Slight 60 Hz hum Aleph J - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 2nd April 2013, 03:06 AM   #1
3GGG is offline 3GGG  Australia
diyAudio Member
 
Join Date: Mar 2010
Default Slight 60 Hz hum Aleph J

Now i have my 110db+ sensitive horn setup i am getting some 50Hz hum. I have disconnected everything upstream and it remains there. Is it realistic to get zero hum?
  Reply With Quote
Old 2nd April 2013, 03:36 AM   #2
PKI is offline PKI  United States
diyAudio Member
 
PKI's Avatar
 
Join Date: Aug 2011
ZM will ask to post photos, so you can impress him and post good photos of your amp and PSU especially, before he asks ;-)
  Reply With Quote
Old 2nd April 2013, 07:22 AM   #3
3GGG is offline 3GGG  Australia
diyAudio Member
 
Join Date: Mar 2010
mobile phone picture
Attached Images
File Type: jpg IMG_1136.jpg (855.0 KB, 190 views)
  Reply With Quote
Old 2nd April 2013, 08:38 AM   #4
diyAudio Member
 
Join Date: Feb 2009
i would recommend to use CRC PSU.
  Reply With Quote
Old 2nd April 2013, 09:25 AM   #5
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
more details : xformer , caps , Iq
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 2nd April 2013, 10:01 AM   #6
3GGG is offline 3GGG  Australia
diyAudio Member
 
Join Date: Mar 2010
PSU is simply two 22000 uf caps per side, transformer from memory is a 2 x 18v 600 va toroid.
  Reply With Quote
Old 2nd April 2013, 10:23 AM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Try twisted pairs for EVERY flow and return pair.
Ensure there is NEVER a flow wire separated from it's return.

This may or may not improve your hum.

But before you start modifying, measure the amplifier output noise and output offset with the input shorted (0r) and with a 1k0 as the dummy input source.
Then you have something to compare with after the modification/s

If all this fails to give a significant improvement, then try the CRC or CLC as the smoothing.
I added ~47uH between the first and second caps and got an ~10dB reduction in ripple on the PSU output.
__________________
regards Andrew T.
  Reply With Quote
Old 2nd April 2013, 11:30 AM   #8
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
if Iq is in area of regular FW Aleph J (say 80W of dissipation per channel ) then 4x22mF is on lowish side

NP is using 8x15mF in common FW PSU

that fact , combined with not perfect wiring and super efficient spks is what is giving that buzz

also - it seems you have sort of separate C banks for each channel which isn't optimal solution , just because they're anyway in parallel , due to common connection at Graetzs

so - either put them (caps) together , physically close , and wire them properly ...... in CRC , then route wires to channels , or make separate channel C banks with each bank having own pair of Graetzs

choice is yours
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 2nd April 2013, 11:53 AM   #9
3GGG is offline 3GGG  Australia
diyAudio Member
 
Join Date: Mar 2010
I have a big box of 25000uf caps i bought on here and will redo into CRC and put them close together.
Thank you all for your help, again
  Reply With Quote
Old 2nd April 2013, 11:54 AM   #10
hates ground loops
diyAudio Member
 
Rodeodave's Avatar
 
Join Date: Dec 2004
Location: in the alps
Blog Entries: 1
Um, it seems that the green wire at the capacitor bank is ground, right? If so, massive ground loop right there.

How? Right input ground going to pcb. Ground wire going to right cap bank. From there to left cap bank. From there to pcb and to the left output. The two channels' grounds inevitably meet somewhere, and thus a massive loop is formed. And the transformer sitting right in the middle of it all.

If there's one thing I loathe, it's ground loops. So help me sleep better, and break the loop (but still ground everything properly!). You should see some improvement by doing so.
__________________
Gravity - Making the G since 13.7 billion B.C.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
does some know how to build a 60hz hum Eliminator which stops the 60 hz hum?? prorms Solid State 21 13th August 2011 08:26 PM
60 hz hum, what causes those? saltmiser Tubes / Valves 7 15th April 2008 03:28 AM
60 Hz hum Adam M. Chip Amps 6 7th September 2004 12:57 PM
60 Hz Hum Chad Solid State 5 26th October 2001 04:16 AM


New To Site? Need Help?

All times are GMT. The time now is 04:03 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2