Wooden OPT SE AMP for Altec 604

All transformers has to have the iron cores. It is a rule. An axiom. Right?
No, actually not, only low frequency transformers. Many high frequency transformers have no cores at all. The higher the frequency, the lower the values that matters - and we are interested in inductance
So... once in a while the crazy ideas comes to mind
And that was such a day...
You know, I am a big fan of the Altec Duplexes, especially 604
I even have invented (and patented) a special crossover, dedicated to the problem of lossless matching of the two drivers
But it was not my last crazy idea of course
Coreless Output Transfomer, than will be suitable to work at higher frequencies
If you know transformers, you will understand (it may take some time, but you will)
We just need a good winding coupling, and primary inductance high enough to provide with the proper AC load at the desired frequency
As simple as that
And I am puzzled again - why no one has done it before?

Here you can see my first unique two channel amplifier with dedicated LOW and HIGH frequency channels
And some measurements of the transformers, as is and in a real amplifier (I have used SE amp build on 4613 DHT)
High frequency channel has no steel core, it is basically "air core" transfomer, but as you can see it is actually Wooden Core Output Transfomer, or... Wooden Transfomer
The channels internally crossed at 2 kHz, with the option of attenuation for HF channel
Must admit, I have NEVER heard Altec 604 plays so beautiful (remember, I am a great fan of 604, and have/had way to many of them)
Stay tuned for a news :)