Pictures of your diy Pass amplifier - Page 24 - 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 24th August 2010, 11:50 AM   #231
Banned
 
Join Date: Nov 2006
Location: Torpoint
I'm surprised at your choice of capacitors for a Class A amplifier.

I'm using 12 x Dubilier Computer Grade 33000uF / 75V caps which actually test at nearly 90000uF each. This gives me approximately 300000uF per supply rail and nearly 150A of ripple current. I bought them on E-Bay from the US and paid about £6.00 each for them.
  Reply With Quote
Old 24th August 2010, 11:54 AM   #232
Banned
 
Join Date: Nov 2006
Nelson is happy using Panasonic tsha. So I am happy using Nippon Chemi-Con KMH.
On top of that I got them very cheap (less than a dollar each).

Last edited by Melon Head; 24th August 2010 at 11:59 AM.
  Reply With Quote
Old 24th August 2010, 11:56 AM   #233
Banned
 
Join Date: Nov 2006
Location: Torpoint
In my first prototype, my heatsinking was just completely inadequate and I cooked the output devices on one channel.

This case has now been scrapped and the components re-used.

Click the image to open in full size.
  Reply With Quote
Old 24th August 2010, 11:59 AM   #234
Banned
 
Join Date: Nov 2006
Location: Torpoint
Personally I would just check the maximum ripple current. Computer Grade Caps are generally HIGH ripple.

There is a very good argument for using LOTS of smaller caps. I've seen a Gain Clone project with over 100 x Black Gates.

I'm using B&W speakers which do require a high current drive, therefore my PSU is designed to give just that. In the Aleph 4 I can happily peak over 150A if the situation desires it.
  Reply With Quote
Old 24th August 2010, 12:49 PM   #235
Banned
 
Join Date: Nov 2006
Quote:
Originally Posted by Andy5112405 View Post
In the Aleph 4 I can happily peak over 150A if the situation desires it.
I do not remember the specs of the Aleph 4 but I am almost certain the Aleph current source would be lucky to deliver 20A/channel (in the Aleph 4) let alone 150A.
If you had a push pull output stage then that is a different matter (eg BA2). From memory the Aleph current source is limited to around twice the bias current. Eg If the bias current is 4A then the maximum output the Aleph current source will deliver is around 8A (could be a bit higher).
Obviously you could tweak the Aleph current source to put out a higher dynamic current, if that is what you wanted to do.

Last edited by Melon Head; 24th August 2010 at 12:53 PM.
  Reply With Quote
Old 24th August 2010, 01:07 PM   #236
Banned
 
Join Date: Nov 2006
Quote:
Originally Posted by Andy5112405 View Post
Personally I would just check the maximum ripple current. Computer Grade Caps are generally HIGH ripple.
Just cheked the data sheet. The ripple current is 5.39A per cap.
I am not sure how many I will use at this point in time. It will come down to listening tests.
I have 24, so I could use up to 6 per rail per channel (if I decide to go monoblock).
In the end the ear will decide.
  Reply With Quote
Old 24th August 2010, 02:36 PM   #237
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Andy, your amp in picture looks real nice

yet, a small note about transistor mount

transistors should ideally be mounted around middle of heatsink, or even better right below, vertically
to me it appears like you have them very close to top of heatsink
__________________
sometimes we know very little, and sometimes we know too much
  Reply With Quote
Old 24th August 2010, 04:04 PM   #238
diyAudio Member
 
LucasAdamson's Avatar
 
Join Date: Feb 2009
Quote:
Originally Posted by thanh1973 View Post
Just cheked the data sheet. The ripple current is 5.39A per cap.
I am not sure how many I will use at this point in time. It will come down to listening tests.
I have 24, so I could use up to 6 per rail per channel (if I decide to go monoblock).
In the end the ear will decide.
Aren't there also arguments for not using an unlimited number of caps? In chip amps, which require less power smoothing, it is quite common to use as little as 4,000uF per channel, the argument being that it increases the audible speed (immediacy) of the amp without losing bass. Obviously that is a different situation, but isn't there an argument to say that too much capacitance might slow a Class A amp down?
__________________
Lucas
  Reply With Quote
Old 24th August 2010, 04:08 PM   #239
diyAudio Member
 
Tripmaster's Avatar
 
Join Date: Feb 2008
Location: UK
Opamps generally have a much better PSRR than Class A amps if my memory serves me correctly. Therefore requiring less capacitance.
__________________
Richard
My photostream: http://www.flickr.com/photos/59839778@N04/
  Reply With Quote
Old 24th August 2010, 04:10 PM   #240
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Quote:
Originally Posted by LucasAdamson View Post

Obviously that is a different situation, but isn't there an argument to say that too much capacitance might slow a Class A amp down?
I would rather suspect that about very big supply caps, and Im not sure its only related to capacitance

Though, with classA, if caps are under rated they might get VERY hot

I doubt there are any simple single answers to that
__________________
sometimes we know very little, and sometimes we know too much
  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
DIY Low Pass and Mid/High Pass (Bass Blocking) Filters runslikealpaca Everything Else 1 19th June 2009 10:59 PM
Naked pictures of Pass Pete Fleming Pass Labs 30 9th December 2006 06:39 AM
My new hifi amplifier (pictures) Wejp Chip Amps 23 15th October 2004 12:16 AM
Pass Diy High Low Pass Please macka Pass Labs 127 2nd March 2004 11:00 PM
DIY Pass labs 100watt amplifier. microwalsh8504 Pass Labs 12 6th February 2004 07:27 PM


New To Site? Need Help?

All times are GMT. The time now is 01:32 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