Passive EQ for STAX

Posted on Feb 4, 2014

Many audiophiles reject equalizers for various reasons, some of which relate not to the EQ circuit itself (or algorithm) but to the surrounding `glue` of op-amps, transistors, A/D and D/A converters etc. The only `passive` EQ I`m aware of is horribly expensive and is not actually 100% passive - it contains some amplifying glue to restore the signal to a usable level. [Hint: Look up the values of inductors

Click here to download the full size of the above Circuit.

you might typically find in a speaker crossover. ] Needless to say, these suckers are not shelf items! It would be nice if they were air-cored but some ferrite may be necessary, especially for L1, where I estimate 250 metres of wire could be necessary otherwise. This is not something you want to try and wind by hand. If you can locate a reel of enamelled wire with both ends of the copper sticking out then you should be so lucky. The good news is you don`t need fencing wire for these - even as fine as SWG 34 (or AWG 31 = 0. 23mm diameter) should be OK, as the impedances are quite high and a few ohms of resistance won`t upset things. The inductors should be placed well apart from each other in a metal box. If you don`t have an inductance meter (who does ), the tank circuits L1-C1 and L2-C2 can be tuned with an audio oscillator and a multimeter. The inductors should be in place in the box when you do this. 2. A Lambda response plot produced by Moller et al. from the article "Transfer Characteristics of Headphones Measured on Human Ears", Journal of the Audio Engineering Society, v43, #4, April 1995, p215. Those Toko inductors are a great find! I searched a bit but didn`t turn up anything with those kinds of values, and they are so compact too(!) This involves compromises of course - they are obviously using a very fine guage of wire so the DC resistance is near the top of the tolerable range. [More than 1 ohm per mH would be...

Visit page

Leave Comment

characters left:

Related Circuits

cd4047 based squarewave inverter oscillator

This simple and cheap(but powerful) squarewave oscillator can give oscillation to any mosfet based inverter/ups. The circuit consists of one central I. C CD4047. I used HCF4047BE from ST...

Cheapest High power LED driver circuit diagram

If you came here through Google, then you might have seen other circuits too for high power LED driving which consists of much parts, like inductors, op-amps, different regulator IC`s, transistor...

convert square wave inverters to sine wave inverter

There`s pretty easy to make squarewave inverters` circuits in the internet. But to run most load like fan, TV, etc you need to have a sinewave inverter. Making sinewave or near-sinewave inverter is...

simple preamplifier for microphones tape heads etc

This circuit consists of a single transistor as amplifier and it gives a nice amplification to weakest and unipolar signals for feeding to a real amplifier. Don`t post your email or phone number in...

simplest modified sinewave inverter without microcontroller

Most of the inverters in the market uses modified sinewave for better output at competitive cost. The modified sinewave unit uses a 50% fixed PWM squarewave and the hikes are balanced by a...

Solar to 6V Batt to LED emergency light circuit

Today we discuss about a simple solar LED circuit. We know that solar panels comes from 12Volt 3watt to larger sizes. So, for storing energy, we need a 12Volt battery. As we don`t want jhamela`, we...

atmega8 voltmeter

This is V2 update of Atmega8 Volt-Ammeter. This new version features the following upgrades, Low power consumption Better Amperes display resolution while using low value drop resistor. Much...

tda2030a amplifier circuit used in home theaters

This IC require less external components too, making it easier for a beginner to make this on veroboard. The original circuit I got from it`s datasheet. A little modified circuit below, This can be...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....