i have had some transformers made by altran for various private products. they are good at following detailed instructions, and are very willing to work with you to make exactly what you need. they are not interested in making one-offs, however; you need to be making commercial quantities of your designs. they do not have extensive audio testing facilities, so you need know exactly what you want and be prepared to evaluate the transformers yourself.
audio transformers are not their core business. i was told, for example, that they sell almost US$1M in power toroids a year. but they are interested in expanding their audio transformer production.
as far as their audio products, you may be familiar with their 1:1 49% nickel bifilar output transformers and 1+1:8 "jensen-style" mic input transformers. both are used by hamptone in their jfet preamp. the same input is used by OSA in their MP-1A. they make another input that is used by universal audio in their solo mic preamp line. and i have had them make the reproduction utc o-12 that is used as the input transformer in the purple audio mc77.
the lo1166 type output was a request made by wade of chandler. i have seen a sample, and it is a well made transformer, but not an exact reproduction of a lo1166. the default model is only 200 to 600 ohms, but they could wind other ratios, and/or use an ungapped core. after altran started manufacturing them for chandler, several other companies began using them. altran now manufactures that unit in batches of 1000, so the price point is relatively low.
they are quite busy; i wouldn't recommend contacting them with offers to buy small quantities. i believe they would sell the C-4000 lo1166 style output transformer to anyone who was willing to make a large enough order. if anyone is interested in their products, i would consider ordering batches of them for re-sale if there is enough interest in any one design.
ed
