5E8-A Tweed Twin Output Transformer

[Diablo]

I just picked up a Weber kit for a 5E8-A and was wondering why Fender used such a small output transformer, compared to the 5F6A (Tweed Bassman). I assume the Weber OT is sized about the same as the Fender. Anyway, I ordered a Heyboer multi-tap OT HYO-18343, the same one I used in my Bassman, and plan to use that in the Twin. Do you think Fender used a larger OT in the Bassman because it was a bass amp (by design) and wanted to make sure they got the low end frequency response? Any reason I shouldn't use the larger Bassman OT in the Twin? The larger OT will fit the chassis and cabinet. The smaller transformer weighs 2.8 lbs. The larger OT weighs 4.5 lbs. All speculation welcome.

[tubeswell]

Hi Diablo

For my tuppence worth - as long as the reflected load of the OT is within the ballpark of what the original is, then use whatever size OT you want. You'll probably will find with bigger iron, that you end up having to tweak the frequency response of your pre-amp somewhere along the way (i.e.; by reducing bypass cap values for V1 or reducing coupling cap values etc) to get it to your satisfaction (or maybe not). Also with bigger iron, it probably won't saturate the-same/as-easily.

[Diablo]

Thanks Tubeswell for your thoughts. My thinking was that the larger iron may only sound different at loud volumes, when the smaller OT would have a tendency to saturate earlier on the bass frequency. What I don't know is if the smaller OT really does saturate with guitar frequency, and if saturation is "part of this amp's characteristic tone". I'm also wondering if the OT provided by Weber (2.8 lb) is smaller than what Fender used?

So, if anyone has a Fender Tweed Twin (57 reissue would do fine) that they can tell me OT dimensions or weight, that would be very helpful.

[Diablo]

After doing a little googling, I found out that the Mojo-767 OT for the Tweed Twin is listed as 5.88 lbs. I think this one is built also by Heyboer. So, it looks like my Bassman OT is actually smaller by 1.4 lbs than what Mojo supplies with their kit. So I'm going ahead with the build using the Bassman OT. As a point of interest, the Mojo high-powered tweed twin transformer is listed as 5.98 lbs. Not much more iron in it than the low powered twin, despite having double the power.