Groove Tubes GT-12AU7 Select Preamp Tube G<div style="text-align: left;"><strong>[Product Information]</strong><ul><li><span class="a-list-item"> Country of origin: China </span></li><li><span class="a-list-item"> The Groove Tubes GT-12AU7 preamp tube is based on a design from the Ei factory in the former Yugoslavia </span></li><li><span class="a-list-item"> The GT-12AU7 is an excellent quality large-plate European-made driver tube， styled after the famous Telefunken line of dual triodes </span></li><li><span class="a-list-item"> The usual application for a 12AU7 tube is as the phase inverter that drives the power tubes </span></li><li><span class="a-list-item"> These are very well matched， and so are highly recommended for Ampeg SVT's and other amps using this tube as a phase inverter </span></li></ul></div><img src="http://ecx.images-amazon.com/images/I/41ZgemyKIvL.jpg" noproxy>