How to make a good transformer for ribbon tweeter?

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#106
You may want to consider starting with a Jantzen toroidal crossover choke and add the secondary by hand. Add a few windings to figure out the turns ratio then the primary turns. figure out the ratio you want then add the right amount of secondary turns to finish it up.
 
#107
alexberg said:
Oh, well...
that's what you need.
Your stripe resistance is 3 milliOhms.
100W yeilds 180A RMS.
Stripe voltage 0.54
Using decent amorph core with 3 sm sq cross section
like stacked 2xM512/522/612 from magnetec
all you need is 35 turns of magnet wire 1.6 mm in dia.
Transformer needs to be balun-like,
see attach. with single turn secondary shown.
Two cores with wound primary stay inside secondary.
Can easily be done from copper pipes, copper sheet and some soldering 😉
Click to expand...
I've done some practical experiments with "one turn" transformers, inspired by alexberg . Very good bandwidth and low distortion. One funny thing happened though. When I measured my speakers with HolmImpulse, all of a sudden, the speaker returned a inverted pulse!
Once every 3:rd or 4:th measurement, the measured impulse was inverted, and you could also see the phenomenon on the phase curves.

Could this phenomenon be a result from when you make a transformer winding with one turn, where the ends of the turn doesn't meet, the one turn winding
cannot be called a clockwise or anti clockwise turn?

Have I invented a new kind of binary random generator?

It might be HolmImpulse pulling my leg, so I shall do some further experiments and measure the signal directly from the transformer...
 

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#108
Lots of information I got from this thread for building my own ribbon tweeter.

Just to share what I have done:

My custom build corrugator
IMG_1488_zpsd75fa4d0.jpg


The mini nickel perm-alloy EI transformer I bought from ebay, can't recalled the ratio but its around Sec : 5 turns and Pri : 70turns
IMG_1506_zps24d1bf67.jpg


Using Woofer Tester to make quick measurements
IMG_1563_zps37dead60.jpg

After_zps1c83b268.jpg


Embedding of the ribbon tweeter
IMG_1519_zps8f39ba44.jpg

IMG_1521_zpsa9e5b6a0.jpg

IMG_1530_zpsc96e6403.jpg

IMG_1504_zps57210cb8.jpg


Measurements
Impedance_zpsd90ce375.jpg

FR_zps3542cc72.jpg
 
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#109
The magnet structure is really nice, but that transformer is not going to do it. I made some of those around 15 years ago, and results are bad. See my previous post on making one with sheet copper and ferrite cores which is almost lossless. Also the wire from transformer to ribbon must be short and very large, like # 8 stranded. Current for those is huge. Over 30 amps at medium volume. I have more photo's of how to do it if needed.
 
#111
Thanks for all the info an cool pic........ on the ribbons&tranfourmers..............i now well pull out my Apogee Stages an Centau Minors......same 26" MT ribbons.....No transfourmers needed..........justsaying

keep up the good work...........
 
#114
I have problems with my ribbons, see avatar.

When I play loud, there happens something at the ribbon connection points.

The volumes goes down, and the only remedy is to dismount ribbon and polish the connection copper plates.

Maybe I must change the copper for gold?
 
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#115
If i am right you ribbon is prue Alumimum some say the best......................Apogee on my stages capton back ribbon for MT..... let the magnet stop at about a 1/2" obove the ribbon connection point .....cooling down point an no move ment.........then latter thay let the magnets go all the way down .... then added a suspensions point in the lower middel of the ribbon............go to the site some info
good luck

http://www.apogeespeakers.com/manuals/stage_midtweeter_replacement.pdf
 
#116
JonasKarud said:
I have problems with my ribbons, see avatar.

When I play loud, there happens something at the ribbon connection points.

The volumes goes down, and the only remedy is to dismount ribbon and polish the connection copper plates.

Maybe I must change the copper for gold?
Click to expand...

Maybe the copper near the connection could be tinned or gold plated.
Or, is the connection just getting loose - could it be soldered instead?
 
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#117
Alu. has an oxide layer on it and this layer is highly insulating.

Have you tried scuffing up the Alu, at the connections as well.

As this may be a bit difficult to do depend on the thickness of your material you can also try removing the oxide layer with a weak solution of Sodium Hydroxide at the connection ends.

I have had similar issues before when using Alu window screen for for my ESL stators as well as connections to the diaphragm using Alu. tape.

So now I soak the screens in the solution (Etching) as this guaranties a positive connection to all of the wires in the mesh before I coat them using only a few wires for connections from the woven mesh.

This works good and I use good ole steel wool to scuff up the Alu. tape parts, these connections have now lasted for at least 10 years or so without any issues as tested.

I few of my panels would not even work at all at First try or just worked for a little while and intermittently , until I had removed the oxide layer and that was at very high voltages too!!!

FWIW

jer 🙂
 
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