3-stage stepped rectifier. Theory? - 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 20th February 2010, 11:04 PM   #1
diyAudio Moderator Emeritus
 
Bas Horneman's Avatar
 
Join Date: Apr 2002
Location: The Netherlands
Blog Entries: 18
Default 3-stage stepped rectifier. Theory?

I've always been interested in power supplies. And often have read that schottky's are still noisier than tube rectifiers. The reason being that the schottky have even more violent reverse recovery spikes. With a tube amp, there are often multiple windings. And the reverse recovery spike "noise" is capacitively coupled to the other winding(s).

This week I saw -ecdesigns- 3-stage stepped rectifier. And subsequently googled it. Not a lot of info or implementations came up.

But I was wondering how this is all that different from just adding a reverse recovery spike filter as for instance the bottlehead folks are fond of doing? I came to think that it perhaps had to do with the fact that the 3 stage stepped rectifier prevents the spikes but can ALSO deliver more current when needed compared to a standard solid state rectifier with RRSF.

I am also curious as how one calculates what value resistors are needed.

And further info on the sense...or non sense of a stepped rectifier would be welcome...

Thanks in advance.

A picture:Click the image to open in full size.

(Oh and yes...I know tube rectifiers have their shortcomings...let's not go there please )

Last edited by Bas Horneman; 20th February 2010 at 11:07 PM.
  Reply With Quote
Old 21st February 2010, 10:45 PM   #2
diyAudio Moderator Emeritus
 
Bas Horneman's Avatar
 
Join Date: Apr 2002
Location: The Netherlands
Blog Entries: 18
No-one?
  Reply With Quote
Old 22nd February 2010, 03:58 AM   #3
star882 is offline star882  United States
diyAudio Member
 
star882's Avatar
 
Join Date: Mar 2007
Put an inductor in series to reduce switching noise and peak current.
__________________
"Fully on MOSFET = closed switch, Fully off MOSFET = open switch, Half on MOSFET = poor imitation of Tiffany Yep." - also applies to IGBTs!
  Reply With Quote
Old 22nd February 2010, 04:43 AM   #4
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Yes, ferrite bead or what have you. It's not like 60Hz has big dV/dt or anything. Regular 1N4007s work fine. If it's buzzing, add a snubber (R+C, not just C which is the brute force method). If it's still buzzing, put a few microhenries in series.

FYI, schottkies have "no" reverse recovery, which means an irreversible gulp of charge when turning off the diode. Junction diodes do, because it takes real work to pull the charge out of the junction when turning off, and to push them back in when turning on. If you drew a plot of V vs. Q (Q is charge, the integral of current) for one cycle, you'd see a skewed hysteresis loop, the area being (mostly) energy lost due to recovery, and the skew corresponding to the amount of charge delivered (since it does rectify, after all). A schottky diode has a big charge, because its capacitance is large (a typical 30V, 30A rectifier found in computer supplies has a whopping ~10nF near zero bias -- it would make an excellent AM broadcast band tuning diode!). But that charge is reversible, so the V-Q curve follows the same path back (again, not counting rectified current).

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 14th June 2011, 04:34 AM   #5
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
If you like the tube rectifier thing, check out the rectifiers from Qspeed
(formerly Lovoltech). Some of their stuff is very fast, high voltage and
has a pretty high forward drop. Not really suitable for what I do, but it
looks a lot like a tube rectifier.

  Reply With Quote
Old 14th June 2011, 05:40 AM   #6
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Good tip!
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 14th June 2011, 06:43 PM   #7
diyAudio Member
 
Join Date: Jul 2003
Location: Bath, UK
Yes, I've had good results from the QSpeed diodes (LQA60A330C, and the 16A version); notably quieter in terms of switch-off behaviour than a regular 35A bridge rectifier block.

For 'small' PSUs I'm just as likely to reach for something like UF4007 - cheap and very effective.

Last edited by martin clark; 14th June 2011 at 06:48 PM.
  Reply With Quote
Old 14th June 2011, 07:11 PM   #8
GoranB is offline GoranB  Poland
diyAudio Member
 
GoranB's Avatar
 
Join Date: Mar 2010
Location: Poland
Quote:
Originally Posted by Bas Horneman View Post
I've always been interested in power supplies. And often have read that schottky's are still noisier than tube rectifiers. The reason being that the schottky have even more violent reverse recovery spikes. With a tube amp, there are often multiple windings. And the reverse recovery spike "noise" is capacitively coupled to the other winding(s).

This week I saw -ecdesigns- 3-stage stepped rectifier. And subsequently googled it. Not a lot of info or implementations came up.

But I was wondering how this is all that different from just adding a reverse recovery spike filter as for instance the bottlehead folks are fond of doing? I came to think that it perhaps had to do with the fact that the 3 stage stepped rectifier prevents the spikes but can ALSO deliver more current when needed compared to a standard solid state rectifier with RRSF.

I am also curious as how one calculates what value resistors are needed.

And further info on the sense...or non sense of a stepped rectifier would be welcome...

Thanks in advance.

A picture:Click the image to open in full size.

(Oh and yes...I know tube rectifiers have their shortcomings...let's not go there please )
I have implemented the EC design almost on the all stages on my CD player, separated trafo's and psu boards for, TDA 1541, SAA7220, SAA7310, RAM.....
Sounds very good.
  Reply With Quote
Old 15th June 2011, 09:13 AM   #9
hesener is offline hesener  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: Munich, Germany
You can always give SiC diodes a try (e.g from Infineon or Cree), they are shottkys, have next to no reverse recovery, and are very low noise - I use them in my tube preamp and they are excellet, albeit expensive.

In this stacked shottky, the issue I see is that D1 will have to support the full input voltage, so this approach cannot be used for tube circuits (at least not with silicon-based shottkys, they are limited to 200V or so).

Calculating the resistors is straightforward, I guess, once you determine the output currents at which the two next diodes are supposed to turn on, and you know their forward voltage drop, R2 =VF/I2, and R1=(2xVF)/I1.

But I wonder why this should be good sounding, imagine a power amplifier (class B) drawing a sinusoidal current at higher power, and this rectifier circuit would introduce two more step functions in the output impedance of the power supply... should show up nicely in a spectrum analyser....
  Reply With Quote
Old 20th February 2013, 03:33 PM   #10
diyAudio Member
 
deduikertjes's Avatar
 
Join Date: Aug 2005
Quote:
Originally Posted by GoranB View Post
I have implemented the EC design almost on the all stages on my CD player, separated trafo's and psu boards for, TDA 1541, SAA7220, SAA7310, RAM.....
Sounds very good.
Can you please post a link to the schematic you've used. I cannot find an example. I don't dare to cobble up one on the info in this thread.

Thank you, arco
  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
converting tube rectifier to solid state rectifier. tubo Tubes / Valves 26 24th December 2009 12:12 AM
Bridge rectifier vs Full wave rectifier hilbert_mostert Tubes / Valves 4 28th April 2009 08:26 PM
6CJ3 rectifier or 6D22S rectifier 56oval Tubes / Valves 10 19th April 2007 09:48 AM
Anybody heard about Tarzian Silicon Rectifier for Tube Rectifier Replacement? zxx123 Tubes / Valves 4 21st February 2005 04:02 AM
Integrated Rectifier Bridge VS Rectifier Diodes Sci Chip Amps 11 16th July 2004 02:43 PM


New To Site? Need Help?

All times are GMT. The time now is 01:41 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