Because of the capacitances from primary to secondary,
Not all 1:1 transformers work very well when wired as a 1:2 auto-former.
Pick one that works good when wired that way.
Your Mileage May Vary.
Not all 1:1 transformers work very well when wired as a 1:2 auto-former.
Pick one that works good when wired that way.
Your Mileage May Vary.
Not for input.
I think a few guys in Pass forum have used Cinemag, Jensen and Edcor 600:600 as 1:2 autoformer with good results, but low impedance driver (similar to B1R2) was used.
If you see -for example- LL7903 and Sowter 9063 parameters, they are similar ones, both configurable as 1:4 SUT.
Both of them use -relatively- large core, heavily shielding.
Lundahl Microphone Transformers – CDA Pro Audio Malaysia
SOWTER TYPE 3575 TRANSFORMER
See Ale's measuring of 7903
https://www.bartola.co.uk/valves/2014/06/28/starlight-discrete-dac-a-learning-experience/#more-3532
and in my #4 post 9063 1:4 curve.
But your pictures show the opposite: the Lundahl is better transformer. It has self-resonance at about 35 kHz, whereas the Sowter is at about 20 KHz. That Lundahl has a hump, it just means it's resonance is underdamped at the conditions used. Sowter's smooth roll-off means it is critically damped or slightly overdamped.
Ale' s graph is more telling as it shows how termination changes the response curve. You should have done the same multiple terminations with the Sowther, otherwise your test does not allow making a fair comparison.
Ale' s graph is more telling as it shows how termination changes the response curve. You should have done the same multiple terminations with the Sowther, otherwise your test does not allow making a fair comparison.
Hi Andy,
I have LL7903 and LL1676 and I prefer LL1676 with amorphous core.
Mu metal has some coloured sound, amorphous is more natural.
Both are excellent choice
Alex
I have LL7903 and LL1676 and I prefer LL1676 with amorphous core.
Mu metal has some coloured sound, amorphous is more natural.
Both are excellent choice
Alex
Thank you for that. I'm not going to buy LL7903. I have a pair of amorphous LL1554 I will connect up. I also suspect that amorphous will sound better. In fact I now have some good driver choices with mu of 30-40 so I won't need a step up right now. Useful information.