Making fun of with the clone ...

Part 1: Design

Last modified: 16-Apr-2003


About a year ago I joined the Gainclone addicts. I still prefer tube amplifiers and I just finished a power supply for the Loekie phono equaliser, but at the same time I'm challenged to build the best sounding amp based on a monolithic chip design.

For the first GeenKloon amp I received a few samples from Sodejuu, two LM3875 which I used for GeenKloon and two LM1875 which I put on the shelve since I wanted more output power than the 25Watts of the LM1875.

However, at this moment I have some spare components and therefore I'm looking for a way to make use of the two remaining amp chips.

Amp Design

For this amp I'm planning to use the inverted design. For cost purposes I will make use of a 12-step attenuator but use general available cheap metalfilm resistors or stick to a high-quality stereo pot. An ALPS blue pot or a 24-step switch may be on the expensive side, but a 12-step attenuator is an economical alternatives.

The LM1875 has a smaller package than the TO-220 package used for the LM3875. As a result, the feedback resistor can not be connected the same way I did for the LM3875. On the positive side: The package does not contain many unused pins.

The following components will be used:

The schematics used for the GainClown are as follows:

I'm still undecided about the input capacitor. If there is no DC at the input it can be omitted without problem.

Power Supply

The power supply is almost identical to the GeenKloon PS. Only the power transformer is not 2*22 but 2*16-18 Volts. I have a spare(/junk) 2*16.5 Volts transformer which I will use for a start.

I'm looking at/for the following component list:

The picture above shows the connector side of the amp.


  1. Craig Fraser Gainclone homepage
  2. Fedde Bouwman's Thor Amp page
  3. More info and links on my GeenKloon page


Read more about the construction of this project on page two.

Page 2: Construction>>


©, April 2003, 2006