Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: markmalin on April 08, 2021, 04:26:13 pm

Title: New build - transformer/tube orientation question
Post by: markmalin on April 08, 2021, 04:26:13 pm

Hello all,


I'm building a single ended EL34 based amp, Plexi style preamp.  I wanted to ask for advice on laying out the tubes and transformers.  Here are a couple questions:
1.) does it make more sense to have the 2 preamp tubes and power tube spaced from the left, then the transformers?  Or does it make more sense to have the 2 preamp tubes, OT, then power tube, then PT?
2.) Is it more advisable to mount the power transformer laying down or standing?  Or doesn't it really matter?  I'm looking for quietest.


Thanks in advance

Humbly,
Mark

Title: Re: New build - transformer/tube orientation question
Post by: T Wilcox on April 09, 2021, 06:14:56 pm

I would probably go with the 2nd pic as it adds more space between the transformers but I would recommend spinning either the PT or OT 90 degrees so the laminates are offset/perpendicular to avoid coupling between them which could cause hum. PT laying down avoids that problem as well

Title: Re: New build - transformer/tube orientation question
Post by: markmalin on April 09, 2021, 06:16:55 pm

Quote from: T Wilcox on April 09, 2021, 06:14:56 pm

I would probably go with the 2nd pic as it adds more space between the transformers but I would recommend spinning either the PT or OT 90 degrees so the laminates are offset/perpendicular to avoid coupling between them which could cause hum. PT laying down avoids that problem as well

Thanks for the input.

Mark

Title: Re: New build - transformer/tube orientation question
Post by: Willabe on April 09, 2021, 10:49:46 pm

Quote from: T Wilcox on April 09, 2021, 06:14:56 pm

I would probably go with the 2nd pic as it adds more space between the transformers but I would recommend spinning either the PT or OT 90 degrees so the laminates are offset/perpendicular to avoid coupling between them which could cause hum. PT laying down avoids that problem as well.

Agree.

Title: Re: New build - transformer/tube orientation question
Post by: DummyLoad on April 09, 2021, 11:06:22 pm

2nd photo, rotate the output transformer 90deg.  :icon_biggrin:


--pete

Title: Re: New build - transformer/tube orientation question
Post by: markmalin on April 10, 2021, 08:06:00 am

Thanks, guys!!