nF 63V Polyester Capacitor

D1,D2,D3,D4___1N4148 75V 150mA Diodes

Q1,Q2________BC560C 45V 100mA Low noise High gain PNP Transistors

Q3,Q4________BC556 65V 100mA PNP Transistors

Q5___________BC546 65V 100mA NPN Transistor

Q6___________BD139 80V 1.5A NPN Transistor

Q7___________BD140 80V 1.5A PNP Transistor

Q8__________MJ2955 60V 15A PNP Transistor

2/01/2014

Mosfet Audio Amplifier 25W

General description:

Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need. Q6 & Q7 must have a small U-shaped heatsink. Q8 & Q9 must be mounted on heatsink. Adjust R11 to set quiescent current at 100mA (best measured with an Avo-meter in series with Q8 Drain) with no input signal. A correct grounding is very important to eliminate hum and ground loops. Connect in the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 at output ground. Then connect separately the input and output grounds at power supply ground.

Amplifier circuit diagram:

Part list:

R1,R4 = 47K 1/4W Resistors
R2 = 4K7 1/4W Resistors
R3 = 1K5 1/4W Resistors
R5 = 390R 1/4W Resistors
R6 = 470R 1/4W Resistors
R7 = 33K 1/4W Resistors
R8 = 150K 1/4W Resistors
R9 = 15K 1/4W Resistors
R10 = 27R 1/4W Resistors
R11 = 500R 1/2W Trimmer Cermet
R12,R13,R16 = 10R 1/4W Resistors
R14,R15 = 220R 1/4W Resistors
R17 = 8R2 2W Resistor
R18 = R22 4W Resistor (wirewound)

C1 = 470nF 63V Polyester Capacitor
C2 = 330pF 63V Polystyrene Capacitor
C3,C5 = 470µF 63V Electrolytic Capacitors
C4,C6,C8,C11 = 100nF 63V Polyester Capacitors
C7 = 100µF 25V Electrolytic Capacitor
C9 = 10pF 63V Polystyrene Capacitor
C10 = 1µF 63V Polyester Capacitor

Q1-Q5 = BC560C 45V100mA Low noise High gain PNP Transistors
Q6 = BD140 80V 1.5A PNP Transistor
Q7 = BD139 80V 1.5A NPN Transistor
Q8 = IRF532 100V 12A N-Channel Hexfet Transistor
Q9 = IRF9532 100V 10A P-Channel Hexfet Transistor

Power supply circuit diagram:

Part list:

R1 = 3K3 1/2W Resistor
C1 = 10nF 1000V Polyester Capacitor
C2,C3 = 4700µF 50V Electrolytic Capacitors
C4,C5 = 100nF 63V Polyester Capacitors
D1 200V 8A Diode bridge
D2 5mm. Red LED
F1,F2 3.15A Fuses with sockets
T1 220V Primary, 25 + 25V Secondary 120VA Mains transformer
PL1 Male Mains plug
SW1 SPST Mains switch

Low pass filter - Subwoofer

General description

The acoustic spectrum is extended by very low frequencies 20Iz and reaches as the 20000Iz in high frequencies. In the low frequencies is degraded the sense of direction. This reason us leads to the utilization speaker for the attribution of very low frequencies. The manufacture that to you we propose distinguishes these frequencies, in order to him we lead to the corresponding amplifier. The acoustic filters are met in various points in the sound systems. The knownest application they are the filters baxandal for regulating tone low and high frequencies and filters crossover where the acoustic region is separated in subareas, in order to it leads the corresponding loudspeakers. The application that to you we propose is a simple filter of region that limits the acoustic region (20-20000Hz) in the region 20-100Hz.

With the manufacture that to you we propose you can make a active filter in order to you lead a loudspeaker of very low frequencies. With this you will place one bigger speaker between the HIFI speakers of you. In order to you have a complete picture of sound you will need also the corresponding amplifier. In the entry of circuit you will connect the two exits of preamplifier or the exit of line of some preamplifier. The circuit of manufacture allocates a exit in order to is led means of circuit of force subwoofer. If for some reason you do not have space in order to you place the third speaker in space of hearing, then you can select smaller speaker. The output will depend from the type of music that you hear. If in deed you have space, then after you make a filter and remain thanked, you can him recommend in your friends or still make other same for your friends.

Circuit diagram:

In the form it appears the theoretical circuit of filter. In first glance we see three different circuits that are mainly manufactured round two operational amplifiers. This circuits constitute mixed, amplifier with variable aid and a variable filter. The manufacture end needs a circuit of catering with operational tendency of catering equal with ±12. the operational amplifiers that constitute the active elements for this circuits of are double operational type as the TL082 and NE5532. The operational these amplifiers belong in a family provided with transistor of effect of field IFET in their entries. Each member of family allocates in their circuit bipolar transistor and effect of field. This circuits can function in his high tendency, because that they use transistor of high tendency. Also they have high honor of rhythm of elevation (slew rate), low current of polarization for the entries and are influenced little by the temperature. The operational these amplifiers have breadth of area unity gain bandwidth 3MHz. A other important element for their choice is the big reject of noise, when this exists in the line of catering.

The price of reject is bigger than 80dB, their consumption is small, from 11 until 3 mA. They are internally sold in nutshell with eight pins and allocate two operational amplifiers, In the same line in nutshell 14 pins they incorporate four operational, In the trade they are sold with code TL074, TL084 and TL064, In nutshell with eight pins they are sold operational amplifiers TL061 TL071 kajTL081. In the manufacture we used the TL082 that has two operational. First operational from the TL082 it works as amplifier and mixed for the two channels, In his negative entry he exists one small mixed with two resistances. A potentiometer in this rung determines the aid of circuit. In the point this left winger and the right channel of preamplifier they are added means of two resistances. En continuity the operational strengthens signal with aid made dependent from the price that has the potentiometer.

The place of runner is proportional with the aid of circuit. The second operational amplifier is the filter of manufacture. The filter of is acoustic frequency of second class and he is made with the materials that are round the operational amplifier. The filter of is low passage with variable frequency of cutting off. This frequency can be altered and take prices from very low frequency the 30Hz or still exceed 150Hz. The frequency of cutting off of filter depends from the prices that have the elements of circuit. Altering the values of elements we can have frequency of cutting off 150Iz, 130Iz, J00Iz, 7Ïz, 6Íz even 3Íz, this prices they can be achieved with the simple rotation of double potentiometer. The circuit of filter has been made around one operational' that it has completed TL082 that is double operational amplifier. In the exit of filter we will link the plug of expense where is connected the amplifier. In the exit of circuit is presented, the limited as for the breadth of frequencies, signal that we apply in the entry of circuit.

Part list:

R1 = 39 Kohm

R2 = 39 Kohm

R3 = 47 Kohm

R4 = 10 Ohm

R5 = 22 Kohm

R6 = 4,7 Kohm

R7 = 22 Kohm

R8 = 4,7 Kohm

R9 = 10 Ohm

R10 = 220 Ohm

C1 = 39 pF

C2 = 0.1 uF

C3 = 0.1 uF

C4 = 0.2 uF

C5 = 0.4 uF

C6 = 0.1 uF

C7 = 0.1 uF

IC1 = TL064

PCB and layout:

Detail of subwoofer

Variations in the anatomy of a subwoofer dramatically changes their performance characteristics. An increase in voicecoil size coupled with a stronger cone material yields a higher power handling and increased output. By combining quality materials with Rockford’s proprietary acoustic technologies, our subwoofer lineup is sure to meet your system’s demands.

Basket - Also referred to as the frame or chassis, this is the skeletal system of the speaker. Here to keep everything in its place.

Spider - Second part of the speakers suspension, connects the cone and voice coil to the basket and controls the travel of the cone assembly.

Voice Coil - The brains of the operation, directing the force from the magnet to push or pull based on the applied electrical signal.

Surround - First part in the speakers suspension, attached to the cone to maintain the centering of the voice coil in the magnetic gap.

Cone - A.K.A the diaphragm, this is the voice of the speaker. Shape and material dramatically change tonality.

Magnet - The heart of speaker, creating the force to push and pull cone assembly. Size, material, and design may differ, depending on performance goals.

Original sourse article rockfordfosgate.com

MAX98500 Amplifier circuit 1x2.2W

MAX98500 general description:

The MAX98500 is a high-efficiency Class D audio amplifier that features an integrated boost converter, to deliver a constant output power over a wide range of battery supply voltages. The boost converter operates at 2MHz, requiring only a small (2.2µH) external inductor and capacitor. The automatic level control has a battery tracking function that reduces the output swing as the supply voltage drops, preventing collapse of battery voltage. The amplifier has differential inputs and an internal fully differential design. The MAX98500 also features three gain settings (6dB, 15.5dB, and 20dB) that are selectable with a logic input. The MAX98500 is available in a small, 0.5mm pitch 16-bump WLP package (2.1mm x 2.1mm). It is specified over the extended -40°C to +85°C temperature range.

MAX98500 applications:

Active Speaker Accessories

Cell Phones

GPS Devices

Mobile Internet Devices

Smartphones

Data Sheet

MAX98500 features:

Boosted Class D Output

Integrated Automatic Level Control

Output Power

2.2W into 8Ω, 10% THD+N

1.7W into 8Ω, 1% THD+N

Wide 2.5V to 5.5V Supply Voltage Range

Undervoltage Lockout Protection

High Total Efficiency of 87%

High Step-Up Switching Frequency (2MHz)

Active Emission Limiting for Low EMI

MAX98500 circuit diagram:

MAX98500 circuit diagram