I am currently building a small tube amplifier for headphones using PCB socket mounted 6AS7 and 6SN7 tubes. my question is, how much clearance should i have to nearby components in order for them not to be affected too much by the heat from the tubes?
The sockets are ceramic and the tubes themselves will be on the outside of the amplifier chassis, and the PCB is standard 1.6mm 4 layer FR4.
The sockets are ceramic and the tubes themselves will be on the outside of the amplifier chassis, and the PCB is standard 1.6mm 4 layer FR4.
Since the parts on the board have to be outside the footprint of the socket, that should be enough in most cases,
except for carbon resistors, etc. Maybe RIAA parts should be a little farther away. The trace and board may well
conduct more heat to the parts than that radiated from the tube. Elevating critical parts a little off the board can
help, especially if they generate significant heat themselves. You can use a thermal gun to check part temperatures
after warm up.
Klein Tools IR5 Dual Laser Infrared Thermometer – Danurote
except for carbon resistors, etc. Maybe RIAA parts should be a little farther away. The trace and board may well
conduct more heat to the parts than that radiated from the tube. Elevating critical parts a little off the board can
help, especially if they generate significant heat themselves. You can use a thermal gun to check part temperatures
after warm up.
Klein Tools IR5 Dual Laser Infrared Thermometer – Danurote
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For now I am trying to keep a minimum of 2.5mm of clearance, and it sounds like that should be more than enough for the plastic housing of the audio PP capacitors and electrolyte PSU decoupling capacitors?
Yes, as long as there is just a bit of natural convection going on. Drift wouldn't be a big factor for
coupling and decoupling film PP capacitors, which can take up to 100C. Hopefully the parts are on
the opposite side of the board from the tube sockets and tubes.
coupling and decoupling film PP capacitors, which can take up to 100C. Hopefully the parts are on
the opposite side of the board from the tube sockets and tubes.
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try the belton octal PCB sockets they are excellent. if you need an Eagle Lib, i have one for those.