The Leach Amp
The Leach Amp or "Low TIM Amplifier" is an amplifier design by Dr. Marshall Leach. He has a webpage which details the circuit design, you may wish to read it as well. I'd like to start off by thanking Dr. Marshall Leach for designing this amp, making the design available to the public for free, supporting his design, and continuing to sell manufactured PCBs (Printed Circuit Boards) for his design. It is truly a wonderful design and I couldn't be happier with my amp's performance. Don't be fooled by the low cost of the parts involved in this project, what you will be building is truly a world class amplifier. You could spend a few thousand dollars on a commercial amplifier and easily do worse than this design. Don't believe me? Read some of the comments. Dr. Leach has done the DIY community a great service. This design produces approximately 120W RMS per channel with an 8 ohm load and 240W RMS per channel with a 4 ohm load.
This project is, in my opinion, larger and more complicated than the other projects on this site so I've decided to sub-divide it. Understand this doesn't necessarily mean this project is "harder" than the other projects, it will probably take longer though. This guide is written so that it can (hopefully) be used by people with a variety of backgrounds in electronics, from the true novice who would follow it step-by-step to the seasoned veteran who would only glean ideas from my implementation. One thing that should be taken very seriously is the fact that this project deals with AC mains voltage and also the construction of a high capacitance power supply. It is extremely important that you take great care when building, testing, and using this amplifier. You could be hurt or killed by the electronics involved in this project while the circuit is connected to AC mains power as well as when it is NOT CONNECTED. The power supply capacitors will retain a charge for a period of time even after AC power is removed. Steps to discharge these capacitors and also warnings about when you need to be extra careful will be included, but my legal disclaimer still applies. That being said there is no reason why you should have to worry about hurting yourself if you follow this guide closely. Below is the overall circuit diagram designed by Dr. Marshall Leach.
Listed below you will find links to the parts lists that I've compiled, I've made several different formats available and hopefully you can find one that suits your particular situation. Please note at this point that the vendor listed for the majority of these parts is Digikey, I picked this vendor simply because they had a large amount of the parts I needed for the project and I felt they had good prices. I'm not affiliated with Digikey in anyway, but I do recommend them because I found their service excellent while building this amp. The other vendors I used are Parts Express, Apex Jr., and Best Byte. Dr. Leach is also listed as a vendor on this list because he is the source for the circuit boards I used. Dr. Leach has been gracious enough to offer these boards (designed by him) sold in pairs, at the time of my purchase they were $25 per pair. Please see Dr. Leach's website for details on order the boards.
These lists have been subdivided into lists of the parts needed for a single mono amp circuit board, a dual mono amp circuit boards, the power supply, and chassis. The first is a Microsoft Excel spreadsheet that includes part descriptions, quantities, vendors (with part numbers), and the prices that were current at the time. For some items the quantity shown is higher than the quantity actually required, this is noted beside the component description. The reason for this is because some components on the list had a minimum order quantity that had to be met, all of the quantities shown on the spreadsheet meet the minimum if it exists for that component. The second is that same Excel spreadsheet in HTML format. The third is a CSV (comma-delimited) file containing all the parts that I got from Digikey in quantities necessary for a single mono amp. The forth is a CSV (comma-delimited) file containing all the parts that I got from Digikey in quantities necessary for dual mono amps. The CSV files are useful because if you create an account with Digikey (which is free) they will allow you to upload parts lists in CSV format. Note the CSV files for the mono amp and dual mono amp also include the parts for the chassis I ordered from Digikey. I've tested these CSV files on Digikey's site and found it to work very well, I hope this will be a big time saver and also help eliminate incorrect orders caused by simple typing errors. For those of you interested in calculating an approximate cost for completing this project I've included totals at the bottom of all the sub-lists.
Leach Amp Dual Mono Amp List (CSV)
The remainder of this guide will be in the four sub-sections listed below. They are intended to be completed in the order they are listed, that is the chassis first, circuit board second, power supply third, and assembly last.
