Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: joesatch on October 21, 2023, 11:41:14 am

Title: potential build transformer placement
Post by: joesatch on October 21, 2023, 11:41:14 am

i've had a tranny set for a TW Express sitting in  box for years. Due to parts availability to build a proper TW i decided to use the set on a JTM45 chassis and build a dirty shirley. The PT is very close to spec for this and has the secondaries for tube rectification. the trannies lined up with the bolt holes make the PT very close to the OT the gap is less than 1/8". Will this be an issue?

Title: Re: potential build transformer placement
Post by: joesatch on October 21, 2023, 12:30:49 pm

might scrap this idea and order a jtm45 PT.

Title: Re: potential build transformer placement
Post by: acheld on October 21, 2023, 01:03:13 pm

Yeah, that's too close for comfort, even with the proper rotation.   Who knows, it might be ok, but it's not worth the risk of going through an entire build only to find that the trannies are indeed interacting . . .

Title: Re: potential build transformer placement
Post by: Ronquest on October 21, 2023, 03:28:08 pm

You can energize the power transformer and listen to the output transformer and know.  I try and do this on every build, unloaded first if it's a new build and loaded in a working amp if I'm chasing hum.  I'd imagine loaded will put off a stronger field, but unloaded works good enough to convince me to keep them on opposite ends and clocked for the least hum.  A few degrees can make a noticeable difference and it looks like I can't measure square, but I don't listen to square.

Title: Re: potential build transformer placement
Post by: joesatch on October 22, 2023, 11:21:41 am

in my infinite wisdom i realized i can remove one of the  end caps and mount the PT sideways. Bolts just about line up and will be fine with some washers

Title: Re: potential build transformer placement
Post by: joesatch on October 22, 2023, 09:05:14 pm

all mounted. One thing i noticed is with the GZ34. all the cap cans will need to go in the chassis, gonna be tight..

Title: Re: potential build transformer placement
Post by: joesatch on October 31, 2023, 08:22:33 pm

will 5881's run okay with this 6.6k OT ?

Title: Re: potential build transformer placement
Post by: sluckey on October 31, 2023, 08:31:25 pm

Depends on what's on the other side of the OT.