Equalizers

Graphic Equalizer circuit

This complete high quality, low noise 5-BAND GRAPHIC EQUALIZER circuit is based around Monolithic Linear integrated circuit LA3600 manufactured by SANYO. This circuit is very easy to build and has good Quality. You can use it with Portable component stereos, tape-recorders, radio-cassette recorders, car stereos etc... It is On-chip one operational amplifier. 5-band graphic equalizer for one channel can be formed easily by externally connecting capacitors and variable resistors which fix fo (resonance frequency)...

Active crossover circuit

A simple 3-way crossover, intended for triamping Hi-Fi systems. This is a conventional 12dB / Octave unit, and cannot be expected to have the same performance as a Linkwitz-Riley aligned filter network. It will still be a vast improvement over nearly any passive crossover, and is ideal for beginners or those who want to experiment further with multi-amping, but without the complexity of a major project. The retuning (to (sub)-Bessel / Linkwitz-Riley alignment) is recommended, as the performance will be more in line with modern standards - see information below...

Expandable Graphic Equaliser circuit

The project described in this article is a constant Q, fully expandable graphic equaliser. Where most "conventional" graphic EQ circuits have a Q that is dependent on the setting of the pot, this one maintains the same Q at all settings. This is achieved by using MFB (Multiple Feedback Bandpass) filters, instead of the more common "gyrator" tuned circuit. As always, there are pros and cons for the approach described here. Phase shifts tend to be a little more radical, and the passband has more ripple than a conventional circuit, but only where a number of sliders are set to boost or cut. On the positive side, specific frequencies are dealt with specifically regardless of the level, and not with a variable Q. The constant Q circuit makes room equalisation and feedback reduction far better behaved...

Quality Graphic Equalizer

Graphic Equalizer Pro is a professional real-time graphic equalizer for Windows 9x/Me/NT/2000/XP. It will add up to 12 dB of boost or cut at any of 15 bands centered around the International Standards Organization (ISO) 2/3 octave frequencies from 20Hz to 20kHz. This two channel system offers completely independent channel control. The perspective used in designing Graphic Equalizer Pro was to obtain the warmth off a classical analog equalizer with the clarity and the accuracy of the digital domain processing. This was achieved adopting the best analog equipment’s topology...

Equalization Circuit

2 versions of the equalization circuit, the first having 6 db less insertion loss than the other. However, some may not be able to find a .68 microfarad capacitor. The second version uses a more common .22 microfarad capacitor. Both of these circuits operate to reduce the frequencies above 2 kHz with a 6db/oct slope until 15 kHz, where they turn flat once again. The source impedance will have a significant effect on the properties of the passive networks and should be less than 50 ohms. These circuits are only for the beyerdynamic DT990 Pro headphones...

5-Band Graphic Equalizer with LA3600

This complete high quality, low noise 5-BAND GRAPHIC EQUALIZER circuit is based around Monolithic Linear integrated circuit LA3600 manufactured by SANYO. This circuit is very easy to build and has good Quality. You can use it with Portable component stereos, tape-recorders, radio-cassette recorders, car stereos etc.....

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. ..

Vinyl equalisation (EQ) has been with us in a stable and predictable form for quite a long time, but for those who are interested in the old 78 rpm records there are a great many problems to overcome. One of these is obtaining a turntable that runs at 78 rpm, and preferably has the range to cover the somewhat variable actual recording speed, which can apparently be anything from 60-odd to over 84 rpm...

I came up with this idea when I was in a situation where ... * I had an amplifier with an unused RIAA input and * I was missing another input for a standard audio signal at this amplifier. So I designed a miniature passive network to convert a normal audio signal into the signal that phono inputs require...

The Linkwitz transform circuit (or EAS principle) will allow any driver to extend to 20 Hz or even lower. A good quick test is to stick the speaker in a box, and drive it to 50 or 100W or so at 20 Hz - you should see a lot of cone movement, a few things will rattle, but you shouldn`t actually hear a tone. A "bad" speaker will generate 60 Hz (third harmonic) - if you don`t hear anything, the speaker will work in an equalised sub...

Using a single op-amp this easy to make equalizer offers three ranges, low frequency,mid frequency,and high. With component values shown there is approximately +/-20dB of boost or cut at frequencies of 50Hz, 1kHz and 10kHz. Supply voltage may be anything from 6 to 30 Volts. Maximum boost 20dB is only realized with maximum supply voltage...

In essence, it uses the same principle as a graphic equaliser, but the simulated inductors are made variable, so the frequency can be swept back and forth. The four 10K pots provide cut (when on the left or anti-clockwise side of centre) or boost, and in the centre position have no effect at all. Maximum boost and cut is about 12 to 14dB (typical)...

A quick word is warranted here, to allow you to determine if the speaker you have will actually work in a small sealed enclosure. The Linkwitz transform circuit (or EAS principle) will allow any driver to extend to 20 Hz or even lower. A good quick test is to stick the speaker in a box, and drive it to 50 or 100W or so at 20 Hz - you should see a lot of cone movement, a few things will rattle, but you shouldn`t actually hear a tone. A "bad" speaker will generate 60 Hz (third harmonic) - if you don`t hear anything, the speaker will work in an equalised sub...

The circuit shown in Figure 1 uses only two ICs, and has a bandwidth that is adjustable from more than one octave down to a tenth of an octave. As shown, the frequency range is 20 Hz. to 20 KHz. in three bands, although a fourth subsonic band could be added to allow very low frequency analysis. A low-noise mike preamplifier is included, and a line input is also available with up to 20 dB of gain. Of course, you could use a mike preamp in your console instead, but at the expense of portability...

If you`re into playing with tone controls and notch filters to see how they change the sound out of your effects, you will undoubtedly have built several glops of R`s, C`s and pots, maybe some L`s to make up the tone networks. While this is fun, it`s not very flexible. Sooner or later you might wonder if there is a more general solution to messing with tone controls...