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A mere 50 years of misunderstanding

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Pilgrim:
I've been surfing info about the Standby switch on my 1967 Fender Bassman and it appears that I've had its function backwards since I got it 50 years ago.

As a radio/TV guy, I always assumed that the proper sequence for turning on this kind of gear was first to turn on the Standby (assuming the meaning is literally "OK boss, I am awake and standing by for orders..."), then to turn the Power switch on when I was ready to make noise.

When taking a break, I have always turned Power off (down) and left the Standby switch in the Up position. In other words, I assumed that Standby On meant "Power is partly engaged, I'm standing by for action."

Now I gather from readings on a variety of websites that I've had it backwards.

It appears that I should have been flipping up the Standby switch first, then turning the Power switch on (upward position) when preparing to play.  When taking a break, it appears I should leave the Power switch on/up and flip the Standby switch off/down position for breaks.

There is much lack of clarity in the language and functional definition of Standby switches.  It is unclear whether leaving the switch in the Up position is "Standby On" or "standby Off." And given the lack of clarity around what Standby actually DOES, is "Off/down" the Standby engaged position, or is it Standby disengaged?

I figure that aside from the potential of prompting train/tunnel, airplane and tank jokes, I can get better info here than any place I know.  So kindly illuminate this poor Padawan, compadres.


* What does the fabled "Standby" switch do?
* Is On/up engaging the function of this switch, or does Down/off engage the function?
* In what sequence should Standby and Power switches be used, (a) turning the amp on, and (b) when taking a break?

Rob:
Being old and playing tubes early on we would bring up power as soon as possible and leave the amp on standby.  (Think Midwest and cold weather )
I was always told that it was good for the filaments but it could be folklore.

Basvarken:
Yep, I always switch the amp on as soon as possible to warm up the tubes properly before actually using the amp.
Of course I leave power on during a break, using the standby knob to silence the amp, while keeping the tubes warm.

lowend1:
The popular theory was that the standby switch, by not allowing full voltage to hit the tubes immediately, helped prolong tube life. You hear tales of a boogeyman called "cathode stripping" from not "preheating" the tubes by using the standby.  Opinions differ on whether the standby is even necessary, in part because tube hi-fi amps don't generally use them - but the majority of the tube hi-fi gear I've owned has been tube rectified, so I guess that debate can continue... They are less common on small amps (lower voltages), and typically those with a tube rectifier because they "turn on" slower than their solid state rectified brethren.
Psycho, yer thoughts?

amptech:
A stand by switch should always be used on tube gear, and as mentioned above it lets the tubes warm up before high voltage is engaged.
Some tubes warm up ok within 10-15 seconds or so, but I usually recommend at least a minute or two. There is no point powering up the amp three hours before using it, you actually wear out tubes somewhat that way too. Most tube datasheets will tell you how long a tube needs to be warmed up.

Amps with very high voltages, silicon diode rectifiers and no stand by switch wear out tubes fast and sometimes develops issues with the amp because of that. but that does not mean that an amp with a tube rectifier is 'safe' without a stand by switch. I've had maaany VOX AC30's that powers up and within 2 seconds develops all kinds of horror that could be avoided with a stand by switch. Early Orange amps comes to mind too.

That said, remember that a small amp does not always run on low voltages. Many early 5W amps with a 12AX7/6V6GT/5Y3GT layout runs the B+ way over 400VDC.

Different tube rectifiers have different heat up time too, there are amps that use the indirectly heated 5AR4/GZ34 tube and does not have a stand by switch that should not be used with directly heated tubes - like the 5U4. Some directly heated tubes put out full potential very quickly. Then again some indirectly heated ones are wey nice and slow - I love the Bendix 6106 (a military 5Y3GT) - it is so slow warming up that a stand by switch is not needed.

Then, on top of that is the fact that some tubes of today is just not as stable as old ones. I'm thinking of the 5AR4/GZ34 tubes here in particular, many of the current ones have stability issues compared to the philips/mullard originals. Being a tube distributor I won't debate wich is better or worse, but lots of amps that made it without a stand by in the 60's might benefit having one installed today.

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