GMA fuse vs GDA fuse

[kidsmoke]

Help a layman out....

My low watt tube amp uses a single 500ma/250v GMA fuse. It blew.

I replaced it with the same rated GDA fuse. It didn't last 5 minutes. I noticed the cosmetic dfference, but didn't notice this alpha designation til after the fact. :thwap

I had been told they were the same, different materials, but I don't think that's true.

What's the difference? I found GMA's, haven't put one in yet.

Ready to be enlightened.

[kidsmoke]

Update. The GMA fuse I installed is holding up fine. THe one that blew had held up for 2 years, so it appears it flat wore out, and there are no other issues afoot. :dance

Still curious about the difference if anyone knows, but I've already learned a little and, thankfully, didn't ruin equipment doing it.

Cheers