Do It Yourself Electronics
Kappa 22w and Calor Gold 40w A class by dr.Bora Jagodic

Before 5 years (4.9.2016) dr. Bora Jagodic was left our world and continue his great work I hope on better place. In the memory to him and his contribution to the Serbian and I can say also world HiFi community I have made his Kappa 22w and Calor Gold 40w amplifiers. After first results I have to say that I would need to build more dr.Bora amplifiers due to in single word, this two are amazing. All info for building them you can find on his page which is still alive ( https://bora.yu3ma.net/ ) .

Kappa 22w

First amplifier which I have tested is Kappa and if you follow Bora pcb population this amplifier is really easy to build and it will work from first plug in, however I like this amp due to there are a lot of option how to tweak it and get the best from him. In the input stage it use’s 2x 2sk170 and we all know how difficult and expensive is to get this transistors , good part is that this semiconductor could be replaced with his smd equivalent 2sk209 and two 2sk209 in parallel will do the job and also 2sk209 is still available , easily. All other parts were not complicated to get so it will not be hard to make an really authentic amplifier. I will not speak about sound due to I did not test them in real condition’s but first impression’s are very good and as always test you can see short video on my facebook page – Kappa 22w .

Calor Gold 40w

Calor gold is another A class power amplifier , this time with power of 40w . As it is in his name “calor” on Spanish mean’s hot and really it need very very good heatsinks . For input stage I have used NE5534 however it is possible to use any other similar Op Amp , but by dr.Bora observation , with no any significant impact to the sound . Personally I like very much how it sound even I have not test it on real conditions and I hope that this small test from my facebook page will help you to make decision to make it – Calor gold 40w . It is also very easy to setup, first short connect input together and start measuring voltage across 0r22 5w output resistors. With trim setup the bias to 220mV which have to provide 1A across each of output transistors. Next , clamp dmm to spk output and ground and again set the output voltage near 0 . That’s all. Leave the amp to warm up and then perform setup once again.

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