I bought these valves to replace a blown rectifier valve in one of the two Vox AC30s owned by our Beatles Tribute band, and to keep as spares. We are a professional act and require top quality and reliability. Sadly, the AC30cc amps that we use have an inherent fault where if you leave them on standby for any length of time, there is a tendency for the rectifier valve to blow. It took us a little while (and a few valves!) to figure this out, but now we know to avoid leaving the amps on standby. With this precaution, and our new TAD RT501 GZ34 valves, the AC30s have been working and sounding better than ever.
