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9/14/1999 5:02 AM
In Gerald Weber's book he says that when fender quit making the tweed amps and switched to the piggy back design, they changed to schumacher transformers and they are not interleaved.Is this true?Question #2-Is interleaved the same as bifilar wound?
9/14/1999 12:49 PM

I don't know what he considers "interleaved", but I haven't seen a professional size tranny (yet) that isn't.. They may have *changed* the interleave (this is likely). Basically if you wind the whole primary and then wind the whole secondary, you have what's called a "layer wound" transformer. I think anything fancier than this qualifies as interleaved (where you mix the sections, P/S/P/S/P etc)  
Depending on *how* you interleave, it can make the transformer more complicated to build ($). I'm of the opinion that the interleave has a lot to do with the tone of the transformer; eg you can wind a 4K:8-ohm transformer a bunch of different ways and how you do that makes all the difference.  
Bifilar refers to using 2 wires in parallel in a winding and is a different thing than interleaving.  
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9/14/1999 1:03 PM

Am not sure I'm correct in this instance but when I hear "interleaved" in reference to a tranny I immediatly think of the interleaved plates in the core of the tranny to limit hysteresis (sp?) loss/heating. My $2/100.  
9/14/1999 1:05 PM

While the laminations are indeed interleaved (and interleaving 1:1 has different effects than interleaving 4:4 or some other numbers, by the way) the windings are also interleaved in quality transformers.
9/14/1999 1:33 PM

They do interleave the laminations as well but i think GW is talking about the windings (I think..). The big Marhslals & Fenders seem to interleave their laminations in pairs.
9/14/1999 1:03 PM

" I'm of the opinion that the interleave has a lot to do with the tone of the transformer; eg you can wind a 4K:8-ohm transformer a bunch of different ways and how you do that makes all the difference. "
You can change that from "opinion" to "fact". The interleave dramatically changes the leakage inductance between primary and secondary, and half-primaries to secondary. These have a measurable and calculable effect on frequency response, as well as little things like how severe any crossover notch and/or glitch when one tube turns off in an AB biased amp.
9/14/1999 1:14 PM
dave r.

I'm considering a transformer for my next home brew project...  
Can anyone tell me current manufactured OT's that are interleavened? The project will have a push-pull EL34 cathode biased output.  
Dave R.
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