Passive DI - Sowter 8044 or 1585 ?

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Well-known member
Aug 2, 2017
Hello everyone, i am about to order some Sowter irons for use in  some projects i am building to a friend, so -in a bulk discount case- i thought why not order an extra trafo for making a decent Passive DI as a gift to myself?  ;D

Having realised years ago that i will not ever  find a Triad iron (and why so? they used the ones they had in hand back then), 

between Sowter 8044 and 1585  what do you think could be the most oldish, decent closer to "Wolfbox" choice?

8044 is the company's  "dedicated DI"  trafo 12:1 
1585 is the company's  "A 11 J replacement"  10:1 (used backwards)

Was about to go for the 1585 (you see they have categorized it in "Vintage Rec Trafos" even i hate this word it's a sign that it is more  oldish-designed  at least).
But then again, i read an older reply mr. Ed Wolfbox gave to a a guy  in an old  Wolf dedicated TapaTalk thread  saying that: 

"As may be noted here, unlike what Wikipedia relates, the output Z of most fender pickups as 40-50K ohms which is an good match to the A-11/12j transformers in the original passive Wolfbox. The Gibson PUs fall between 40-90K and as appear here are all over the ballpark. They would not match as well but since most of the Funks used Fender instruments, this was best choice."
, so maybe 12:1 would be better (wider range) ?

Will use the box mostly for passive basses, guitars and some old organs (Farfisa's, Philicorda etc) .

8044 or 1585?


Well-known member
Nov 10, 2006
Norfolk - UK
Transformer do what they say on the tine - they transform voltages, currents and impedances. The impedance a DI transformer presents to the instrument depends therefore on what the secondary of the transformer is connected to.  A 10:1 transformer will multiply this impedance by 100 and a 12:1 by 144. If it is connected to a mic pre with a typical 1K5 input impedance the the 10:1 will make this looks like 150K and the 12:1 will make it look like 216K. On the other hand, if the mic pre input impedance is 600 ohms then these figures become 60K and 86K respectively.

So it is  not just about the transformer but what you connect it to at both ends.