Greetings from the UK to you and all at Ampslab.
As promised here are my thoughts on building and listening
to your LM60 amplifier kit. I was very impressed with the
delivery time after ordering (12days) The kit was supplied
with good quality components, a good PCB with heavy solder
tracks and component marking and a CD containing schematics,
component list, build and test instructions. I think the
inclusion of a photo of a completed board would be helpful.
You did supply me one when I ran into a minor problem of
my own making. in fact you could not have been more helpful.
For anyone able to solder the kit is simple and straightforward
if the instructions are carefully followed but care in soldering
is critical. I had a dry joint on 1 of my 2 boards which
caused biasing and overheating problems when tested. With
good help from Michael Chua this was resolved.
the 2 boards (Stereo format) case mounted I connected to
a single power supply, twin power supplies are recommended
and probably best, but I only had a single supply to hand.
This consisted of a 350Va - 24-0-24V toroidal transformer
and 2 x 10,000mF caps in each power line and a 35amp solid
state rectifier, giving me +/- 38vdc unloaded. This would
result in a very slight reduction in power from the 60wpc
output of the recommended power supply. Testing and biasing
is simple following the instructions. DC offset in my case
was about 5Mv and biasing set at the recommended 22Mv.
connected to my 2 way monitor speakers (Ribbon Tweeters)
with a frequency response from 35Hz - 40Khz and ran a a
CD for listening test. I was totally amazed. Here was a
very budget amplifier kit that had pretensions to be a Krell.
There was no trace of hum or any other extraneous noise
to interfere with the music even at high listening levels.
Instruments and performers were very firmly locked into
their own piece of the soundstage. Bass was very firm and
deep and the Treble was as clean and open as a whistle.