adding a standby switch

[i love everyone]

where exactly in an amp's circuit is the standby switch located? i was looking at getting a Valve Junior amp soon, because i'm moving into an apartment in the fall and want an amp that i can crank a little, but not shake the floor with it, and want to add a standby switch to the stock version. i know it makes it so the power tube(s) still get current but not the pre-amp, but i'm not sure where i would put it. any help would be appreciated.

 

[Reload in 5]

Re: adding a standby switch

just put a switch in series with the wire going to the T2 connector on the circuit board

 

[devastone]

Re: adding a standby switch

i know it makes it so the power tube(s) still get current but not the pre-amp, but i'm not sure where i would put it. any help would be appreciated.

No, it lets the heaters get current so the tubes can heat up they get hit with the high plate voltage. It's more important for the power tubes, especially in higher wattage amps. Not sure your Valve Junior really needs one.

 

[Empty Pockets]

Re: adding a standby switch

The Valve Junior goes into 'standby' when you put the volume knob down all the way.

 

[Fresh_Start]

Re: adding a standby switch

Here's a forum with more info than you could possibly want about modding the Valve Jr. http://www.sewatt.com/epivjmods

You still don't need a standby switch for a small, relatively low voltage single-ended amp IMHO. If the Champ was good enough for Leo without one, that's ok with me.

Chip

 

[The Golden Boy]

Re: adding a standby switch

Why?

 

[some_dude]

Re: adding a standby switch

The Valve Junior goes into 'standby' when you put the volume knob down all the way.

+1.

Cheap.

 

[Rich_S]

Re: adding a standby switch

Alright - everybody who does't know, stop throwing wrong info around.

The deciding factor on whether an amp "needs" a standby switch or not is the type of recitifier tube it has. It has nothig to do with the size of the amp, or whether it's single-ended.

Solid state rectifiers hit the tubes with high voltage (B+) as soon as the power switch is turned on. If you hit tubes with B+ before their filaments are heated up, it's bad for them. So, amps with solid-state recifiers need a standby switch, which should not be turned on until all the filaments have had a chance to warm up.

The Champ didn't need a standby because is has a tube rectifier. Tube recitifiers warm up slowly just like the other tubes, so the B+ comes up slowly, and doesn't hurt them. On an amp with a tube recifier, the standby switch is a convenience for the player.

Unfortunately, I'm stuck in a hotel without a Valve Jr. schematic, so I can't tell you exactly where to wire it. Does the volume pot actually have a switch on it, or were you guys just kidding about the volume control? Because "standby" is not just about keeping sound from coming out of the amp - it's about keeping B+ off cold tubes.

 

[Reload in 5]

Re: adding a standby switch

Alright - everybody who does't know, stop throwing wrong info around.

The deciding factor on whether an amp "needs" a standby switch or not is the type of recitifier tube it has. It has nothig to do with the size of the amp, or whether it's single-ended.

Solid state rectifiers hit the tubes with high voltage (B+) as soon as the power switch is turned on. If you hit tubes with B+ before their filaments are heated up, it's bad for them. So, amps with solid-state recifiers need a standby switch, which should not be turned on until all the filaments have had a chance to warm up.

The Champ didn't need a standby because is has a tube rectifier. Tube recitifiers warm up slowly just like the other tubes, so the B+ comes up slowly, and doesn't hurt them. On an amp with a tube recifier, the standby switch is a convenience for the player.

Unfortunately, I'm stuck in a hotel without a Valve Jr. schematic, so I can't tell you exactly where to wire it. Does the volume pot actually have a switch on it, or were you guys just kidding about the volume control? Because "standby" is not just about keeping sound from coming out of the amp - it's about keeping B+ off cold tubes.

it does NOT have a switch on the volume. They were referring to the fact that those of us who dont know better think it is just about sending sound to the tubes. (I thought this until 2 minutes ago)

anyway, see post #2 for where to wire the switch.

 

[Fresh_Start]

Re: adding a standby switch

Alright - everybody who does't know, stop throwing wrong info around.

The deciding factor on whether an amp "needs" a standby switch or not is the type of recitifier tube it has. It has nothig to do with the size of the amp, or whether it's single-ended.

Solid state rectifiers hit the tubes with high voltage (B+) as soon as the power switch is turned on. If you hit tubes with B+ before their filaments are heated up, it's bad for them. So, amps with solid-state recifiers need a standby switch, which should not be turned on until all the filaments have had a chance to warm up.

The Champ didn't need a standby because is has a tube rectifier. Tube recitifiers warm up slowly just like the other tubes, so the B+ comes up slowly, and doesn't hurt them. On an amp with a tube recifier, the standby switch is a convenience for the player.

Unfortunately, I'm stuck in a hotel without a Valve Jr. schematic, so I can't tell you exactly where to wire it. Does the volume pot actually have a switch on it, or were you guys just kidding about the volume control? Because "standby" is not just about keeping sound from coming out of the amp - it's about keeping B+ off cold tubes.

Hi Rich -

Kevin O'Connor has been wrong about other things, so maybe he's off base regarding standby switches too. However, he seems to think that you don't really need a standby switch until you get relatively high voltages (e.g. over 800 volts DC).

Fender's Blues Jr. has a solid state rectifier and only an On/Off switch. So do lots of other small amps. Maybe it's just cheaper for amp builders (and more profitable for tube merchants) to eliminate a standby switch...

On the other hand, you have a good point about the type of rectifier - sand diodes pass current to the plates right away while a tube rectifier (diode) warms up along with the other tubes, creating a slight delay in delivering current to the plates of the other tubes. The AX84 small, single-ended designs all have standby switches - and solid state rectifiers.

Bottom line - this seems to be a subject where there are more opinions than certifiable facts.

Chip

P.S. I hope you're staying somewhere more like a Marriott than a Motel 6