new Trannies - 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 25th November 2005, 11:37 AM   #1
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Default new Trannies

Hi Folks,

got me some new toroids 230V/2x6V, 50VA. Wired two of them in series (230V) and parallel (6V). This gives a factor of theoretical ~1:75 (in praxi it measures 1:68)

Here are first measurements of my panel (1.2nF) connected to these toroids in nearfield (10cm) (Spl is recalculated to 2m)

As one can see linearity is very good. The upper bandwidth is well above 20kHz (micīs not compensated for and starts to roll off beyond 15kHz).

jauu
Calvin
Attached Files
File Type: pdf rk 1_68 10cm amp 251105.pdf (31.8 KB, 670 views)
  Reply With Quote
Old 25th November 2005, 11:40 AM   #2
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi Folks,

the impedance plot prooves the high bandwidth. Plots are nearly identical to those measured with the 1:75 Amplimo. The resonance of trannies stray inductance with the panels capacity is above 20kHz.

Conclusion: Even with high capacitive panels simple and cheap toroids work and they work better than lot of so called specialized audio-trannies!

jauu
Calvin
Attached Files
File Type: pdf rk 1_68 10cm imp 251105.pdf (30.7 KB, 288 views)
  Reply With Quote
Old 25th November 2005, 12:30 PM   #3
diyAudio Member
 
Join Date: Jul 2005
Location: Georgia
Is there a link to these toroids.
  Reply With Quote
Old 25th November 2005, 03:12 PM   #4
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

its a German company named BSAB. They distribute the Amplomos over here too :-))

jauu
Calvin
  Reply With Quote
Old 25th November 2005, 06:33 PM   #5
diyAudio Member
 
Join Date: Nov 2002
Location: California
I measured the Avel Lindberg 50VA 115x2 : 6x2 transformer this morning (part number Y236200, two wired as above).

Effective turns ratio measures and calculates to about 68:1

The leakage inductance looks good, the effective secondary inductance looks not so good.

For leakage inductance (secondary, high impedance side) I get about 28 mH, which is good.

For effective secondary inductance, I get about 5.3 Henries. This is not so good, making to difficult to design a passive crossover, and being problematic for direct coupling to an amplifier due to low impedance at low frequencies.

Effective secondary capacitance is about 1200 pF.

The impedance curve shows a peak impedance at about 1400 Hz when loaded with 1000 pF. This is quite a bit higher (in frequency) than shown in the impedance curve above.

Apparently not all cheap toroids are built the same.

For comparison, the 75:1 Plitron ESL transformer specs are:
22 mH leakage
1600 Henries
800 pF

This transformer provides a very good higher impedance at low frequencies.

Another comparison, the E R Audio ESL transformer (my measurements):
22 mH
64.8 Henries
308 pF
  Reply With Quote
Old 25th November 2005, 10:21 PM   #6
Bazukaz is offline Bazukaz  Lithuania
diyAudio Member
 
Bazukaz's Avatar
 
Join Date: Nov 2005
Location: Vilnius
Send a message via Skype™ to Bazukaz
Distortion measurements would be very interesting ...
I doubt the core of cheap toroids is made of wrong steel and plates are badly isolated between each other.

Also , what do you think about taking one of secondary windings and making additional feedback to amp ? Wouldn't it decrease distorition caused by the transformer ?
  Reply With Quote
Old 26th November 2005, 08:14 AM   #7
diyAudio Member
 
Join Date: Nov 2005
Location: Southern Germany
Hi Folks,

first let me introduce myself. Since 15 Years I am an ESL enthusiast and gained some experience by building more than 50 iffernet types of ESL.

regarding toroids it needs to be said that standard transformers suffer from disadvantages as follws:

1. There is no insulation between the layers of the secondary winding. Additionally cheap transformers do not use double insulated copper wire. This means that there is a high potential of electrical short cut of the secondary winding depending on output voltage. The tested voltage handling capability is just true between primary and secondary winding.

2. The missing insulation of the secondary winding increases internal capacity of the secondary winding, which is contra regarding step-up ratio. In addition cheap transformers are wound very lousy,leading to crossing wires (results in additiional capacitance and short cut potential)

3. Typically core material of standard transformers is ferrite and not oriented and heat treated silica. Ferrite has its limitations regarding saturation and more important harmonic disssortion of the signal. Those ferrits are not designed for frequencies up to 20Khz.

In summary, toroids are really a good choice, but need to be specifically designed for ESL as well as EI or M-Types.

Do not expect miracles from cheap standard transformers.

Regards, Capaciti
  Reply With Quote
Old 26th November 2005, 09:38 AM   #8
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

I donīt claim the standard toroids to be superior to specialized toroids, but since the built is similar it was worth giving them a shot. And the results are very promising even with high capacitive panels in ML-style.

The backdraws Capaciti mentioned are true, but do they count in praxis?

1. Is special insulation on the secondary necessary? If the secondary is the low-voltage-side, than the answer is no. On the high-voltage-side it depends on the needed voltage-levels of the panel. Highly capacitive high-efficiency panels donīt need much voltage, and if the primary is wound in just one turn, the problem doesnīt appear anyway. We do need high dielectric strength between primary and secondary windings and this we have.

2. Is it of interest, when the reached transformation factor is sufficient? It seems that 1:75 could be limiting border for standard toroids. With even higher transformer ratios the demands will probabely too high.

3. Typical core material of nearly each power transformer I found on the net is grain orientated material with 0.3 to 0.35mm thickness. Anyway everybody can look up datasheets


In summary, within certain restrictions I see no reason not to use off-the-shelf standard toroids. The measurements I made with my panel showed an astonishingly close similarity to the excellent Amplimos but to app.1/10 the cost.

Still, I donīt expect wonders from these Trannies, but they are imo much closer to that than specialized and overprized ones

jauu
Calvin
  Reply With Quote
Old 27th November 2005, 12:39 AM   #9
BillH is offline BillH  United States
diyAudio Member
 
BillH's Avatar
 
Join Date: Mar 2005
Location: Wisconsin
Calvin, can we have some details of your ESL panel? I'm also wondering what crossover point you chose for the ESL.

I've just ordered four of these toroid transformers to try out. They should give about 50:1 step-up when connected in pairs.
  Reply With Quote
Old 27th November 2005, 09:55 AM   #10
diyAudio Member
 
Join Date: Nov 2005
Location: Southern Germany
Hi BillH,

really compelling pricing !

This transformer is small in size and has a limited core area. My guess is, that this transformer will show saturation if you go lower than 200-400 Hz (depending of input level).

It would be interesting to get some feedback from your trials with this size of toroids.

Whats the secondary output voltage required for appropriate sound pressure of your Panels ?

regards, capaciti
  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
Trannies in parallel Dan2 Power Supplies 13 12th September 2011 11:37 PM
Want to trade: 6.2K/4 trannies for 5K/8 trannies mashaffer Swap Meet 1 8th June 2008 06:34 PM
little trannies looking for amp wazabee Pass Labs 10 25th January 2008 09:18 AM
output trannies flodge Planars & Exotics 4 21st August 2005 06:35 PM
Any feedback on these trannies? gjo Tubes / Valves 0 27th January 2005 09:32 AM


New To Site? Need Help?

All times are GMT. The time now is 12:05 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