Your idea in post 7880 and 7881 could work, if all mating surfaces are flat and you use thermal grease.
Looks bad for servicing though, you'd probably have to take the entire thing apart if you ever had to replace the output-transistors.
If you are short on heatsinking, consider the use of fans, this will greatly increase efficiency of the heatsinks.
Good industrial quality fans are reliable and can be quiet if you use then at low rpm.
Regards,
Klaas
Looks bad for servicing though, you'd probably have to take the entire thing apart if you ever had to replace the output-transistors.
If you are short on heatsinking, consider the use of fans, this will greatly increase efficiency of the heatsinks.
Good industrial quality fans are reliable and can be quiet if you use then at low rpm.
Regards,
Klaas
If i understand your idea in post 7882 correctly,
you will have poor thermal coupling between the npn and pnp devices.
To be honest, i dont know if this will lead to serious problems, so i cant give you any good advice.
Have you considered using more output-pairs ?
Imo, the thermal interface between the outputs and the heatsink is a bottleneck when using only 2 pairs.
Krell used only 2 pairs, they run their outputs at VERY high temps, heatsink at ~ 70 degrees celcius
This leaves you with very little room for error, imo not advisable for a diy-amp.
Regards,
Klaas
you will have poor thermal coupling between the npn and pnp devices.
To be honest, i dont know if this will lead to serious problems, so i cant give you any good advice.
Have you considered using more output-pairs ?
Imo, the thermal interface between the outputs and the heatsink is a bottleneck when using only 2 pairs.
Krell used only 2 pairs, they run their outputs at VERY high temps, heatsink at ~ 70 degrees celcius
This leaves you with very little room for error, imo not advisable for a diy-amp.
Regards,
Klaas
Adi2009 said:
Two of these per channel (monoblock) will definitely do for 130-140W dissipation, if these are the 42x17.5x3.4cm ones you mentioned.
Under 50C, and maybe even below 45C, for an ambient temperature of 25C.
For a C/W indication reference, see the SK03 and SK39 heatsink profiles by Fischer, or the KL102 from Seifert.
50V rails means ~175-180W dissipation for a 50W Class A level in 8 Ohm.
Not sure if you can keep the heatsinks below 50C for that heat level, but definitely under 55C.
Loaded with a bias current of 1.8A, the rails will likely drop below 50V, which will lower the dissipation sum, resulting in a lower heatsink temperature.
Not sure if you can keep the heatsinks below 50C for that heat level, but definitely under 55C.
Loaded with a bias current of 1.8A, the rails will likely drop below 50V, which will lower the dissipation sum, resulting in a lower heatsink temperature.
