How to make a good transformer for ribbon tweeter?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Thanks, I already visited Michael Gaedtke Ribbon 3 site, and there was many basic explanation. He mentioned that many profesional engineers keeps their secret about carrefulu nesting of coils, to reach determined and desired best result. It wold be nice to know something more about such things, also to consider more and tell more concrete about influence in using of available different and quality core materials and type of cores, o.e. with concrete data about their permeability...

Also I visited Wireless World, butI can not to find some concrete links.

I found something interesting on Transmission Audio site. They have their caled "interface" for connecting their ribbons directly (?) on the amplifier. They said inside have not any magnetic materials, and this interface is exactly (like they said) one of their the most secret things.

Also is maybe interesting to really connect ribbon directly on some low impedance current amplifier. It is possible to find some project of such amps?
 
Ex-Moderator R.I.P.
Joined 2005
It wold be nice to know something more about such things

Also is maybe interesting to really connect ribbon directly on some low impedance current amplifier. It is possible to find some project of such amps?

ribbon, trafo winding
I guess it should be bifilar wound, as kindly shown by Gaedtke in the updated version
another trick may be to use foil for speaker winding
and just wire for amp side
and yet another trick may be to use silver foil, for the speaker side

a PASS design like F5 should be no problem to build for 1ohm load
and a ribbon trafo for just 1ohm would easier, and better, right ?
or will it have too low inductance ? I dont know
 
200 W is probably red heat for that surface area, low emissivity - Al will burn thru

the "program power rating" of commercial tweeters is a bad hoax - assuming pink noise and >2 KHz xover the tweeter only sees a few watts for a "loudspeaker program power rating" of 200 W

you should search for continuous power ratings of commercial ribbons of similar dimensions to what wou want to build - I expect only a few 10s W

as you can see from the size of commercial true ribbions that include the xfmr it isn't that large, special winding techniques aren't as important at the low impedance these work at - especially if you don't expect to make the most material efficient xfmr as the manufacturer's have to strive for to keep their cost low
 
You can see how small the Pioneer ribbon transformers are, this is a PT-R30A

rgds
jms
 

Attachments

  • DSCF0016-1.jpg
    DSCF0016-1.jpg
    163.6 KB · Views: 2,488
The attached picture of the RAAL 150-10 transformers shows a C-core and copper foil. From what I have seen, this RAAL transformer is larger than most competitor ribbons.

I use a tri-filiment windings on a toroid core for short tweeter ribbons. I use a DIY solid state amp to direct drive 0.1 ohm ribbons.
 

Attachments

  • raal4_4.jpg
    raal4_4.jpg
    134.9 KB · Views: 2,605
Ex-Moderator R.I.P.
Joined 2005
I guess it should be bifilar wound, as kindly shown by Gaedtke in the updated version

I think the right word should have been interleaving layers

power rating
if using kitchen foil, and relative wide, as shown by Gaedtke, it will take quite a lot of power
maybe even use for roasting a chicken :D

I think power rating of the trafo would be the worst of your worries
anyway, who would burn 200watt into such a delicate ribbon tweeter :eek:
 
The foil sticking out of the coils as shown seems to indicate the intended use for driving a low low Z ribbon load...

The WW mag article is from the late 50s early 60s, iirc.

You don't have to do that much in the transformer, since ur covering a very very small frequency range, like what, two octaves or slightly more?? The core can be pretty small as well, and there is no DC to handle. You just need one heck of a step down with the secondary able to handle current, but then the issue is one of obtaining good coupling, since yr secondary will have few turns...

_-_-bear
 
I think that when we want to consider the maximum power ribbon tweeter, we must always bear in mind the extremely high current that flows through a thin strip at any time. Conclusion would be that such a track is very sensitive to any excess electricity, which is logically prior to appearing on the lower frequencies. It is therefore essential, especially at lower cutting frequency crossover, that this cut must be very steep, which is obviously o.e. like RAAL all the time recommend the 4 order crossover for the recommended power, also with logically slightly larger transformer...

What you think about idea to winding secondary coil maybe with litz (stranded) wire to avoid eddy current in transformer?
 
AMCC = Amorphous Metal C-Cores are a good choice for high-end ribbon set-up transformers. The Hitachi Metglas product family available from US companies like ELNA magnetics is the industry standard, and these AMCC cores have been cloned by many China manufactures.

Amorphous metal C-cores allow for operation at higher frequencies at the same flux level. Where traditional steel cores need to operate at increasingly lower flux densities as the frequency increases, which creates distortion.

Some RAAL ribbons use the AMCC-4 size C-core.

http://www.metglas.com/downloads/powerlite.pdf

The RAAL literature mentions that the inductance of the transformer primary winding is designed to be used as a LR slope 1,600Hz crossover element.


Powerlite offers an amorphous metal toroid core with a small slit cut to reduce inductance and help high frequency operation.
 

Attachments

  • img_1204_c_cores.jpg
    img_1204_c_cores.jpg
    273.6 KB · Views: 1,622
  • img_1201_amcc-100_closeup.jpg
    img_1201_amcc-100_closeup.jpg
    124 KB · Views: 1,524
Hello everyone, it has been a while since i have been able to do any posting.
I have been working on my studio so I haven't been working on my diyaudio stuff latley.

But may I suggest using a torrid power transformer like some of us have used on our ESL's but in reverse.

My transformer has to 120v primary's and I hooked one to the amp and the other to a fullrange speaker and found very hardly if any degradation in sound quality.

Here you have primary wind that is already designed for 120v at 60hz so it lowest frequency saturation now becomes 15hz at 30v.

And every time you double the input frequency you effectively double the power handling of the transfromer.

For an example, A 50 watt core at 60hz becomes a 400 watt core at 480hz ,or, an 800 watt core at 960hz (suggested crossover frequencies) and so on.

By going stepdown you won't experience any of the problems we have while stepping up for an ESL.
You can easliy add your own secondary winding of heavy gauge wire to a transformation ratio of your choice.

more can be found here ,http://www.diyaudio.com/forums/planars-exotics/161485-step-up-transformer-design.html#post2093314

These cores (at least mine) exhibit a ruler flat response up to and well above (in some cases) 100khz.


p.s. I had promised to finish that study for everyone,so when I get my studio and lab bench back in order I will resume. Thanks ,jer.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.