(Transformer Placement / Listening Test Question) New Princeton Build Log.

[ToneJunkie]

Hey everyone,
Starting up a new Princeton build and thought I’d start a log to document the process. I’ll be working on it a couple hours at a time, so this one’s going to come together slowly — but I’m excited to dig in.
First off, I finally built my own amp cradle for this project. I’m honestly surprised I hadn’t done that sooner — what a game changer! Got the chassis and laid out the board today. Probably hard to decipher my board layout but I think it should be fine. 
I already started a thread about the grounding scheme here if anyone wants to follow that part of the discussion:


https://el34world.com/Forum/index.php?topic=33091.0
More updates soon!

[ToneJunkie]

I tape my layout onto I think its called G10 fiberglass board for the drilling process.  I will use turrets and mostly eyelets.  I start with the red mounting spots first and then cover them so I know they are done due to the different hole size.  Then to the turrets same due to the different size and then the rest of the holes for the eyelets.  I don't know how others do this parts so I'm just sharing. 

[ToneJunkie]

Last one of the day... board built.  Two drill presses are nice one for holes and the other for staking (is that how you spell it?).  I also got the holes lined up in the chassis too. 

[SEL49]

What is the purpose of the two long slots (seem to be about 3/8") in the board? Also, the single 3/8" hole?

[ToneJunkie]

What is the purpose of the two long slots (seem to be about 3/8") in the board? Also, the single 3/8" hole?

I just like wires to go under the board but I'm always scared I'm going to make a mistake or want to move something so I'm trying a under the board through the hole and to the eyelet method.  Don't know how its going to work out.  Never tried it before like this... I have done small holes and through the board to the eyelet like the picture below. 

[ToneJunkie]

Put the grounding bus's in and starting to populate the board.

[ToneJunkie]

Here is my mostly populated board and the heaters wired up.  Also here is the schematic I'm using as well as the grounding scheme.  Is it ok to use the bus wire at the power end of the board for all the GA grounds from the schematic and then wire one wire with a ring terminal to chassis?


Note: I did see that I wired my heaters to pin 6 not pin 7 of my power tube sockets... I will fix that right away :-)

[ToneJunkie]

I got a Heyboer PT that has two 120vac taps for the primary.  Do I wire them in parallel or just use one of them?  Also if anyone has a minute any suggestions on the grounding question in the previous post?  Thanks for looking!

[tubeswell]

I got a Heyboer PT that has two 120vac taps for the primary.  Do I wire them in parallel or just use one of them?!

You can absolutely wire both primaries in parallel if they are each the same number of turns, and if they are wired in-phase.

[ToneJunkie]

You can absolutely wire both primaries in parallel if they are each the same number of turns, and if they are wired in-phase.

Sounds good... I will ask to make sure that is the case and the wire it up!

[pdf64]

Here is my mostly populated board and the heaters wired up.  Also here is the schematic I'm using as well as the grounding scheme.  Is it ok to use the bus wire at the power end of the board for all the GA grounds from the schematic and then wire one wire with a ring terminal to chassis?  ....

It would probably work out ok, but it may not be ideal, would be contrary to Merlin's' multiple star grounding suggestion.

Connect the HT winding CT to GA. Then GA to GB.
Connect all other GAs to GB rather than GA.
Then GB to GC.
Then GC to GD.

Ideally just one connection between circuit ground and the amp chassis, at or near the input sockets.

[ToneJunkie]

You can absolutely wire both primaries in parallel if they are each the same number of turns, and if they are wired in-phase.

Yep talked with Heyboer and they said in phase and same turns :-)

[ToneJunkie]

It would probably work out ok, but it may not be ideal, would be contrary to Merlin's' multiple star grounding suggestion.

Connect the HT winding CT to GA. Then GA to GB.
Connect all other GAs to GB rather than GA.
Then GB to GC.
Then GC to GD.

Ideally just one connection between circuit ground and the amp chassis, at or near the input sockets.

I'm going to have to study merlin's article again.  I thought I was using his method.  I will go back over everything and check with your ideas above.   

[ToneJunkie]

Installed the PT and tacked in the OT to do the hum listening test.  There is substantially less hum with the OT further away from the PT.  The angle effects the hum a little but mostly just distance.  It just keeps getting quieter as you move it away from the PT... how far would you go? Any issue with the OT being under V3 or even V2?