Matthew Cattle's Website

The time is and it is

DIY Audio
The website where I got most of the information that allowed me to make my 'Gain Clone'. My nickname there is matttcattt.

Texas Instruments
The website of Texas Instruments. This is where I got my free samples of the OPA541, OPA548 and OPA549 High Power Operational Amplifiers.

This site is a member of WebRing. To browse visit here.

This is Matthew Cattle's website. My hobbies include electronics, robotics and HiFi. This website is about these hobbies. This page is about HiFi as this is my most active hobby at the moment.

I have finished making my first amplifier, a stereo 'Gain Clone'. I chose to make this amplifier due to its simplicity (only 7 components per channel and a simple unregulated power supply) and price, as I got the amplifier chips free as samples from Texas Instruments. I first started using the OPA548 High Power Operational Amplifier as this was the least powerful of the chips that I got as samples. I made a simple Gain Clone using the circuit below and used my bench power supply to power it.

Fig.1

The amplifier worked first time and I was impressed with the results. I though that, for such a simple circuit, the amplifier was very good. I do not have a detailed opinion on the quality of sound as I am not an audiophile. If you were looking to make a simple amplifier as a first project, I would recommend a 'Gain Clone'.

I decided then to make a more powerful copy of this amplifier using the OPA541 High Power Operational Amplifier's that I got as free samples. I was impressed with the results of this amplifier as well, considering the low- quality components I used. A picture of this amplifier is below.

Both the above amplifiers were power by my bench power supply for testing, with the positive supply of one for the positive rail, the 0v of this supply, and the positive supply of the other for ground, and the 0v of the second supply for the negative power rail. This gave me +/- 0-30v supplies, of up to one amp, easily enough for testing purposes.

I then found two 15v 5A supplies, and used these as the above. I am still in the constructional stages for my final power supply. This will be a large supply of +/-40v. This supply shall be able to provide my amplifier with enough power.

At the testing stage, I used 4,700uf per rail as I had these capacitors lying around at the time of construction. Soon after finding the two 15v supplies, I found four 33,000uf capacitors and I am now using two of these per rail, giving 66,000uf total per rail. This amount of capacitance, in my opinion gives much better bass. This is because bass uses more power than treble, and with large capacitor banks, the capacitors help provide the required power.

I have just made a Gain Clone using the circuit below. This circuit uses two OPA541/9 Power Operation Amplifiers, in parallel configuration, to allow the use of 4ohm speakers with the amplifier, unlike one using a single IC, which could not handle a 4ohm load.

Fig.2

After this, I tried the circuit below, which uses the same method as the one above, but using 4 OPA541/9 Power Operation Amplifiers to allow the amplifier to theoretically power 2ohm speakers safely (not having any 2 ohm speakers, I paralleled two 4ohm ones).

Fig.3

I also tried the two circuits below, which use two, and four OPA541/9 Power Operation Amplifiers to achieve two and four times the power of a single IC, respectively, using bridged configuration. I used the Texas Instroments DRV134 for IC1.

Fig.4

Fig.5

I then worked on construction of a 6 channel Gain Clone for car audio use. 4 channels will use Fig.4, and 2 channels will use Fig.5. this is a total of 16 OPA541/9 Power Operation Amplifiers. The four channels will be for two front and two back speakers, and the two, more powerful channels will be for two sub woofers.

Making a large power supply for this amplifier would be expensive to build, so I currently use two separate 12v batteries to get the +/-12v supply required, and trickle charge the batteries.

My latest amplifier is a subwoofer amplifier using Figure 5, the bridged parrallel circuit with OPA541 chips to achieve ~100W into an 8 ohm load. This amplifier is complete and in use, but I dont have any photos of it completed.

Here are some photos of my prototype, and the final amplifiers:

My first test setup. You can see the amplifier in the top right, the star ground in the center, the star +V and -V connections at the bottom, and in the top left corner, two large electrolytics (33,000uf). +V is red, -V is black, and ground is yellow. The wires in the bottom right are the speaker outputs.(~9/03)