Low filament circuit voltages

[Dead Short]

First time build! I just completed my 1st amp build. A simple 5f1 Tweed. I wanted to thank all on this board as you all saved me tons of time and mistakes. I made a few mods to it along the way. I added a NFB toggle, a independent on/off switch and a three way rotary  switch for 4/8/16 ohm speaker selection. Ran out of room on the chassis.  I checked continuity, grounds and voltages all the way around. Everything was spot on except the ac voltage on the filament circuit. It measured 3.4 vac not 6.3? I used a Classictone 40-18019 PT.. (green wires). I fired it up and the amp works perfectly---no humms WSE!   Any harm in running at 3.4 vac to heaters?  Everything seems to be in order otherwise.  Thanks in advance

[sluckey]

Don't measure filament voltage with one probe on chassis because that only measures half the voltage. Instead, measure across the tube socket, ie, for the 6V6 put one probe on pin 2 and the other probe on pin 7. Then you'll see all the filament voltage.

[Dead Short]

Thanks Sluckey,  all the reading and vids I watched I didn't pick that bit up...I knew it was something I should have known..Amp sounds great. I am now deflated since that project is done..It was a ton of fun building it. Just a matter of time before I start a new build, but a bit more complex...although I dont need another amp...any suggestions on a next build thats fun and affordable?

[sluckey]

Hoffman has several nice projects. Or you may find something interesting on my website. You may find that you always need just one more amp. 

How 'bout showing us some pics of your build? We like that stuff.

[Dead Short]

Pics

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Pics

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More pics

[Dead Short]

Waiting for 112 -  Tweed Cab to come in, (vintage Jensen C12R speaker)
then touch up cosmetics - let her rip

[Dead Short]

Last pic.

[sluckey]

Wow! Wish my first amp had looked that good.

One cosmetic tip... Put those star washers (switches and jacks) on the inside of the chassis for a cleaner look.

[Dead Short]

Thank you Sluckey!

I noticed that washer foul!  Moving those is on my list. I was focused purely on mechanics and nothing of cosmetics when I put those things on the outside.  I was in a  zone. 🎯
This amp really sings I am very happy with the outcome.



I will post more pics when clean it up and mount it a cab....

[Dead Short]

Just for the heck of it and since I have the 15w PT and OT(40-18031/40-18019) I am going to swap some tubes. If I use a change the rectifier to a gz34 and output tube to a 5881 and switch the impedance switch to the 16 ohm  tap, will  I have to re-bias the cathode resistor or could I just plug and play?

[PRR]

> change ....output tube to a 5881

What do you gain? 5 Watts to 9 Watts? That won't put your record in the Top Ten.

[Dead Short]

True that! Especially since my playing is novice at best😅.  I gues I am just bored and looking for something to tinker with...maybe I will build another amp entirely instead and give it to someone who can play but can't afford a beauty!

[Dead Short]