Sonaro EL34 or 6550?

[moe]

Hey guys looking for some help here. I picked up a 1968 Sunn Sonaro head that needs some restoration. It came without any tubes and I'm wondering if this is an EL34 or 6550 amp, or can it run either? I've seen some schematics that seem to show a number of the Sunn heads are identical.

The power transformer in this one has an "Ester" name on it and the codes are T27s, 776, 28-2340. The output transformer has the codes 3-40T, 606838.

Thanks!

[EdBass]

If it's a '68 it's an EL34 amp, and the 3-40T is the code on your 40 watt OT would support that. Sunn only used two 2 output tube circuits, on designed for EL34's and one designed for KT88/6550's, but marketed them with several different names, largely dependent on what speaker cab it came paired with from the factory.
You're better off staying with the tubes the circuit was designed for.