Hi all,
I've just built myself a little valve amp and now need to put it into a box.
Am going to make the box from plywood and am wondering if anyone has any ideas as to how high above the EL34's the top of the box needs to be. ie so it doesn't burn the top.
That, and any other tips you may have on the process.
many thanks.
John
I've just built myself a little valve amp and now need to put it into a box.
Am going to make the box from plywood and am wondering if anyone has any ideas as to how high above the EL34's the top of the box needs to be. ie so it doesn't burn the top.
That, and any other tips you may have on the process.
many thanks.
John
Consider how convection currents will flow. If you can put a vent right over the tubes, great, as long as there is an entry vent for makeup air near the bottom of the tubes. otherwise you will have to rely on whatever can flow around the tubes. You need enough space to remove tubes from the sockets. In guitar amps there is often not a lot of clearance. You might glue or staple a layer of aluminum foil above the tubes to reflect heat from the wood. or thin sheet metal. Tubes do get hot, but not hot enough to ignite wood.
I used to have a Simms-Watts 100 watt valve amplifier.
It used EL34's in two pairs.
It had a gap along the bottom of the tubes the width of the case.
It also had a metal mesh above the tubes to let heat out.
It used EL34's in two pairs.
It had a gap along the bottom of the tubes the width of the case.
It also had a metal mesh above the tubes to let heat out.
Thanks Enzo and Nigel,
Yeah wasn't really expecting it to burst into flames 😉 but rather just scorch the wood form the radiant heat, as convection can, as you say, be dealt with using vents, but as Enzo said, a sheet of some reflective material would sort that out. I didn't really want to put vents on top due to possible liquid ingress from above (spilt beer) but I like the idea of in the back panel.
Also, hadn't really considered the space to get the valves in and out and that's maybe more of the issue than any kind of heat excess as it's easy to jerk a valve out if you're not careful.
Reckon I'll go for a good 4cm+ above the EL34s for plenty of 'jerk' clearance 😉 and see how that goes.
Many thanks,
John
Yeah wasn't really expecting it to burst into flames 😉 but rather just scorch the wood form the radiant heat, as convection can, as you say, be dealt with using vents, but as Enzo said, a sheet of some reflective material would sort that out. I didn't really want to put vents on top due to possible liquid ingress from above (spilt beer) but I like the idea of in the back panel.
Also, hadn't really considered the space to get the valves in and out and that's maybe more of the issue than any kind of heat excess as it's easy to jerk a valve out if you're not careful.
Reckon I'll go for a good 4cm+ above the EL34s for plenty of 'jerk' clearance 😉 and see how that goes.
Many thanks,
John
Two observations 1. If you have a mostly open back of the cab, great. If it's mostly closed, better to install a top vent to let out heat. The wood will be fine either way, shield or no shield. Think about keeping the the electronics as cool as you can. 2. Find a different place to put your liquid refreshments.
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