Anyone know of a US source for ESL toroids? - Page 2 - 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 21st September 2009, 04:18 AM   #11
diyAudio Member
 
chinsettawong's Avatar
 
Join Date: Jun 2006
Hi Calvin,

In Thailand, it is possible to have a toroid custom built. If I would like to be able to produce low frequencies as low as 40Hz, do you think that a 300 watt toroid would be sufficient? If not, what would be the ideal size?

Wachara C.
  Reply With Quote
Old 22nd September 2009, 10:05 AM   #12
Calvin is online now Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

it doesnīt need to be a 300VA-core, because sizing up the core improves some parameters but deteriorates others. The Amplimo-toroids use 100VA-cores and this is sufficient even for driving large panels fullrange.
What counts in first place is the primary inductance value. The higher it is, the lower is the lower bandwidth limit.
It might help to read the papers and patent of Mr. vanderVeen et al.
Patent:
"step-up-Transformator", NL A 9300433 (in dutch)
Papers:
"Toroidal Step Up Transformers for Electrostatic Loudspeakers", Plitron Website.
"Theory and Practise of wide bandwidth toroidal output Transformers", 97th AES convention 1994, San Francisco
You can of course have Your special tranny wound to Your specs and probabely need to if You want a FR-tranny. Standard toroids are a very affordable way to get Your hands on a good quality audio tranny for hybrids.
How much bandwidth you can squeeze out of the tranny-ESL-system depends on individual factors. Just try

jauu
Calvin
  Reply With Quote
Old 22nd September 2009, 08:31 PM   #13
diyAudio Member
 
Join Date: Oct 2005
Are you folks talking about using power transformers for audio?
  Reply With Quote
Old 23rd September 2009, 09:08 AM   #14
Calvin is online now Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

Yes. To be precise just toroidal power transformers. With segmented low-cpacitance panels even arrays of EIs can work sufficiently well.

jauu
Calvin
  Reply With Quote
Old 24th September 2009, 11:34 PM   #15
diyAudio Member
 
Join Date: Oct 2005
Default Power xformers for audio

Please correct me if I am wrong, but whether toroidal or E-core, aren't power transformers designed with high inductance, no regard for minimizing capacitance, high hysteresis core materials, and with an expectation of hundreds rather than thousands of volts?

I would expect the result to be a rather low upper cutoff frequency, not a lot of volts without risk of breakdown, high distortion at low amplitudes, and a major self-resonance in the audio band. Of course, I think it would be great if OTS power transformers would work, but never thought of trying it.
  Reply With Quote
Old 25th September 2009, 03:42 PM   #16
Calvin is online now Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

core material of Audio trannies for ESLs and power trannies is often the same, especially so for toroids. Audio trannies using īspecialī core-material are easily detected by exceptionally high price tags.
The upper bandwidth limit (major self resonance) is defined by the stray inductance and winding capacitance of the tranny and the panels capacitance. Larger panels and smaller stator-stator distances increase the panelīs capacitance and as such the resonance lowers in frequency. You can identify the resonance as the upper minimum in the impedance plot. On the other hand the impedance of the pure panel drops with increasing capacitance and You need smaller values of the transformation factor to match panel and amplifier. Luckily physics are such that smaller transformation factors allow for a raise of the resonance frequency as well as easier construction and an overall improved behaviour of the tranny.
With toroids stray inductance can be very low and as such the resonance frequency high (around 20kHz with a 2nF load possible!). Standard EI-cores are much worse here. But quite often the resonance is used to fudge the frequency response of the panel and to push up the highs a bit. Additionally it easens the stress on the driving amplifier. So You can use the worse transformer to correct for deficiencies in other fields.

Over the years I have tested many different trannies, specialized ones as well as standard types. Typically most of the specialized trannies failed sooner or later because of internal flashovers. The trannies that never failed were the standard toroids with single primary and single secondary winding connected as pair. Besides....most transformer manufacturers are very unwilling to supply even basic parameters of their trannies. So You donīt actually know how much voltage the tranny can withstand in reality.
Standard power trannys are almost always tested on prim-sec-flashover voltages (~4kV in many cases, and double with a pair). Audio trannies are not at all better in this regard.
So what does it cost You?
- You probabely couldnīt use the standard toroids for fullrangers (low prim-inductance). But for Hybrids they are fine.
- A pair would be of bigger size.
- the transformation factor is typically lower than 1:70 because 6V/230V is usually the highest standard value.

jauu
Calvin
  Reply With Quote
Old 25th September 2009, 04:02 PM   #17
diyAudio Member
 
Join Date: Oct 2005
Default Audio power trannies

Thank you, Calvin. Very interesting. I may be asking you some questions later, if that is alright.
  Reply With Quote
Old 3rd October 2009, 05:12 AM   #18
diyAudio Member
 
chinsettawong's Avatar
 
Join Date: Jun 2006
Hi Calvin,

I was able to find a pair of toroids with only primary windings - 0-110-220. They were very cheap. Using 0-220 for testing, I wound 10 rounds of copper wire in and I got 2.6 V. That's about 1:85 ratio. I'm thinking of winding 3 sets of 10 rounds of copper wire and parallel them all together. What do you think?

Oh, the toroids are about 8 cm in diameter and rated for 200 watts. They're Chinese made and the rated capacity might be overrated. I think.

Wachara C.
  Reply With Quote
Old 3rd October 2009, 05:53 AM   #19
r8833 is offline r8833  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: Moose Jaw, Sk
try this site..I have a pair of his esl's

http://www.justrealmusic.com/content/pricing3.htm
  Reply With Quote
Old 3rd October 2009, 07:32 AM   #20
Calvin is online now Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

the count of turns defines the primary inductance. The primary inductance defines the lower bandwidth limit in first case. So for a sufficiently low bandwidth limit You need a lot of inductance, hence increased number of turns. Just 3x10 turns won´t lead You far. When You turn the windings try to wind over the ´complete´ toroid core once. Lets say You use 5 paralleled windings, each winding should cover an angle of 72°.
Do You intend to use one tranny in 1:85 mode or two trannies in 1:170 mode?
In the first case it is important to know how the 0-110-220V coil is wound!
Best would be if each winding-half covers half of the core. But probabely the windings are wound on top of each other, which might lead to insulation breakwown. The best insulation is always between prim and sec-winding.
Since You wind Your own sec winding You could even improve the insulation by winding some plastic band on the tranny before winding the sec-windings.
If You want to use a pair of trannies 1:170 would be a very high transformation factor which is only usable for low capacitance panels -->electrically segmented panels.

jauu
Calvin

Last edited by Calvin; 3rd October 2009 at 07:37 AM.
  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
Source follower and common source output stages slogan2112 Pass Labs 2 9th October 2008 09:19 PM
WTB: 43-0-43 or 46-0-46 Toroids K-amps Swap Meet 3 17th November 2006 09:03 PM
Aleph-type current source, but source follower this time tschrama Pass Labs 4 29th July 2005 01:55 PM
High power toroids source Lupulroz Swap Meet 10 30th July 2003 03:38 PM
Source follower electret mike -> use with current source? capslock Solid State 1 28th February 2003 01:54 PM


New To Site? Need Help?

All times are GMT. The time now is 11:30 AM.


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