Horizontal EL84?

[Ritchie200]

I am trying to shoehorn (2) 12AX7's and an EL84 into a limited space - horizontally.  Does anyone know of any issues running an EL84 in this position?  I know the others will be fine.  I may need a fan on this one...

Thanks!
Jim

[jhadhar65]

Horizontal is fine, but you'll want to use good retainers.  I'm partial to the wire-bail type even for vertical installs.  I think Peavey and H&K have both used this arrangement, too.  I can't remember if it was H&K, but I think it was.

[Dave]

I don't think it'll hurt a thing.

Look at a Peavey Classic 50 / 100 head. They run 'em sideways no problems.

Dave

[HotBluePlates]

If I were building it, I'd want to make sure the control grid and screen grid support rods were positioned vertically, when the tube is horizontal. Mullard and GEC used to spec a particular angle of rotation to mount the socket for tubes being placed horizontally.

So what I mean is look at your tube. hold it horizontally, while rolling it until the support rods are positioned one over the other. Note the postion of the pins, and orient your socket so the tube will be held in this manner.

The idea is that if there should be any sagging of the grid wires as the tube is hot, they will have less tendancy to be pulled by gravity to where the grids can short to the suppressor or to each other.

And yeah, good retainers are an excellent idea.

[FYL]

I am trying to shoehorn (2) 12AX7's and an EL84 into a limited space - horizontally.  Does anyone know of any issues running an EL84 in this position?  I know the others will be fine.  I may need a fan on this one...

No restrictions listed in the datasheet, but I'd follow HotBluePlates' suggestion.
Re. thermal behavior, those lil' buggers run quite hot and could be problematic in cramped spaces. Forced air flow is strongly recommended.

[phsyconoodler]

I use the 9 pin sockets for 12AX type tubes.The EL84's stay snug with the aluminum shield base hugging the tube.I find those wire retainers to be poor at best.Still better than none,but I find the shield bases to actually hold better.
  They work very well when the tubes are horizontal.I've built a few 18 watters with horizontal head style chassis in combo amps and they work great.

[FYL]

I use the 9 pin sockets for 12AX type tubes.The EL84's stay snug with the aluminum shield base hugging the tube.

Do large EL-84's such as the Russian 6P14P-EV fit? They are too large for the shield bases I use.

[Ritchie200]

Thanks guys!

I remember the old spiral shields that used to be in the old tv sets.  They would shrink or expand to fit with little clips to hold it.  I wonder if those are still around?  Or did I just give away my age.....

Jim

[PRR]

I thought there was some issue using generic shields on POWER tubes?

There are some shields which pull heat away. But the shields used for cool bottles like 12AX7 just trap heat.

[HotBluePlates]

There are some shields which pull heat away.

Are you talking about IERC tube shields?

For those who haven't seen these, you find them often in old military or (sometimes) industrial gear. From the outside, the shield is black, and the nubs on the shield base fit into slots in the shield, rather than being held on bayonet-style with a spring. These type, you push-on and pull-off. But be warned! They fit very, very snugly.

Inside, if you pull off the outer shield, you may or may not (probably not) take the inner wrap along with it. This wrap is metal, punched to have fingers that have some springiness to them, and it completely wraps around the tube. When you push on the outer shield, you wind up with a outer case that seems pretty-well thermally bonded to the tube.

I don't know how much cooling they provide, but I bet it's better than the dead air between the tube and shield of a typical amp. Also, these shields don't just come in 12AX7-size... there are taller ones to fit things like the 12BH7 and (maybe) EL84's.

[jhadhar65]

I use the 9 pin sockets for 12AX type tubes.The EL84's stay snug with the aluminum shield base hugging the tube.

Do large EL-84's such as the Russian 6P14P-EV fit? They are too large for the shield bases I use.

They're too snug for some of the vintage 6BQ5's I have as well.  I like the wire bails.  There are also spring retainers if you don't like the wire or the bayonet bases don't work for you.

[FYL]

I thought there was some issue using generic shields on POWER tubes?

You just use the shield base, wich somewkat clamps the bottom of the EL84.