Output transformer cores - 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 19th November 2009, 02:23 PM   #1
diyAudio Member
 
Join Date: Aug 2007
Default Output transformer cores

I was looking at transformer cores for the past few months as I am looking to start winding my own trafos. The M6 silicon steel has been a favorite to many people - it is cheap, not that hard to find and has good parameters. However, I was looking into something more exotic, no matter what the price would be.
What I found so far is a material called Metglas Magnetic Alloy 2714 which shows superb qualitues - it has the lowest core loss, permeability is many times higher than M6 so it should allow a much smaller core size, which means a reduction in the turns radius and thus less losses in the copper. This material also has a freq range up to 250Khz and is often used in aviation and medicine transformers. There are a few companies that offer C-core laminations of this material. To me it looks like the ideal core material, any thoughts?
  Reply With Quote
Old 19th November 2009, 02:51 PM   #2
WBS is offline WBS  Tibet
diyAudio Member
 
Join Date: Jan 2007
C-core is the way to go if you've got the dough.
  Reply With Quote
Old 19th November 2009, 04:02 PM   #3
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
Max flux density and power at the lowest audio frequency sets the core size, not the permeability. Metglas 2714 only has .57 Tesla saturation (annealed) and only .25 Tesla un-annealled. So this will require a 3 to 6 times larger core area than M6. (which translates to 5 to 14.7 times the core volume of M6)
__________________
I want a Huvr-Board!!
  Reply With Quote
Old 19th November 2009, 06:31 PM   #4
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
hey-Hey!!!,
I'd go for 49% Ni stuff. I suspect I can get C-cores in the size I want; it is unavailable in the larger sizes of scrapless E-I. Near the saturation flux density of M6( or M4 and M3 for that matter ), higher permeability and lower loss than 3.5% Silicon steel. Nice stuff indeed, though I suspect it'll be $60-70 per pound... I'll be using it in a coil design set for a 2.5" stack of 1.5" center leg width scrapless E-I.
cheers,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 19th November 2009, 11:21 PM   #5
Matt BH is offline Matt BH  United Kingdom
diyAudio Member
 
Join Date: Jul 2009
Location: Cheltenham
Hi Mario,
Could you let us all know where you can get the Metglas stuff. I have a pair of M6 c-cores but as two they are big enough for one transformer but I need two. I have been thinking about winding my own output trannys for a while, even built a lathe type lash up with a counter etc. The cores I have a are marginal after doing all the math. I really dont want to wind some trannys on the off chance. Even after measurement with my cores. I get 300W with the two at 50Hz with minimal distortion. So c-cores can be a fair bit smaler for push pull. Langford Smiths papers show this but there is very lttle info out there about it.
Cheers Matt.
  Reply With Quote
Old 20th November 2009, 06:31 AM   #6
diyAudio Member
 
Join Date: Aug 2007
There is an English company that supplies these materials. I do not have the pricing as I have not figured out what would be good as material.

I did a mistake when pasting the Metglas number, it is the 2605SA1 and I found a work by a Swedish aircraft electronics designer who said they are best for transformers used in the Grippen aircraft. What I am looking is this:

http://www.amorphousmetals.com/products/page5_1_6_2.htm

Last edited by Mario Pankov; 20th November 2009 at 06:54 AM.
  Reply With Quote
Old 20th November 2009, 01:25 PM   #7
diyAudio Member
 
alexberg's Avatar
 
Join Date: Oct 2009
Quote:
Originally Posted by Mario Pankov View Post
There is an English company that supplies these materials. I do not have the pricing as I have not figured out what would be good as material.

I did a mistake when pasting the Metglas number, it is the 2605SA1 and I found a work by a Swedish aircraft electronics designer who said they are best for transformers used in the Grippen aircraft. What I am looking is this:

Powerlite C-Cores
What is the purpose of using low loss cores? Losses are extremely small - you will be getting a lot of unwanted resonances... unless you know for sure how to deal with it.
BTW
1.Package factor is less than 0.8.
2.I would not recommend flux density more than 1T.
In respect to iron cores amorph core will be at least two times bigger by the volume.
  Reply With Quote
Old 20th November 2009, 03:01 PM   #8
Arnulf is offline Arnulf  Europe
diyAudio Member
 
Join Date: Feb 2009
Quote:
Originally Posted by Mario Pankov View Post
I found a work by a Swedish aircraft electronics designer who said they are best for transformers used in the Grippen aircraft.
Grippen is a fighter plane, not a tube amplifier
  Reply With Quote
Old 20th November 2009, 03:38 PM   #9
diyAudio Member
 
Jacques Merde's Avatar
 
Join Date: Oct 2009
Have you considered Vanadium Permendur (2% vanadium, 49% cobalt and 49% iron), AKA Hiperco 50? It has a significantly higher saturation flux density of about 2.4T compared with 1.5 for the Metglas 2605SA1.

Hyperco 50 datasheet

I noticed that for the 2605SA1 the material properties looked great, but the published B-H curve in the C-Core Technical Bulletin for the AMCC6.3 C core did not look so swell. Specifically, B vs H is not very linear at reasonable inductions.

That high value of permeability on the material data sheet sure looks good though.
__________________
"For every complex problem, there is a solution that is simple, neat, and wrong." -- H.L. Mencken
  Reply With Quote
Old 20th November 2009, 04:34 PM   #10
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
OT:
Jacque Merde.... As a user id, clever...
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  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
Output transformer cores Mario Pankov Tubes / Valves 1 19th November 2009 02:24 PM
Russian Transformer cores Jaime Tubes / Valves 4 5th November 2007 10:39 PM
Adding secondary of output transformer into cathodes of output stage ? Eico ST-70 freddymac406 Tubes / Valves 3 21st April 2007 06:15 PM
filling air gap in transformer cores maudio Parts 22 24th June 2006 01:19 PM
Transformer wiring with different cores rtarbell Power Supplies 3 20th January 2006 07:46 AM


New To Site? Need Help?

All times are GMT. The time now is 07:05 PM.


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