The nonsense is deliberately building a hot device that both generates and needs air flow one way or the other anyway and then debate ventilation holes and risk of cleaning dust.
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nice ..but we need some thermal mass on ceramic socket that can dissipate the hot pin too.
Post on old TV is a non sense as have 16000 volt that capture the dust
Right, I've NEVER seen any dust inside any of my tube amps nor tube amps that I have serviced. surely not enough that would require cleaning. And trust me when I say my house, having a dog living in it with me, has a lot of dust and dog fur everywhere else.
The tube will benefit from these holes, but the effect will be minimal. The whole principle of convection is that the heat the tube generates rises, which creates a (very) small low pressure zone around the foot of the tube. So air will be drawn to the foot of the tube no matter what. I'd say the argument for the holes is that the tube then draws in air that hasn't been preheated already by other components. But like other comments already stated, that's providing the case has holes in the bottom as well to allow for that cooler air to be drawn in.
Summarizing: it will help, but the effect is minimal.
Same. Anything with a fan always gets full of dust, but passive enclosures seem fine. Or maybe the dust all gets stuck to the high-voltage conductors only 🤣
The original poster stated his question related to the tube and not the parts inside the chassis. In which case if there was a problem with the temperature of a tube then there would be a mention in the tube data sheet. For some small output tubes (like 6AQ5) there is a mention, but it is to prevent extreme situations from occurring since 250C is the maximum.
I would suggest that a significant part of the bulb temperature limitation is the glass-to-metal seals, as is true for larger transmitter class valves. As trobbins pointed out in post #57 large amounts of internal heat try to escape through the nice high thermal conductivity metal pins, rather than the poor thermal conductivity vacuum and glass.
This would imply that keeping the seals as cool as possible might be as important, or perhaps even more important, than cooling the glass envelope, except near the seals.
All good fortune,
Chris
This would imply that keeping the seals as cool as possible might be as important, or perhaps even more important, than cooling the glass envelope, except near the seals.
All good fortune,
Chris
But then wouldn't cooling holes around the tube sockets help cool the (wait for it...) tube sockets and pins?
Sure, and for a guitar amp that's probably the cheapest and most effective solution. But if you want to keep your high-end pre-amp as clean as possible, aka no noise, purists will argue that fans, even undervolted slow turning fans, are simply not an option. And then you have to get the max cooling out of convection, which is where the holes come in.
Modern day computer cases use very thin and very fine mazed dust filters, often with a magnetic frame, so nothing prevents you from buying one or more of those and cover the case openings to prevent a huge part of the dust being able to enter the case.
No need , work fine ,pre -power amp, phono on wood as diy , never have problem from simple dust ,computer too just clean cpu fan one time at year , on Pass we move open baffle
Acamini 6w classA with 12cm silent fan as babysitter on top is perfect in summer🙂 ,
btw if you live in harsh place just cover when not in use
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🙂 As Mr Perkins reports, it's long been known that cooling tubes is a fine thing to do (fans, holes and radiators, please!) and he published results for convection and fan-forced cooling (https://pearl-hifi.com/03_Prod_Serv/Coolers/Coolers.html)
I´ve seen some rather utopic modern tube amp designs having heatsinks on tubes; not a good idea as tube envelopes made from soda glass doesn´t like unequal thermal metallic contact, which can cause localized cracking. This occurred on an amp with EL84 tubes. As for tube pins; a dead end issue as the Kovar base pins have same thermal coefficients as the glass itself. All this stuff has been worked out now 100 years ago.
Bench baron
Bench baron
There are heatsinks for forced air flow and for natural convection. The latter perhaps is applicable to the "cooling holes", without a fan. Anything less than 10-12 mm or 1/2 of an inch between fins is not good for a natural convection. Fin height exceeding one inch is not good either. Anyhow, even performance heatsinks for high power modules with huge air flow have 1/4" openings between fins. Drilling 1/8"... 1/4" holes around tube base without a funnel/chimney/fan is, at best, useless.
P.S. Tubies are not made from a soda lime glass. It's a borosilicate one.
P.S. Tubies are not made from a soda lime glass. It's a borosilicate one.