Building a good interstage for SE to PP is very difficult. I used the 1660S to do that.
I believe that transformer is built and connected this way to do SE to PP: 2 sets of windings, one set over each core air gap (call them Left and Right gaps). Primary winding on Left in series with Primary winding on Right. Primary windings are coupled by the (series) current through them, and more loosely coupled by magnetics (so some leakage reactance). One primary is wound over Left secondary; one primary is wound over Right secondary. In relative terms, Secondary winding in Left is 'Push'; Secondary winding on Right is 'Pull'.
I also tried the 1660S with the 2 Primaries in Parallel, but the inductance is only 10 Henry. Harder to drive, but if I remember, that was a little better high frequency response.
I believe that transformer is built and connected this way to do SE to PP: 2 sets of windings, one set over each core air gap (call them Left and Right gaps). Primary winding on Left in series with Primary winding on Right. Primary windings are coupled by the (series) current through them, and more loosely coupled by magnetics (so some leakage reactance). One primary is wound over Left secondary; one primary is wound over Right secondary. In relative terms, Secondary winding in Left is 'Push'; Secondary winding on Right is 'Pull'.
I also tried the 1660S with the 2 Primaries in Parallel, but the inductance is only 10 Henry. Harder to drive, but if I remember, that was a little better high frequency response.
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But my 2A3 can do this- Waaah! Not what I expect from an expensive Lundahl! Nothing I can do to fix?
you are chasing flaws that you cant hear ....
oh btw... if u are obsessed with low thd, flawless sound - then go solid state...
dont waste time with tubes....
I had problems before with ultrasound and a tweeter broken, you do not listen but tweeter can. Flawless sound, well I think that the tubes amp give the better sound possible far of SS, only that me, I am very perfectionist, if I use a 2a3 as driver, LL1660S splitter to 300B PP I am not looking the easy way, I am looking the best way or I try, if I use Duelund Cast CAP or amorphous core OPT I am not lazy to work in the best
note: Per Lundahl for this model does not recommends any Zobel compensation to show a beautiful square wave, he affirm that sound is is much more better without. " the sound will become uninteresting and dull."
note: Per Lundahl for this model does not recommends any Zobel compensation to show a beautiful square wave, he affirm that sound is is much more better without. " the sound will become uninteresting and dull."
No!
It should be root(2.25/2)*5 - a little more than 5K. As it it is a step down, it will be step up when you go the other way.
Thorsten 😉
I tried that device 15 years ago and saw similar waves as well as phase goofyness around 20khz.
I don't have any scientific data but think C Core is a poor choice for SE to PP. Having two sets of windings 180 degrees and physically separated didn't work out for this device.
I had my own ideas for a device with split bobben on EI where the primary was shared across the bobbens and secondaries had their own side of the bobben but wound in reverse. No one would build it so I'll never know.
Anyway, a centertapped choke praafeed worked well to about 30khz.
I don't have any scientific data but think C Core is a poor choice for SE to PP. Having two sets of windings 180 degrees and physically separated didn't work out for this device.
I had my own ideas for a device with split bobben on EI where the primary was shared across the bobbens and secondaries had their own side of the bobben but wound in reverse. No one would build it so I'll never know.
Anyway, a centertapped choke praafeed worked well to about 30khz.
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