A standard E61 Group head from a commercial coffee machine is a big block of brass weighing approximately 2.5kg.
Whilst the surface area for dissipation relative to the volume is on the lower side.
Would the enormous thermal mass make up for the low dissipation area and therefore make an acceptable heatsink for a lower power AB amplifer or perhaps even a low power class A?
I think there is sufficient area on the 'back' where the group head mounts to the chassis to mount a pair of output devices.
Whilst the surface area for dissipation relative to the volume is on the lower side.
Would the enormous thermal mass make up for the low dissipation area and therefore make an acceptable heatsink for a lower power AB amplifer or perhaps even a low power class A?
I think there is sufficient area on the 'back' where the group head mounts to the chassis to mount a pair of output devices.
You have identified one problem already.
The surface area is limited so average/long term heat dissipation would be limited compared to a conventional finned heatsink with much greater surface area. The high mass is good for soaking up a short term power surge but you still have to get rid of the average heat load.
The second problem is that bronze has a much lower thermal conductivity than aluminium (the usual/best compromise choice for a heatsink material), being in the range of 60-120 W/m-K (depending on the actual alloy) compared to 230-240 W/m-K i.e. thermal conductivity is in the range of 2-4x worse.
If it was solid copper, it might make a useful thermal coupler between your power devices and the actual heatsink
The surface area is limited so average/long term heat dissipation would be limited compared to a conventional finned heatsink with much greater surface area. The high mass is good for soaking up a short term power surge but you still have to get rid of the average heat load.
The second problem is that bronze has a much lower thermal conductivity than aluminium (the usual/best compromise choice for a heatsink material), being in the range of 60-120 W/m-K (depending on the actual alloy) compared to 230-240 W/m-K i.e. thermal conductivity is in the range of 2-4x worse.
If it was solid copper, it might make a useful thermal coupler between your power devices and the actual heatsink
Nice thing about that head is that the underside with no portafilter exposes a fair bit of surface area. Other thing is that with that same pocket, you could park a fan, and some fans are silent. You mention lower power use. If I had a vision for an art piece, I'd stick something on it and see how much it could dissipate.
Note that even a low powered Class A amplifier would produce a latte heat.
No this was entirely a conceptual question.
We do have a few machines to be scrapped at work but I'm not sure when we will get around to doing it.
I'm sure the boss would be happy to donate some to an art piece. I have promised him a small integrated amplifier for his computer desk.
I think a pair of lm1875 chips would have more than enough Heatsinking with a grouphead each.
We do have a few machines to be scrapped at work but I'm not sure when we will get around to doing it.
I'm sure the boss would be happy to donate some to an art piece. I have promised him a small integrated amplifier for his computer desk.
I think a pair of lm1875 chips would have more than enough Heatsinking with a grouphead each.