Standby Switches are they necessary

[TIMBO]

  I'm sure this must have been a topic at sometime. I am guided by you guys to how an amp is put together and trust that your technical knowledge and hours of tweaking have made certain parts a must have in a build.
So do we need a standby switch????

I was directed to this http://www.ozvalveamps.org/standby.htm and left me   and scratching my head.

All of my builds have a STANDBY Sw. and they all work well, but there seems to be some side effects of doing this, and I will say that like everything, there is always two sides of the story, what are you to believe??

The most common type is as fender does with a SW. after the rectifier and at times there are some pops and thumps and at worst the SW. has a meltdown and welds the contacts together.

IS there a better way or has the big boys already got it right. Thanks

[jazbo8]

The page you linked to was a bit long, so I did not read it... But, other than being a convenient way (out of habit most likely) to mute the volume, there is really no reason to install a stand-by switch. Merlin's book also has a bit more detail if you want to look them up.

[tubeswell]

I don't think a standby switch is necessary. A 'soft-start' switch is kinda funky tho'.

(But neither is necessary.)

[stratele52]

  I'm sure this must have been a topic at sometime. I am guided by you guys to how an amp is put together and trust that your technical knowledge and hours of tweaking have made certain parts a must have in a build.
So do we need a standby switch????

 

My  answer ; it is usefull. So yes.

For most of the  amps , it save tubes . For other amps with slow start its usefull for a break on a gigs .

[jazbo8]

For most of the  amps , it save tubes...

Convenient to have, perhaps, but the stand-by switch does not save tubes, at best, it saves the under-rated filter caps in some amps.

[stratele52]

For most of the  amps , it save tubes...

Convenient to have, perhaps, but the stand-by switch does not save tubes, at best, it saves the under-rated filter caps in some amps.

I desagree.
Cold power output tubes receiving B+ voltage may have their plate damadged . Never this will happen  with standby switch .

I desagree  with under -rated filter caps ; Use of Stanby switch is worst with these caps .

Anyway this is a topic discussed a million times on the web

[jazbo8]

Sigh... have to agree to disagree then...

[Ed_Chambley]

I put them on amps because people expect the to be there.  I still flip both at the same time.  My tubes seem to last a very long time and I have never noticed cothod stripping.  I have a friend who is a well respected amp tech who says you should wait 5 minutes to allow your heaters to warm up, then he will flip both within a few seconds and say "I have plenty of tubes".

My 5C1 champ is missing the standby and the power and rectifier tube is so old they may be original.  Does single ended change things?

[Willabe]

Does single ended change things?

No but some rectifier tubes have a controlled warm up time (GZ34/5AR4) so they don't send B+ to the other tubes right away.


            Brad   

[Ed_Chambley]

Does single ended change things?

No but some rectifier tubes have a controlled warm up time (GZ34/5AR4) so they don't send B+ to the other tubes right away.


            Brad   

I knew this, but never considered it really.  In this instance you think letting the rectifier warm up before unloading the DC is beneficial?

[Willabe]

The dcv B+ does not get sent to the other tubes right away. The rectifier tube has to warm up 1st then it starts to send the B+dcv to the other tubes. The controlled warm up time makes the rectifier tube it's own standby.


               Brad     

[Platefire]

I don't think it's necessary for your amp to function correctly but I like them and include them on every amp I build. I do most of my playing in Church services and it requires starting and stopping the music up to three or more times in a service or one to two hour period, so being able to mute it and having it warmed up and ready to work at a flip of a switch is important to me. Also during a song service I may switch back between acoustic and electric a couple of times during a service. So in my case it's necessary for my operation. Platefire

[tubeswell]

The dcv B+ does not get sent to the other tubes right away. The rectifier tube has to warm up 1st then it starts to send the B+dcv to the other tubes. The controlled warm up time makes the rectifier tube it's own standby.


               Brad     

This is definitely the case for indirectly-heated rectifiers like the 5Y3GT and the 5AR4

[printer2]

For most of the  amps , it save tubes...

Convenient to have, perhaps, but the stand-by switch does not save tubes, at best, it saves the under-rated filter caps in some amps.

I never put one in an amp yet but my latest one might get one. It has SS rectifiers and when the output tubes are conducting the voltage is about 350V but with them cold it is 425V on 400V caps. As far as cathode stripping, if you put 400V between two pieces of metal in normal atmosphere would one strip the coating off the other? I would expect it not to, so why would it be able to do it in a vacuum? Especially when the coating is designed to stay on the metal when heated. I would expect the coating to be more likely to come off when hot.

[Willabe]

FWIW, I always used my standby switch playing in clubs, church or at practice. It was very convenient to have it. The big boss man didn't like it when he hit the stage and would have to wait for you, "got a dollar waitin on a dime."   


             Brad     

[jazbo8]

If all you want to do is to mute the output of the amp, it is easier and cheaper to install a mute switch at the input - you don't have to deal with the HV, the in-rush current that the stand-by switch requires. There is no science to back up any of the claims about cathode striping, improved life span of the tubes, etc. nor empirical evidences to suggest otherwise, since there are probably far more hi-fi amps in service than guitar amps, and most did not used a stand-by switch.

[SoundmasterG]

It says right in the RCA tube manual that cathode stripping is not a concern with receiving tubes. The voltages just aren't high enough to damage the tubes in that way. Receiving tubes are what are used in guitar amps....I have a 1956 Fender 5E3 here with original RCA tubes in it. It was used at church gigs by the original owner for years and years. The amp does not have a standby switch and the original tubes are still going strong 58 years later....a lot of hifi amps don't use standby either....so the conclusion is that a standby switch is not necessary for guitar amps to save the tube life or anything of that nature. That said though, a standby switch or at least the mute function of it is useful in a performing application, and it is almost expected by most guitar players to be in an amp. It is useful for the repairman when working on the amp and the B+ can be shut off, at least if the standby is wired up like a Fender and interrupts the B+.

Greg

[TIMBO]

Hi guys, I like a standby sw. as well, cause most of my builds start off as one and by the time I'm finish its something else, so that standby gets a real workout.

The conclusion is that the standby is a usable component.  

There is an argument to its use and strain on the PSU design,to which I don't think we'll never agree to how the best way to incorporate it. I think that you do what you feel comfortable with or what works for you.

Reflecting back to my Fi Sonic restore, the HT centre tap of the PT was used to disconnect the power transformer but still have the heaters winding active. The rotary switch could then be rotated to ON and the centre tap grounded to activate the HT supply.

After reading Merlins chapter on "standby Sw." the alarm bells started ringing to the demised of the original PT. The first mistake of the design was a under size rectifier (EZ81 suppling PP 6L6s) although it was cathode bias to 30w but having a standby on the centre tap was a big NO NO according to merlin. These two factors lead to a flashover in the rect tube and the rest was history............

Fender style standby is a common design and I use it a lot in my builds and although the switch itself is NOT designed for DC power, i must flick it a hundred times while tweaking, still works fine.  

Marshall style (SPST or DPDT on HT leads) could this be a better way as it is less strain on the switch but brutal on the rect tube.

I've been told that there is NO proof that an amp suffers any damage or fatigue by subjecting the tubes with full B+ at the flick of a mains sw. so this is why a standby sw. is not necessary, but if a standby sw. is to be added it would be by grounding out the signal path at a volume wiper. Thanks

 

[stratele52]

Sigh... have to agree to disagree then...

If we take example of Fender amplifiers, how then explains that all are equipped with "stanby switch"?

Otherwise the philosophy of Leo Fender was to build the best amplifiers at the best price. It would not have installed a "stanby switch" if it would have been helpful.

All those who wanted to imitate later did the same thing.

[Merlin]

If we take example of Fender amplifiers, how then explains that all are equipped with "stanby switch"?  Otherwise the philosophy of Leo Fender was to build the best amplifiers at the best price. It would not have installed a "stanby switch" if it would have been helpful.

Fender was trying to protect the power supply capacitors. In the 1950s, big, high-voltage capacitors were both expensive and unreliable. Fender used capacitors that could not withstand the peak (cold) voltage that exists if you don't use the standby switch. So he added the standby switch to allow the tubes to warm up, so when the switch it thrown, the supply voltage is pulled down to normal working levels, protecting the capacitors (and possibly the DC-coupled cathode follower too)

Cold power output tubes receiving B+ voltage may have their plate damadged .

The plate is a big piece of metal. How do you think it will be damaged?

 Every shred of evidence shows that tubes do not live longer with a standby switch, especially if you leave them in standby for minutes or hours on end, because that leads to interface resistance (a sort of cathode poisoning). In other words, a soft start (milliseconds or seconds) may help, but the crude user-operated standby switch that most amps have is more likely to shorten the tubes' life.

One of the worst things you can do is to 'hot switch' rectifier tubes. In other words, letting the rectifier warm up before letting current flow into the reservoir cap. That's an excellent way to kill the rectifier tube, and rather a lot of amps make this mistake!

[jjasilli]

This is an old recurring topic.  Cathode stripping, a somewhat controversial notion, has not been mentioned in this thread.  See:  http://www.peavey.com/monitor/pvpapers/Chapter6.pdf  http://www.chiark.greenend.org.uk/scopes/weyer.txt  http://www.diyaudio.com/forums/tubes-valves/79405-doubts-cathode-stripping-tubes.html

[stratele52]

If we take example of Fender amplifiers, how then explains that all are equipped with "stanby switch"?  Otherwise the philosophy of Leo Fender was to build the best amplifiers at the best price. It would not have installed a "stanby switch" if it would have been helpful.

Fender was trying to protect the power supply capacitors. 
Capacitor could be more damaged with ( yes with ) stanby switch than no stanby switch ; standby to play position = surge

Cold power output tubes receiving B+ voltage may have their plate damadged .

The plate is a big piece of metal. How do you think it will be damaged?

 It is well know chemical reaction . Sorry but just by reading that from you show your lack of information

One of the worst things you can do is to 'hot switch' rectifier tubes. In other words, letting the rectifier warm up before letting current flow into the reservoir cap. That's an excellent way to kill the rectifier tube, and rather a lot of amps make this mistake!

How often do you replace a rectifer tube on  Fender like amp ? Almost never  . Output tubes yes, preamp tubes  some times.

[jazbo8]

It is well know chemical reaction . Sorry but just by reading that from you show your lack of information

It would help if you can show some creditable references or explain such chemical reaction. Some of us lack the information - the wrong kind.

[tubeswell]

If we take example of Fender amplifiers, how then explains that all are equipped with "stanby switch"?  Otherwise the philosophy of Leo Fender was to build the best amplifiers at the best price. It would not have installed a "stanby switch" if it would have been helpful.

Fender was trying to protect the power supply capacitors. 
Capacitor could be more damaged with ( yes with ) stanby switch than no stanby switch ; standby to play position = surge

Cold power output tubes receiving B+ voltage may have their plate damadged .

The plate is a big piece of metal. How do you think it will be damaged?

 It is well know chemical reaction . Sorry but just by reading that from you show your lack of information

One of the worst things you can do is to 'hot switch' rectifier tubes. In other words, letting the rectifier warm up before letting current flow into the reservoir cap. That's an excellent way to kill the rectifier tube, and rather a lot of amps make this mistake!

How often do you replace a rectifer tube on  Fender like amp ? Almost never  . Output tubes yes, preamp tubes  some times.

Subscribed! 

[TIMBO]

I think that this is a good way to look at how a switch operates under AC and DC...............

AC versus DC load breaking comparison with a knife switch

[Platefire]

I'm Fixing to give my opinion on Stanby Switches---Standby!

[TIMBO]

Don't hold back PLATE the fuse is ready to blow................

[TIMBO]

HI guys, I revised the build I am doing and have taken the standby out of the HT line and put it on the AC leads on the transformer, to me this is the best place (if you are going to have one)that will cause less problems.

With heaters warmed up and the standby turned on it takes a few seconds for the tubes to hit running speed, I can only think that this is good.

My amps will never really be put on standby (unless I forget to turn it off) for long periods of time.

There is always fore's and against to every thing, so do what works for you 

[tubenit]

Sorry to revisit an old thread.  However, I did a search on this forum & on the internet about whether a standby switch is needed with solid state rectification.  After reading Valve Wizard,  Peavey, Dr. Z, etc ..............     I found ongoing conflicted viewpoints.  Some say not needed, some say needed, some say harmful. 

It seems like the "most represented" position is no standby with tube rectification and that standby switch is needed with solid state rectification.

However, it appears that the Fender Pro Junior and Fender Blues Jr use solid state rectification without a standby switch? :

http://el34world.com/charts/Schematics/files/fender/Fender_Pro_JR.pdf
http://el34world.com/charts/Schematics/files/fender/Fender_BLUES_JUNIOR_REV_D.pdf

I'm slowly collecting parts to build a HoSo56 using 6BM8 tubes and a 5879 V1 preamp tube for a 7-9 watt push/pull amp. I'm going to build this in as small of a cab and chassis as I can and still use a 10 " speaker.   (16" x 18" x 9.5")     So, space is something of a factor.

I found Hoffman's on/off/standby switch so that is an option:    http://el34world.com/charts/SwitchDPST.htm

My preference is a simple on/off switch with no standby IF that is not an issue with solid state rectification and 6BM8 tubes?

Thoughts?         With respect, Tubenit

[VMS]

Not needed on my opinion. Also i don't get how the on-off-standby switch would be any good, first you switch the amp on standby then off again and the on, what good does that too   

[VMS]

...also i have learned most of my stuff reading TUT books so that might have some affect on how i think:


http://www.londonpower.com/standby-switch

[sluckey]

Tubenit, I would not put a standby switch on that small amp, even if space was not a factor. But if you feel you just gotta have one, Hoffman's progressive switch is an elegant space saving solution.

...i don't get how the on-off-standby switch would be any good, first you switch the amp on standby then off again and the on, what good does that too

The switch doesn't work that way. Down is off, center is standby, and up is on.

[VMS]

The switch doesn't work that way. Down is off, center is standby, and up is on.

Sorry my bad, didn't check the link. For mains switch i like to use double-pole switch so it switches off both live and neutral wire.

[tubenit]

Helpful responses, guys!  Thanks!   I'm gonna skip the standby and simply have on/off.

With respect, Tubenit

[Ed_Chambley]

Most guys who have been playing a while expect a standby switch.  And again in this thread, a person stated Leo Fender would not have used one because he was cheap.  What crap!  Airline amps were cheap, Fender amps traveled the world and back and if you are lucky you may have one.


A cheapass buys his wife used tires!  I can assure you as busy as Leo Fender was building a manufacturing company, he certainly did not have time to run around California changing his wife's flat tires.  In addition, the switches were quite nice.  I wish someone would provide some proof as to where Fender cut corners while under Leo Fenders Ownership.


Now be truthfull here.  Say you won a contest and got to choose between a handwired Fender Deluxe Reverb or a Bugera V22 INFINIUM?  The Bugera has more features and are said to have a good build quality.  Today, supposed high quality Botique amps actually brag about using the SAME High Quality Components.  Some even brag that cloth covered wire and Carbon Comp resistors are the only way to go.  Just like a Swart Atomic Jr., which is a Champ with a tone control and no transformer reverb for $1300.


I own a 1964 Fender Super Reverb, now that is at least 53 years.  I have not replaced a single component.  Yes, it has a 2 prong cord and voltage to it is regulated to 117vac.  It has never been anywhere except inside my house and my Fathers house.  It gets about an hour workout every 2 weeks.  The standby switch has never been down, only the AC switch is used.


My early 62 Bassman standby switch is about to go.  They just do not like DC.  Now I need to find an old USA Carling switch.  I have one somewhere.


I do not ever switch to standby.  All, every single amp I have, the DC switch is on all the time.  I know some feel leaving an amp hot keeps tonal quality, but I have checked this.  My slowest amp to reach full power is a Princeton Reverb Build when I have a GZ34 in it.  This one takes almost 2 seconds longer for a total of 9 seconds.


I did this because of this topic all over the place.  I even went as far as flipping the switch, pick up the guitar and put the strap over my head.  Mind you, I still have not checked tuning, which all players should.  The amp is ready even if the guitar is not.  Amps also have volume controls which are mute, but if you are too drunk to remember the volume you were playing, you were already too loud.


So when the guy called to come to look/buy my Twin, I asked if he was wanting it to have a loop.  Twins are great country amps and a slapback is really nice.  He said no, he was looking for a regular Twin.  I said come on over, I got what you want.  Pulled the loop and put the switches back.


My point is I simply put one in and I do this because everyone who knows you do not need one, still doesn't mind one being there.  You can bet if they do know they will inform you it is not necessary.  Whatever!  If they do not know and visited similar music stores as I have, usually to test an amp the Owner or Employee will get the amp out, and tell you about warming it up properly.  I remember being told 30 seconds by the owner of the music store nearest my home.


Why should I believe some old electronics nutbag?  Certainly, a music store owner knows and everyone seems to agree.


So after someone has been doing this, thinking it is the correct thing to do for the last 20 years, the last thing one person can con them of is the switch is not needed.  That is one no vote to 20 years experience and the potential buyer will think you are crazy.  After all, it has been working like this for 20 years and at least 1,000 other players disagree. 

I just put in a switch because the Parker Fly didn't go over very well.  Players still prefer wood guitars and standby switches, however, you could wire the on the lamp to the main switch and only the lamp and everything else on the standby.  The only problem here is the amp would work without the light being on and you know good and well that little jewel lamp is where the mojo lives.

[Deric]

...if you are too drunk to remember the volume you were playing, you were already too loud.

 

[jjasilli]

I love standby switches.  I could not imagine life without them.  IMHO the 3-position Carling Standby SW (which Doug sells) represents the pinnacle of human achievement & evolution -- for guitar amps.  For hi-fi, or home theater (tube amps of course), my standby's are automated:  octal plug-in time delay relays; or a clever SS circuit that flashes the power light during the warm-up period.  A tube amp without a standby SW is like a day without sunshine. 


Short version:  I agree with Ed.

[kagliostro]

I prefer mute switch

Franco

[jjasilli]

   Mute SW's are only for yucky SS equipment! Someone should pass a law. 

[tubenit]

"IMHO the 3-position Carling Standby SW (which Doug sells) represents the pinnacle of human achievement & evolution"

A tube amp without a standby SW is like a day without sunshine.

I got a real grin out of your response!  Thanks!  Fun way to start the day.

 

With respect, Tubenit

[pompeiisneaks]

Okay so I'm going to explain this as it's been explained to me, so that it hopefully makes sense.

Leo Fender first put standby switches on amps due to him seeing them on industrial tube equipment, and thinking it was necessary.

It IS necessary and cathode stripping is real ONLY IF you're using tubes at voltages OVER 1000V.  And it may have even been over 2000V I can't recall. 

In tube guitar amplifiers, the most robust tubes (6550 and the like) only go up to teh 600V range, never even exceeding 1000V. 

So basically standby switches protect nothing, work fine as a mute option but only if setup rigth and CAN do damage to rectfiers and caps if the amp design is poor due to inrush current etc.  So don't use them unless you absolutely think you'd prefer not to put a mute somewhere in the signal path dumping the signal to ground.

~Phil

[SnickSound]

I've stopped bothering with them. The surge of current when you flip it on can damage tube rectifiers and often require a bigger than necessary high-voltage fuses.

Had a small 8W amp that kept popping the small 250mA fuse when going out of standby (47uF reservoir cap). That was already twice the current the amp would pull under normal usage. I removed the standby switch, problem solved

You want to mute the amp? Ground the grids (or lift the cathode if you really want to stop the power tubes from conducting).
There are many commercial amps on which the standby switch only mutes the power amp, this allows keeping the preamp on for recording.

I can only think of ONE use for a real standby switch: switching speakers (I just flip the amp off and back on, tubes don't get cold that fast)

[jjasilli]

"IMHO the 3-position Carling Standby SW (which Doug sells) represents the pinnacle of human achievement & evolution"

A tube amp without a standby SW is like a day without sunshine.

I got a real grin out of your response!  Thanks!  Fun way to start the day.

 

With respect, Tubenit

[Ed_Chambley]

Okay so I'm going to explain this as it's been explained to me, so that it hopefully makes sense.

Leo Fender first put standby switches on amps due to him seeing them on industrial tube equipment, and thinking it was necessary. 

~Phil

Please link a reliable source to this about Leo Fender. The only thing I know for sure is it was extremely common for him to talk to musicians to find out what they liked. There were many. Eldin  Shamblin in the early days. The showman was a push to make Dick Dale the amp he wanted.


Leo Fender owned a radio repair shop and some of the giant radios had voltages very high and loads of current. Never seen a radio with a standby, doubt Leo Fender installed standby switches on repaired radios. Why, he knew they did not need them.


So, considering his first amp was actually lower current than radios he repaired daily, then unless he was stupid he had another reason. The statement about old caps of the time PRR mentioned is logical, but still doesn't explain why I have never seen a radio with a standby. I am sure there is one somewhere, I just have not seen one.


There is also the great debate on rectified tubes,  you know they are not needed and sag  can be replicated by resistors. They cost more and generate more heat and are not very efficient compared to the ultra fast switching diodes of today. Take up a lot more room.


Why are we still using tubes for rectified?


One day I read someone explain why fender amps used cloth covered wire and why he made the brown tone stack with the 350k 70k tap and this guy told it was because he could purchase them surplus. His story was his grandfather knew Leo and one night they were having dinner together and Leo Fender told him he sourced the wire and pots so cheap he had to redesign amps to use the parts. Every year that passes Leo stories grow.


The only  reason I ask about these comments is until the early 1980s USA manufacturers were copied by everyone and the ones who copied them had to cheapen the product to sell it for less than fender. I remember very well guys buying Silverstone wanting a fender, but the price was a lot more. The American public supported US products, now you can get a 18 watt front China for 99 dollars.


And finally, the Champ does not have a standby, but I have put them in Champs. Some people like them and there is a simple way of installing one that Wil not damage the amp. The HT center tap is a good option.

[kagliostro]

......... but still doesn't explain why I have never seen a radio with a standby. I am sure there is one somewhere, I just have not seen one.

Not on radios but BIG radio Frequency transmitters with Huge Power Tubes (at high voltage)

Try to ask to old Radio Amateurs, they will tell you about the ignition procedure on big transmitters

Franco

[Ed_Chambley]

......... but still doesn't explain why I have never seen a radio with a standby. I am sure there is one somewhere, I just have not seen one.

Not radios but BIG radio Frequency transmitters with Huge Power Tubes (at high voltage)

Try to ask to old Radio Amateurs, they will tell you about the ignition procedure on big transmitters

Franco

I have been in a transmission station, I know exactly what you mean. I go to hamfests often and see some of the guys with big stuff, but that is nothing compared the old WAGA station transmission here in Atlanta GA.


I toured the place when I was in grade school. These places were putting out wattage! They used to say it on the radio, WSB, 10,000 watts of power.

[mresistor]

Ed   the Princeton (rev) doesn't have a standby either..

[pompeiisneaks]

Okay so I'm going to explain this as it's been explained to me, so that it hopefully makes sense.

Leo Fender first put standby switches on amps due to him seeing them on industrial tube equipment, and thinking it was necessary. 

~Phil

Please link a reliable source to this about Leo Fender. The only thing I know for sure is it was extremely common for him to talk to musicians to find out what they liked. There were many. Eldin  Shamblin in the early days. The showman was a push to make Dick Dale the amp he wanted.

I don't have one, and I read this a long time ago, maybe 2 years ago or so, and it may have been anecdotal like the point you and PRR made about protecting caps.  Since there's no quote of leo saying that either, it has possibilities, but it isn't proof.  The bigger point is the science that is proven, that cathode stripping is a thing and can only happen over 1000V so the high voltage amplifiers for RF output were the only ones that needed it.  They had standby switches for that reason, so the tubes could heat up before the 1000 V was pumped into them.  There is also known proof that poorly constructed amps with standby switches in the wrong place put overly excessive inrush current on things that aren't ready for it.  Yes you can design around it 'if you must' but you can decide not to, and I never do, unless for some reason the amp I'm cloning already had one, and there's a hole in the chassis for it, if not I don't.

~Phil

[PRR]

I have seen a communications receiver with standby. Tube radios drift. You like to keep them hot. But in some communications services the traffic happens on a schedule. So you keep it in standby until 7:59:30. Not a common feature.

BIG tubes need more than a standby, but a whole start-up sequence.

[shooter]

BIG tubes need more than a standby, but a whole start-up sequence.

Yup, I've never used a stby in my builds, my career, ALL the tubes had standby
most of the X-ray tubes, used a start-step, logic type switching, while in standby they also spun down the Anode.  the RF transmitters took ~6 minutes to get up to operate, then kick down to standby electronically and start a timer, if it was in standby >10minutes, you waited another 6minutes for warm-up.

I'd guess I got paid ~ 2years wages waiting for systems to get up to temp