LA3a T4 autoformer info

[Aleguitarpro]

I built years ago a clone of la3a using a Monacor 100v speaker transformer.
It has't the .31 tap so I can wire it using 5w, 2.5 and 1.25 tap only.
Now I like to change them for something "better": I find that it react not very well to low freq material.
Is there somewhere a winding info for B11184 T4 transformer?

Thanks for help

 

[Rob Flinn]

I bought some replica replacements from David Kulka, Studio Electronics some years ago. They work very well.

https://www.studioelectronics.biz/sunshop/index.php?l=product_detail&p=1169

 

[MatthewF]

Hairball audio have one too:
https://www.hairballaudio.com/catalog/parts-store/audio-transformers/ea-11184-autoformer-

 

[Aleguitarpro]

Thank you for the answers.
I knew that there are commercial solutions to the problem, but I'd like a more DIY one.
I would a couple of transformers by myself and turned out great so I'm wondering if there's an advice to build and wound an autotransformer.
I think that in reality it's like building a transformer with a primary connected to a secondary.
But if someone more knowledgeable than me has to point me into right direction to calculate it would be .

 

[Jase_Sanderson]

Is the Sowter 1493 not the same thing?

I just got one for my Serpant Audio SA3A but i'm unsure of the wiring since they are labelled differently

site lists the 1439a transformer as

blue - common
pink - 1:
red - :10

but the original schematic and this board it's listed as

5
2.5
.31

 

[Aleguitarpro]

Is the Sowter 1493 not the same thing?

I just got one for my Serpant Audio SA3A but i'm unsure of the wiring since they are labelled differently

site lists the 1439a transformer as

blue - common
pink - 1:
red - :10

but the original schematic and this board it's listed as

5
2.5
.31

Original autotransformer if I understand correctly the math is 8:1.
Sowter is 10:1

So following the schematic you have to connect common to ground, 10 to the cell and 1 at the cap (c9, negative end) of sidechain part.

 

[Jase_Sanderson]

Thanks so much @Aleguitarpro, you're a life saver