Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

5U4G power supply to 274B
5U4G power supply to 274B
5U4G power supply to 274B Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th May 2019, 01:02 AM   #21
Peckjed is offline Peckjed
diyAudio Member
 
Join Date: Jan 2018
Quote:
Originally Posted by grovergardner View Post
Um, I wouldn't put a switch at full B+. Just use 10uF, the 5U4's will last longer that way.
Sounds like a 10uF would probably work with a 274B and 5U4. I may be being sent some Mundorf 3.9uF for free, it seems like these would work well for the 274B... would it also work for the 5U4?
  Reply With Quote
Old 25th May 2019, 02:45 AM   #22
grovergardner is offline grovergardner  United States
diyAudio Member
 
Join Date: Apr 2010
Quote:
Originally Posted by Peckjed View Post
Sounds like a 10uF would probably work with a 274B and 5U4. I may be being sent some Mundorf 3.9uF for free, it seems like these would work well for the 274B... would it also work for the 5U4?
Sure, if they're rated for 600+ vdc. Check your B+ afterward, though, it may be lower than you want. And you may get an increase in ripple noise.
  Reply With Quote
Old 25th May 2019, 05:56 AM   #23
fred76 is offline fred76  Philippines
diyAudio Member
 
Join Date: Jan 2005
Location: Manila
Quote:
Originally Posted by grovergardner View Post
Actually, the datasheet specifies 4uF for max duty. This circuit draws about 80mA, about a third of the max for a 274A. In my experience 10uF here is not a problem.
Thanks Grover.. The 5R4G is close in ratings and might be a good substitute too for the PSU I linked. Peckjedís circuit looks like it could work with the 5R4G(Y) too if input cap is reduced to 10uF..
  Reply With Quote
Old 25th May 2019, 08:20 AM   #24
grovergardner is offline grovergardner  United States
diyAudio Member
 
Join Date: Apr 2010
Quote:
Originally Posted by fred76 View Post
Thanks Grover.. The 5R4G is close in ratings and might be a good substitute too for the PSU I linked. Peckjedís circuit looks like it could work with the 5R4G(Y) too if input cap is reduced to 10uF..
The 5R4 is a nice tube.
  Reply With Quote
Old 25th May 2019, 09:06 AM   #25
TonyTecson is offline TonyTecson  Philippines
diyAudio Moderator
 
TonyTecson's Avatar
 
Join Date: May 2003
Location: Maybunga, Pasig City
5U4G power supply to 274B
what is the dc resistance of the windings feeding the plates of the rectifier? if lower than 100 ohms you can series connect 3 watt resistors to make the dc resistance to about 100 ohms per side, even somewhat more can help....
__________________
hard work erases ignorance.....
  Reply With Quote
Old 2nd December 2019, 11:53 PM   #26
Peckjed is offline Peckjed
diyAudio Member
 
Join Date: Jan 2018
I know this was from a while ago. I installed the 10uF cap in place of the 30uF and the diodes on the rectifier. No issues with the rectifier anymore! However, I am noticing a hum from the choke that’s seems to be transferring to a 60hz hum on the speakers. Could lowering the 30uF to 10uF have caused this?
  Reply With Quote
Old 3rd December 2019, 12:05 AM   #27
kodabmx is offline kodabmx  Canada
Spreading triode love.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
5U4G power supply to 274B
No. That hum (if any) would be 120Hz. Are you sure it's not 120Hz?

60Hz usually is caused by ground loops/heater hum. If you short the inputs to ground, does the hum go away? If yes, it's a ground loop.
Does the hum go away as soon as you switch the amp off? If yes, this means it's coming from the power supply of the amp, either electrically, or magnetically.
  Reply With Quote
Old 3rd December 2019, 12:14 AM   #28
Peckjed is offline Peckjed
diyAudio Member
 
Join Date: Jan 2018
Quote:
Originally Posted by kodabmx View Post
No. That hum (if any) would be 120Hz. Are you sure it's not 120Hz?

60Hz usually is caused by ground loops/heater hum. If you short the inputs to ground, does the hum go away? If yes, it's a ground loop.
Does the hum go away as soon as you switch the amp off? If yes, this means it's coming from the power supply of the amp, either electrically, or magnetically.
There is a small amount of 120hz hum, but also lower frequency 60hz. (If my understanding is correct 120hz is higher pitched, almost a buzz and 60hz is lower pitched hum).

Iíll test if the hum goes away when shorting the input.
Yes, the hum goes away as soon as I power the amplifier off.

This is the power simply schematic: Legend power supply - Album on Imgur

Dumb question - can a choke be wired backwards?
  Reply With Quote
Old 3rd December 2019, 01:02 AM   #29
kodabmx is offline kodabmx  Canada
Spreading triode love.
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
5U4G power supply to 274B
Not usually, no... However I've read that the polarity can make a difference on certain chokes that were designed a certain way...

Last edited by kodabmx; 3rd December 2019 at 01:12 AM.
  Reply With Quote

Reply


5U4G power supply to 274BHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: TJ Full Music 274B/n Mesh Plate craigtone Swap Meet 1 1st November 2017 09:05 PM
Is my 274b/n defective cowneko Tubes / Valves 98 1st August 2016 06:40 AM
replace 5R4GA to WE 274B audioland Tubes / Valves 2 9th May 2016 03:34 AM
FS: Western Electric 274A & 274B tubes thehoj Swap Meet 1 9th September 2015 03:38 PM
WE JAN 274B Dating tvan56 Tubes / Valves 0 27th July 2012 11:18 PM


New To Site? Need Help?

All times are GMT. The time now is 07:57 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki