Secret of Lovely Cube :

Many Users of Lovely Cube are worrying about the temperature of various parts of Lovely Cube.

Belows are the worries found in the Head-Fi forum :

  • I wouldn't even try putting my finger on any of the transistors or voltage regulators on mine.
  • Is it ok for 4 output transistors on radiators to be burning hot? After about one minute, I can't just touch them for longer than 0.5 sec (However, it is not instantly burning my fingers, so i assume temperature is lower than 100 C ) .Two stabilizators are just warm

Remember that Class A Headamp is built to hear , not to touch.


In order to smooth the worries about HEAT in Lovely Cube , here I disclose the SECRET of Lovely Cube (also for Lehxxxn)

SECRET of Lovely Cube :

  1. It runs in Class A (everyone knows) , In Class A , NO HOT NO GOOD.
  2. The 4 output transistors (BD139/140) have BEST performance at about temp 70°C
  3. The 4 Capacitors (470uF) have BEST performance at about 50°C

This is the heatsink used in Lehxxxn . Does Lehxxxn want to save few dollars on Heatsink ? Absolutely not. They use this small heatsink in order to let the transistor heat up to about 70°C . Salute to the Lehxxxn PCB designer, they arrange the 470uF capacitor nearby this heatsink (act as a heat radiator) to let 470 uF capacitor be heated up to about 50°C .

Also Salute to the Lehxxxn Case designer , the long rectangular shape case trap the heat at accurate position.


My Advices :

  1. Don't try to cool down the transistors by changing large heat sink or remove and mount on the case . No worries about burn out the transistor , the transistors' (BD139/140) max. junction temp is 150°C (
  2. Don't try to make holes on the case for ventilation. This doing will destroy the heat traps.
  3. Use similar case. It is recommended not to use large case, large case cannot trap heat well.. If cannot find suitable case , buy from me :) .


Research for you :

I got a new Toy - Infra Red Thermometer


Result of temperature at various area



On the other hand , OPA should not operate in high temperature, although the max operating temperature of , for example, 627 is 80°C. In my opinion , the best operating temp. of OPA should be 40-50°C


Below is the GIF animated , total 9 pic each 5 seconds , describe the making dual 627 adding with heatsink. After using this , the temperature of the heat sink is about 40°C.