Need Help with Combo Amp Transformers and Layout

[lacrebob]

Hey everyone, it's been a while since I tried to build an amp, but I've made a New Year's resolution to build one in 2024.

A number of years ago, I purchased a new 1 x 12 combo amp cabinet and empty chassis from S2 Amps - a circuit board wasn't included. I think S2 used this combo for a 6V6 Deluxe variant.

I wanted to build a 30-35 watt 5F6-A circuit and get a speaker strong enough to handle the power.

I finally got started today and it looks as if the planned space for an output transformer is in the middle of the chassis which would only allow for a maximum of 3 inches between the chassis and the apex of the speaker.

I have a huge 50+ output transformer that I wanted to use, but it seems just too large regardless of where I put it.

I also have a 25 watt output transformer with a 9K primary and 4/8/16 secondary that is 3.25 inches long, but alas it is too long to fit in the middle of the chassis. The 25 watt output transformer seems to fit if moved to the far side in these photos and the bells are oriented lengthwise.

If you were in my situation, what would you do?

Would you instead build a 6V6 amp, move the output transformer to the outer portion of the chassis?

Are there any issues with the output transformer orientation that are important?

[Phil_S]

If you don't like the layout there are at least two choices. One is get another chassis. If I were in your shoes, I'd think about fitting a PT near the IEC inlet (rectangular hole) and put the OT next to it -- basically both transformers on the end. This, IMO, will open up many possibilities. When it is time to mount in the cab, it will be unbalanced. A counterweight on top of the chassis or on the side of the cab will fix that. I'm guessing that spot near the IEC was meant for a choke? Meh...you might need to drill a few extra holes. Be careful. Unlike wood, where you an plug a hole with a dowel, there is no real tidy, easy equivalent to undrill a metal chassis.

You've also got the two elongated slots at the other end. You might be able to mount an output tranny there.

[leadfootdriver]

Here's a Combo with the OT on the right where V1 is.

[lacrebob]

This chassis fits the cabinet, so I expect to use it. The photo of completee chassis gives me inspiration - that's the route I'll take. Thank you.

[leadfootdriver]

Waiting for some lower voltage Caps to replace the Chunky ones, but it still works..

[bepone]

I finally got started today and it looks as if the planned space for an output transformer is in the middle of the chassis which would only allow for a maximum of 3 inches between the chassis and the apex of the speaker.

3" is ok