Can anyone please tell me what the difference is between these tubes - one is listed as Voshod 6ZH1P-EV / 6AK5 and the others as Voshod 6Zh1P-EV / 6AK7 - With thanks
http://cgi.ebay.co.uk/VOSHOD-6ZH1P-EV-6AK5-NOS-Little-Dot-Amplifier-EF95_W0QQitemZ280268869219QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item280268869219&_trksid=p3286.m63.l1177
http://cgi.ebay.co.uk/6Zh1P-EV-6J1P-EV-EF95-6F32-6AK7-NOS-MATCHED-tubes-4_W0QQitemZ130281239812QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item130281239812&_trksid=p3286.m63.l1177
http://cgi.ebay.co.uk/VOSHOD-6ZH1P-EV-6AK5-NOS-Little-Dot-Amplifier-EF95_W0QQitemZ280268869219QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item280268869219&_trksid=p3286.m63.l1177
http://cgi.ebay.co.uk/6Zh1P-EV-6J1P-EV-EF95-6F32-6AK7-NOS-MATCHED-tubes-4_W0QQitemZ130281239812QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item130281239812&_trksid=p3286.m63.l1177