trinityamps.com

Trinity Amps Guitar Amp Forum
It is currently Wed Aug 05, 2020 1:09 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Tue Mar 10, 2020 3:15 am 
Offline
Friend
Friend

Joined: Tue Mar 10, 2020 2:55 am
Posts: 13
I'd like to install the film capacitors in their ideal direction. I've identified the shielded side on each and i understand that it needs to go to the low impedance side of the circuit. However I can't identify the low impedance side of the circuit for all of the caps. I'm including the two youtube videos i used as reference. The longer video points out shield towards plate or unshielded towards grid. However aside from the obvious ones, i'm not certain. I'd default towards ground in general but my circuit knowledge is limited. So can someone chime in here. I'm thinking using the color diagram from left to right listing whether the shielded side is north (up) or south (down).
Thanks!

https://www.youtube.com/watch?v=BnR_DLd1PDI

https://www.youtube.com/watch?v=zHuW082TGXg


Top
 Profile  
 
PostPosted: Wed Mar 11, 2020 2:21 pm 
Offline
Expert
Expert

Joined: Sat Dec 04, 2010 3:42 pm
Posts: 501
Location: Qualicum Beach, BC
That's an interesting question. Yes, the link you posted to Paul Carlson's video on the subject is very informative and the little testing jig he made is neat. His videos are always very detailed with lots of good information about building unique test equipment and restoring vintage electronics.

Referring to the Tramp layout drawing, most of the capacitors should be mounted so the outside foil is towards the tube end of the chassis. Except for the .1uF and .047uF at the end of the board. Their outside foil should be towards the pot end of the chassis.

I marked the outside foil end of the capacitors on this drawing.

Attachment:
TrampLayout27.pdf [447.55 KiB]
Downloaded 31 times


Top
 Profile  
 
PostPosted: Wed Mar 11, 2020 5:54 pm 
Offline
Friend
Friend

Joined: Tue Mar 10, 2020 2:55 am
Posts: 13
Thank you for that. Bonus points for marking up the schematic. My one question for my education is why the .01 tone stack cap is not best the opposite way? it's 22k resistor to ground vs 56k resistor to plate.


Top
 Profile  
 
PostPosted: Wed Mar 11, 2020 9:00 pm 
Offline
Friend
Friend

Joined: Tue Mar 10, 2020 2:55 am
Posts: 13
After creating this thread I did happen upon a thread where Coco said the shielding direction doesn't matter for this build. Just an FYI for anyone that doesn't want to fuss over it.


Top
 Profile  
 
PostPosted: Thu Mar 12, 2020 4:15 am 
Offline
Expert
Expert

Joined: Sat Dec 04, 2010 3:42 pm
Posts: 501
Location: Qualicum Beach, BC
I was wondering about the .01uF capacitor in the tone stack, too. It's sort of 50-50 which way it should go.

On the one hand, the lower impedance is towards the plate of the previous stage and the higher impedance is towards the grid of the following stage. I tend to think of the tone stack as a single filter network between the two stages, so I suggested orienting all of its capacitors with their outside foil towards the plate of the previous stage.

On the other hand, if you consider the individual components in the network, the lower impedance end of the .01uF capacitor could be towards the 22k resistor to ground.

Impedances in filter networks are tricky to figure out. Lots of math is involved. Luckily, as Stephen said, which way the capacitors are oriented doesn't really matter in this circuit. I doubt if you would hear any difference in the hum and noise no matter which way the tone stack capacitors are mounted on the board.

It doesn't hurt to try to get the capacitors in their optimum orientations, though. When we build amps for ourselves we have lots of time to take extra steps that go beyond what factories have time for.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group