Equalizers

This circuit uses a single chip, IC BA3812L for realizing a 5 band graphic equalizer for use in hi-fi audio systems.The BA3812L is a five-point graphic equalizer that has all the required functions integrated onto one IC. The IC is comprised of the five tone control circuits and input and output buffer amplifiers. The BA3812L features low distortion, low noise, and wide dynamic range, and is an ideal choice for Hi-Fi stereo applica-tions. It also has a wide operating voltage range (3.5V to 16V), which means that it can be adapted for use with most types of stereo equipment.

This circuit allows you to equlize the audio signals in ten band. It uses low cost op-amps to form a professional equalizer circuit. The heart of the design is a classical band-pass active filter. The U11 acts as an attenuator to prepare the signal level for equlizing. The U13 acts as a final voltage amplifier to deliver the equlized audio signals to the next stage. The VCC is in range of +12 ~ +15 VDC and The VDD is in range of -12 ~ -15 VDC respectively.

Another one unit of graphic EQ. five bands. The basic difference with the other circuits is, that I use instead of IC, transistor and the power supply, go up in +/- 24V DC, ensuring low distortion and bigger margins of overloading. With switch S1, we can isolate the EQ. inside or except operation, leaving the musical signal to pass without no alteration.

Because of the increasing use of digital techniques in consumer audio equipment, National has developed a digitally controlled graphic equalizerΠthe LMC835. This chip replaces the potentiometers used in a conventional graphic equalizer with digitally controlled step-variable resistors, thereby allowing computer manipulation of an analog signal path. The LMC835 is configured such that a high degree of flexibility remains in the overall equalizer design, without compromising the quality of the analog signal path.

The volume control in a hi-fi amp or preamp (or any other audio device, for that matter), is a truly simple concept, right? Wrong. In order to get a smooth increase in level, the potentiometer (pot) must be logarithmic to match the non-linear characteristics of our hearing. A linear pot used for volume is quite unsatisfactory. Unless you pay serious money, the standard "log" pot you buy from electronics shops is not log at all, but is comprised of two linear sections, each with a different resistance gradient. The theory is that between the two they will make a curve which is "close enough" to log (or audio) taper. As many will have found out, this is rarely the case, and a pronounced 'discontinuity' is often apparent as the control is rotated.

Audio graphic equalizers are very common as commercial products (for Hi-fi, car audio and stage use) but circuits for them are very rarely published. I didn't design this one but it's really very simple. The details shown are for a 7 band but the principle can be extended to almost any number of bands - if you can find accurate enough components.

The circuit of graphic equalizer, allocates ten adjusting potesometer , that each one from them affects in a predetermined area of frequencies, the central frequency of which abstains a octave (double), from the central frequencies of her neighbouring regions. Each unit has common materials with remainder and it differs only in the capacity of capacitors that constitutes the filter in each unit. When the runner of fader regulation RV1 until RV10, is in the middle then we do not have no intervention of filter above in the signal that passes from in his and gain of particular unit, is one [ X1 ]. On the contrary if the runner is moved to a side of exit, the unit acts as filter of cutting off of area and it degrades the signals of predetermined area of frequencies.

The circuit constitutes a natural extension of Mic-Line balance unit, but can be adapted to any other audio circuit. It is made up of two units in the series : A) A classic unit bass/ Treble and B) a parametric unit of mid frequencies. Both units can also be used autonomously or each one separately, with the required buffer unit, from previous and subsequent circuits. With the R2 we requlate the High frequencies +/- 18 db/oct at 20 KHZ, with R5 the Low frequencies +/- 18bd/oct at 20 KHZ, with R11 the Mid freq. +/- 15 db/oct and with R10 the center of mid freq. at 200 HZ - 6 KHZ band.

This project is based on a 10 band October 1977 project from ETI (Electronics Today International). The center frequency of each band is determined by 2 caps, CA and CB. The schematic shows a table with values of CA and CB for various the center frequencies. This layout is for a 6 band equalizer. If you want to have a 5 band EQ instead, just don’t populate the CA, CB and pot positions for one of the channels. The first channel (62.5Hz) has very little effect with a 6 string, but would be more useful with a 7 string. This project can be powered with a single 9v battery. It is not recommended to power it with an AC adapter if that AC adapter also is powering other effects connected to this EQ. It can also be powered with a bi-polar (+/-) 9v supply for increased headroom. Refer to the schematic for power supply connection details. Current draw with a single 9v supply is 12.6 mA.

In audiophile circles, equalizers are prescribed only as a last resort to correct imbalances in recordings and room acoustics for loudspeaker playback. The case for using equalizers with headphones is simply this: headphones by their very nature change the tonal balance of music. The acoustic shaping that results from sound interacting with a listener's head and outer ears varies from person to person and is missing in headphones, which play directly to the eardrums. Therefore, not only does music in headphones have a different tonal balance than was intended, but each listener hears a slightly different presentation.

This project can be powered with a single 9v battery. It is not recommended to power it with an AC adapter if that AC adapter also is powering other effects connected to this EQ. It can also be powered with a bi-polar (+/-) 9v supply for increased headroom. Refer to the schematic for power supply connection details.

This is an image Schematic. No Description available.

This is an image Schematic. No Description available.

This equaliser is designed as a preamp suitable for musical instruments - guitar, bass and keyboard in particular. Unlike most conventional graphic equalisers, each slider ranges from fully off to fully on, and not the more conventional +/-12dB or so that is normally available. As a result, there is no flat setting (other than all off!). This graphic is designed to be used to create a sound, and is not suitable for hi-fi. It may be used as an add-on unit to existing instrument amp preamps, tone controls, etc. The flexibility is extraordinary, allowing a hollow "single frequency" type sound, right through to almost any tonal variant imaginable. This is the first of several projects based on the multiple-feedback bandpass filter described in Project 63, it can be made with as many (or as few) filter sections as you want.

This is an image Schematic. No Description available.

This is an image Schematic. No Description available.

This is an image Schematic. No Description available.

This is an image Schematic. No Description available.

This circuit uses a single chip, IC BA3812L for realizing a 5 band graphic equalizer for use in hi-fi audio systems.The BA3812L is a five-point graphic equalizer that has all the required functions integrated onto one IC. The IC is comprised of the five tone control circuits and input and output buffer amplifiers. The BA3812L features low distortion, low noise, and wide dynamic range, and is an ideal choice for Hi-Fi stereo applica-tions. It also has a wide operating voltage range (3.5V to 16V), which means that it can be adapted for use with most types of stereo equipment.

This is an image Schematic. No Description available.