Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bakerlite on March 08, 2015, 10:56:24 am

Title: Pilot Light at "the end of the line"
Post by: bakerlite on March 08, 2015, 10:56:24 am

Hey Folks
 I gotta build here where its gonna be easier to place the 6.3v jewel light at the end -  by that I mean after the last tubes heater in the line of tubes.


I cant for the life of me think it will be a problem - but that sure dont mean there cant be one I guess!??

Title: Re: Pilot Light at "the end of the line"
Post by: Willabe on March 08, 2015, 11:04:30 am

You can hook up the pilot light anywhere in the 6.3 volt string.


                   Brad    :icon_biggrin:

Title: Re: Pilot Light at "the end of the line"
Post by: jjasilli on March 08, 2015, 07:12:47 pm

Quote from: Willabe on March 08, 2015, 11:04:30 am

You can hook up the pilot light anywhere in the 6.3 volt string.                     Brad    :icon_biggrin: 

True, BUT. I submit that messing with proven Layout may invoke the Wrath of the Gods.  Incandescent filaments are noisy.  There may be a benefit to having them at the power amp side of the chassis, along with the ground reference resistors (if any).  Any issues may show up in only a small percentage of builds;  but this cloud be a factor for volume manufacturers.

Title: Re: Pilot Light at "the end of the line"
Post by: HotBluePlates on March 08, 2015, 09:38:33 pm

Quote from: jjasilli on March 08, 2015, 07:12:47 pm

Incandescent filaments are noisy.  There may be a benefit to having them at the power amp side of the chassis ...

That's my preference too, but it seems both the original and modern Standel amps get away with it.

See the image below. There is a pilot light on both sides of the faceplate, with one right next to the input jack. The original 25L15 did something similar, with both amps doing this to light up the faceplate. Yet they don't seem to have hum issues.

(http://www.tdpri.com/forum/attachments/amp-central-station/36653d1260984111-echosonic-information-100_2169-jpg)

And Matchless had a bunch of pilot lights arranged behind the front panel to get their light-up lettering, and you'd assume it would cause more hum problems but didn't seem to.

FWIW, I was concerned enough when I built my 25L15-style amp that I left off the lighting at the input jack side, but am thinking about going back to add it back in.

Title: Re: Pilot Light at "the end of the line"
Post by: hesamadman on March 08, 2015, 10:23:47 pm

I just did it out of error. I made sure the wires were as far from everything as possible but I didn't have a noise problem.