Need Amorphous Core Matching Transformers for Ribbon Drivers - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

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 27th May 2008, 07:50 PM   #1
NV&H is offline NV&H  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Charlotte, North Carolina
Default Need Amorphous Core Matching Transformers for Ribbon Drivers

I know folks like Lindahl and others sell amorphous core
transformers, but I am only finding them for tube amp outputs, ribbon microphones and interstage applications. None for ribbon speaker matching.

Anyone know of a source?

Push comes to shove, I guess I could buy tube amp output transfs. and just use the core (remove the factory winding) and wind it myself. Problem is, most of those have air gaps in them.

Thoughts...comments?
__________________
NV&H
  Reply With Quote
Old 27th May 2008, 10:00 PM   #2
diyAudio Member
 
Join Date: Sep 2004
Location: Oregon
Talk to Jack at Electra print. He should be able to help you out.
  Reply With Quote
Old 27th May 2008, 10:01 PM   #3
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
http://www.intactaudio.com/

-its all custom here.
__________________
perspective is everything
  Reply With Quote
Old 3rd June 2008, 09:54 PM   #4
andrics is offline andrics  Yugoslavia
diyAudio Member
 
Join Date: Apr 2006
Location: Bgd
Try to find Amidon FT240-77 or FT240-J or FT240-K . You can use up to ~45 wats
  Reply With Quote
Old 21st June 2008, 05:59 PM   #5
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
There is (imho) likely nil difference between an "ESL matching xfrmr" and any other xfmr designed for audio. The only possible difference might be in the breakdown voltage that the transformer is designed to handle.

Any reasonable manufacturer can advise you on the suitability of their product for your application (that being the voltage swing on the secondary).

EDIT: oh wait a second, you said RIBBON!
In that case you need a custom wind to get the low Z winding for the ribbon side. No HV to worry about... heh.

Inquire of various mfrs. many will wind custom transformers - but be prepared to know something about what you want/need in terms that they will understand and recognize. In other words, read up on transformer design, and ribbon transformer design. There are various resources on these topics.

EDIT 2: buying an expensive output xfmr to rewind just to get the core is a bad idea. Usually there is nothing special about the core. Any gapped core can be made ungapped, that includes EI and C cores. The gap may or may not be an advantage depending on the specifics of your application.

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 12th July 2008, 04:42 PM   #6
jzagaja is offline jzagaja  Poland
diyAudio Member
 
Join Date: Jun 2004
Location: Szczecin
Send a message via Skype™ to jzagaja
I have made quick and dirty amorphous c-core ribbon transformer. What do you think about it? Does it have too large inductance? Overall efficiency is quite low. Ribbon influence on impedance is very very small .
Attached Images
File Type: gif impedance_1.gif (22.4 KB, 270 views)
  Reply With Quote
Old 12th July 2008, 04:46 PM   #7
jzagaja is offline jzagaja  Poland
diyAudio Member
 
Join Date: Jun 2004
Location: Szczecin
Send a message via Skype™ to jzagaja
And transformer look.
Attached Images
File Type: jpg eda7717993.jpg (40.5 KB, 290 views)
  Reply With Quote
Old 12th July 2008, 09:32 PM   #8
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Shouldnt the windings be on top of each other ?

http://www.michaelgaedtke.de/Home/index.html

Look under Lautsprecher/Ribbon III
__________________
sometimes we know very little, and sometimes we know too much
  Reply With Quote
Old 12th July 2008, 10:32 PM   #9
jzagaja is offline jzagaja  Poland
diyAudio Member
 
Join Date: Jun 2004
Location: Szczecin
Send a message via Skype™ to jzagaja
Found reduction of inductance taking secondaries (ribbon side) closer together. Right point Tinitus. Take a look here:

http://www-s.ti.com/sc/techlit/slup125.pdf

Quote:
If the primary winding is put on one leg of a simple C-core, and the secondaries across the other leg, then the full magnetic force appears across the two core halves, radiating considerable stray flux to the outside world, resulting in high EMI and high leakage inductance. But if the secondary winding conforms to the primary, i.e., is wound directly over the primary on the same core leg, then the ampere-turns introduced by the primary are offset by the secondary ampere-turns, turn for turn, and the total magnetic force never builds to a substantial value. There is almost zero magnetic potential across the core halves which act simply as a short-circuit return path for the flux. There is very little stray flux, and leakage inductance is small. On a toroidal core, all windings should be uniformly distributed around the entire core.
Most important question still remains - what makes ribbon/transformer so inefficient.
  Reply With Quote
Old 13th July 2008, 11:11 PM   #10
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
A few problems to the naked eye...

Not enough turns by a factor of maybe 100 or more?

A true ribbon is a lower Z than the amplifier, so needs fewer turns on the ribbon size, fatter wire and the proper ratio at that.

Measure the impedance WRT frequency looking into the transformer with the ribbon hooked on the other end. Is that the upper graph?

The phase shift shown looks not good also.

You need coupling between the two windings.

It's unclear that you have coupling between your two core sections.
The usual method of winding on C cores is to place the bobbin on one or both of the legs.

The gap is adjusted with a spacer, IF used.

Why are you concerned about too large an inductance?
The worst case for that is that ur LF response is lower than you might expect - but you need turns.

You need turns to handle V/A...

The efficiency may not be off if the ribbon is not getting sufficient flux across it...

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  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
Plate choke material, why to use amorphous core? noyan Tubes / Valves 5 7th July 2008 01:25 PM
amorphous iron core good or not nhuwar Tubes / Valves 12 28th April 2007 05:00 AM
Amorphous core power trannies for SS amps rick57 Solid State 11 16th April 2006 01:47 AM
Amorphous core transformers only work above 20KHz? edonion Tubes / Valves 12 24th November 2004 12:30 AM


New To Site? Need Help?

All times are GMT. The time now is 02:33 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