I plan to build a Firstwatt F6 and just ordered the parts and boards. The plan is to build a separate PSU unit where i can swap out different amp sections which is house in another enclosure in future builds. This means I can get smaller enclosures. But is there a problem with smaller casing/heat sink for the amp section? What do I need to be warry of?
Hi.
I plan to do the same. My view is that the major heat input is from the transistors, so the heat sink size would stay the same. This may allow slightly higher bias as some heat does come from transformers, chokes and diodes which can be taken care of by local heat sinking and venting. (PSU caps should be cooler overall). So it may lead to a narrow but same depth case. (thus same size heat sink) if one really wants to reduce the overall footprint. I will probably go the route of mono blocks, (as it will be for a higher output amp) using one common PSU box supplying both. Obviously, case size is matched to heat output in any situation.
I plan to do the same. My view is that the major heat input is from the transistors, so the heat sink size would stay the same. This may allow slightly higher bias as some heat does come from transformers, chokes and diodes which can be taken care of by local heat sinking and venting. (PSU caps should be cooler overall). So it may lead to a narrow but same depth case. (thus same size heat sink) if one really wants to reduce the overall footprint. I will probably go the route of mono blocks, (as it will be for a higher output amp) using one common PSU box supplying both. Obviously, case size is matched to heat output in any situation.
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This seems to be a fairly common approach, but here are a few things I think are worth considering. There might be quite a few more...
1) As long as the heatsinks for the output devices are appropriate, in general, you will be fine.
2) Not all FW amps have the same dissipation. If you plan to be "on the edge" for the F6, which is a fairly cool running amp when built to spec, you may not have enough heatsinking for some other amplifiers you are considering. See #1
3) If you go smaller with internal volume, the ambient temp inside the chassis will likely be higher. How much higher? I have no idea. Will those higher temps lead to meaningfully shorter part life? It's unlikely, but it's a consideration.
4) Will smaller sinks, smaller internal area lead to uncomfortably warm to the touch heatsinks for you?
1) As long as the heatsinks for the output devices are appropriate, in general, you will be fine.
2) Not all FW amps have the same dissipation. If you plan to be "on the edge" for the F6, which is a fairly cool running amp when built to spec, you may not have enough heatsinking for some other amplifiers you are considering. See #1
3) If you go smaller with internal volume, the ambient temp inside the chassis will likely be higher. How much higher? I have no idea. Will those higher temps lead to meaningfully shorter part life? It's unlikely, but it's a consideration.
4) Will smaller sinks, smaller internal area lead to uncomfortably warm to the touch heatsinks for you?