Cap on Standby switch

[fdesalvo]

Have any of you guys placed a cap on the standby switch to ground to supress noise when operating the switch?

[plexi50]

On the AC side of the power switch yes. Called a death cap. But the standby switch has the B+ resivour power supply caps. They would be supressing any filtering any noise

[fdesalvo]

Right - I get that, but I've read that pople have found that placing a cap from one lug of the stdby switch to ground will eliminate the pop or discharge noises you hear when operating the switch.

[sluckey]

Fender did in the 5F6A, and probably others too. Weber does. Ceriatone has a slight variation. They put a .047uF cap and 100K resistor across the standby switch. I'm sure there are others that do something similar. I have never done so.

[fdesalvo]

Thanks much

[kagliostro]

if I remember well Colas LeGrippa experimented that

K

[HotBluePlates]

I may have to try something like that on my present build. There is a pop through the speaker when turning the amp off (no standby switch).

[JayB]

I've been doing it the marshall way now.

[plexi50]

Something to use when i hear a pop from the standby from now on. Good posting

[HotBluePlates]

Oh yeah... If you're worried about a possible "death cap" from a high voltage to ground, use a Class Y cap. They are specially made to to be safe to from a line voltage to ground. Specifically, they are made to fail safely (fail open, not fail as a short circuit).

I'll have to look up the available voltage ratings for such a cap. They might not be rated that high. If so, even a 1kV cap at 0.05µF is not that large.

[kagliostro]

What about the use of two cap in series (regardless of the type) ?

K

[Ed_Chambley]

I do this sometimes.  Here is a schematic from Mojo for a ???? Jtm-45.  It has a cap to ground on the standby.  When I built the amp the only cap I had in that value was Sozo and did not want to "waste it".  It popped like hell when switching off standby.  I don't know why some do and some don't other than in this case.  BTW, there is a Mojo Dijon cap in there now.

[Tyrannocaster]

I thought standby switches were a bad idea now: http://www.freewebs.com/valvewizard1/standby.html

[HotBluePlates]

I thought standby switches were a bad idea now: http://www.freewebs.com/valvewizard1/standby.html

Smoking while filling your gas tank is a bad idea. A standby switch is just not that necessary.

[Platefire]

I love standby switches---so it's subjective. I play in Church a lot and in the course of one service I may go from pew to stage several times in one service and need my amp ready to go at a flip of a switch.

Yep! I have stanby problems on my Mesa Boogie Rocket 440. When I switch off stanby to play, I get static. Pretty obvious in a Church service. I'm also going to attempt converting the reverb from a small midi Mesa tank to a full size Accutronics tank--so I will be starting a new tread on it soon. I've been having the special made tank for a long time, just need to install it along with connections. Guess I'll use my Allen Accomplice in its place. Platefire  

[Fresh_Start]

I do this sometimes.  Here is a schematic from Mojo for a ???? Jtm-45.  It has a cap to ground on the standby.  When I built the amp the only cap I had in that value was Sozo and did not want to "waste it".  It popped like hell when switching off standby.  I don't know why some do and some don't other than in this case.  BTW, there is a Mojo Dijon cap in there now.

That layout drawing is very confusing to me.  It looks as if the "B+ Fuse" is on the power transformer's center tap.  Not necessarily the best idea since there still would be high voltage on the power rail if something made the fuse blow Merlin on fuses.

Merlin also warns against putting the Standby switch immediately in front of a choke.  However, most Blackface Fender amps do exactly that...

Respectfully,

Chip

[fdesalvo]

I thought standby switches were a bad idea now: http://www.freewebs.com/valvewizard1/standby.html

Yeah, I read this, as well.  Seems like there is no consensus either way, though this article is very convincing..

[bobmegantz]

I prefer placing the standby switch after the reservoir cap.  That way the cap charges when you turn the amp on, preventing a big rush of current (and a spark across the switch contacts) when you flip the standby switch. 

[PRR]

> go from pew to stage several times in one service and need my amp ready to go at a flip of a switch.

Leave the B+ going, but short the signal.

I mean, unless you pray/play 6 times a day (like some monks), you probably are not putting a lot of hours on the amp. Tube-wear is a minor issue. But in a respectful Service, odd pops or "waitaminute..." are inappropriate. So leave the tubes hot, short the signal somewhere.

[Platefire]

PRR I'm in contact with the Lord all day long 24/7, don't have to be on my knees to do that. 

I hear what you saying that the tube life is very little effected by use of a standby and another way to mute my sound would be just as effective. On the other hand, I have an existing standby that should be working right without static/pop issues. I think I want to try to correct that first, so I started another thread regarding that. Please take a look--I got pixs and a schematic! Platefire 

[Ritchie200]

Hay Plate, the static in you amp - could that be related to the walls shaking when you enter the church?

Jim

[Platefire]

Har! Roof aint fell on me yet. Good thing Jesus in merciful.   

What a comment coming from a "Cathode Follower"    Plate

[Ritchie200]

Ha!

Not sure if I told the story behind that.  Early WWII, the American Airmen in England were assigned to all sorts of scut "duties", especially on the weekends.  The only guys who got off on Sunday were those whose religion called for a day of rest.  An enterprising young radio operator/technician listed Cathode Follower as his Sunday off excuse - as a joke.  He was granted the day off.  As others heard about this windfall, there were growing numbers of Cathode worshipers.  I'm sure it was the fastest growing religion in the history of man!  That is, until a senior officer with an electronic background came across the list of "Followers".  The story has it that everyone had a good laugh and no one was disciplined. 

Today there would have been a congressional hearing, some poor general would have been forced to retire, and some useless sack of plasma from the ACLU would have filed suit because some fabricated person was offended.  

Jim

[The_Gaz]

Hey I worship Satan, and I like standby switches too :)

[Willabe]

Hey I worship Satan

Sorry, But that's not funny, IMO.    


                 
                        Brad       

[Platefire]

Hay Jim

  Interesting story. I worked for the Army almost 30 years for DPW--Department of Public Works--so we maintained the post grounds and facilities at Fort Polk. I've been in a lot of those old World War II Chapels for renovations/repairs over the years and they all had old Hammond Organs & Tone Cabinets. Most of them no longer in use because most of the soldiers were using the more modern Chapels. I was always checking them out and  wondering how I could get my hands on one--but with the Army you have to wait until they dispose of property through government Auctions. I eventually did get my hands on two Hammond PR-40 Tone cabinets but they are pretty useless for amp building other than a few parts--those ventage speakers are pretty cool. Most of that old WWII wood had been torn down before I retired, so  it's all gone now. So I wonder how many soldiers that processed through Fort Polk in WWII ended up being Cathode Followers     Now we know as Paul Harvey use to say "The rest of the Story". Platefire

[Ritchie200]

I'm sure you reported directly to the base commander!  Every one of them wanted their base to look like a country club!  My sis-in-law was a lifer in the Air Force and retired full bird Colonel.  She worked public affairs for most of her career.  I got to see some really cool stuff and meet some amazing heroes, thanks to her.  I wonder what those Hammonds would go for?!?!  Is there a main clearing house for these auctions?  Might be something to keep an eye on!

Jim