Aleph 4 PSU capacitors - 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 28th November 2001, 08:06 PM   #1
diyAudio Member
 
Join Date: Aug 2001
Location: Indiana
Am I correct in thinking that 4 25,000uf capacitors are needed for the entire stereo version of the Aleph 4 or does each channel need its own bank of 4 25,000 uf caps. Looking at the schematic I don't feel I can really tell.

Rob
  Reply With Quote
Old 28th November 2001, 08:15 PM   #2
jduncan is offline jduncan  United States
diyAudio Member
 
Join Date: Nov 2001
Location: Boston, MA, USA
Send a message via AIM to jduncan
It depends on whether you make one or two power supplies....

There are all kinds of variations you can make here....

I'm personally just using a single power supply but I also have a bit of extra capacitance...I'm going to run 4 (maybe 6 I'm still thinking) x 33,000uF of capacitance because I found a surplus store that sold the 33,000uF caps for $15 each.
  Reply With Quote
Old 29th November 2001, 06:25 PM   #3
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
The production Aleph 4 had four of the caps,
but if you can use more, then build a pi
filter with a 2 to 4 mH inductor and the
additional caps. This takes the ripple out
of the supply and gives you a lower noise floor.
  Reply With Quote
Old 29th November 2001, 07:09 PM   #4
jduncan is offline jduncan  United States
diyAudio Member
 
Join Date: Nov 2001
Location: Boston, MA, USA
Send a message via AIM to jduncan
so say i use 6 total 33,000uF capacitors.

Should I use 2 of them per rail, then one inductor per rail, then another 1 capacitor?
  Reply With Quote
Old 29th November 2001, 10:32 PM   #5
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
You'll want most of your capacitance after the inductor:
rectifier->one cap->inductor->two caps->circuit

Grey
  Reply With Quote
Old 29th November 2001, 11:33 PM   #6
jduncan is offline jduncan  United States
diyAudio Member
 
Join Date: Nov 2001
Location: Boston, MA, USA
Send a message via AIM to jduncan
OK, thanks Grey.
  Reply With Quote
Old 30th November 2001, 08:20 AM   #7
hifi is offline hifi  Sweden
diyAudio Member
 
Join Date: Mar 2001
Location: sweden
hmm...having more capacitance will give you lower output impedance from the ps?

btw i once heard that it could be a good ide to have and inductor directly after the rectifier and then capacitance...hmm that would limit inrush currents...but i think that was for a tube amp?


just checkin....
  Reply With Quote
Old 30th November 2001, 02:52 PM   #8
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
Oh dear, oh dearie me...
Now, you're getting into perilous waters. I'm going to keep this short, 'cause I'm short on sleep. If you want to mess with it in more detail, catch me when I'm fully awake.
The filter section can begin with a resistor, a cap, or an inductor. Most people don't pursue the resistor option (at least not for audio), so we'll ignore that one for the moment. Generally speaking, if you begin the filter with a cap, you'll get more voltage, but less current capability. If you use an inductor first, you'll get a lower voltage, but more current capability. I suppose that it goes without saying that these parameters have to be balanced with the circuit draw and the power transformer parameters.
As a practical example, the power supply I'm using for my tube phono stage starts with an inductor. The transformer had more voltage than I needed; if I'd used a cap input filter, the voltage would have been on the order of 545V. Since I only wanted a 300V rail, but wanted lotsa current (6922s are hungry little devils--they draw about ten times the current that a 12AX7 does), I started with an inductor, which gave me a beginning rail of about 350V, which I then regulated down to what I wanted.
Does that help?

Grey
  Reply With Quote
Old 30th November 2001, 06:34 PM   #9
diyAudio Member
 
Join Date: Aug 2001
Location: Indiana
Thanks for all of the information guys. If you couldn't tell already this is my first real diy project and I'm trying to take it slow and understand what's going on. This forum has been an invaluable resource, as has being able to obtain info from the designer of the amp itself. Thanks to Nelson, Grey and everyone else who has been patient and generous with their time.

Thanks guys,

Rob
  Reply With Quote
Old 3rd December 2001, 03:48 PM   #10
diyAudio Member
 
Join Date: Aug 2001
Location: Indiana
O.K. now about the rated voltage needed for the caps. I'm going to be powering my aleph with a 1010 VA transformer using dual 37.5 volt primaries. Assuming no loss due to the rectifier for now that would mean my capacitors will each be seeing 53 volts rms of dc, but they will also be seeing a peak of 75 volts. On top of this I heard somewhere that a twenty percent change in voltage provided by the power company is not uncommon, on the otherhand I've read of people running an aleph 4 using 50 volt PSU caps so what kind of voltage rating do I need on these caps? Are the figures I came up with accurate.Thanks.

Rob
  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
aleph capacitors available MikeZ Pass Labs 0 15th September 2006 02:04 AM
Aleph-x capacitors anders.a Pass Labs 1 9th April 2005 02:55 PM
Capacitors at Aleph 3 Odysei Pass Labs 1 27th July 2004 03:29 AM
Capacitors for the Aleph 2 Hydesg Pass Labs 2 23rd February 2003 03:31 PM
Aleph P Capacitors USI Pass Labs 1 23rd January 2002 10:31 PM


New To Site? Need Help?

All times are GMT. The time now is 02:50 AM.


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