Power Supply Resevoir Size - Page 4 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 July 2012, 06:31 AM   #31
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by Nico Ras View Post
Hugh, AndrewT, Carlos, Andrej, Homemodder, Michael, Sakis,...... .
Where is AndrewT ? Its been nearly a month now since he was last on here.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 19th July 2012, 06:46 AM   #32
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Thanks for the info Tom, I think I will implement the idea of distributed power "supply" with a star arrangement which would effectively remove modulation between power lines to different areas as well.

One is inclined to think of a power supply as a separate self contained unit and normally design it as such. Looking inside 9/10 amps the power supply sits in the middle of the box instead of being distributed to areas as needed.
__________________
Kindest regards
Nico
  Reply With Quote
Old 19th July 2012, 07:47 AM   #33
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Nico,

I began using onboard power supplies, separate full wave rectification and filter bank for each rail, several years back. This keeps track lengths very short. I also use two filter caps per rail, with 0.15R resistors between them on both terminations. This means one cap takes the aggressive charge pulse while the other cap, with much reduced and longer duration charge cycle, handles earth return for the speaker voice coils.

I believe the amps sound better as a result. My FetZilla design, done with Greg Peters and Mike Meares, uses this principle, and all seem to agree it sounds damn good, with subjective power way beyond its rating.

Cheers,

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 19th July 2012, 08:41 AM   #34
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Thanks Hugh, I appreciate your contribution. I have followed the Fetzilla thread for a long while and what Hugh says makes sense also. So what do we have so far:

Caps should not be too bulky. Should be distributed where current is needed or voltage need be held constant, tracks should be kept short to what it is sourcing, some series resistance on the incoming lead act as ripple filtering.

It is getting interesting. What difference would it make if rectifiers are close to caps or should one try and mount them separately. The leads to the caps would act as both series resistance and inductance. So lets say one runs a star connection from the diode block to the various on board smoothing caps, and calculate the cap value for the job it needs to do.
__________________
Kindest regards
Nico
  Reply With Quote
Old 19th July 2012, 09:16 AM   #35
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Hi to all DIY friends

Nico it's good that a discussion about amp PSU-s is opened from time to time, to share experiences and to enlighten certain practical guidelines for DIY-ers to make better amps.

From mine past amps I learned that separate PSU rails for a front-end/output stage is a way better solution, simply because relation between front-end and output stage is similar to Beauty and the Beast like. PSU's impedance/current capability demands for the two are so apart from each other that the best solution is to supply them separately and than allow them to dance together.

In short, my practical instructions for amp's linear PSU would be:
- 4 times VA to Wrms rating for the mains transformer, over current capability (low impedance, core magnetic reserve) to fast charge the caps
- fast/ultra fast on amp PCB rectifier pairs, separate for front-end and output (4 all together)
- 2000 uF/A capacitance bank in my SSA/CSA case it means 2200 uF/rail for front-end and 22000 uF/rail for output stage (100 Wrms/8 ohm), all caps on amp PCB mounted
- as short as possible PCB tracks to the outputs
- on PCB two star grounds (one front-end PSU GND, other output stage PSU GND) connected together with 5-10 mm track, prevents interference between high/low currents in each GND
- quality of the electrolytic caps is a must
- decoupling with 1 uF/0,1 uF, especially in splitting/ending points on PCB

Example is CSA PCB in attachment. Nothing new but just one more practical example from the real build.
Attached Images
File Type: jpg CSA BIGBT HP PCB.jpg (776.0 KB, 961 views)
  Reply With Quote
Old 19th July 2012, 11:39 AM   #36
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Andrej, thank you for your most informative comments, it would seem that splitting the power supply up is becoming a confirmed choice of some of our experienced members.

Hugh, in my one comment I mentioned your simple but effective means of decoupling of front- and back-end of your earlier amplifiers by means of a diode and resistor/capacitor filter.

Do you still subscribed to this method for the same reasons Andrej mention above, or have you discarded it because there is no sonic benefit.
__________________
Kindest regards
Nico
  Reply With Quote
Old 19th July 2012, 11:43 AM   #37
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Andrej, do I understand you correctly that you use two completely different supplies on the front and back end.

Do they share the same secondaries of the transformer or are they actually different transformers, which of course is more expensive but probably makes sense or maybe the diodes block the power modulation effectively.
__________________
Kindest regards
Nico
  Reply With Quote
Old 19th July 2012, 11:48 AM   #38
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
MiiB, have you actually done a practical layout as we have discussed a few years back with a large reservoir caps between each power device on the PCB and if you had, can you comment that you recognized the benefits from doing so.
__________________
Kindest regards
Nico
  Reply With Quote
Old 19th July 2012, 11:57 AM   #39
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Nico,

Under persuasion of my EE mate Paul and a lot of spice simulation, I have discarded it.....

Check your intray.

Cheers,

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 19th July 2012, 12:01 PM   #40
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by Nico Ras View Post
Andrej, do I understand you correctly that you use two completely different supplies on the front and back end.

Do they share the same secondaries of the transformer or are they actually different transformers, which of course is more expensive but probably makes sense or maybe the diodes block the power modulation effectively.
Four completely separate secondary windings, two 52 Vac for the front-end and two 45 Vac for the output. Each winding is connected to full wave rectifier bridge.
  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
Valve power supply - How to size transformer? SanderW Power Supplies 25 4th January 2013 04:12 PM
How do you calculate choke size in a power supply? Original Burnedfingers Tubes / Valves 25 5th January 2012 12:23 AM
power supply bypass cap size BigE Power Supplies 11 5th July 2011 02:59 PM
Power Supply Case Size diymixer Power Supplies 1 10th October 2010 05:47 AM
What size power supply should I get for repair work? spooney Car Audio 3 6th December 2007 11:50 PM


New To Site? Need Help?

All times are GMT. The time now is 04:58 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