Diodes in a Graetz Hybrid - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 13th March 2012, 04:31 PM   #1
diyAudio Member
 
Join Date: Sep 2006
Default Diodes in a Graetz Hybrid

IXYS HiPerFreds, Fairchild Stealths, Cree SIC Shottkies.

I know the technical differences, but.....

What are the "sonic" differences when used in a Greatz Hybrid bridge?

Since the tube is the "slowest" recovery element of the equation, and the one that gives the bridge it's basic sonic signiture, does the type of diodes mentioned above really make a substantial audible difference?

Say the tube will be a 5U4G and the B+ around 490 VDC after the filter.


JD
  Reply With Quote
Old 13th March 2012, 04:56 PM   #2
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
I believe that is very stupid to mix tubes and semiconductors in the same circuit. Use Si diodes OR tube in full wave.
__________________
LW1DSE
  Reply With Quote
Old 13th March 2012, 05:06 PM   #3
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally Posted by Osvaldo de Banfield View Post
I believe that is very stupid to mix tubes and semiconductors in the same circuit. Use Si diodes OR tube in full wave.
It's not IMHO, works fine and in the case of the 5AR4/6V4/6CA4 provides useful warm up delay that you don't get with a solid state bridge without significant additional complexity.

The 5AR4 is also noted for hot start arcing issues, particularly current production and placing a UF4007 in series with each plate completely prevents this issue and does not otherwise alter rectifier performance wrt voltage regulation, warm up delay or EMI.

I would not spend the money on exotic solid state rectifiers for use in the Graetz bridge, nor probably anywhere else for that matter because I can't hear any difference in a properly designed circuit. UF series rectifiers are cheap and help wrt to EMI, anything beyond that in low current high voltage supplies may be overkill. (JMO)
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 13th March 2012, 05:32 PM   #4
diyAudio Member
 
Join Date: Sep 2006
good opinionated debate on the merits or not of a hybrid rectifier, methinks that's off topic from the start gents. What are the sonic differences between the diodes I mentioned?
Any ears here ?

JD
  Reply With Quote
Old 13th March 2012, 05:49 PM   #5
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
As I stated in my last post I have not been able to demonstrate any audible difference in tube gear between any solid state rectifiers in a properly implemented design. IMHO it's an audiophile fashion statement. I've wasted money on hexfreds because of the hype and won't do that again. Last time I checked I had a fairly good pair of ears.

Seriously though you should just go out and try them - nothing like direct experience, perhaps you will not be as disappointed as I was..

In the Graetz bridge the type of SS diodes used make no audible difference that I can discern.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 13th March 2012, 05:54 PM   #6
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
Quote:
Originally Posted by Jeffrey Davison View Post
What are the sonic differences between the diodes I mentioned?

JD
I donīt know. One time power is rectified, and filtered, I canīt understand which may be the difference between SS rectifiers and VT ones. I found in a regenerative receiver I made 2 years ago, first with SS rectifiers, and latter with a 6X4 is the time takes to get +B at the bus. I rewind the Xformer to get same voltage with both rectifiers, and no audible difference, except for the level of ripple (Diodes were doubling in half wave, tube is full wave). And, the change was in order to get this regen all tubes. But, again, I couldīt find audible differences.
__________________
LW1DSE
  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
Graetz Field Coil Shoog Full Range 12 14th July 2011 08:31 PM
WTB - pair or current regulator diodes for millet hybrid mekanoplastik Swap Meet 11 8th March 2011 07:06 AM
Hybrid Graetz Bridge alexg Tubes / Valves 3 9th April 2008 03:45 PM
hybrid graetz in PSUDII JoshK Tubes / Valves 1 27th January 2007 01:50 AM
[Hybrid Amp] Questions about the use of zener diodes Johnix Solid State 30 26th September 2004 08:00 AM


New To Site? Need Help?

All times are GMT. The time now is 05:28 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2