Lundahl LL1931AG STEPUP Transformer

Hello Victor,

I have some questions about the Lundahl SUT kit.

First, what is the purpose of what looks like a socket and shorting jumpers. The label to the right seems to imply that it might provide a way of switching from transformer secondaries grounded to transformer secondaries not grounded:

Screenshot 2024-10-02 at 22.52.54.png


Next question -- is there a schematic available for the completed circuit? Not being able to see the traces of the PCB it's not possible to figure out what is and isn't grounded. I prefer a SUT circuit like this:

Screenshot 2024-10-02 at 22.56.39.png


Rather than this:

Screenshot 2024-10-02 at 22.57.05.png


(Attribution for the two schematic drawings to Alexey Korf from his excellent blog at https://korfaudio.com/blog99 )
Thanks!

Steve Z
 

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Lundahl LL1931AG Kit $1895
Assembled version $2100

  • LL1931AG X2 + PCB + switch
  • WBT RCA Sockets 0244 2X Red + 2X White
  • 4 x HEX M3-7 screw
  • 1 FT copper-vcap 24 AWG 1ft
  • Pure wool damping material
  • CMC metal enclosure with 4 footers
 
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All of this to listen to Hotel California? Anyway, the price is peanuts compared to AN SUTs Nice touch with the wool damping. Hashimoto does that too . I bet they listen to hotel California to test their gear too. I mean , it's probably overkill reference point for American customer anyway .
 
Hi Victor,

My low-output moving-iron Grado Aeon3 is kind of an in-between case -- at 1.0 mv output (and internal resistance of 74 ohms) the output is too high for high or medium ratio SUTs such as the LL1931 or LL1933 and the reflected load from a 47K MM phono input is way too low for Grado's recommended 10K to 47K load.

Do you have the Lundahl LL1961 or LL1963 available for your SUT enclosure and parts kit? Series connected either one should give me a more usable voltage into my MM stage and while still a lower than optimum load for the Grado, hopefully will be acceptable in terms of tonal balance.

1:18 and 1:24 SUTs really roll off the high frequencies of the Grado relative to mids and bass.

Thanks!

Steve Z