re:6550?

[Marc]

I was seeking help from anyone about the 6550 tubes. My dad recently gave me a SUNN Sarado head and I was replacing the two 6550 tubes in the head, but there is a slot to the far left, viewing it from the back, near the transformer. I'm not sure what came out of that slot. If anyone could help, or tell me what supposed to go there it would really be appreciated. Thanx!

[Ryan Phelps]

Marc;
If the "slot" is a rectangular hole on the vertical face of the chassis near the power transformer, then that was where the accessory 2-prong AC outlet went. These were originally a Dynaco part made for their pre-amps. You can buy them from a vendor who sells them regularly on eBay (just check under Consumer Electronics for "Dynaco").
The other possibility is if the "slot" is round and on the horizontal surface of the chassis, it could be where the 8-pin octal socket for the 5AR4 / GZ34 rectifier tube mounted. Is the socket still in the amp? Pull the chassis from the cab to see if a pair of diodes were soldered across the socket lugs as replacement for the tube rectifier. Or perhaps the repacement diodes were soldered to an internal lug strip.

The only other option for this mystery "slot" would be a round hole on the vertical surface of the chassis. That would be for the fuse holder. Unless of course you are missing the AC power cord which also lives in this same area!

Good Luck!
Ryan