Are combo cabinet vents really necessary?

[Silvio55]

Hi guys! Iīm building an 18 watt lite combo from scratch, itīll be a 2x12 combo. Since itīs an open back cab, with the tubes hanging down, itīs really necessary to cut the vents in the top of the cab, like the original Marshall combo? I doesnīt make much sense to me, the tubes are haging just throug the opening of the cab, and the transformers donīt get that hot.
Thanks in advance!

[cbarrow7625]

The tubes will get hot (it's what they do) and heat rises. Do you want to trap that heat and risk damages / failures / shortened life of anything that is getting unneccessarily hot? Or do you want to let the excess heat out and avoid the bad possibilities altogether? Can you get away with omitting it? Maybe / probably. But why risk it? If it never leaves your house it will probably never be an issue. Playing for a few hours at a gig? I dunno

[big_teee]

Hi guys! Iīm building an 18 watt lite combo from scratch, itīll be a 2x12 combo. Since itīs an open back cab, with the tubes hanging down, itīs really necessary to cut the vents in the top of the cab, like the original Marshall combo? I doesnīt make much sense to me, the tubes are haging just throug the opening of the cab, and the transformers donīt get that hot.
Thanks in advance!

With an 18 Watt, you could probably get by without it.
But like was already said why risk it!
The combo is IMO less efficeient than a head to start with, Running in a upside down format.
So even if, just a small vent right at the top, it would allow air flow.
Good Luck,
T

[Enzo]

Can't say as I recall many Fender combos with a top vent, their tubes hang down, and they don;t seem to melt.

[Tom Phillips]

Keeping the spilled beer out of the chassis is one reason not to use a vent.

[Silvio55]

Keeping the spilled beer out of the chassis is one reason not to use a vent.

Ah, thatīs why I donīt drink beer, Jack Daniels is better for cleaning the circuits of a tube amp!
So well, just in case Iīll build the cab with the vents!

[tubeswell]

Depends how many tubes you have in there and what sort they are and how far apart they are from each other. A quad of 6L6s hanging upside down an inch apart from each other might need more ventilation than a couple of EL84s spaced 3 inches apart.

[Enzo]

But where you are, don;t the tubes stick UP?

[tubeswell]

Depends whether the wind is blowing from the northern hemisphere

[soundmasterg]

It probably depends on ventilation and spacing most of all. A lot of the old Voxes were in super small cabinets with not enough ventiltion, and so some of them would burst into flames as a result, even with top vents that were probably too small. Fenders always seemed to have a lot more ventilation, even if the heat from the tubes would go up into the circuitry.

Greg