CloneKit

Gainclone Monoblocks based on a board/kit of BrianGT

Page 2: Construction

Last modified: 08-Sep-2004

Parts

As said before, once the amp kit is assembled and the two small PCB's are ready, there are not many parts needed to build an amp. The picture on the left shows all components needed for assembly, this is for one channel of-course, and as you can see it will be small monoblocks. The panel in the upper left is the combined heat-sink and shield for the toroid. Also shown quite well in the picture is that I kept the rectifier and amp section of the boards together.

The Amplimo toroid transformer is the 120VA version which is the largest value fitting in the box. I'd rather have the 160VA toroid but it's size (11 cm diameter) is simply too large so I had to settle for less. All components on the board are supplied with the kit, I did order the deluxe kit after finding out that I'd had to pay a lot more myself should I want to order the chips and resistors separately.

The speaker terminals are NOT the WBT ones but a nice look-alike which sells for less than half the price and works just as well. Not shown in the picture is the power switch which I half-way the building process.

Box

I decided to cut the PCB in two, one for each channel. This means that each halve of the PCB kit contains a recification section and the amp itself.

It will be a real challenge mounting both the power transformer and the amp/rectifier PCB in the box. A few millimeters room for a vertical screen will probably all I have for mounting the toroidal in the box. So I'll try to mount the toroidal vertically. The other way would have been to mount the toroid vertically which would have given me much more space but would also have meant I'd had to find a stable/rigid mounting method for it.

Partlist power Supply section (for one channel only):

Building

The construction process is in this case rather simple: Once the board has been completed the only thing left to do is find their best place in the box and solder transformer leads to the board and connect it to the speaker and input terminals.

In my case I wanted to shield the toroidal transformer from the amp itself so I had to carefully divide the available roo into two compartments. This was done by a small vertical aluminum plate which shields the transformer from the rest. The wire going to and from the transformer are passed through holes in the plate and twisted carefully in order to minimise their influence on the sound.

The fact that there was so little room left for the amplifier board itself has some advantages too: Input and speaker cable leads can be kept VERY short.

After measuring the resulting DC-offset for one channel I was very pleased: Just 2.8mV DC with the standard parts (no tweaking).

Result

This is a picture of the finished amp (first channel) without the power switch which is located under the AC inlet. On the other pictures of the finished set, the power switch is already present (but this was a picture just a few hours before finishing the second amp).

Please continue on the next page for a listening impression (which will be there once I finished both channels of-course).

© Maarten@Platenspeler.com, 2004