diegoribba wrote:Hi Dr Tony Balls
i have a question for you: is it possible to use another output transformer? i really like the Classictone ones (http://shop.amppartsdirect.com/Transformers_c2.htm) and i would really appreciate if you could help mi out finding a replacement (this is not because i'm lazy, its just because i really don't know the value of the output resistance in ohms) of the Heyboer HY OT45.
i thought that this one (http://www.classictone.net/40-18039.pdf) would do it, but i'm not shure.
i'd really appreciate it!
thanks!
Diego
Hey Diego,
The OT you picked would work, but the primary impedance is listed at 8K (probably its intended to be used with KT66s). 2 EL34s like in this schematic should produce an output impedance of around 3.4K (roughly half of 8K). So if you used that transformer you'd have to half all of the secondary impedances also. Instead of 4/8/16ohm taps, they would be 2/4/8ohm. Its probably more convenient and less confusing to go with the following transformer which is made for the correct primary impedance, and will provide you the 4/8/16ohm outputs you probably want: http://www.classictone.net/40-18025.pdf