Audio Transformer for Pickup Emulator

[patrick398]

Thinking of throwing one of these pickup emulators (http://www.muzique.com/lab/pickups.htm) together to bolt in front of my hyper light since it seems to like being first in the chain but i don't want to run it there.
Will either of these audio transformers work?
https://www.cricklewoodelectronics.com/LT44-Miniature-Audio-Driver-Transformer-20K-ohms-to-2-x-1K-ohms.html

https://www.cricklewoodelectronics.com/LT700-Miniature-Audio-Output-Transformer-1000-ohms-to-3.2-ohms-3.2-ohms.html

I not familiar with transformers at all. The site suggests one with a 600 ohm dc resistance so i guess the first one is closer to that?

[Rob Strand]

Go here and have a look at the PDF,
https://au.mouser.com/productdetail/xicon/42tm019-rc?qs=LQJGOuQCHKQk%2faBX9yNCGw==

You will see each winding of the transformer has two characteristics:
- The nominal impedance
- The DC resistance

The key characteristic for the pickup emulator is the inductance.  You want the inductance to be close to the pickup inductance.  Keep in mind the inductance of pickups varies so there's no "right" inductance value but there is a ball-park.     The problem is the small transformer specs don't specify inductance.   So what people do is dig around for available transformers that have an inductance similar to the pickup.

So what to do?

Using the idea of similarity: If two transformers are the same size and nominal impedance is about the same then the inductance will be in the same ball-park.    Also, in practice, for a given size transform the resistance gets kind of linked to the nominal impedance.   There's many caveats, but if you can find a transformer the same size and the nominal impedance is close and/or the DC resistance is close then it will probably have an inductance which is close.

So to get to the point, the 20k ohm transformer is likely to be closer.   The size is close to the Xicon.  Ideally  you would go for a 10k ohm transformer.    The 1k is probably going to be off quite a bit.

[patrick398]

Amazing, thanks so much for the info!

[mac]

I bought those LTs @ Maplin, UK, to build a Deacy Amp.
They are driver and output transformers for old small radio amps.
Of course they can be used in another applications.

https://www.esr.co.uk/electronics/transformer-audio.htm

The second one is about 10k. The ones I bought are blue and 20k.

Cricklewood... made me remember an old Ten Years After vynil

mac

[digi2t]

42TL019-RC

Use the primary side. It's slightly lower resistance DC resistance (450R) than the 42TM019, but works fine.