A tube shield for the internet age. The 12AX7 pre-amp tube that is found in the majority of guitar amps first appeared in 1947. At that time an amp would be subjected to radio interference from a handful of AM radio stations and possibly an FM station. Today the frequency spectrum is far more densely populated with interference-producing sources, from nearby Wi-fi and wireless devices, to cellphones, satellites, and of course television and radio signals. Even the spaces between FM stations are now filled with various kinds of data-carrying signals. If you've ever heard the ghostly signal of a radio station coming through your tube amp that doesn't even have an input connected then you know radio interference can be a problem. Most signals are not recognizable sounds and instead simply add to the noise floor of your amplifier. The most effective way to block all interfering EMF signals (which includes all the sources mentioned above) is to use a Faraday Cage. For a Faraday Cage to block signals it must have these properties: - it must completely enclose the space you are trying to block. Any sizable hole - like the ones found in most tube shields - will make it useless to block interference. - it must be electrically grounded. Pre-amp tube sockets with shield holders are always grounded. - it must be a good electrical conductor, like copper mesh. The Tube Cage from thetubestore.com is a tube shield that works as a Faraday Cage for the most sensitive part of the gain stage in your amp: the pre-amp tubes. It is a tube shield wrapped in 100-thread copper mesh and grounded through the connection to the socket. Use it to replace the existing tube shield on your amp. For guitar amplifiers only one Tube Cage should be necessary to tame fizz and hiss, on the V1 tube where the biggest increase in gain happens and interference is most likely to be amplified. Please note that these cages will only work on tube sockets that have a base that looks like this, where the shield is twisted onto the socket base.