Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on November 23, 2010, 07:09:44 am

Title: Standby needed?
Post by: tubenit on November 23, 2010, 07:09:44 am

Guys,

Do I really need a standby switch with this FX-Reverb?

I typically use one when there are power tubes involved and SS rectification, but I am not sure if a 12A_7 really needs one?

I hope to have this outboard unit built by this wkend.

With respect, Tubenit

Title: Re: Standby needed?
Post by: sluckey on November 23, 2010, 07:19:24 am

I don't think so. I'm building a stand-alone vibrato unit that uses 4 12A?7s and wont be using a STBY switch.

Title: Re: Standby needed?
Post by: jjasilli on November 23, 2010, 07:21:38 am

Many people claim standby does not save tubes.  Some amps have standby service only the power tubes.  The logical conclusion is that it will not prolong the life of preamp tubes.  But standby might be handy to keep the tubes warmed up while plugging, unplugging cables, etc.

Title: Re: Standby needed?
Post by: FYL on November 23, 2010, 08:06:57 am

Quote

Do I really need a standby switch with this FX-Reverb?

Not really, except if you want to manually delay B+ and/or mute the unit.

Title: Re: Standby needed?
Post by: jojokeo on November 23, 2010, 02:01:40 pm

I thought cathode stripping only really occurred with high voltages, like over 500v so it doesn't really apply to our usages?

tubenit, if space is your concern I've used standard small toggle on/off/on DPDT switches that work perfectly fine. center = off, down = standby, and up = on.

Title: Re: Standby needed?
Post by: RicharD on November 23, 2010, 07:28:18 pm

Search Merlin's posts.  He wrote a nice long essay about standby switches.  I would agree you do not need a standby switch for this circuit.  I've seen so much old stuff that doesn't have a standby switch and is still running strong.

Title: Re: Standby needed?
Post by: PRR on November 24, 2010, 12:54:51 am

Standby is for a quick pee and a beer and back to work.

It does not save tubes.

Leave the amp ON as long as you will be needing it, and don't mind the hum/hiss/heat. Turn it off before you leave the house (tho in fire-resistant studios I usually left every-day tube amps on all night).

Title: Re: Standby needed?
Post by: tubenit on November 24, 2010, 04:59:16 am

Gentleman,

Thanks for the replies and humor (PRR)!   :laugh:

With respect, Tubenit