I ordered 2 of them. The adapters are good. However, for the 6GH8A tubes, they came in as one RCA tube and one GE tube. I thought they should be same brand, though I don't really care which brand. BTW, the RCA 6GH8A is not working properly on my dynaco sca-35 with original PC-10 board. It squeals when gets hot (after 20 min or so).

I used these to replace the 7199 tubes in a Heathkit AA-100 amplifier. Even on the adapter there is plenty of room to fit into the case. The tube sockets are rather tight but I viewed this a feature rather than a bug. I like that the tube isn't going to easily come out of the socket. I gently rocked the tube as I pressed down and the tube seated nicely. I'm not a music critic but the tubes sound fine in my amp.

Does work-converts 6gh8a to 7199 for the Dynaco ST-70. 7199 is now mostly unobtainable. This will help to keep your Dynaco working. Just a note- takes a lot of force to get the tube (the NOS ones I got with this order) into the socket. Just gotta work it in. Was hoping I would not break the glass. It ended up fine. Will not work itself out of that socket for sure!

First off, there should be a WARNING: DON'T ORDER THIS IF YOU HAVE A TUBE SHIELD on your socket. This adapter is wider than the shield base so you'll need to perform surgery on the socket to make it work. Might as well just rewire the socket.

Secondly, it was nearly impossible to get the tube into the adapter. The sockets were tight and also misaligned. We were afraid we were going to crack the tubes because of all the pressure we were using trying to get it in.

We ended up using a sharp, pointy tool to bend the sockets into place and slightly open them.

Probably will work fine for sockets without the shield base once you get the individual sockets right.