At the time when I saw circuit$ that used the Tango NC14, I could not even think of purcha$ing them.
Phase splitters were well-known by about 1938, and both cheaper and better than coupling transformers, which haven't been used much since. No reason to go backwards.
Transformer coupled circuits can sound very, very good...but keep them away from oscilloscopes and other test equipment if you still want to enjoy the sound 🤐
Lynn Olson's Amity and Karna are examples of amps using transformers from input through to output as phase splitting/balanced circuit elements (here: http://www.nutshellhifi.com/triode2.html)
The Karna has now taken form as a commercial product, the Blackbird (here: https://www.spatialaudiolab.com/blackbird-monoblock)
The Karna has now taken form as a commercial product, the Blackbird (here: https://www.spatialaudiolab.com/blackbird-monoblock)
In fact transformers were used as phase inversion components along with transformers as coupling components between stages, simply because RC coupling wasn't invented yet. It's hundred years old technology.
Nowadays we have far superior ways to do the phase inversion, hence, transformers are obsolete here.
Best regards!
Nowadays we have far superior ways to do the phase inversion, hence, transformers are obsolete here.
Best regards!
@HeyBill: Feral Eye SP# 14 see https://www.enjoythemusic.com/magazine/sound_practices/14/feral_eye.htm
I did a lot of work with transformer phase splitters. The 1660s is light in the bass but also has phase crazies between 10-20Khz. Inductor phase splitters can work well but there is still a capacitor in the circuit. Best bandwidth came from a small 120+120:120+120 power toroid but again needs a capacitor and care with matching up the 4 sections.
I tried to get someone to wind a split bobbin with each section having a primary and secondary but one secondary wound in reverse. No one would do that.
I tried to get someone to wind a split bobbin with each section having a primary and secondary but one secondary wound in reverse. No one would do that.
In non loop feedback designs, transformers (OPTs) and interstage ones can work well, but in loop feedback designs, great care about stability must be taken. There are excellent designs with transformers used in feedback loops, so it is doable.
efellings,
Which is why I am a fan of Forward Facing signal path circuits . . . Whenever interstage transformers and auto transformer phase splitters are employed.
But now, I only use RC coupling, after years using interstage transformers, and auto transformer phase splitters.
Just my preference, not right or wrong.
Which is why I am a fan of Forward Facing signal path circuits . . . Whenever interstage transformers and auto transformer phase splitters are employed.
But now, I only use RC coupling, after years using interstage transformers, and auto transformer phase splitters.
Just my preference, not right or wrong.
6A3 may I ask which brands interstage transformers and auto transformer ?
I had LL1660S as IT, don't like it.
I had used LL1660S secondary, intact audio transformer, and LL1670 as "autotransformers".
I had LL1660S as IT, don't like it.
I had used LL1660S secondary, intact audio transformer, and LL1670 as "autotransformers".
fossa,
I used Lundahl LL1635 20mA interstage in single ended (tried both 12AT7 and 6N1P to drive them), and Lundahl LL1660S interstage in push pull driven by a pair of 6C45pi with a choke CCS for the direct connected cathodes (phase splitter & driver in one stage).
I also used Electra-Print Audio single ended bifilar wound interstage; and Electra-Print Audio push pull interstage;
Both models driven by JJ ECC99(s).
The auto transformer phase inverter was Electra-Print Audio, PSA-2.
I did enjoy listening to all the amplifiers that used those products.
If I read your post correctly, you used only the secondaries of Lundahl as autotransformers.
Did you just let the primaries "flap free in the breeze", or did you use an RC termination on each primary?
I used Lundahl LL1635 20mA interstage in single ended (tried both 12AT7 and 6N1P to drive them), and Lundahl LL1660S interstage in push pull driven by a pair of 6C45pi with a choke CCS for the direct connected cathodes (phase splitter & driver in one stage).
I also used Electra-Print Audio single ended bifilar wound interstage; and Electra-Print Audio push pull interstage;
Both models driven by JJ ECC99(s).
The auto transformer phase inverter was Electra-Print Audio, PSA-2.
I did enjoy listening to all the amplifiers that used those products.
If I read your post correctly, you used only the secondaries of Lundahl as autotransformers.
Did you just let the primaries "flap free in the breeze", or did you use an RC termination on each primary?
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I like to play around phase split -on no account to the refinement level of your designs- and I just wanted to say that this one should also work with SE source.
Thank you 6A3. The primary of LL1660S was "flap free in the breeze."
12AT7 is an excellent driver for Push Pull, particularly those super triodes like A2900 and ECC801s,
really enjoy them.