Orientation and Horizontal Mounting

[SY]

Embarrassed to ask such a newbie-type question, but... what's the deal with vertical versus horizontal mounting of tubes and pin orientation? I've seen both vertical and horizontal mounting, and seen spec sheets which have recommended specific pin orientations for horizontal orientation, but wondered about general rules for this. Most spec sheets are mute on the subject. Different for power tubes versus small signal? Beam tubes versus pentodes? High versus low perveance? High versus low mu? Grid supports oriented 12oclock-6oclock or 3oclock-9oclock? And so on and so on...?

[Aud_Mot]

Somewhere, somehow (from what I recall was a good source) I was told, in general, tubes were designed to be mounted horizontal. Does that mean that when you mount tubes horizontal, that there is proper orientaion? Example pin one is at the top of the pin circle. Never heard that kind of detail

Oh well, that is my two cents, now I have to go out and index my spark plugs.

Aud_Mot

[sreten]

horizontaly mounted tubes get better airflow, simple as that.

(Unless it is restricted of course)

sreten.

[Tom Bavis]

Many don't have any required orientation - but many directly heated ones do - they'll typically tell you which pins should be in the vertical plane on the data sheet. Reason is that heater may sag and short. If the heater is inside a cathode sleeve, no such problem.

[fdegrove]

Hi,

horizontaly mounted tubes get better airflow, simple as that.

True and also recommended to reduce impact from airborne vibrations.
Always keep them out of the direct soundfield, alot of valves are much more microphonic than people think.

However I'd only mount preamp valves this way for practical reasons.

Most valves can be mounted in any position bar upside down unless a special retainer is used.

Quite often the datasheets states what can't be done when a valve deviates from the "any mounting position" practice.

As far as orientation goes, I can't remember reading anything in particular with the possible exception of some powertetrodes orientation related to magnetic flux...
Can't remember the details but I assume the usual 90 degrees rule applies.

The big bottle DHT valves should never be mounted horizontally as the heater would eventually sag away due to gravitational forces. Keep this in mind if ever you intend to ship valves like this across the globe; it wouldn't be the first time a 845 arrived with a broken filament.

Other than that, I wouldn't know any secrets about mounting tricks.

Cheers,

[SY]

However I'd only mount preamp valves this way for practical reasons.

OK, what are those reasons? I ask because I specifically want to horizontally mount some power tubes (not DHTs!).

[fdegrove]

Hi,

OK, what are those reasons?

Mostly convenience really. It's much easier to pull a tube out upwards by grabbing it by the collar than forwards or towards you where you stand the chance of hitting the one on the opposite side for instance.

Another reason is that mostly we have more real estate available in the vertical plane than in the horizontal one so the amp would have a smaller footprint...

That's all I can think of for now...

Cheers,

[SY]

Thanks, guys, I'll feel at ease layin' those bad boys down. If the grids sag and blow the amp up, I'll send it to Belgium for a proper burial.

[Sch3mat1c]

The reason for DHTs like 5U4 is because the filament is flat, so stiffer in one direction (in line with the width) than the other. Sweep tubes often have a similar requirement, presumably to prevent the screens from shorting out say, the control grid. Such shouldn't happen in normal use but perhaps TVs ran them near toaster grid levels...if nothing else, when something else goes bad and it *does* go toaster grid, then it won't be insta-ded.

Everything else here sounds good...

Tim

[SY]

Sweep tubes often have a similar requirement, presumably to prevent the screens from shorting out say, the control grid.

I haven't seen this on any sweep tube data sheets. Are you familiar with any that have such a requirement? (This isn't idle curiosity- my application is, in fact, sweep tubes)