Low pass filter for subwoofer

admin January 4, 2011 74 Comments
Description. Many low pass filter circuits for subwoofer are given here and this is just another one. The circuit given here is based on the opamp TL062 from ST Micro electronics. TL062 is a dual high input impedance J-FET opamp which has very low power consumption and high slew rate. The opamp has excellent audio characteristics and is very suitable for this circuit. Out of the two opamps inside TLC062, first one is wired as the mixer cum pre...
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Active Filter Types

jojo April 14, 2011 No Comments
Types of Active Filters Butterworth, Chebyshev, Bessel and Elliptic filters. There are basically 4 types of active  filters. They are butterworth, Chebyshev, Bessel and Elliptic filters. Butterworth Filter: This filter is also called as maximally flat or flat flat filter. This class of filters approximates the ideal filter well in the pass band. Frequency response curves of different types of filters are shown in figure. The Butterworth filter has an essentially flat amplitude-fre­quency response upto the cut­off frequency. The sharpness...
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State Variable Filters

jojo April 14, 2011 2 Comments
With the advancement in IC technology, a number of manufacturers now offer universal filters having simultaneous low-pass, high-pass, and band-pass output responses. Notch and all-pass functions are also available by combining these output responses in the uncommitted op-amp. Because of its versatility, this filter is called the universal filter. It provides the user with easy control of the gain and Q-factor. It is also called a state-variable filter.   The filters we have discussed so far are relatively simple...
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All pass filters

jojo April 14, 2011 5 Comments
An all-pass filter is that which passes all frequency components of the input signal without attenuation but provides predictable phase shifts for different frequencies of the input signals. The all-pass filters are also called delay equalizers or phase correctors. An all-pass filter with the output lagging behind the input is illustrated in figure.   The output voltage vout of the filter circuit shown in fig. (a) can be obtained by using the superposition theorem vout = -vin +2vin...
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Band Stop Filter

jojo April 14, 2011 12 Comments
The bandpass fil­ter passes one set of frequen­cies while reject­ing all others. The band-stop filter does just the opposite. It rejects a band of frequencies, while passing all others. This is also called a band-reject or band-elimination filter. Like band­pass filters, band-stop filters may also be classified as (i) wide-band and (ii) narrow band reject filters. The narrow band reject filter is also called a notch filter. Because of its higher Q, which exceeds 10, the bandwidth of the...
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Band Pass Filters

jojo April 14, 2011 12 Comments
Band Pass Filter A band-pass filter is a circuit which is designed to pass signals only in a certain band of frequencies while attenuating all signals outside this band. The parameters of importance in a bandpass filter are the high and low cut-off frequencies (fH and fl), the bandwidth (BW), the centre frequency fc, centre-frequency gain, and the selectivity or Q. There are basically two types of bandpass filters viz wide bandpass and narrow bandpass filters. Unfortunately, there is...
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Higher Order Filters

jojo June 13, 2011 2 Comments
Higher Order Filters From the discussion made so far on the filters, it may be concluded that in the stopband the gain of the filter changes at the rate of 20 db/decade for first-order filters and 40 db/decade for second-order filters. This means that as the order of the filter is increased, the actual stopband response of the filter approaches its ideal stopband characteristics. In general, a third-order filter produces 60 db/decade, a fourth-order filter produces 80 db/decade and...
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Butterworth Filter

jojo October 7, 2009 No Comments
In many low-pass filter applications it is necessary that the closed-loop gain is as close to unity as possible within the passband. The Butterworth filter is best suited for such applications. This filter is also called a maximally flat or flat-flat filter. Ideal and the practical frequency responses for three types of Butterworth low-pass filters are depicted in fig. (a) by solid line and dashed lines respectively. As the roll-off becomes steeper, they approach the ideal filter characteristics more...
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Classification of Active Filters

jojo October 7, 2009 62 Comments
The most widely used active filters are (i)                 low-pass (ii)                 high-pass (iii)                band-pass (iv)               band-stop or band reject (also called the band-elimination or notch) and (v)                 all-pass filters. All of these filters use op-amps as the active elements and R-C networks. Although the 741 type op-amp operates satisfactorily in these filter circuits, high­-speed op-amps like the LM 318 or ICL 8017 improve the performance of the filter circuits through their increased slew rates and higher unity GBW. Low Pass...
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Active and Passive filters

jojo October 7, 2009 2 Comments
Active and Passive filters – A Comparison: The simplest approach to building a filter is with passive components (resistors, capacitors, and inductors). In the R-F range it works quite well but with the lower frequencies, inductors create problems. AF inductors are physically larger and heavier, and therefore expensive. For lower frequencies the inductance is to be increased which needs more turns of wire. It adds to the series resistance which degrades the inductor’s performance. Input and output impedances of...
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