Leach super Amp heatsinks

[bremen nacht]

hi,

Can anyone advise me on what rating heatsinks I should use on the driver transistors in a Leach superamp? I built a standard Leach and used 10C/W sinks on Q16 and Q17 and they only just get warm; should I use the same on Q26 and Q27? Or do they share the power, so I could use something smaller?

Planning on using MJE15032/3, and MJE340/350 for the preceding stage, as these work well in the standard Leach amp.

Thanks,

Chris

[AndrewT]

Hi,
what Pq are you planning?

Identify your Iq and Vce for each device.
r52 & r54 share the voltage almost equally between q16 & q26.

10C/W will allow about 2W and 20C/W about 1W.

Depending on your Vcc and Iq you may be able to share one 20C/W between the pair (q16+q26).

[acenovelty]

The Prof. recommends:
Heat sinks for Q16 and Q17 are Aavid 5741B (DigiKey HS111-ND).
The newer Aavid part # is Part Number - 574102B00000.
Thermal Resistance 23.20
Thermal resistance value is based on a 75°C rise in natural convection.

This is what it looks like.

Regards

[bremen nacht]

Thanks!