static noise and hum - Page 2 - 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 19th June 2002, 07:33 PM   #11
diyAudio Member
 
chris ma's Avatar
 
Join Date: Sep 2001
Location: Pickering, Canada
Mr. Pass,

Actually what I really meant to ask was a basic question, because I do not know how to measure a capacitor using a multimeter to check whether it is working or not.

Sorry...

from a guy with O level physics more than 20 years ago!

Chris
  Reply With Quote
Old 19th June 2002, 09:03 PM   #12
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
The Aleph design is quite stable without bypass
caps, even with some length on the supply lines,
and so I am inclined to presume that your caps
are fine, but that you have another problem.

Those lead lengths do look a bit long, tho.
  Reply With Quote
Old 19th June 2002, 11:12 PM   #13
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Quote:
Originally posted by Nelson Pass
The Aleph design is quite stable without bypass
caps, even with some length on the supply lines,
and so I am inclined to presume that your caps
are fine, but that you have another problem.

Those lead lengths do look a bit long, tho.
Thanks,

does power supply lines are that long, for flexibility reasons, this way I can move the heatsinks, turn, flip, lay them on their back etc. When I am going to build them in a case I will remove most of them, and put the shortest path between the powercaps and the boards!

I will shorten them just to see what happens!

Edwin
  Reply With Quote
Old 19th June 2002, 11:15 PM   #14
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Quote:
Originally posted by Nelson Pass
The noise goes away.
I had a major crash when I shorten a resistor with the 9610's (see other thread). After I recovered from this crash, the channel with the '50hz buzz' in the tweeter, is completely silent now.

The hum in the woofer of the channel has reduced but it is still there for a bit.

Edwin
  Reply With Quote
Old 20th June 2002, 02:42 AM   #15
PassFan is offline PassFan  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Central FL
I know it's a dumb question but, while you are testing this thing do you have anything plugged into the input or have the input shorted to signal ground? If you don't have anything plugged into it or have it the input shorted it will hum. I'm not out to be insulting but I always look for the simple things first as they're the ones that throw the hardest curves.
  Reply With Quote
Old 20th June 2002, 03:32 AM   #16
diyAudio Member
 
Join Date: Dec 2001
Location: Philadelphia
Quote:
Originally posted by PassFan
If you ....... ....have it the input shorted it will hum.
Skippy-
I would think that that is the best kind of "no input" if that's what you want. No?

It's important to me since I have some problems of my own, and could benefit from this thread.

I have hum in my pearl phono stage, and when I short an input it is reduced.
__________________
Vince Harris
  Reply With Quote
Old 20th June 2002, 04:18 AM   #17
PassFan is offline PassFan  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Central FL
Vince:
That should have read "and not have the input shorted". Thanks for catching that. You should not have an open input when testing, naturally when it is in use something will be plugged in, but when you are testing you must give the circuit a point of reference in order to adjust it, it keeps the noise down as well. Everything I have tried has hummed with an open input. If you have an o-scope it should be easy to find. Start looking back towards the power supply. Phono stages are high gain and more prone to these problems. I have a problem with a borbely phono stage that I recently built and it turns out it was coming from the turntable. Simply plugging in some shorting plugs showed me that without any tools or meters. You can also use a meter on the output to see if it is dc offset. You should read under .050 millivolts dc. Most stuff will go down to under.010 + or -. If the pearl has a servo circuit it will be around.002 or zero, I hav'nt looked at the pearl very well yet but I am sure it is an excellent preamp. Good Luck and thanks again.

  Reply With Quote
Old 20th June 2002, 07:47 AM   #18
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Quote:
Originally posted by PassFan
I know it's a dumb question but, while you are testing this thing do you have anything plugged into the input or have the input shorted to signal ground? If you don't have anything plugged into it or have it the input shorted it will hum. I'm not out to be insulting but I always look for the simple things first as they're the ones that throw the hardest curves.
Hello,

it will hum a bit (I should stress the bit part, it is not a 300mV ground loop hum, I know when they hit me ;-) however one channels hums less than the other. So I know it is possible to get the hum down with these wires, power supply etc. When I swap boards or swap powersupply, the hum always stays with the board!

So this why I asked for parts more prone to hum, or parts which suppress hum on the boards, so I could swap a few. I read somewhere that the 220uf C8 does something like this, so I will buy 2 new ones and try them...

The inputs are shorted, or connected to my Pass Aleph P (a real one, not a DIY, which I could buy for a good price second handed) .

Edwin
  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
Static noise in K-16LS Rukahs Tubes / Valves 2 16th June 2009 05:49 PM
Static noise from new system 79corona Car Audio 1 5th September 2007 08:53 PM
B&O Turntable static noise Please help! danioh Analogue Source 2 11th April 2007 07:29 PM
static noise question kambrian Car Audio 2 15th July 2005 11:59 PM
Removing static noise from stereo. Trist Everything Else 2 7th June 2002 05:57 PM


New To Site? Need Help?

All times are GMT. The time now is 10:00 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