How to make a good transformer for ribbon tweeter?

[pecamuzicar]

Hi everyone!

Do you know something more about building quality transformer for smaller ribbon tweeter:

-8ohm, 150-200w, frequency response 3khz-40khz,

-ribbon length around 8-10cm, 1cm wide, 0,006m thick,

-strength of magnetic field in the gap of about 0.7 Tesla?

[tinitus]

.: Michael Gaedtke :. | Röhrenverstärker , MOSFET-Endstufe, EF95, 6Sh1P, Russische Röhren, Hybridverstärker, 6N3P, 1Sh29B, Gitarren-PreAmp, TCA5500, Ribbon, Bändchen-Lautsprecher, Übertrager

go to 'lautsprecher' / 'Ribbon III'

looks like its been updated
very nice, thanks Michael

[bear]

doubtful that a true ribbon can handle 100watts... not an aluminum ribbon...

but there was a Wireless World article on building a ribbon tweeter and the transformer, back when Magnetron magnets were large... the basic info still works.

_-_-bear

[pecamuzicar]

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?

[tinitus]

Originally Posted by pecamuzicar

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

[jcx]

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

[tvi]

You can see how small the Pioneer ribbon transformers are, this is a PT-R30A

rgds
jms

[LineSource]

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.

[tinitus]

Originally Posted by tinitus

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

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

[jcx]

some of the RAAL offerings are intended as SE triode tube output transformers and have to withstand DC bias current and have KOhm pri impedance

if you only want 4-8 Ohm pri for easy SS drive then the problem is much easier