so i built a talk box today. pretty simple really. just wired a speaker to a jack, put the top of a pop bottle over the speaker, put it in a bucket with an old sheet to hold it in place and muffle unwanted noise, and cut holes in the lids for the cable and the tube. i just need to buy a tube tomorrow.

1st problem- it works. BUT, for some reason it only works when the cable is only partly in the headphones jack on my amp. any way to fix this?

2- im assuming i could use it with my bigger, 50w tube amp through the extension jack. but that wouldnt mute the amp itself im also assuming. is there a way to do this? should i just have a small amp for the talk box and maybe do a A/B box to switch to it when doing the talk box?